Small-Scale Metastability in a Coastal Ecosystem of The Baltic Sea

A high-resolution ecosystem model of the Gulf of Riga was used to describe gradients and small-scale persistence of patches of two bivalve species (Macoma Baltica and Mytilus edulis) between 1970 and 2003. Weekly estimates of biomass estimates (g DW soft tissue/m2) were extracted from the model output, and long-term trends in spatial structure were analyzed on biomasses at a scale of 5 km. The distribution of the modelled biomass was extremely patchy for both species. High levels of patchiness were superimposed on seasonal trends. Yet, despite the patchiness, the spatial gradients in the biomass showed remarkable stability and persistence over the studied 34 years, and the mean distributions of biomasses were highly correlated between decades (r 0.972-0.979 for Mytilus and 0.812-0.982 for Macoma). The results highlight the challenges using largescale ecosystem model results to describe spatial gradients and patchiness in benthic productivity found in coastal ecosystems. The spatial structure of the modelled biomass of both species clearly indicates the occurrence of pervasive patchiness and strong persistence in spatial patterns of distribution. The spatial stability of distribution patterns has important implications for the requirements for high-resolution model data needed to establish the status and trends of benthic habitats in coastal ecosystems.

Keywords: Food web models; Coastal ecosystems; Long-term trends; Baltic Sea; Bivalves; Mytilus edulis; Macoma baltica