Natural variability in hard-bottom communities and possible drivers assessed by a time-series study in the SW Baltic Sea: know the noise to detect the change

[摘要] In order to detect shifts in community structure and function associated withglobal change, the natural background fluctuation in these traits must beknown. In a 6 yr study we characterized the composition of young benthiccommunities at 7 sites along the 300 km coast of the Kiel and Lübeckbights in the German Baltic Sea and we quantified their interannual variability oftaxonomic and functional composition.Along the salinity gradient from NW to SE, the relative abundance of primaryproducers decreased while that of heterotrophs increased. Along the samegradient, annual productivity tended to increase. Taxonomic and functionalrichness were higher in Kiel Bight as compared to Lübeck Bight. Withincreasing species richness functional group richness showed saturationindicating an increasing functional redundancy in species rich communities.While taxonomic fluctuations between years were substantial, functionalityof the communities seem preserved in most cases. Environmental conditionspotentially driving these fluctuations are winter temperatures and currentregimes. We tentatively define a confidence range of natural variability intaxonomic and functional composition a departure from which might helpidentifying an ongoing regime shift driven by global change. In addition, wepropose to use RELATE, a statistical procedure in the PRIMER (PlymouthRoutines in Multivariate Ecological Research) package todistinguish directional shifts in time ("signal") from natural temporalfluctuations ("noise").

[学科分类] 地球化学与岩石