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BIOACID II – Consortium 5: Ocean Services

Lead Proponents: Katrin Rehdanz (Kiel Institute for the World Economy and Christian-Albrechts-Universität zu Kiel CAU), Martin Quaas (CAU, Kiel)

Consortium 5 “Services of the Ocean” aims to investigate social and economic consequences of ocean acidification and to quantify them. Thus, stakeholders will be able to recognize consequences of their behaviour as well as ways to reduce climate change or adapt. Based on the scientific evidence, politics, economy and society can take joint action. They shall ensure that the oceans continue to provide food and energy, promote recreation and health, drive the tourism as an economic factor, or – and this service is considered to be economically most important – store carbon dioxide from the atmosphere and thus slow down climate change.

Model calculations show how the use of the seas impacts them and how the use options may change in the future. The focus is on the function of the ocean as a CO2 sink and fishing.

In 2008, the oceanic content of carbon increased by 2.3 gigatons. This corresponds to 8.4 gigatons of CO2. In the European Union Emissions Trading Scheme, a ton of CO2 emissions is calculated with ten euros. If the ocean absorbs only one percent less CO2 per year due to climate change, this would generate “costs” of about 0.84 billion euros. Such a development seems realistic. Reason number one is the fact that warmer water absorbs less CO2 than colder. Secondly, many plankton organisms seem to form less calcium carbonate in a more acidified water and thus fix less carbon. The natural CO2 storage device reaches its limits.

Will the future ocean provide enough food? Photo: Maike Nicolai, GEOMAR

Because it sits at the base of the marine food web, modifications in the plankton community evoked by climate change also affect fish stocks. But even some direct consequences for the extension of habitats, the growth or body functions of fish are known. At global and regional levels, biologists and economists therefore determine future changes to marine fisheries engage stakeholders in the discussion about possible options for adaptation or prevention.

More about the science of Consortium 5.

BIOACID II – Consortium 5: Ocean Services

Lead Proponents: Katrin Rehdanz (Kiel Institute for the World Economy and CAU, Kiel), Martin Quaas (CAU, Kiel)

Ocean Acidification (OA) has been gaining increasing recognition in the policy circles recently, due to an increasing number of studies on biological and ecological impacts of OA (e.g. Turley et al. 2010). However, estimates of socio-economic impacts are still almost absent (Brander et al. 2009, Cooley and Doney 2009, Cooley et al. 2011, Narita et al. 2011), although such impacts constitute key information for formulating international policies for greenhouse gas emission reduction as well as for climate engineering and strategies for adaptation. Hence, research on socio-economic impacts of OA has strong policy relevancy.1
The oceans provide goods and services, which are used directly and indirectly by human societies and economies. These include food and health, energy, mineral resources and system services. Ocean services include ecosystem services (e.g. fish and seafood, biodiversity, tourism) as well as the role of the ocean in the climate system. Fig. 5.1 provides an overview of categories of ecosystem services including those of the ocean.

Among the economically most important ocean services are CO2 storage (a regulating service) and fisheries (a provisioning service). In the year 2008, the oceanic carbon content increased by 2.3 +/- 0.4 Gigatons (Gt) of carbon, equivalent to 8.4 Gt CO2 (Le Quéré et al. 2009). At the current price of about 10 Euros for a ton of CO2 emissions in the European Union Emissions Trading Scheme, which is a very conservative estimate of the social costs of CO2 emissions, a one percent decrease, or increase, of this service of the ocean would generate a cost, or value, of 0.84 billion Euros per year. The world-wide marine capture fisheries land about 80 million tons of fish per year, generating revenues of about 65 billion Euros per year, but also exerting a huge impact on marine ecosystems (World Ocean Review 2010).

Ocean acidification interacts with these economically important ocean resources and services (Fig. 5.2). Most directly, OA is a consequence of the use of the oceans as a sink of anthropogenic CO2. However, the quantity of CO2 stored in the oceans is also affected by ocean change, including the processes of acidification and warming, as ocean biogeochemistry is affected by these processes. These effects need to be quantified on a global scale and the associated uncertainties have to be assessed.

The way how fish stocks are managed influences the marine carbon cycle (Wilson et al. 2009) with potential impacts on marine CO2 uptake and, hence, OA. There is thus a possible trade-off between the ocean’s provisioning service (fishery yield) and the ocean’s regulating service in terms of taking up anthropogenic CO2. A close interaction of biogeochemical and ecological modelling with a socio-economic analysis is required to elucidate this potential trade-off in a quantitative way.

To ensure that scientific results will be used most effectively in adaptation and policy making, results of bio-geochemical models and socio-economic analyses have to be shared with affected stakeholders, preferably beginning at an early stage. In addition to valuing changes in ecosystem services in objectively derived monetary terms, it is advisable to let stakeholders value their perceived potential damage on their own. It is very likely that stakeholders are then much more willing to take ownership of the problem of OA, which greatly enhances the motivation for participating in mitigation and adaptation measures.

General objectives:

The general objective of Consortium 5 is to assess and quantify how OA interacts with the provision and use of ocean services, notably with the services of oceanic CO2 storage and fisheries, to reduce the scientific uncertainties associated, and to inform stakeholders about potential impacts and engage them in discussions about options for adaptation.

For CO2 storage, several studies already exist that quantify the effects in physical terms using global biogeochemical ocean models. Our main interest is to assess and reduce the uncertainties associated. Work package 5.1 will focus on uncertainty of model predictions and aims at improving the performance by means of data-based model assessment. Work package 5.2 will assess the effect of environmental variability on the oceanic carbon sink within a global biogeochemical ocean model.

The impact of potential consequences of OA on phytoplankton C:N ratios and hence on the food quality and food web dynamics will be investigated in Work package 5.3, which will also investigate potential effects of changes in fishing pressure on zooplankton mortality and, eventually, on the oceanic biological carbon pump.

The effect of OA on fisheries and other services is much less clear. Ocean acidification and warming (OAW) is likely to have an impact on the stock dynamics of commercially important fishes, as it will probably alter recruitment success, growth, size and extension of suitable habitats (Beaugrand 2009). OAW thus will have implications for fisheries catch potential via impacts on ecophysiology and plankton dynamics (Cheung et al. 2011). These effects on fish stocks and reproduction still have to be quantified in physical terms. To assess the economic impacts of OAW in fisheries, these effects have to be incorporated in ecological-economic models, and the economic effects in terms of changing fishing opportunities have to be assessed.

The existing economic studies point to small impacts of OA on global welfare compared to the impact of climate change (Brander et al. 2009, Narita et al. 2011). However, on the regional or local level significant differences exist but little detailed knowledge exists. Work package 5.4 will focus on two specific environments taking into account location-specific characteristics and different levels of economic development. Moreover, while the aggregate effects on a global scale may be small, there may still be significant local changes in fisheries incomes (for example due to OAW-induced movement of fish stocks), and the effects may strongly depend on the management regime. Work package 5.5 will address these questions and quantify the aggregate and distributional effects of OAW on commercially important cod fisheries.

Differences exist among regions and countries regarding vulnerability and adaptive capacity. An indicator is location, since there is a strong regional variation in the ocean’s buffer capacity and the sensitivity to acidification. Affluence is another important factor. The adaptive capacity of a relatively rich country in the tropics may be higher and therefore the impacts lower, compared to a less developed country in the temperate climate zones. For a developing country in the tropics other issues such as increase in population, public health and education are likely to be more relevant. If OA would affect food security, it would be an additional reason of concern.

Even less is known about a potential feedback of fisheries on OA, although it is well known that fisheries exert a strong impact on marine ecosystems, and some effects on the oceanic carbon cycle have been quantified before (Wilson et al. 2009). A feedback on OA may exist if trophic cascades from fish preying on zooplankton and phytoplankton affect biological production and the oceanic biological carbon pump at a significant scale. Work packages 5.3 and 5.5 will cooperate in studying these feedback effects attempting quantification at the global scale.

Impacts on ecosystem services are region-specific and valuation is depending on local, social, and cultural circumstances. Also, impacts can only be quantified with substantial uncertainties, further complicating the process of adaptation and policy formation. However, adaptation strategies need to be knowledge driven and need to find a broad support among stakeholders. Work package 5.6 will approach this issue with a regional focus on the habitats of two interacting cod species in the North Atlantic.

Research approaches

The main research approach employed is numerical modelling, in particular using global biogeochemical models and ecological-economic models for fisheries.

In work package 5.1, data-based model assessment will be used to evaluate and calibrate global biogeochemical models used for predictions of oceanic CO2-storage.

In 5.2, the impact of environmental uncertainties on carbon storage and acidification will be assessed using a global biogeochemical ocean model.

In 5.3, the impact of OA on biological processes and the feedback of varying fish stock abundances on OA will be studied by means of the UVic Earth System model.

In 5.4, the impacts of OA on mollusc fisheries at the German/Danish coast and its economic implications will be studied in numerical models.

In 5.5, an ecological-economic model of the different cod fisheries that incorporates the effect of OA on recruitment and fish growth will be used to study the efficiency and distributional impacts of OA under various management regimes. The feedbacks between fisheries and OA will be studied using a similar model at a global scale that is coupled to the Earth System model of 5.3.

In 5.6, involving stakeholders will be facilitated by aggregating the results from work packages in consortium 5 and consortium 4 into a comprehensible frame for presentation and discussion with stakeholders at two workshops (preferably related to the annual BIOACID meetings). Within the model frame, stakeholders will be encouraged to explore different scenarios with varying potential impacts on ecosystem services.

In addition, we will use empirical methods to assess the economic significance of OA effects.
In work package 5.4 we will employ a survey approach with choice experiments to evaluate potential negative values of OA on coral reefs and the related services in Papua New Guinea.

Work package 5.6 will additionally employ stakeholder participation approaches and will use discourse-based measures for evaluating OA impacts on ocean services and for deriving options for a resilient management.


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BIOACID II – Consortium 4: Effects of Ocean Acidification in a Warming Climate on Species Interactions at Distribution Boundaries: Mechanisms and Consequences at Ecosystem Level

Lead Proponent: Dr. Felix Christopher Mark (AWI, Bremerhaven)

Organisms in the polar regions are expected to be most affected by ocean acidification: The cold water can take up more carbon dioxide from the atmosphere than the water in warmer regions. Even in colder body fluids, the solubility of CO2 is higher. At the same time, species adaped to a colder habitat are more sensitive to the temperature rise as a species from temperate latitudes.

In view of these facts, consortium 4 investigates, how the North Atlantic Stock of Atlantic cod Gadus morhua and the Polar cod Boreogadus saida coexist in Arctic waters over their life cycles. Since the Atlantic cod moved northwards and shifted its spawning grounds northwards as an reaction to rising temperatures and juveniles became common in the region of Spitsbergen, a strong competition developed between by the Atlantic and the Polar cod. The latter, as the dominant species of the region, is currently playing a key role in the Arctic food web. The competition between the two species is also influenced by the availability of food – they feed on planktonic organisms that might respond to climate change much earlier than the fish themselves.

Colder waters of the Arctic and Antarctic can take up more carbon dioxide from the atmosphere. Photo: Maike Nicolai, GEOMAR

Some research results shed light on the impact of rising water temperatures on the distribution and physiology of the two competing species. But the knowledge about whether or not their development or their behavior is influenced by hypercapnia, increased carbon dioxide levels in the blood, is small. Assuming that the two species respond differently to warming and ocean acidification, and are threatened of hypercapnia to varying degrees, consortium 4 aims to determine how the competition between Atlantic and Polar cod will develop in the various stages of life.The strength of the consortium lies in its integrative approach across levels of biological organization, from the genome to the ecosystem. For various laboratory experiments, larvae and juveniles are cultivated in the laboratory, in the wild and in aquaculture, some fish are caught in the sea as well. Measurements and analyses are to show to what extent the two species can adapt to warmer water temperatures and at elevated CO2 concentrations and whether fitness and body functions are influenced. In comparison on the various life stages, the most sensitive phase shall be identified. Furthermore, it is examined how these factors are affected by food quality and availability.

More about the science of Consortium 4.

BIOACID II – Consortium 4: Effects of Ocean Acidification in a Warming Climate on Species Interactions at Distribution Boundaries: Mechanisms and Consequences at Ecosystem Level

Lead Proponent: Dr. Felix Christopher Mark (AWI, Bremerhaven)

Ocean acidification is an additional stressor developing in parallel to ongoing climate warming. Future impacts of ocean acidification on organisms and ecosystems are expected to be greatest in Polar Regions, owing to enhanced CO2 solubility in cold waters and body fluids and to the concomitant exposure of organisms to a strong warming trend. At the same time, thermal tolerance windows are narrower and thus sensitivities to combined stressor effects are likely to be higher in cold-adapted polar compared to temperate species. The expected rise in carbon dioxide concentrations and temperature in the oceans (800-1000 μatm and 1-2 °C, respectively, until the year 2100 (IPCC, 2007)) may thus prove to be particularly threatening to Arctic ecosystems.

As the oceans are warming, fish stocks are moving with the water masses of their preferred temperatures to stay within a physiologically optimal temperature range, provided further factors such as food availability and competition with other species allow for that. This has already been documented for several fish species of the North Sea, which have been moving northward at a rate of approximately 12 km per decade (Drinkwater 2009, Perry et al. 2005). In response to this warming trend, the North Arctic stock of Atlantic cod (Gadus morhua) has also shifted spawning areas to the north (Sundby and Nakken 2008) and expanded its range into the Barents Sea (Drinkwater 2009). For the greatest part of the year, juvenile Atlantic cod are now frequently found in the coastal waters of Spitsbergen (Olsen et al. 2010), leading to strong competition with native Polar cod (Boreogadus saida). Polar cod is a dominant fish species on the Arctic shelf and is considered a key species in Arctic ecosystems. It is not clear, however, how these two species will interact in the long term and whether the ecosystem’s species composition will change due to the range expansion of the Atlantic G. morhua into the Arctic (Renaud et al. 2011).

Ecosystem-level perspective of how species interactions are affected by the synergistic effects of shifting temperatures, CO2 and hypoxia levels, building on a mechanistic understanding. The integration of CO2 sensitivity on a thermal matrix as defined by the principles of oxygen- and capacity-limited thermal tolerance emphasizes how species-specific sensitivities and their minimal levels of performance influence the window of temporal and spatial overlap defining the temperature range of coexistence as well as the changes in relative performance. Graph modified from Pörtner and Farrell 2008, Pörtner 2010.

The effects of ocean warming on fish distribution and physiology have been studied and documented to some extent in Atlantic cod (e.g. Colosimo et al. 2003, Lannig et al. 2003, Loeng and Drinkwater 2007, Mueter et al. 2009, Pörtner et al. 2008, Pörtner et al. 2001, Rose 2005) and to a lesser extent in Polar cod (Gjosaeter and Ajiad 1994, Graham and Hop 1995, Hop and Graham 1995, Nahrgang et al. 2010). However, very little is known about how the physiology or distribution of these species is altered by the additional effects of hypercapnia. Moreover, we lack data about how hypercapnia will modify the interactions between species, which are already affected by the warming trend. Using Atlantic cod and Polar cod as model species, we therefore propose to study the competitive interaction between two currently coexisting Arctic fish species under the combined effects of ocean acidification and warming (OAW) in an Arctic ecosystem, the Kongsfjord in Spitsbergen.

In this case study we intend to take into account species physiology, behaviour and life cycle and to investigate the hypothesis that these species will be impacted differently by OAW, with the result of future changes in their competitive interaction. In the coastal waters of Spitsbergen, Atlantic cod find themselves at the northern limit of their geographical distribution and thus at the lower end of their thermal tolerance range. The opposite holds true for Polar cod. Spitsbergen marks the southern boundary of its distribution range and the upper end of its thermal tolerance range. This implies that within the range of their coexistence around Spitsbergen, Atlantic and Polar cod are both energetically limited and their physiological performance should be highly susceptible to further stressors. The increasing concentration of carbon dioxide is clearly one of them (Pörtner 2010). From that perspective, it is our view that ocean acidification may be a critical factor controlling the interaction of coexisting species and that it is likely to determine the outcome of their different abilities to face OAW, i.e. be displaced or restricted to a less favourable habitat (Fig. 4.1, Abrams et al. 2008, Matthews et al. 2010).

For a holistic and integrative analysis of OAW, it is important to consider the different sensitivities and susceptibilities of the various life stages of the two species, as well as their interaction with their prey organisms and thus, their dependence on the food web.

Previous research on the effects of elevated CO2 levels on marine fishes led to the general notion that due to their powerful mechanisms of ion regulation they are not particularly vulnerable to ocean acidification. Adult cod are able to compensate for acid-base disturbances (Larsen et al. 1997) and show no substantial effects of hypercapnia on physiological performance (Melzner et al. 2009a). However, studies in various species demonstrated chronic effects of environmental hypercapnia on juveniles (Moran and Stottrup 2010), and a sensitivity of eggs and early life stages that was higher than in adults. It must be mentioned, however, that all of these observations were reported for CO2 concentrations beyond realistic ocean acidification scenarios (Ishimatsu 2005, Kikkawa et al. 2004). The resulting view that fish are largely insensitive to OA may therefore be premature.

In fact, recent findings demonstrated behavioural disturbances in tropical coral reef fishes exposed to hypercapnia levels according to ocean acidification scenarios (Munday et al. 2009c); as well as alterations in larval development of cod (Frommel et al. in press) and herring (Franke and Clemmesen 2011). Also, the hypothesis that sensitivity to thermal extremes is enhanced under projected ocean acidification levels was confirmed in coral reef fish (Nilsson et al. 2009, Pörtner and Farrell 2008). In general, sensitivity of fishes to ocean acidification may be higher at temperature extremes, a hypothesis to be tested in fishes from various climate zones. At the same time, the allometry of thermal limitation indicates that tolerance to temperature extremes varies across life stages and decreases with increasing body size (e.g. Pörtner et al. 2008, Pörtner and Knust 2007, Storch et al. 2011). Accordingly, sensitivity to OAW may also vary during ontogeny as recently seen in crustaceans (Schiffer et al. in prep). The consequences of these observations for larval recruitment also remain to be explored. This fragmented knowledge base clearly calls for a better understanding of how exposure to combined CO2 and temperature scenarios contribute to shaping fitness windows. This includes the question whether all life stages respond similarly or whether some of them represent potential bottlenecks for population survival.

Most life stages of Atlantic and Polar cod feed on planktonic organisms (Levasseur et al. 1994, Lowry and Frost 1981, Renaud et al. 2011). Their availability and nutritional quality are a very important secondary effect of OAW, likely influencing development and performance of the early life stages of both fish species. Driven by climate change, plankton communities undergo well-documented shifts in composition and spatial ranges (Beaugrand et al. 2009), which, in a bottom-up control process, influences the biogeographic distribution of the fish stocks that prey upon them (Drinkwater 2009, Drinkwater 2006). In this respect, it is of considerable importance, that, by nature, invasive species are more likely to be generalists than specialists and thus might be more successful than natives at adapting to changes in food availability and composition (Dukes and Mooney 1999). In the coastal waters of Spitsbergen, this is mirrored in the diets of Atlantic and Polar cod (Renaud et al. 2011) that show a more varied food composition for Atlantic cod. This might prove advantageous for the fitness and potential of Atlantic cod to adapt to a changing climate.

The success of predation, and thus survival, also depends on dedicated behaviour of the predator and its prey. Studies in tropical coral reef fish revealed that exposure to increased CO2 strongly disturbed avoidance behaviour in juveniles and, as a consequence, resulted in their enhanced predation. These behavioural changes are presumably elicited by hypercapnia effects on the central nervous system. By changing species behaviour, hypercapnia likely has the potential to overthrow the balanced food-web interactions in this particular ecosystem (Ferrari et al. 2011, Munday et al. 2009a, Munday et al. 2010). This aspect has never been studied in adult or juvenile temperate and boreal fish and therefore needs to be addressed in the interactions between Atlantic and Polar cod and their prey.
The Gadidae family comprises some of the commercially most important fish species in the North Atlantic, namely cod, haddock, pollack and whiting, and Polar cod has also been the target of substantial industrial fishery in the Arctic (FAO Fishery Statistic). The Atlantic cod is now the subject of intensive aquaculture in Norway. It is therefore clear that any shift in the population structure, caused by OAW could have far reaching effects not only on the ecosystem itself but also on fisheries. It has also been suggested that OAW may have deleterious effects on aquaculture (Guinotte and Fabry 2008). The socio–economic consequences of such scenarios need to be explored.

General objectives:

This consortium sets out to investigate how the combined effects of OAW will affect different life stages of the interacting fish species Gadus morhua and Boreogadus saida and their prey. Its strength lies in the integrative approach across levels of biological organisation, from the genome to the ecosystem. Tightly intertwined work packages, which will rely on several joint acclimation experiments, will allow a thorough analysis of putatively shifting species interactions and their implications at ecosystem and socioeconomic levels.

Objectives include addressing the question whether OAW affects interacting species differently due to divergent physiological optima and ranges, expressed in thermal tolerance windows and associated performance capacities and phenologies of specific life stages. Crucial mechanisms as well as causes and effects will become accessible from unravelling the connections between levels of biological organisation, from genomic, molecular to cellular, individual and population level. Scopes for acclimation (physiology and behaviour) and adaptation (evolution) that together define species resilience will be studied in various life stages (eggs, larvae, juveniles, adults) and the most sensitive one(s) identified. Functional determinants of individual fitness such as ion and acid-base regulation, mitochondrial energy metabolism and immune response will also be examined. Furthermore, it will be addressed how these processes as well as fitness may be influenced by food quality and availability.

This consortium will address the following questions:

  • How will OAW influence species distribution, competitiveness and behaviour (WP 4.1 and 4.6)?
  • Will food web mediated OAW effects influence the vulnerability of species (WP 4.5, 4.8, 4.9)?
  • Which life stages are most susceptible to OAW and contribute most to ecosystem level effects (WP 4.1, 4.4, 4.5, 4.6 and 4.7)?
  • How do OAW effects become manifest on different levels of biological organisation, how are they linked and interdependent across levels of organisation (WP 4.1, 4.2, 4.3, 4.4, 4.5 and 4.7)?


Research approaches:

Each of the nine work packages in this consortium will engage with a specific level of biological organisation to have their results integrated into a projection of responses at ecosystem level and their socioeconomic consequences in consortium 5 (WP 5.6).
Experiments will be conducted at various laboratories. At the Alfred Wegener Institute in Bremerhaven, Germany, adult and juvenile fish as well as copepods will be kept in specifically designed OAW acclimation systems that were refined (and in part already acquired) during BIOACID I. Cultures of larval and juvenile fish and pteropods will be set up under laboratory conditions at the University of Bergen, Norway and of juvenile fish, pteropods and copepods at the AWIPEV laboratory in Ny-Alesund, Spitsbergen. Fish and copepods will be caught from wild populations with RV Heincke around Spitsbergen and Norway in 2012 and 2013 in close cooperation with our Norwegian project partners in Bergen and Tromsø. We will further include fish and eggs from Norwegian aquaculture and also rely on various life stages cultured at the Sven Lovén Centre for Marine Sciences in Kristineberg, Sweden (Atlantic cod adults, eggs, larvae) and the National Cod Breeding Centre in Tromsø (Polar cod adults, eggs, larvae).

Work packages 4.1, 4.2, 4.3, 4.6 and 4.7 will rely on juvenile animals from common incubations of juvenile Atlantic cod (spring 2013) and Polar cod (spring 2014) at various temperature-pCO2 combinations at the Alfred Wegener Institute. These incubations (organized by WP 4.1) will thus serve as a central hub for several work packages, ensuring thorough connections between the work packages while at the same time reducing the effort and number of individuals needed per incubation.

To trace individual acclimation histories for each juvenile fish, individuals from all stocks will be tagged and populations screened for their bandwidth of growth and other environmental adaptation-relevant physiological performances (‘whole organism phenotype’, WP 4.1), as well as for genetic variability (‘genotypes’, WP 4.3). The studies will also define the diversity of responses from which selection and further adaptation will be possible, increasing the resolution and accuracy for predictions at the population level. Analysis of transcriptomic responses (WP 4.3) along with adaptations of the proteome (WP 4.2) will provide information on adaptation mechanisms, which become manifest at cellular and systemic levels.

Consideration of within population diversity will increase the resolution and accuracy for predictions at the population level. Such predictions also require the identification of the most sensitive life stages and transition phases, including reproduction, fertilisation success, egg and larval development and larvae to juvenile metamorphosis (WP 4.4 and 4.5). Species-specific differences and shifts in performance characters are hypothesized to shape interactions within food webs (WP 4.5 and 4.6). CO2 may affect such processes due to changes in relative performance and in behaviour. WP 4.6 will set out to identify behavioural changes in juvenile fish and elucidate the neuronal underpinning of OAW effects on behaviour using MRI and NMR spectroscopy.

For an inclusion of food web effects, we will integrate the copepods and pteropods reared under the same schemes of OAW in WP 4.8 and WP 4.9 and quantify prey uptake, catch rate by juvenile cod (WP 4.6) as well as potential changes in their food quality (WP 4.8 and 4.9).
To this end, work packages 4.8, 4.9, 4.4, 4.5 and 4.7 will conduct joint experiments on copepod and pteropod performance, on the responses of eggs and fish larvae to CO2 and changing food availability, one to be carried out in summer 2013 at AWIPEV in Ny-Alesund, in spring/summer 2014, Bergen, Norway, and at the AWI facilities. Experiments will be carried out in close collaboration with our external co-operators. For testing the role of such phenomena under field conditions, these work packages will also join BIOACID consortium 1 during the common mesocosm studies (KOSMOS) in Gullmar Fjord, Kristineberg, Sweden, in spring and summer 2013.

In cooperation with the bridging WP 5.6 in consortium 5, we will finally address the socio- economic implications for fishery and aquaculture and establish their societal relevance. To do so, we will connect to an international network of ocean acidification researchers who already investigate the socioeconomic aspects of OAW. This will provide a means to further extrapolate from the findings of this consortium and disseminate them to the public.


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BIOACID II – Consortium 3: Natural CO2-rich Reefs as Windows into the Future: Acclimatization of Marine Life to Long-Term Ocean Acidification and Consequences for Biogeochemical Cycles

Lead Proponent: Dr. Dirk de Beer (Max-Planck-Institute for Marine Microbiology, Bremen)

The acidification of the oceans due to rising carbon dioxide concentrations in the atmosphere can be predicted quite well. In contrast, its effects on biodiversity and biological functions are still difficult to foresee. For organisms with long life spans, it is difficult to estimate, if and how these organisms and their communities will adapt to the future pH decrease. This can definitely not be addressed by short-term laboratory experiments. For example, in a short-term experiment, the initial stress responses can blur possible acclimatization mechanisms. Furthermore, evaluations of evolutionary consequences by short incubations could also be very uncertain.

Consortium 3 focuses on natural reefs such as those created by tropical corals or cold-water corals or mussels. These animals depend on calcification.
If more CO2 is dissolved in sea water and thus less carbonate ions are available, reefs might be endangered or even erode – growth is only possible at high energetic costs or the more acidic water might affect the calcium carbonate structures. Oases of biodiversity and spawning or nursery areas of important fish species could be lost this way.

Three locations in the Arctic, the temperate and the tropical climate serve as natural laboratories. At CO2 sources off Papua New Guinea, mussel reefs in the North and Baltic Seas and at the cold-water coral reefs off the Norwegian coast, the scientists study microbes, micro- and macro-algae, invertebrates and the corals or the mussels themselves in connection with the carbonate chemistry of the water and nutrients. With their different living conditions, the natural reefs can be used as windows to the future. This allows to determine changes of physiology and fitness of the organisms, the composition of species, and finally of the reef ecosystem.

Measurements and long-term experiments in the laboratory accompany the observations and experiments. Population surveys provide insights into how locals use the fragile ecosystem and how they will cope with expected changes, particularly the potential economic losses.

Cold-water coral reef in Arctic climate.
Photo: JAGO-Team, GEOMAR

More about the science of Consortium 3.

BIOACID II – Consortium 3: Natural CO2-rich Reefs as Windows into the Future: Acclimatization of Marine Life to Long-Term Ocean Acidification and Consequences for Biogeochemical Cycles

Lead Proponent: Dr. Dirk de Beer (Max-Planck-Institute for Marine Microbiology, Bremen

We would like to predict the state of the future oceans. Which organisms will be present? How will the seas function in global element cycling, and how can oceans be used as a resource for humans? The importance of the seas for humanity as a source of food, for recreation and even as aesthetic and spiritual resource can not be overestimated.

Ocean acidification (OA) by rising atmospheric carbon dioxide (CO2) concentrations can be predicted reasonably well. Conversely, the effects on marine diversity and biological functions are very hard to predict. Since often organisms have long life spans, estimating how organisms and communities will adapt to the future pH decrease is difficult and cannot be addressed by short-term laboratory experiments. For example, in a short-term experiment, the initial stress responses can blur possible acclimatization mechanisms, and furthermore, evaluating the evolutionary implications would also be challenged by short incubation.

Moreover, the complexity of OA is increased by other environmental changes than pH. For instance, OA predicts surface temperature, increased evaporation and therefore salinity changes, a change in metal and nutrient chemistry and concentrations, and combined or separate, each change will effect species fitness and community productivity. Biogenic reefs, which depend on calcification, may be particularly vulnerable. Decreased oversaturation may endanger reef building and increase erosion. Reefs deserve special attention as they are hotspots of biodiversity and productivity, and are important spawning and nursing grounds.

We will study ecologically and economically important reef communities from tropical, temperate and sub-arctic CO2 enriched habitats to assess crucial questions on the long-term effects of ocean acidification. At such sites, species should be adapted and acclimatized to high seawater pCO2 or have disappeared, and therefore, the community reflects potential directions of future changes to new equilibriums in the future oceans. We will focus on benthic organisms that have key roles in ecosystem engineering: the reef builders and primary producers.

The chosen sites serve as our windows and models for the future oceans. Whereas the views are obscure and narrow, what we will see is a realistic approximation. We will use the sites as natural laboratory, and by studying acclimatization and adaptation of microbes, micro- and macro algae, invertebrates and corals along gradients of carbonate chemistry and nutrients. We will transplant micro and macro-organisms (corals, algae) in order to study their physiology and acclimatization potential. Laboratory measurements will be included, on site and in the institutes, to separate out effects of specific environmental variables and to study experimental evolution and adaptation capacity of model organisms over longer time scales. Finally, we will talk to stakeholders, the local communities and others directly depending on the reefs. We hope to learn how these ecosystem users will cope, or plan to cope, with the expected changes, and how they will estimate the magnitude of economic losses or gains under different scenarios of acidification.

General objectives:

The studies we propose encompass three levels: 1) organism physiology, 2) biodiversity and 3) ecosystem functioning. We will determine the impact of OA on metabolic functions, and determine if OA increases energy demands. Knowledge on which organisms are affected, and which not, will be used to predict changes in diversity. Finally, the measured decrease or increase in diversity and changes in metabolic performance will lead to predictions in the changes of key ecosystem functions. A decreased pH, altered carbonate chemistry and nutrient levels may not necessarily affect the key ecological process rates of primary production and degradation. Diversity may change in response to OA, but the major biogeochemical processes may be sustained with a modified species assemblage (Kelly, Barott et al. 2011). For example, calcifying organisms may be replaced by non-calcifiers. We will investigate the underlying physiological mechanism for pH dependent competiveness of species, with a focus on pH/pCO2 dependence of their energy budgets. We will study if and how adaptation and acclimatization to enhanced pCO2 occurs, by studying natural habitats that are since centuries enriched in CO2. An important benefit for studying the physiology of organisms from such natural CO2 sites is that this biota has been exposed to rising CO2 for longer duration, and therefore we avoid studying stress responses, and rather assess acclimatization and impact.

We plan to address the following basic hypotheses:

Hypothesis 1: Adaptation and acclimatization leads to communities that are more resistant against low pH, their action spectrum has a lower pH optimum. The specific carbonate chemistry of selected sites has existed for centuries to millennia. This is crucial for assessing long-term effects of ocean acidification on community structures and ecosystem functioning.

Hypothesis 2: Adaptation and acclimation of calcifying organisms to elevated seawater pCO2 requires surplus energy. Energy demands impact growth and thus reduce competitive abilities. Ensuing increased vulnerability of reefs will lead to significant reductions in economic revenue generated from these ecosystems.

Hypothesis 3:
Low pH is accompanied by increased nutrients and trace metals that can protect against low pH. We will assess physiological responses with an emphasis on growth rate, gene expression, and primary and new production estimates. Furthermore, responses will be assessed with single cell and bulk approaches, as often a response could be variable even within a group (genus) of organisms.

These hypotheses will form the basis of the research on the arctic, temperate and tropical reefs.

Consortium 4 studies reef communities in arctic, temperate and tropical waters.

Research approaches:

We will study a variety of benthic organisms: corals, macrophytes, microphytobenthos, bivalves, bacteria and archaea. Comparisons of warm water and cold water corals in mesocosm experiments will be included. The integration of the consortium will be strengthened by joint campaigns to the field sites.

Study sites will be the CO2 seeps in Papua New Guinea (PNG, tropical), bivalve reefs in the Western Baltic and North Sea (temperate), and cold water corals reefs along the Norwegian shelf (sub-arctic). The biological diversity of the PNG site is among the highest in the world (Fabricius, Langdon et al. 2011). There are several well defined gas seeps (sulfidic and pure CO2), that maintain gradients in habitat from acidic to seawater, harbour a variety of sediment types (pH 6 to 8.2, iron-rich clay, siliceous and calcareous sands). The first field surveys on the reef off PNG indicate pronounced shifts in the abundance of different functional groups of benthic primary producers (corals, macrophytes, coralline algae) along the pH-gradient. The western Baltic is characterized by pronounced seasonal oscillations in pCO2, with average surface gradients in pCO2 between 400 and 700 μatm, and summer averages of >1000 μatm at some locations (Thomsen, Gutowska et al. 2010). CaCO3 under saturation is a common phenomenon. We will compare differently impacted sites in the Baltic (low pCO2, high pCO2) with sites in the North Sea (low pCO2) and study, whether populations have adapted to high pCO2. Mesocosms in Kiel will be used to study physiology of cold water corals retrieved during cruises from sub-arctic sites (in situ pH ~7.8).

The field work will consist of sampling for diversity, rate measurements and experimental transplantation of living specimen to assess their capability to acclimatise to environmental changes. In addition, artificial settlement plates will be exposed within pCO2 gradients to study colonization, diversity and productivity of developing communities. Laboratory studies will accompany field work to determine action spectra for pH and nutrients and to study energy budget allocation, as well as adaptation capacity of model species.

Cruises to PNG are planned for February 2013 and August 2014. Fieldwork in the Baltic and North Sea will be planned in a flexible manner.

Biogeochemistry and microbial processes:

We will determine physico-chemical habitat parameters (e.g. pCO2, pH, nutrients, metals, O2, salinity, temperature). Different spatial resolutions are required to determine variability within the site using microsensors on a micro-scale (10-100 mm), and by geochemical analyses of sediments and porewater. Loggers for pH, Temperature (T) and dissolved oxygen (O2) will be moored at sites to assess temporal variations. In addition, carbon and nitrogen cycling, such as carbon (C) fixation, degradation of organic matter (aerobic and anaerobic respiration), and N2-fixation will be measured along gradients by whole water bottle incubations. The main functions may not be influenced by OA, but the microbial communities performing these tasks may differ. Furthermore, single cell approaches using a high-resolution nanometre scale secondary ion mass spectrometry (nanoSIMS) will help assess the cell to cell variation in metabolic activity (i.e. C and N2 fixation) within a given community.


Effects of pCO2, temperature and nutrients on organism performance will be assessed. Special attention will be paid to energy budgets, as these might be modulated and decrease a group’s competiveness, particularly in calcifying organisms. Energy budgets will be determined on an organismal and cellular level to determine costs for pH homeostasis, calcification, stress and immune responses. Carbonate structures (stability, composition, microstructure) will be analyzed, and related to erosion of reefs. Effects of pCO2 on key processes in primary production of calcifying and non-calcifying algae will be determined. Comparative studies on tropical and cold water corals will determine their pH dependant fitness and growth rates. Action spectra with regard to pH and nutrients of key microbial processes will be determined. Laboratory experiments will be conducted in Bremen, Kiel and Sylt laboratories that have facilities for CO2 perturbation experiments, and during field campaigns on site.

Diversity and adaptation:

We will determine community compositions by molecular methods along gradients of pH and nutrients, and determine the main parameters driving community shifts using mathematical methods. Physiology and community structure will be linked to water and sediment chemistry. Evolutionary biology experiments on model invertebrates (bivalves) will investigate whether high CO2 tolerance observed in populations from high pCO2 sites is an inheritable trait, allowing us to determine the extent of past selection events on genotype x environment interactions (Hoffman and Sgro, 2011). The studies will focus on low dispersive taxa, such as brooding corals, seagrass and ascidians.

Socio-economic consequences of ocean acidification on reefs:

Economic impacts of ocean acidification on coral reefs will be performed through a choice experiment (Brander, Rehdanz et al. 2009). An assessment of potential changes in mollusc fishery and aquaculture revenues will be performed using partial-equilibrium analysis, global up scaling will be attempted using the climate-economy models IMPACT and FUND (Narita, Rehdanz et al. 2011). This study is now placed in WP 5.4 and will there be described in detail.

Integration and management:

The consortium is conceptually unified by the addressing the same hypotheses, and practically by implementing similar research approaches in the three different habitats:
The physico-chemical habitat descriptions (pCO2, pH, temperature, salinity, nutrients, metals, POC, currents) will be a joint effort and the same techniques will be used.
We will determine the microbial community structures (incl. diversity, richness) and functions (primary production, mineralization, N2-fixation), as well as the shifts therein along pH gradients.

At all three sites settlement experiments will be done, using colonization tiles, to study the microbial and macrobiota (animal and plant) diversity, succession and competition. Furthermore the tile approach can assess impact on biomass and CaCO3 production. Physiological responses of the ecosystem engineering species (bivalves and corals) will be determined following long-term acclimatization. The energy budgets will help explain competitive strength of the key species, responsible for the structural integrity of reefs. Studies of the carbonate skeletons of bivalves, corals and coralline algae will be performed in the three climatic sites.

We will perform joint studies at each field site, share methods and data, exchange students, and present and discuss each others results in regular meetings.

Laboratory experiments accompany the fieldwork.
Photo: Armin Form, GEOMAR

Output for the BIOACID consortium:

Data on the effects of pH change on primary production of benthic communities and general element cycling will become available for foodweb studies/modeling. The effects of enhanced metabolism of calcifying organisms, and ensuing reduced growth rates of e.g. bivalves are essential for bivalve fisheries and aquacultures.
We expect that we will be able to predict if and what form reefs will be able to survive the pH decrease. Especially important here is whether calcifying key-players will be outcompeted by non-calcifying populations. E.g. will corals as primary producers be replaced by macrophytes, or will mussel beds be overgrown by algae.
Finally, the cruises to New Guinea will host social and economic scientists from Consortium 5. Using the habitat descriptions we will construct future ecosystem scenarios, which will be used to investigate how the coastal populations will adapt to the consequences of pH decrease.

Back to Scientific Programme BIOACID II

BIOACID II – Consortium 2: Responses of benthic assemblages to interactive stress

Lead Proponent: Prof. Dr. Martin Wahl (GEOMAR, Kiel)

The geographical distribution of species are the result of ecological and evolutionary (adaptation, niche differentiation), geological (e.g. distributional barriers) and oceanographic or climatic settings (e.g. salinity, temperature, light, and their fluctuations) (e.g. Kearney et al. 2010). The overlap of species’ distributional areas in a given region together with habitat conditions (depth, substratum, biotic interactions) determines the composition of local benthic communities. Finally, species identities and relative abundances in an assemblage determine its ecosystem services, their fluctuations in time and the community’s sensitivity to stress and disturbance (Wahl 2009 and articles therein). When the abiotic setting is shifting in the course of climate change, it can be expected that the composition and functioning of local communities change as well (e.g. Harley et al. 2006). During the coming decades many environmental variables will shift simultaneously both at the global scale (e.g. temperature, pH) and at the regional scale (e.g. salinity, stratification, eutrophication, oxygen concentration). In addition, the rate of re-structuring of benthic communities is further accelerated by other features of Global Change, such as bioinvasions, overfishing, pollution and coastal constructions (e.g. IPCC 2007). Numerous studies have shown the impact of single stressors on single species, but the combined effect of multiple variables on a multi-species assemblage – the natural scenario – is virtually uninvestigated (e.g. Wahl et al. 2011). The extent to which community diversity and biotic interactions modulate the impact is vividly debated (e.g. Mooney et al. 2002, Raffaelli 2006).

The most wide-spread and perhaps most severe effects of climate change at a global level are expected from a rise in temperature and a decrease of pH (e.g. Kroeker et al. 2010). Regionally, however, other shifts like the increasingly severe and/or frequent occurrence of eutrophication, hyposalinity and hypoxia may equal or surpass the importance of the former factors (e.g. BACC author team 2010, Schernewski et al, 2011).

The lack of investigations in near natural scenarios (multiple stressors, multi-species communities) creates the unfortunate situation that we know that our marine communities will change, but not in which direction, to which extent and with which functional consequences. Consequently, the motivation for this consortiums’ project was to improve our understanding for the ongoing and future re-structuring and re-functioning of an essential part of the marine ecosystem, macrophyte communities. This project will focus on the impact of multi-factorial climate change scenarios on the structure and functioning of macrophyte communities of the Baltic and the North Sea, composed of a metaorganism (macrophyte plus epibionts) and its consumers. Focal species of these communities are the sea grass Zostera marina/Z. noltii, living on soft bottom, and the brown macroalga Fucus vesiculosus, living on hard substrata. Seagrass and wrack communities are widely distributed in both seas, and play an important ecological and economic role as primary producers, carbon sinks, water purifiers, stabilizers of sediments, energy sources for microbes and herbivores, and providers of substratum and structure of epibionts and juvenile fishes (e.g. Mangi et al. 2011).

General objectives

We intend to study the direct impact of single and combined stresses on the performance of the macrophytes (tolerance width, physiological plasticity, survival, productivity, reproduction), as well as on similar metrics of their associated fauna and flora: epibiotic communities (bacteria, diatoms, macroepibionts) and consumers (snails, crustaceans). We will establish the capacity of the macroorganisms to adapt to the future climate scenarios by phenotypic plasticity and selective mortality, and we will assess how the microbial and macrobial communities re-structure under the applied environmental pressure. Finally, we will assess how the genetic and/or taxonomic re- structuring at the population and the community levels affect major services of the assemblage such as oxygen production, carbon fixation, productivity, uptake of nutrients and more. Thus, the project will span biogeochemical, genetic, physiological, biological, ecological and economic aspects, and will include a wide range of phylogenetic groups such as bacteria, diatoms, bryozoa, barnacles, polychaetes, crustaceans, various macroalgae and sea grasses. Obviously, this challenging scope requires a wide array of techniques and expertise. This critical mass will be achieved by clustering all sub-projects and their PhD students around a series of core experiments run in the benthocosm facilities of Kiel (Baltic Sea) and Sylt (North Sea).

We will ask the following main research questions:

How will environmental stress affect

  • the physiology of macrophytes?
  • the genetic composition of the macrophyte populations and their sensitivity to further 
  • the interaction among macrophytes and their epibionts and consumers?
  • the composition and functioning of epibiotic bacterial communities?
  • the composition and functioning of microepiphytic communities?
  • the fluxes of energy and matter across the macrophyte communities?
  • the ecological and economic“ value” of the macrophyte communities?

Research approaches

The entire research will concentrate around a series of core experiments with macrophyte communities run in the Kiel and Sylt benthocosms. The Kiel infrastructure consists of 4000 litres experimental units, sub-dividable into two subunits each of which are independent of each other in every aspect except temperature. A similar facility will be constructed at the Sylt site in summer 2012. Important environmental variables such as temperature, pH, oxygen and salinity are continuously logged and automatically controlled. Additional variables such as light, pCO2, nutrients, DOC, POC, Chl a, alkalinity, DIC will be “manually” monitored and controlled (see WP 6).

We will run several consecutive experiments with Zostera and Fucus, each of 3-4 months duration. This time span allows for physiological and genetic (selective mortality of recruits) responses of macroorganisms, re-structuring of microbial communities, and a re-functioning in the sense of biotic shifts and biogeochemical signals of all.
The consecutive experiments will permit to investigate the single and interactive impacts of a variety of potential stresses at the species and community level. As acidification will be part of all experiments, the project will also allow assessing the relative importance of this factor as compared to other aspects of Global Change (warming, hyposalinity, hypoxia, eutrophication). The various components of the communities passing though different stages of their life cycle and different physiological states in the course of a year, we will repeat the first experiment (acidification x warming) in all four seasons.

Importantly, we will take into account the natural fluctuations of all environmental variables and superimpose our treatment factors onto these. We, thus, work with delta-treatments in all seasons, i.e. ambient Kiel Fjord temperature plus the predicted 3-5°C of warming by the end of the century (e.g. Schernewski et al. 2011) or the ambient Baltic or North Sea pH (or pCO2) minus (plus) the predicted change for the year 2100 (e.g. BACC author team, 2010). A moderate flow-through with unfiltered sea water (ca one re-fill per week) will “connect” the benthocosm units to the natural fluctuations in nutrients, salinity, or plankton (including potential recruits) composition in the adjacent sea. In summary, the “non-stress” treatments will always be similar to the in situ conditions, while the stress treatments consist of the delta (Global Change) values for 2100 added to the in situ conditions.

Seagrass communities will be investigated primarily in the Sylt benthocosms, while Fucus communities are investigated primarily in the Kiel benthocosms. This reflects the expertise of the local groups and the relative regional importance of the two macrophyte groups. At the same time, at both locations, comparative experiments will be run with primary target group of the other location, i.e. Fucus in Sylt and Zostera in Kiel, allowing to compare stress impact among populations. The experimental approach of this consortium will, thus, cover the two large groups of macrophytes (algae and seagrasses) and two major habitat types (hard bottom and sediments).

The Benthocosm Core Experiments (CE):

Four major CEs will be run.

  • (1) In a first phase, we will orthogonally cross the two factors acidification and warming and study their impact on the Baltic and North Sea Fucus community subsequently in all four seasons. This design allows disentangling single and interactive stress effects and the influence of season. On Sylt, in parallel tanks the same treatment combinations will be applied to North Sea Zostera communities. Replication is 3.
  • (2) Then we submit Fucus communities to a 3-factorial treatment of acidification, warming and eutrophication both on Sylt and in Kiel using the respective populations. This experiment will run in a “climate simulation mode”, i.e. we do not orthogonally cross the 3 factors (for lack of experimental units) but rather run single benthocosm units under a future climate setting with regard to these three factors. This approach allows evaluating the impact of complex global change in two seasons (winter, summer) with a replication of 6.
  • (3) In a third CE (intercalated into CE2) the same experiment as CE2 will be run with Zostera communities in spring and autumn (Kiel and Sylt) and summer (Sylt).
  • (4) The last experiment is similar to CE2, but the third factor is the predicted decrease in salinity. It runs in a season (spring) not covered by CE2 and lasts a month longer. Target communities are Fucus (Kiel) and Zostera (Sylt). Replication is 6. Response data for all WPs will be taken regularly (see WP descriptions). Two weeks before the end of a CE a pulse of unfavourable conditions (hypoxia, heat wave) will be applied to assess how communities stressed by the simulated climate differ in their sensitivity to an additional disturbance relative to unstressed communities.

The PhDs of the six WPs will closely cooperate on these core experiments and take all their samples and data from the same system. This ensures a maximal comparability. Additional small experiments for questions complementary to the core experiment will be run in the lab or the climate chambers of the institutes. To keep the workload and costs realistic, WPs 1 and 6 will do comparative work on Zostera and Fucus in Kiel and Sylt, WP 4 will put major emphasis on Fucus (Kiel) while not disregarding Zostera, whereas WPs 2,3, and 5 will limit their efforts to the Kiel CEs on Fucus.

Thus, WP 4 provides the information how much and in which regard the focal species (Fucus, Zostera) are affected by the treatment regime(s). The interaction of early life-stage stress sensitivity to these scenarios and intraspecific genetic diversity is treated by WP 5. The influence of these physiological responses of the substratum organisms, the direct treatment impact on the biofilms and the interaction among biofilm components will be disentangled by a close cooperation among WPs 2, 3 and 4. The results of these WPs will explain a major portion of the interaction shifts studied by WP 1, which in turn will provide insight how the impact of abiotic stresses are modulated by biotic shifts. At the community level, finally, the shifting fluxes among components will be investigated by WP 6, thus quantifying the re-functioning with regard to the ecosystem services. The added value of this close and complementary cooperation on a focal meta-organism in common core experiments is a complete picture of community level responses to single and interactive stresses.

All data obtained by the WPs will be fed into two independent modelling approaches. (1) A mechanistic community model will simulate the influence of all abiotic and biotic interactions of Fucus vesiculosus and the impact of the interacting factors on its performance (growth, maximal depth distribution). (2) An Ecological Network Analysis will synthesize the results for each of the treated community modules used as experimental units. This allows a comparison of system behaviour of stressed and unstressed systems and indicates changes by altering specific system indices as well as the cycling structure of material and energy flow, particularly between primary and secondary producers. It also allows comparing the provision of ecosystem services for each of the analysed systems and characterises their global system properties.

BIOACID II – Consortium 2: Responses of Benthic Assemblages to Interactive Stress

Lead Proponent: Prof. Dr. Martin Wahl (GEOMAR, Kiel)

The distribution of species is a result of ecological, evolutionary, geological, oceanographic and climatic conditions. The characteristics of these species and their number determine the different roles and functions within the system and how the whole community might react to to stress and disturbances. Global factors such as temperature and pH and regional ones like salinity, eutrophication or oxygen concentration can disrupt the assemblage. Additionally, the immigration of new species, overfishing, pollution and structural changes of the coast mean further stress.

Previous studies have explored effects of individual stressors to individual species. Little is known about how a whole system reacts to a combination of factors: We know that there will be changes in marine communities – but not in which direction, to what extent and with what consequences for the ecosystem.

The consortium BIOACID 2 “Responses of benthic assemblages to interactive stress” will simulate a combination of climate change factors in communities that exist on the floor of the North and Baltic Sea. As most dominant parameters, the increase in temperature and decrease in pH in water (acidification) are focused on.

For the experiments, typical water plants and their dependant species were selected from the North Sea and from the Baltic Sea: the bladder wrack Fucus vesiculosus and the seagrass Zostera marina / Zostera noltii. Seagrass and wrack communities are widely distributed in both seas and play important roles as primary producers, carbon sinks, water purifiers, stabilizers of sediments, energy sources for microbes and herbivores and providers of substratum and structure of epibionts and juvenile fish.

To investigate how these communities alter due to climate change, benthocosms, experimental tanks equipped with a capacity of 4,000 liters, were set up in Kiel and in List (Sylt island). In the containers, temperature, pH, oxygen, salinity, light, CO2 pressure, nutrients, and other control values can be adjusted precisely. Several three to four months long experiments in List and in Kiel help to better understand individual and interactive effects of a variety of stressors on the represented species.

BIOACID II – Consortium 1: Pelagic ecosystems under ocean Acidification: Ecological, Biogeochemical and Evolutionary Responses

Lead Proponent: Prof. Dr. Ulrich Sommer (GEOMAR, Kiel)

The importance of the ocean’s pelagic system is beyond doubt. It covers 70 per cent of the Earth’s surface and contributes ca. 50 per cent to global primary productivity. The human interest in the pelagic system rests on the following ecosystem services:

  • Biological carbon pump: The production of organic matter in the sunlit surface ocean and its export to depth is the main process sequestering atmospheric CO2 in the deep ocean.
  • Fisheries: Pelagic production forms the nutritional basis of pelagic fisheries.
  • Recreational value of the sea: A malfunctioning of the pelagic ecosystem may lead to harmful algal blooms (HABs) which might seriously impair the recreational value of the sea.

Until now, ample evidence has been found for the impact of ocean acidification on individual planktonic species. As hypothesized before, the calcifying groups being the most sensitive ones. In addition, there is scattered evidence that acidification insensitive phytoplankton species might respond with biochemical changes reducing their nutritional value for zooplankton and thus impairing the upward transmission of matter and energy in the food web. From the perspective of ecosystem services this is an amplification of effects. It is not known, to which extent this effect can be compensated by alternative trophic pathways, e.g. by feeding of mesozooplankton on heterotrophic protists (“trophic upgrading”; Klein Breteler 1999) which could dampen the effect. Overall, we do not yet know to which extent the interactions and feed-back mechanism within the pelagic ecosystem act as amplifiers or shock absorbers of acidification effects.

While the effects of acidification and other kinds of environmental change (e.g. climate warming, eutrophication) have mostly been studied in isolation from each other, there is a lack of studies how these factors interact. In theory, additive, synergistic (more than additive) and antagonistic (less than additive, i.e. compensatory) interactions of effects are possible, but a priori knowledge is not possible without studying the effects in a crossed, factorial design. A high priority should be given to the factors CO2 and warming, because both are inevitably linked by the greenhouse effect. Recent research in evolutionary ecology suggests that evolutionary adaptation of species could be a potential dampening mechanism (Hoffmann and Sgro Nature 2011). It could permit the persistence of species in spite of environmental conditions moving outside the present niche of a species. When dealing with short-generation time microbes, i.e. unicellular phytoplankton, the ‘gold-standard’ of demonstrating evolvability are experimental evolution experiments (Collins and Bell 2004), yet most of these have so far been conducted with single species subjected to a single and constant selection factor. It is unknown, whether such rapid evolution will also occur in natural ecosystems, where interactions with other species impose additional, and temporally variable selection factors beyond the change in the physico-chemical environment. Preliminary modelling results suggest that diversity at the species level may prevent adaptive evolution (De Mazancourt et al. 2008) but empirical data are entirely lacking.

Recent research in evolutionary ecology suggests that evolutionary adaptation of species could be a potential dampening mechanism. It could permit the persistence of species in spite of environmental conditions moving outside the present niche of a species. However, rapid evolution at ecological time scales, i.e. the time scale of species replacements has so far been shown only in simplified experimental systems with single species subjects to a single and constant selection factor. It is unknown, whether such rapid evolution will also occur in natural ecosystems, where interactions with other species impose additional, and temporally variable selection factors beyond the change in the physico-chemical environment.

In summary, we need an ecosystem perspective and a combination of the factors CO2 and warming in BIOACID II.

Laboratory experiments have shown that certain species might be able to adapt to climate change by evolution. Photo: Maike Nicolai, GEOMAR

General objectives

In order to predict the impact of ocean acidification and its combination with warming on the ecosystem services provided by the pelagic system, we have to understand how it will affect the distribution of energy and matter fixed by primary production into the different competing channels of the pelagic system: grazing food chain, microbial loop, export production and production of refractory DOM. We have to know to which extent ocean acidification and its combination with warming will change the incidence, magnitude and toxicity of HABs. All these changes might be dampened by evolutionary adaptation which has to be understood before reliable predictions are possible.

We prose the following overarching research hypotheses:

  • Ocean acidification and the combination of ocean acidification with warming will reduce carbon sequestration via changes in vertical flux and/or partitioning between dissolved and particulate organic matter.
  • Ocean acidification and the combination of ocean acidification with warming will increase the role of the microbial loop relative to the grazing food chain.
  • Ocean acidification and the combination of ocean acidification with warming will enhance microbial turnover of organic matter and enhance the natural release of CO2 from the ocean.
  • Ocean acidification and the combination of ocean acidification with warming will change the production of bio-resistant DOM.
  • Ocean acidification and the combination of ocean acidification with warming will deteriorate the quality of microbial food (share of poorly edible algae, stoichiometry, fatty acids) for mesozooplankton, in particular copepods, and thus deteriorate the nutritional base of pelagic fish.
  • Ocean acidification and the combination of ocean acidification with warming will increase the incidence, magnitude and toxicity of harmful algal blooms.
  • The response at higher aggregation levels (trophic levels, entire ecosystem) will be less pronounced than the response of single species found in BIOACID I.
  • Short-lived species will be able to track environmental change via adaptive evolution and prevent local extinction, while long-lived species will not.
  • Evolutionary adaptation embedded in experimental ecosystems may modulate all of the above short term changes. Adaptation will however be slower in an ecosystem context than in single species-single factor experiments.

We are aware, that several of the predicted responses might depend on specific features of regional ecosystems, e.g. presence/absence of calcifying plankton, N2-fixers or toxic dinoflagellates. Therefore, we propose to perform our experimental studies in three different ecosystems, the subtropical North Atlantic Ocean near Gran Canaria representing the oligotrophic ocean, the North Sea as representing of coastal, eutrophic seas and the Baltic Sea, representing coastal, eutrophic seas with a reduced alkalinity and prone to nuisance blooms of N2-fixing cyanobacteria.


Research approaches

As a consequence of our ecosystem-oriented approach, the core activities of the consortium will consist of mesocosm experiments where the response of the plankton part of the pelagic food web and the biogeochemical processes can be studied in response to the experimental manipulation.

We will use two types of mesocosm systems: The large systems (KOSMOS: Kiel Offshore Mesocosms for Future Ocean Simulation) have a volume of up to 80 cubic metres and will be deployed in situ off Gran Canaria (subtropical Atlantic Ocean) and in Gullmar Fjord near Kristineberg, Sweden (North Sea water).

The small systems (Kiel indoor mesocosms, Fig. 1.2) have a volume of 1.4 m3 and are installed in four temperature-controlled rooms, thus permitting a factorial combination of CO2 and temperature change. They will be used for two Baltic Sea experiments (one in the cyanobacteria-season, one in a diatom-dominated season). Each ecological and biogeochemical WP of the consortium will participate in two or more of the mesocosm experiments, while the evolutionary WPs will participate in at least one mesocosm experiment and will in parallel conduct single species experiments to compare the evolutionary velocity of their target species in isolation with the evolutionary velocity embedded in a stressed ecosystem.

The KOSMOS experiment at Gullmar Fjord (January to July 2013) will comprise nine mesocosms with pCO2 levels ranging from ambient to ca. 1800 μatm. The unusually long duration will permit for a succession of phytoplankton blooms and is particularly attractive for the evolutionary WPs. The plankton community at Gullmar Fjord contains several dinoflagellates with the potential to form harmful blooms.

The KOSMOS experiment off Gran Canaria (tentatively scheduled for spring 2014) will comprise nine mesocosms with pCO2 levels ranging from ambient to ca. 1800 μatm. It will be conducted in a season when nitrogen fixing cyanobacteria and calcifying phytoplankton (coccolithophores) contribute substantially to the phytoplankton community.

The Baltic Sea fall experiment (September/October 2012) will comprise 12 mesocosms combining three pCO2 levels of 390, 750 and 1200 μatm and two temperature levels, each replicated twice. The experiment falls into a season when diatoms and dinoflagellates dominate the phytoplankton community.

The Baltic Sea summer experiment (July/August 2013) will comprise 12 mesocosms combining three CO2 levels of 390, 750 and 1200 μatm and two temperature levels, each replicated twice. The experiment falls into a season, when diazotrophic cyanobacteria can for nuisance blooms.

The evolutionary WPs will use bacteria, phytoplankton and a copepod as model organisms, thus having a gradient in generation times (from <1 d to several weeks) and from asexually reproducing unicellular species to metazoans with obligate sexuality.

Large mesocosms floating in ocean waters like giant test tubes include up to 80 cubic metres of water for long-term experiments. Photo: Maike Nicolai, GEOMAR
BIOACID II – Consortium 1: Pelagic Ecosystems under Ocean Acidification: Ecological, Biogeochemical and Evolutionary Responses

Lead Proponent: Prof. Dr. Ulrich Sommer (GEOMAR, Kiel)

The ocean covers about two thirds of the earth’s surface. Marine plants and bacteria produce about half of the global biomass. Three “services” of the oceans are most important to mankind:

  • The ocean absorbs carbon dioxide (CO2) from the atmosphere and stores this greenhouse gas in the deep
  • The ocean provides fish and other marine animals for food.
  • The ocean represents an irreplaceable recreational value

Scientists have found out that plankton responds sensitively to ocean acidification. While some species are suffering from acidification, others seem to benefit if more carbon dioxide is dissolved in the sea water. These effects continue from the base of the food chain to its very end – for example if economically important fish species or fish stocks already threatened by overfishing find less food.

It is still unclear, how material and energy flows vary as a result of ocean acidification and how these variations may affect each other. In addition, the impact of other environmental changes, in particular rising temperatures, but also over-fertilization (eutrophication) and pollution as well as the reciprocal influences of these factors have been explored only partially yet. It is also uncertain if organisms are able to adapt to environmental changes through evolution. Laboratory experiments with various species suggest this, but studies under natural conditions are due.

Consortium 1 “Pelagic ecosystems ocean acidification” therefore aims to examine the effects of various environmental changes, in particular acidification and warming, to the whole ecosystem in the open water. In consequence, it is easier to better assess if and to what extent the ocean of the future can provide his “services”.

In several mesocosm experiments in the laboratory and in the field, BIOACID scientists simulate possible changes: The Kiel mesocosms – floating structures, each including up to 80 cubic metres of water – are employed in 2013 for studies in the Swedish Gullmar Fjord and 2014 in the North Atlantic Ocean in Gran Canaria. At GEOMAR Helmholtz Centre for Ocean Research Kiel, four laboratories with indoor mesocosms are used to learn how communities in the Baltic develop in autumn and summer under elevated temperature and CO2 conditions.

More about the science of Consortium 1.

In so-called mesocosms, scientists simulate future ocean conditions.
Photo: Maike Nicolai, GEOMAR
Indoor-mesocosms allow experiments under controlled conditions.
Photo: Aleksandra Lewandwoska, GEOMAR
BIOACID I – Theme 5: Integrated Assessment: Sensitivities and Uncertainties
Objectives and overarching questions

  • Synthesize information obtained in Themes 1 to 4 in order to achieve an integrated understanding of biological responses to ocean change.
  • Develop a framework for integrating ocean acidification sensitivities at the organism level into ecosystem models.
  • What are the integrated effects of ocean acidification and warming on ecosystem to global ocean scales?
  • What are the critical threshold levels (‘tipping points’) of ocean acidification for irreversible ecosystem changes?
  • What is the most suitable definition of dangerous ocean acidification in terms of the goods and ecosystem services lost due to OA?

In its Special Report “The Future Oceans – Warming up, Rising High, Turning Sour”, the German Advisory Council on Global Change (WBGU, Berlin 2006) recommends a guard rail for future ocean pH decrease of 0.2 units as a margin of safety according to the precautionary principle. This suggestion is motivated by the intention of avoiding an aragonite undersaturation in the ocean surface layer. As stated in the report, the tolerable window for ocean acidification defined by WBGU presently relies on an extremely small data base. In fact, rather than using the limited data on observed biological consequences of ocean acidification, the WBGU reaches its recommendation on the basis of projected changes in water chemistry (aragonite saturation state). While this is an appropriate approach in view of the scarcity of biological information, there is a clear need to establish a reliable data base on tolerance levels for ocean acidification in key groups of ocean-acidification sensitive marine organisms in order to reach a more informed recommendation.

Theme 5 of BIOACID will take the challenge of integrating the information gained under Themes 1 to 4 in order to identify the potential thresholds associated with ocean acidification. Uncertainties, probabilities and risks to the marine environment have to be assessed as well as their feedback to climate system. This will be achieved through a meta-analysis of process studies and process parameterisations, and by combining models and data in a data-assimilative framework. In return, feedback from the modelling work will inform the experimental work in BIOACID about uncertainties in models and the relevant process parameterisations.

During the first 3-year phase of BIOACID, our main aim is to develop and establish the tools that will allow us to fulfil the BIOACID synthesis needs. For the three subprojects proposed here, the synthesis tools to be established within BIOACID range from meta-analysis techniques over regional and global numerical ecosystem models to economic methods of integrated assessment. These tools will help to better understand ongoing changes in chemical and biological state of the North Sea from alkalinity fluxes originating from the Wadden Sea over a synthesis model that integrates OA sensitivities at organism level into a North Sea ecosystem model (5.1) to an economical impact assessment. (5.3). Newly developed assessment tools will also be used to improve parameterisations of calcium carbonate production in global biogeochemical climate models (5.2). By investigating the combined effects of variations in temperature and ocean acidity, such parameterisations will allow to put better constraints on possible threshold levels on ocean acidification in a warming world.

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BIOACID I – Theme 4: Species Interactions and Community Structure in a Changing Ocean

Overarching questions

  • What is the role of differential sensitivities to OA at the community, species and intraspecific (ontogenetic stages, genotypes) level? Are there emerging properties resulting from organism interactions that are not visible from single-species investigations alone?
  • Does the community structure change as a consequence of OA and how do shifts in competitive abilities of benthic and pelagic organisms affect community structure?
  • What is the role of OA induced changes in food quality and quantity in primary producers to higher trophic levels?
  • To which extent will energy transfer between lower and higher trophic levels change as a result of changing competitive interactions and/or changes in the feeding environment?
  • Do different types of communities (benthic – pelagic, microbial – macrobial) react differently to acidification/warming stress?

Observed effects of low pH and/or high CO2 conditions are mostly based on experiments with single species. Hence, not much is known about how these factors affect interactions between species and, through that, communities. Indeed, the projected shifts in pCO2 and pH in many species often only slightly impact performance and fitness of a given species, and many studies find reactions in single species experiments only with very high CO2 concentrations or at unrealistically low pH (e.g. Mayor et al. 2007). However, as shown for other stressors (Christensen et al. 2006) ensuing modifications of species interactions may substantially amplify or buffer the original stress (Wahl 2008). How environmental stress spreads through a community via shifts in composition and interaction is still very much an open question.

Theme 4 will therefore address the pivotal role of interaction modulation in close cooperation with a number of projects from other themes which, in contrast, focus on single species reactions to ocean acidification. Thus, Theme 4 is the logical extension of these projects, placing the responses of individual organisms to OA into a community and ecosystem context. We expect to find effects of OA on community structure and interaction that are not visible when studying single organism reactions. Hence, we will focus on shifts in competitive and trophic interactions as well as on community structure. Organisms will vary considerably in their reaction to ocean acidification. As a consequence, formerly superior competitors may be weakened, as is the case in interactions between calcifying and non-calcifying species (e.g. Kuffner et al. 2007), or relative susceptibility to predation may change (Swanson & Fox 2007). Furthermore, there may be strong selective pressures within species, if susceptibility to stress differs between genotypes or between ontogenetic stages. At the unicellular level, less sensitive clones or strains may become more dominant under ocean acidification, and sensitive rare populations may disappear. In multicellular species, the most sensitive ontogenetic phase will determine survival, and genetic diversity may determine the fate of a population under OA.

The changes in species composition on one trophic level will obviously affect the transfer of energy and matter to higher trophic levels. Shifting species composition at the base of the food chain may represent different quality feeds for predators, which may result in a complete restructuring of the trophic web. Also, direct effects of increased CO2 availability may change the quality of organisms as food for higher trophic levels. Higher carbon availability will typically result in higher carbon to nutrient ratios in primary producers. This has on the one hand been linked to decreased toxicity of some dinoflagellates (Parkhill & Cembella 1999), with the potential of higher palatability of previously noxious algae, but on the other hand to a decrease in the quality as food for higher trophic levels (Malzahn et al. 2007).

So, if we are to understand the effects of OA on ecosystem structure and function, it is essential that we understand the shifts of interaction mode or strength (Tortell et al. 2002), because the typical non-linearity of the ensuing effects has the potential to cause regime shifts in marine ecosystems. To date, regime shifts have mainly been linked to climate forcing, but we expect ocean acidification – amplified by interaction modulation – to have the same potential.

In Theme 4, we will investigate how interactions between and within species in benthic [4.1.1.- 4.1.4] and pelagic [4.2.1-4.2.2] communities shift under the influence of OA. We investigate changes in trophic grazer- alga interactions in the benthos [4.1.1], and competitive interactions between sessile organisms [animals 4.1.2 and plants 4.1.3]. Moreover, we will investigate the effects of ocean acidification on bacterial communities, both directly, as well as a result of altered excretion products of algae and herbivores faced with resources of different quality [4.1.4 for the benthos, 4.2.1 for the pelagic zone]. Competition between pelagic microalgae will be studied in 4.2.2, and the resulting prey community will be fed to pelagic herbivorous grazers in 4.2.1


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BIOACID I – Theme 3: Calcification: Sensitivities across phyla and ecosystems

Overarching questions

  • What are the cellular mechanisms of calcification and decalcification in different marine organisms, particularly with regard to ion transport to and from calcification sites?
  • How will OA and pH stress affect calcification at the level of organisms, communities and ecosystems? Will concurrent temperature change modulate these effects?
  • What changes will occur in the ultra-structure, trace element partitioning, and isotopic signature of the shells and skeletons of calcifyers in response to pH stress?
  • How does the changing water column chemistry influence carbonate dissolution and deposition in sedimentary systems?
  • Are past OA events (e.g. in the Cenozoic) useful analogues for projected future OA in their effects on calcifying organisms? Is the performance and sensitivity of past and present calcifyers comparable, and does this information help to assess the future?

Calcification, the precipitation of calcium with carbonate, is influenced by the current increase in atmospheric CO2 levels and its concurrent gradual decrease in ocean pH. Since acidification leads to a decrease of the carbonate ion concentration, ocean acidification causes a decrease of the carbonate saturation sate. Hence we can expect a future reduction in calcification rates, or even net decalcification. Indeed reduction of calcification rates have been observed upon acidification in several marine calcifying groups, but not in all. This is indicative for a variety of calcification mechanisms. Calcification is a proton-generating process, and decalcification is proton consuming. Thus, these processes are typically coupled to either proton consuming (calcification) or proton producing (decalcification) processes. Conversely, calcification and decalcification can buffer other pH changing processes, and will thus to some extend buffer the oceanic pH.

Biological calcification always occurs in more or less isolated microenvironments, in which the carbonate and/or calcium concentrations are changed by biological activity. These changes can be driven by ion pumps in specialized transport tissue, e.g. for Ca2+ or H+, which is typical for the highly controlled calcification in corals, foraminifera, bivalves and coccolithophores. Alternatively, calcification can be a side effect of metabolic activities such as photosynthesis, occurring in a matrix with mass transfer limitation (a sediment or microbial mat). We will investigate if some calcification mechanisms are more sensitive than others, and the extent to which decalcification can buffer the decrease in oceanic pH. We will further investigate if decalcification can contribute to pH buffering of the oceans. We will finally investigate if the oceanic pH may leave signatures in the biogenic carbonates, and learn from acidic events in the past what the effect is on biodiversity on calcifying nano-plankton.


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BIOACID I – Theme 2: Performance characters: Reproduction, Growth and Behaviours in Animal Species

Overarching questions

  • Which physiological mechanisms define sensitivity or tolerance of marine animals to ocean acidification and how do they set or modify performance levels and fitness?
  • Can acclimation capacity (gene expression capacity) for such mechanisms explain physiological plasticity?
  • How does acclimation or adaptation to new levels of CO2 and temperature affect organism performance?
  • In a comparison of species and their populations from temperate to polar climates, do they differ in their sensitivity or capacity to resist ocean acidification through acclimation or evolutionary adaptation? How do these findings relate to differences in temperature and associated ocean physicochemistry?
  • Which life stages of functionally important marine organisms are most sensitive to ocean acidification and how does the level of sensitivity relate to the ontogeny of physiological mechanisms?

Ecosystem effects of ocean acidification include those on metazoan life. However, while ecosystem effects of warming trends have clearly been identified, those of ocean acidification are still equivocal. Within the next decades, elevated CO2 levels are expected to affect marine water breathing animals directly through effects on the physiology and performance of the individual organism and indirectly through changes in food web structure. Emerging knowledge indicates that sensitivity to elevated CO2 levels differs between animal phyla and species. It may also differ depending on geographical latitude and associated climate conditions. Effects may be large and potentially detrimental especially in life forms with a low metabolic rate, for examples among calcifying benthic macroorganisms (Wood et al., 2008) or in the deep sea. This hypothesis is in line with recent observations in habitats contaminated by natural CO2 emissions, e.g. in volcanic areas around Ischia (Hall-Spencer et al., 2008). Initial findings suggest decreased growth and enhanced mortality of sensitive species such as among molluscs or echinoderms in response to a doubling of CO2 from pre-industrial levels to 560 ppm (Shirayama and Thornton 2005), a value which is likely surpassed during this century. As effects of ocean acidification are expected on top of those of ocean warming, studying ecosystem effects of OA will thus need to consider both, the direct influence of ocean physicochemistry on individual organisms and species, and also the CO2 dependent modulation of responses to temperature in particular.

For an in-depth cause and effect understanding, it is essential to unravel the physiological mechanisms that define whole organism sensitivity to ocean acidification (e.g. Pörtner et al. 2004, Fabry et al. 2008) and especially those, which synergistically interact with temperature effects on marine organisms (cf. Pörtner et al. 2005). A current hypothesis emphasizes a key role for the capacity of acid-base regulation in defining sensitivity (Pörtner, 2008 for review). Available data indicate that deviations of extracellular pH from its setpoint mediate several of the observed whole organism effects. Theme 2 will investigate how and to what extent these disturbances affect whole animal performance and how acclimation to various CO2 levels can alleviate some of these effects. It will also address to what extent sensitivity to ocean acidification interacts with thermal stresses and is shaped by the specialization of organisms on ambient climate conditions according to latitude.

Effects of anthropogenic ocean acidification on animal communities are expected on medium to long time scales, due to the progressive accumulation of CO2 and due to long generation times. In variable environments (e.g. upwelling areas, Feely et al., 2008) not only the drift in mean physicochemical parameters but also enhanced amplitudes will require consideration in analyses of CO2 effects. For an analysis of the interaction between specialization on various climates on the one hand and sensitivity to ocean acidification on the other hand, physiological studies (of e.g. performance and acid-base regulation) as well as investigations of gene expression patterns and population structure will be carried out in species and populations living in a climate gradient across latitudinal clines. Comparisons of fertilized eggs, juvenile and adult life stages will be essential to identify the bottlenecks of sensitivity throughout ontogeny as well as their physiological background. The physiological principles shaping performance may also control calcification, and thus the shell growth of bivalves and other calcifiers over time. Performance has been shown to link climate change to ecosystem effects of warming (Pörtner and Knust 2007). Performance characters like growth or foraging capacity are likely also involved in multistep processes affecting marine food webs. Here, species-specific responses and sensitivities cause various species of an ecosystem to be affected differently, resulting in changes in species interactions, population adaptability, food web structure and associated carbon fluxes. The work will include species of coastal areas and relevant to fisheries and other marine services. Theme 2 also includes approaches to test and further develop mechanistic concepts and models of effects of ocean acidification. This includes kinetic modelling of the mechanisms of ion and acid-base regulation for an improved quantitative understanding of effects, to generate a basis for a more comprehensive, mechanism based modelling approach.


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Scientific Programme BIOACID II

To address and better understand the chain from biological mechanisms, through individual organism responses, food web and ecosystem effects, to economic impacts, five consortia were established for BIOACID phase II:

Scientific Programme BIOACID I

Five thematic areas have been identified which cover the range of processes from the base of the marine food chain to the community and ecosystem level, and of mechanisms from the sub-cellular to the whole organism level. In view of their distinct sensitivities to ocean acidification, calcification and carbonate dissolution processes will be the focal point of a separate theme. According to these research priorities the scientific programme of BIOACID I is structured as follows:

BIOACID I – Theme 1: Primary Production, Microbial Processes and Biogeochemical Feedback

Overarching questions

  • How do marine primary producers and heterotrophic bacteria of diverse taxonomic groups respond to ocean acidification (OA) and increase in CO2 concentration on? Which groups/species (e.g. calcifying vs. non calcifying species) are negatively impacted and which benefit?
  • To what extent will key phytoplankton species and bacteria be able to acclimate to OA? What is the potential for evolutionary adaptation and concomitant genetic changes within 100s to 1000s of generations?
  • What are the consequences of ocean acidification for the turn-over and export of organic matter?
  • What are the combined effects of CO2 and temperature changes on the marine soft tissue pump and DOC export and the air-sea exchange of CO2?

Primary producers in the marine realm encompass phylogenetically very diverse groups (Falkowski et al. 2004), differing widely in their photosynthetic apparatus and carbon enrichment systems (Giordano et al. 2005). Preliminary data reveal that species with effective carbon concentration mechanisms (CCMs) are less sensitive to increased CO2 levels than those lacking efficient CCMs, analogous to findings in terrestrial vegetation. Currently, our ignorance of the metabolic diversity of oceanic autotrophy and microbial heterotrophs hampers any projection of total marine primary production and regeneration in response to increased carbonation. A focus of Theme 1 will therefore be to identify critical physiological traits that determine the sensitivity of key groups of primary producers and bacteria to increases ocean acidification and carbonation.

Most of the biological oceanic carbon uptake is driven by regenerated production and only ~20% by new nitrogen input to surface waters (Laws et al., 2000) which drives the export of organic carbon from surface waters (Eppley and Peterson 1979). While the export of carbon, nitrogen, and phosphorus is generally considered to be closely coupled in marine biogeochemical cycling, recent work in mesocosms shows increasing C:N and C:P ratios during primary production with increasing CO2 concentrations (Riebesell et al., 2007). Excess carbon assimilation partially ends up as dissolved organic carbon and may increase the export of organic matter through the formation of gel particles that enhance particles aggregation, such as transparent exopolymer particles (Arrigo, 2007; Engel et al., 2004). These processes, if representative for pelagic autotrophic communities, could give rise to a biologically driven feedback to the climate system.

What controls the release of dissolved organic matter by either phytoplankton or bacteria, and how these substances affect the nutrition and aggregation of pelagic organisms needs further investigation in order to improve the description of biogeochemical turnover processes and their sensitivities to increasing pCO2 (Figure 4).

Theme 1 will study plankton communities in controlled lab experiments on several relevant time scales, from short-term physiological adjustment, to acclimation, to longer-lasting evolutionary adaptation. Treatment levels, experimental set-ups and response variables were chosen concordantly among diverse target groups in order to ensure full comparability of results in the subprojects.

Theme 1 will combine laboratory-based work with field campaigns to assess the responses of natural plankton communities. Given the importance of coastal areas to fisheries and other marine resources and services, the coastal ecosystems constitute an important target region. Insitu experiments and sampling will be carried out in the Baltic Sea, an enclosed sea with high nutrient input and anthropogenic pressures.

An improved implementation of possible impacts of ocean acidification and sea surface warming influence on the marine soft-tissue pump and the cycling (and export) of dissolved organic carbon in global marine carbon cycle models, like the model PICES, is urgently needed. As part of the modeling component of Theme 1 new parameterizations will be incorporated based on empirical results generated under this theme.

Scientific Programme BIOACID III

BIOACID III bridges between different branches of ocean acidification research and provide an assessment of short- to long-term responses and their underlying mechanisms at the level of organisms, populations, communities and ecosystems to multiple drivers leading up to ecosystem services.

Synthesis activities will be structured into three major themes. Each of them covers the range from organism responses to community and ecosystem effects, to biogeochemical impacts and consequences for ecosystem services. Also, each theme will contribute to the Integrated Assessment, which includes risk assessment as well as the development of future scenarios, management options and offering policy advice.

The scientific programme is devided into the following areas:

BIOACID III: Integrated Assessment

The Integrated Assessment (IA) is an overarching activity, which involves all BIOACID principle investigators. Information exchange for the Integrated Assessment will be active throughout the duration of the project. It will be guided initially by the theme leaders, followed up by the Integrated Assessment task force, which will commence its work after twelve months into the project (September 2016) and continue for six months after the end of the core project.

Integrated Assessment Members:
Ulf Riebesell, GEOMAR
Hans-Otto Pörtner, AWI
Thorsten Dittmar, Universität Oldenburg
Maren Voss, IOW
Martin Wahl, GEOMAR
Ulf Karsten, Universität Rostock
Felix Mark, AWI
Stefan Gößling-Reisemann, Universität Bremen
Kathrin Rehdanz, IfW
Martin Quaas, CAU
Wolfgang Koeve, GEOMAR
Felix Ekardt, Universität Rostock
Konrad Ott, CAU

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BIOACID III – Theme 3: Ocean Acidification and Warming Impacts Across Natural Systems and Society: From Mechanisms to Sensitivities and Societal Adaptation

Theme leaders:
Felix Christopher Mark, AWI
Stefan Gößling-Reisemann, Universität Bremen

Theme members:
Daniela Storch, AWI
Catriona Clemmesen, GEOMAR
Martin Quaas, CAU
Felix Mark, AWI
Silke Lischka, GEOMAR
Hans-Otto Pörtner, AWI
Stefan Gößling-Reisemann, Universität Bremen

Marine ecosystems will be increasingly affected by the effects of ocean acidification and ocean warming, which can be exacerbated by further stressors such as hypoxia. Environmental change can either influence the physiology of plankton, marine fish and invertebrates directly across all life stages or affect them indirectly by changing the composition and quality of food web connections. This will alter the species abundance and composition of future ecosystems, entailing putative changes in ecosystem services for humans by e.g. affecting artisanal and industrial fisheries and the oceans’ value for recreation and tourism.

Many effects of ocean acidification and warming on organismal physiology can only be traced back from the organismal to cellular and molecular levels. Projecting species robustness and ecosystem resilience requires integration of these levels. Projecting future species composition at ecosystem level requires the integration and extrapolation of variable species responses. These responses are currently identified only for a number of selected taxa, and knowledge is especially needed for those species projected to be invasive and undergo changing interactions.

This can be accomplished by meta-analyses and models that consider climate scenarios, multiple stressors and species interactions over time. Both have been included in the recent IPCC AR5 WGII report, based on emerging data of synergistic effects of ocean acidification and warming mainly for fish and marine invertebrates, including also estimates of economic impacts. A range of marine ecosystem services to human societies might be impacted by ocean acidification and warming. First results from BIOACID II show concern among affected stakeholders – ranging from fishers to tourism operators – is growing.

For fish stocks, which comprise the most important food provision service of the oceans, available data are still too patchy to support a high level of confidence in projection of ocean acidification and warming impacts and, so far, the effect of ocean warming alone has been modelled to project changes in catch potential. There is an urgent need to increase the level of knowledge and data available for modelling at the ecosystem level, including food webs and higher trophic levels such as fish to reliably project the synergistic effects of ocean acidification and ocean warming on marine ecosystems and their services to inform economists, political decision makers and society.

More about the science of Theme 3

BIOACID III – Theme 3: Ocean Acidification and Warming Impacts Across Natural Systems and Society: From Mechanisms to Sensitivities and Societal Adaptation

Building on the knowledge and capacities of ocean acidification and warming effects on marine fish and invertebrates that were generated in BIOACID I and II, this theme sets out to integrate ecophysiological data across all levels of biological organisation (molecule – organism – population – ecosystem) for marine fish and invertebrates.

In an integrative manner, Theme 3 will build a database comprising ocean acidification and warming effects on marine fish and invertebrates from single metabolic pathways to life stage sensitivities and food web and ecosystem interactions. The database will be tailored to the specific needs of this theme and thus allow for a classification of positive and negative effects, of vulnerabilities as well as a parameterisation of effect sizes for several pCO2 ranges, thus making data available for meta-analyses and model information. Such efforts will be carried out within this theme by close cooperation between the different work packages, ranging from fisheries and bio-economic to social-ecological models. The results will then support an integrated assessment of risks associated with ocean acidification across all of BIOACID III.

The main objectives of this theme are:

  • Identification of critical metabolic processes, key metabolic thresholds and sensitivity levels within and across several taxa
  • Identification of most vulnerable life stages and transition phases of several major taxa to assess consequences for species and whole animal groups in life history
  • Evaluation of OAW effects on species and food web dynamics
  • Evaluation of OAW driven shifts in ecosystem functioning, habitat loss, marginalization and species replacement in ecosystems of high and low variability
  • Meta-analyses and generation of input parameters for models
  • Evaluation of trade-offs between ecological (stock size), economic (profits), consumer-related (harvest), and social (fishing effort) objectives for fishery management
  • Quantification of uncertainties of OAW effects on commercially important fish populations, ecosystem resilience evaluation and suggestions for economically efficient adaptation of fisheries management
  • Evaluation of impacts on ecosystem services and identification of stakeholder concerns and societal adaptation strategies to changes in ecosystem services provision

Research Approaches

In seven work packages, Theme 3 assesses vulnerabilities of marine ectotherms and their life stages from different taxa, habitats, and ecosystems. Based on this assessment, the risks for ecosystem services and affected human societies will be derived. The goal of these work packages is to develop a comprehensive picture of mechanisms causing effects, of the resulting sensitivity thresholds and effect sizes indicating vulnerability of various species and taxa, of effects on selected food-webs and ecosystems, and finally of the socio-economic consequences of ocean acidification and warming.

Led by specialists in their respective fields, the analyses of the work packages of this theme will be based on data available from BIOACID I and II and the current literature, with a specific interest on economically important species in boreal and Arctic latitudes. In a close cooperation between experimental biologists, (socio-) economists, and modellers, the results of the different meta-analyses will be directly incorporated into fisheries and bio-economic models, as well as social-ecological and socio-economic models.
All work packages will develop their own methods of data analysis and also contribute to a shared database, in which current knowledge will be entered and categorised. We will include all available studies that provide information on effects of PCO2 set by carbon dioxide bubbling and within the ranges of a) 500-650, b) 651-850, c) 851-1370, d) 1371-2900, e) 2901-10.000 and f) > 10.000 µatm.

The first level of analysis is directed towards organism responses, and strives to identify sensitive metabolic processes and threshold levels, as well as vulnerable life history stages in various taxa. Via the shared database, this data will then be passed on to the respective stock assessment and ecosystem models directly, as well as to the work packages of higher integration at species, taxon and community levels. The latter will also collect and evaluate ecological and physiological data available for marine ectotherms, yet with a focus on species interactions in food webs and the role and fate of selected taxa in their specific ecosystems. At the highest level of integration, the available data will be used to model and evaluate putative changes in ecosystem services and to develop and inform societal adaptation strategies. These models strive to evaluate the socio-economic costs and uncertainties of ocean acidification and warming for fish stocks and to inform ecosystem-based management and adaptation strategies. In this respect, this topic is directed to provide advice to economic and political decision-makers.

As there is an international recognition of the need for a higher level of certainty in predicting the socio-economic consequences of effects of ocean acidification and warming on marine ecosystems, this theme is also closely linked to the efforts currently made in the UK Ocean Acidification programme (UKOA) to create synergies and prevent parallel developments. Connections exist e.g. with the Centre for Environment, Fisheries & Aquaculture Science (CEFAS), the University of Strathclyde in Glasgow and the Plymouth Marine Laboratory.
Work packages and structure of Theme 3

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BIOACID III – Theme 2: Shifts in Benthic Ecosystems and their Services

Theme leaders:
Martin Wahl, GEOMAR,
Ulf Karsten, Uni Rostock

Theme members:
Tal Dagan, CAU
Thorsten Reusch, GEOMAR
Birte Matthiessen, GEOMAR
Helmut Hillebrand, Universität Oldenburg
Frank Melzner, GEOMAR
Ulf Gräwe, IOW
Ulf Karsten, Universität Rostock
Martin Wahl, GEOMAR
Katrin Rehdanz, IfW

Ocean acidification is still an ongoing problem and has been the major research focus in BIOACID I and II as well as in numerous other research efforts worldwide. While a number of direct effects have been shown in the previous project phases, it became increasingly apparent that a simplistic approach is not suitable to reveal the real ecological importance of ocean acidification. 

As a consequence, in the second project phase we scaled up substantial along several dimension: complexity of the stress regime applied, incorporation of natural fluctuations, complexity of the biological system studied, and complexity of the responses assessed.

Using the novel Benthocosm system in Kiel (GEOMAR) and at the island of Sylt (AWI), the reactions of benthic communities (including macroalgae, mussels, seastars, gastropods, and crustaceans together with hundreds of associated species, e.g. ciliates, polychaetes, filamentous algae, microalgae, epibiotic bacteria) to the interacting factors warming, acidification, season as well as eutrophication and hypoxia. In the third phase of BIOACID, the diverse reactions of complex benthic communities to the multi-factorial and fluctuating climate change are modelled. Also, the socio-economical relevance of our findings shall be evaluated and recommendations developed for societal and economical decisions.

More about the science of Theme 2

BIOACID III – Theme 2: Shifts in Benthic Ecosystems and their Services

The challenge for Theme 2 will be to feed the complex results into synthesising models to adequately exploit the newly achieved insights. The prime objectives of BIOACID III with regard to benthic ecosystems are the following:

  • collecting and archiving all available data from the core experiments in BIOACID II but also from other BIOACID consortia and from published literature
  • evaluating the potential for adaptation to environmental stress (also in an effort to compensate the inherent weakness of temporally restricted experiments)
  • developing three different and complementary models with primarily descriptive but also some predictive intention
  • developing a user interface allowing laymen to explore the impact of different aspects of global change on benthic communities
  • assessing the awareness and responsiveness of the public to different ways of communicating the new information on global change impact and in particular ocean acidification

Research approaches
During a synthesis phase, we plan to pursue five parallel research lanes which complementarily and in close cooperation will deliver the essential pieces of the final picture.
The capacity of species (and, ultimately, communities) to adapt to a shifting environment will be evaluated based on an extensive meta-analysis of the rapidly growing body of literature. This capacity will help evaluating the trans-generation stress-sensitivity of a species.

Another potential buffering (or amplification) mechanism of stress is the associated shift in biotic interactions. In order to correctly weigh the importance of observed shift it is mandatory to have knowledge how much indirect and direct interactions contribute to the structuring and functioning of a community. This evaluation will be done using Structural Equation Modelling.

In an effort to project some of our findings onto a larger spatial scale, the interaction between climate change, Baltic hydrology and oceanography as well as the sensitivity and distribution of the ecologically and economically important bivalve Mytilus edulis will be modelled.

The multitude of data obtained from the series of core experiments in the Kiel Benthocosms will be used to assemble a new benthic model describing the drivers, interdependencies and responses of benthic communities under environmental pressure. The model is intended to describe the stress impacts at the organism to community level and to facilitate an evaluation of shifts in ecosystem services to be expected. The algorithms of the model will be incorporated into an interactive digital user interface.

A major challenge of global change impact research is to transport the new insights into public awareness. Ways to improve the “transport” of scientific insights into public awareness to increase societal acceptance for adaptation to ongoing environmental shifts shall be explored. We further expect that we will be able to extrapolate from shifts in ecosystem services to the socio-economic consequences of global change and provide valuable advice for managers and decision makers.

Work packages and Structure of Theme 2

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BIOACID III – Theme 1: Pelagic Ecosystems and Biogeochemistry

The goal of this consortium is to deepen and consolidate our understanding of ocean acidification effects and other stressors on plankton communities in terms of plankton ecology and biogeochemical functioning. This information will be implemented into an integrated assessment of ocean acidification effects on mainly pelagic ecosystem including possible feedback mechanisms.

We will synthesize the results of previous experiments obtained in BIOACID I and II and in related projects such as the Pelagic Ecosystem CO2 Enrichment Studies (PeECE) and Surface Ocean Processes in the Anthropocene (SOPRAN). Data-model synthesis will provide the necessary information on how to implement CO2/pH sensitivities into biogeochemical models that are used for regional to global scale simulations and future projections. These projections will provide a basis for better risk assessments, management options, and policy advice and will allow for evaluation of socio-economic consequences under different ocean acidification scenario

Theme 1 will address the following questions:

  • What is the plankton community response to ocean acidification?
  • Which biogeochemical impacts derive from changes in plankton community composition and activity?
  • Are elemental budgets affected by ocean acidification?
  • Which global ocean feedbacks might result from changes in ecological and biogeochemical states?

Research approaches

We will combine budget calculations, meta-analysis, and modelling to obtain a sound understanding of the effects of ocean acidification in combination with rising temperatures on the entire plankton food- web and fluxes of major elements.

The first step is a comprehensive review on the impacts of ocean acidification on marine planktonic communities, their vulnerabilities, and potential carry-on effects on higher trophic levels.

The second step is a network and meta-analysis aiming to assess the potential vulnerability of ocean acidification-induced changes in species composition and concomitant changes in the productivity of marine systems.

The final step is a dynamic modelling that synthesises information from the meta-analyses and improved process understanding at the community level. The findings will be extrapolated to the global ocean considering the complex interactions between atmospheric forcing, ocean dynamics, and biogeochemistry. Finally, three-dimensional scenarios will be generated on system-wide, large-scale responses on ocean acidification and other stressors.

Our synthesizing approach is essential to forecast how, when and where the impact of ocean acidification and co-occurring stressors act on the ecosystems and biogeochemistry of the ocean.

Workpackages and structure of Theme 1.

Back to Scientific Programme BIOACID III

BIOACID III – Theme 1: Pelagic Ecosystems and Biogeochemistry

Theme leaders:
Thorsten Dittmar, Uni Oldenburg
Maren Voss, IOW

Theme members:
Maarten Boersma, AWI
Kai Wirtz, HZG
Hans-Peter Grossart, IGB
Thorsten Dittmar, Universität Oldenburg
Ulf Riebesell, GEOMAR
Maren Voss, IOW
Andreas Oschlies, GEOMAR
Wolfgang Koeve, Julia Getzlaff, GEOMAR

To secure ecosystem properties and services in the future ocean we need to improve our understanding on response of pelagic communities to climate change, in particular to the emerging threat of ocean acidification.

In the recent years, a large effort has been set on elucidating responses to ocean acidification. Studies addressed responses from single organisms to plankton communities in experimental settings and in the ocean. These studies often included additional environmental factors, such as temperature or light.

A direct functional effect of ocean acidification was found for calcification which seems to be the most pH-sensitive process with decline by 25 per cent in projected acidification scenarios of the 21st century. Likewise, reproduction in decapod crustaceans, oyster and bryozoa seemed to be directly harmed when water pH drops below certain thresholds. Similarly, increased growth- and photosynthetic rates have been documented for elevated ocean acidification, most likely promoting photoautotrophic processes in algae with higher carbon assimilation rates in response to increased levels of dissolved CO2. Impacts of ocean acidification on traits such as elemental stoichiometry were also identified.
Ocean acidification and warming as combined stressors caused significant negative effects on calcification, reproduction, and survival of early life history stages of e.g. spider crabs and a significantly positive effect on photosynthesis.

It has to be clarified to what extend observations from experiments can be extrapolated to natural planktonic food webs and large biogeochemical cycles. Further uncertainties derive from the differing experimental set-ups. These have to be quantified in order to evaluate the significance of individual results.

To draw a more holistic picture, an integrative assessment of ocean acidification effects in combination with co-varying factors is urgently needed. Based on a review of empirical insights, more mechanistic process need to be described and substantiate model-based projections of how ocean acidification will impact on pelagic ecosystems and the services these provide.

More about the science of Theme 1