Changes in benthic communities in two Arctic fjords, Svalbard, Norway: photographs from 1984 and 2006

Changes in benthic communities in two Arctic fjords, Svalbard, Norway: photographs from 1984 and 2006

LifeLinkedtoIce Changes in benthic communities small

 

Box 5. Abrupt ecosystem shifts in benthic communities

A combination of warmer waters and increased light from longer ice-free seasons led to shifts in benthic ecosystems in two Svalbard fjords. Seawater temperatures and ice cover changed gradually over the study period from 1980 to 2010, but the flora and fauna on the rocky bottoms of both fjords remained stable and then changed abruptly at the end of the 1990s, with sudden increases in growth of filamentous and leaf-like seaweeds. The dominant invertebrate fauna also changed at both locations (Figure 22). This is believed to be a regional trend, as seaweed biomass increased three-fold between 1988 and 2008 in Hornsund, to the south of Svalbard [174]. In West Greenland, kelp beds have become more productive and grow to greater depths, changes that are strongly associated with the increase in the length of the ice-free season [175].

If these increases in seaweed persist and expand around the Arctic, as is projected [175, 176], they will be accompanied by changes in the species composition of  invertebrate communities on coastal rocky sea floors. These seaweeds provide more food and living space than the thin layer of rock-encrusting algae they replace, so are capable of supporting a greater biomass and diversity of invertebrates [172]. On the other hand, species typical of communities dominated by rock-encrusting algae may decline in numbers or even disappear.

 

Figure 22. Changes in benthic communities in two Arctic fjords, Svalbard, Norway: photographs from 1984 and 2006

 

The photographs represent benthic communities in the two fjords before and after abrupt ecosystem changes characterized by a shift from rock-encrusting types of algae to taller filamentous (C) and leaf-like (D) forms of seaweed. Areas within the white lines are covered by these seaweeds. The invertebrate communities changed at the same time. In Kongsfjord, for example, the sea anemones that were common before this regime shift (visible in A) declined rapidly and sea urchins increased.
From Kortsch et al. 2012 [172]

 

 

Conservation of Arctic Flora and Fauna (CAFF) 

The data can be downloaded freely. Users are requested to reference the source.

Eamer, J., Donaldson, G.M., Gaston, A.J., Kosobokova, K.N., Lárusson, K.F., Melnikov, I.A., Reist, J.D., Richardson, E., Staples, L., von Quillfeldt, C.H. 2013. Life Linked to Ice: A guide to sea-ice-associated biodiversity in this time of rapid change. CAFF Assessment Series No. 10. Conservation of Arctic Flora and Fauna, Iceland. ISBN: 978-9935-431-25-7.

 

 

172. Kortsch, S., Primicerio, R., Beuchel, F., Renaud, P.E., Rodrigues, J., Lonne, O.J., and Gulliksen, B. 2012. Climate-driven regime shifts in Arctic marine benthos. Proceedings of the National Academy of Sciences of the United States of America 109(35): 14052-14057. doi:10.1073/pnas.1207509109.

 

174. Weslawski, J.M., Wiktor, J., Jr., and Kotwicki, L. 2010. Increase in biodiversity in the arctic rocky littoral, Sorkappland, Svalbard, after 20 years of climate warming. Marine Biodiversity 40(2): 123-130. doi:10.1007/s12526-010-0038-z.
175. Krause-Jensen, D., Marba, N., Olesen, B., Sejr, M.K., Christensen, P.B., Rodrigues, J., Renaud, P.E., Balsby, T.J.S., and Rysgaard, S. 2012. Seasonal sea ice cover as principal driver of spatial and temporal variation in depth extension and annual production of kelp in Greenland. Global Change Biology 18(10): 2981-2994. doi:10.1111/j.1365-2486.2012.02765.x.
176. Mueller, R., Laepple, T., Bartsch, I., and Wiencke, C. 2009. Impact of oceanic warming on the distribution of seaweeds in polar and cold-temperate waters. Bot. Marina 52(6): 617-638. doi:10.1515/bot.2009.080.

 

 

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