Rising temperatures and sea-ice free winters affect the succession of Arctic macrozoobenthic soft-sediment communities (Kongsfjorden, Svalbard).

CHRISTOPHER NOWAK; JÜRGEN LAUDIEN; RICARDO SAHADE

POLAR BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2016

0722-4060

Arctic macrozoobenthic soft-sediment communities areconsiderably disturbed by iceberg scouring. The latter intensified during recentyears due to the warming of the northern hemisphere, coupled with increasedcalving of icebergs from tidewater glaciers. In 2002, in an attempt to describethe primary succession of macrozoobenthic communities in soft-sediments, scientificdivers installed 28 containers in the soft-sediment of Brandal (Kongsfjorden,Spitzbergen, Arctic) at 20 m water depth. The containers were filled witha bentonite-sand-mixture resembling the natural sediment. Samples were takenannually in late summer between 2003 and 2007. A shift from pioneer species(e.g. the cumacea Lamprops fuscatus) towards more specialist taxa,as well as from surface-detritivores towards subsurface-detritivores was observed,which is typical for an ecological succession following the facilitation andinhibition succession model. Similarity analyses revealed a significantdifference between the mature and the developing community. Similarity betweenexperimental and natural communities of 2003 was the highest after three yearsof succession and thereafter decreased again, since the fjord-system did notfreeze in the following years due to elevated temperatures. This demonstratesthat interannual changes, such as rising temperatures coupled with an increasingfrequency of ice-free days per year and enhanced food availability, may have a strongereffect on succession than exposure time. Some organisms numerically importantin the natural, non-manipulated community (e.g. the polychaete Dipolydora quadrilobata) did not coloniesthe substrate during the experiment, suggesting that the community had not yet fullymatured. This demonstrates the long-lasting effects of severe disturbances on Arcticmacrozoobenthic communities.