BIOACID Programme - Natural Environment Research Council

5.4.2. Progress expected
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BIOACID: Biological Impacts of Ocean Acidification
Theme 4 will further our understanding of between- and within-species interactions under OA
stress. We expect that after a successful completion of the project we will be able to define the
expected impacts of ocean acidification that go beyond single species reactions but are a result of
changing interactions between and within species. As stated above, only by taking these
interactions into account we will be able to truly appreciate the potential impact of OA. More
specifically we expect progress in the following areas:
1. Assessment of the role of differential sensitivities to OA at the intra-species (ontogenetic
stages, genotypes), and species level. Populations and communities can only re-structure and,
thus, adapt if their respective components differ in sensitivity towards the stressor(s). In close
cooperation with appropriate projects in the other themes we will quantify how the responses
to stress varies within species between life stages (not applicable for unicellular organisms),
genotypes/strains, and between species in the focal communities.
2. Shifts in competitive abilities of model organisms. Co-culturing of organisms exhibiting
differing stress sensitivity (at the ontogenetic, genetic, species level) allows the quantification
of the stress-induced shifts in competitiveness as compared to a low-stress situation. Strong
shifts will lead to fast changes in relative abundance of the components in the focal
communities: benthic and pelagic microbes, microalgae, macroalgae, macroalgae/sea grass,
sessile invertebrates. This issue will highlight the role of genetic and functional diversity for
the adaptability of populations and communities. Further, prolonged co-culturing of simple
communities in micro- and mesocosms will produce re-structured communities adapted to
the OA scenario applied. Since such a re-organization depends on the gene and species pool
available, and on the number of generations allowed, and both these conditions can not be
simulated realistically in experiments we do not pretend to simulate the ecosystem changes
which will happen in the future. However, the kind of shifts among functional groups – e.g.
macroalgae vs. seagrass or calcifiers vs. non-calcifiers – will improve our capacity for
plausible projections.
3. Quantification of the changes in community structure and community services. The structural
shifts driven by OA will lead to changes in the functions within communities. Thus, an
altered prey community will differ with regard to food quality and quantity. How this affects
structure and dynamics of primary or secondary consumers, and storage in or flow of
energy/matter between different strata of the system, will be a further outcome of Theme 4.
Ultimately, we aim to make predictions of how OA is likely to affect issues such as surface
water quality or the yield of economically relevant species.
4. We will strive to incorporate the findings on direct and indirect OA impacts at the different
organisational into descriptive and/or predictive models.
5.4.3. Projects under this Theme
Project 4.1: OA impacts on interactions in and structure of benthic communities
(Martin Wahl)
Project 4.2: OA effects on food webs and competitive interactions in pelagic ecosystems
(Maarten Boersma)