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The ecological functioning of the Antarctic benthos: vulnerability to climate change

Dr Cath Waller (UoH), Dr Bryony Caswell (UoH)

Project partner(s): British Antarctic Survey Dr DKA Barnes, Dr Huw Griffiths

Contact email: B.A.Caswell@hull.ac.uk

Summary

Antarctic ecosystems are unique, due to both their environmental distinctiveness and the ~40 million years of relative biogeographic isolation from the fauna and flora of most of the other major oceans1,2. However, the Antarctic ice sheet is now rapidly retreating and the circumpolar current is weakening thus the physical barriers that have isolated the Southern Ocean for millennia are breaking down (Fraser et al., 2018). Climate models3 show that the effects of climate change (e.g. SST and ocean acidification) will be most intense at the poles. Ecosystem models4-6 and past geologic periods of climate change3 suggest that marine invasions and extinctions will reach a maximum at the poles: as the habitat available for stenothermal marine species contract their biogeographic ranges shift towards the poles. 

The nearshore shallow Antarctic bottom fauna has been described as being ‘Palaeozoic’ in nature with high relative abundances of epifaunal suspension feeders, and few shell-crushing predators (e.g. crabs and sharks), and so is more similar to the fauna present during the Palaeozoic compared to all the other major oceans today1. The Antarctic seafloor has a high degree of endemism with high diversities of crinoids, brachiopods, sponges, nematodes, pycnogonids, ostracods and isopod crustaceans7. The fauna also exhibit marked physiological differences including gigantism, high longevity and late maturation. Antarctic ecosystems are therefore functionally unique and are particularly sensitive to invasion by non-native predators, and there is evidence to suggest that this has already begun8. 

For all of the above reasons the Southern Ocean is likely to experience extreme environmental changes in the near future, and these ecosystems appear to be highly susceptible to such changes. This project will explore how the Antarctic benthos will change and the implications of these difference for ecosystem functioning. In general, our knowledge of the Antarctica benthos is limited (Dissanayake et al.; Waller et al. 2007)…..

We will compile existing and collect new data on the macroinvertebrate communities inhabiting intertidal and the shallow subtidal seafloor across a range of habitat types (e.g. rocky substrates, and different types of soft sediment) at sites in the South Atlantic and on the Antarctic peninsula near British Antarctic Survey stations9. The following questions will be addressed:

1. What taxa are most sensitive to the impending environmental changes? and, what taxa are functionally important within Antarctic benthic communities? (systematic literature review).

2. What are the direct and indirect effects of climate change on benthic communities? e.g. the direct effects of increasing water temperature or the indirect effects of say ice retreat whereby previously the regular intertidal ice scour is diminishing effecting the distribution of macroalgae. The indirect effects will also include changes in species interactions (e.g. competition and predation) as species are lost and/or non-native species arrive.

3. What are the impacts of changes in key taxa likely to be for the ecological functioning of the Antarctic benthos? Field and laboratory experiments will be used to simulate species loss and invasions and their impacts on core ecological functions will be determined e.g. benthic nutrient cycling, primary production and food for higher predators

4. Finally, experimental manipulations of environmental conditions (e.g. by increasing nutrient loading in nutrient poor intertidal areas) will be used to explore the impacts of some of the anticipated environmental changes further

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References

1. Aronson, R.B. et al. (2007) Annu. Rev. Ecol. Evol. Syst. 38, 129–154;

2. Aronson, R.B. (2009) Metaphor, inference, and prediction in paleoecology: climate change and the Antarctic bottom fauna. In Conservation Paleobiology: Using the Past to Manage for the Future (Dietl, G.P. and Flessa, K.W., eds), The Paleontological Society Papers, vol. 15, pp. 177–194, Paleontological Society;

3. IPCC (2013) Climate change 2013—the physical science basis. Working Group I Contribution to the Fifth Assessment Report of the IPCC, New York, NY;

4. Cheung, W W L et al. 2009. Fish and Fisheries, 10, 235-251;

5. Pereira HM et al. (2010) Science 330: 1496−1501; 6Ridgwell, A. and D.N. Schmidt, 2010: Nature Geoscience, 3(3), 196-200; 7Barnes DKA et al. (2009) J Biogeogr 36: 756−769; 8Thatje, S. et al. (2005) Ecology 86, 619–625; 9British Antarctic Survey. 2018. URL: https://www.bas.ac.uk; 

Related undergraduate subjects:

  • Biodiversity
  • Biodiversity conservation
  • Biology
  • Ecology
  • Environmental biology
  • Environmental conservation
  • Evolution
  • Natural sciences
  • Spatial ecology
  • Zoology