North Sea ecosystem change from swimming crabs to seagulls
C. Luczak, G. Beaugrand, J.A. Lindley, J-M Dewarumez, P.J Dubois and R.R. Kirby
Biology letters (online) 2012 doi: 10.1098/rsbl.2012.0474
What is this about? Changes in the sea surface temperature (SST) are affecting the abundance and
distribution of higher trophic levels such as crab larvae, crab adults and sea birds. The effect of
increasing SST has on higher trophic levels of the food web.
Why is it important? There is growing evidence that the North Sea ecosystem is being affected by
shifts in temperature and anthropogenic pressures (such as overfishing). The paper reveals a link
between an increase in SST, swimming crab larvae and lesser black-back gull colonies.
Why does it matter? A prolonged or semi - permanent change in the plankton community of the
North Sea is highly likely to affect the abundance of other species of fish and other organisms further
up the food web which rely on them as prey.
What does the paper tell us?
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The abundance of swimming crab larvae is positively correlated with an increase in SST in
the North Sea.
An increase in SST in 1989, followed by another in 1997 has resulted in an increase in the
overall abundance of swimming crab larvae and then adult crabs.
There has also been an increase in the warm water swimming crab species Polybius
henslowii in the North Sea.
Swimming crabs are important food resource to the lesser black-back gull during the
summer breeding months.
An increase in SST, the number of crab larvae and number swimming crabs has led to an
increase in the breeding success of the lesser black-back gulls.
Climate-induced changes are being seen across the food web from marine fauna to sea
birds.
Lesser black-back gulls live in coastal terrestrial regions and feed at sea. Therefore, this
paper suggests that climate driven changes in the marine food web may also start to affect
the coastal ecology and the terrestrial environment of the North Sea regions.