Submersed Aquatic Vegetation Enhances Density and Diversity of Epifaunal Invertebrates Compared to Filamentous Mats in the Central Baltic Sea
Submersed aquatic vegetation (SAV) provides essential habitat and food to numerous coastal invertebrate species. In the eu-trophic Baltic Sea, fast-growing drifting algae form extensive mats that can negatively impact SAV. However, these mats alsooffer additional habitat and food to epifauna. The aim of this study was to assess the effects of SAV and filamentous mats onepifaunal communities in shallow soft-bottom habitats around Gotland, Sweden, in the central Baltic Sea. We used generalisedlinear models (GLMs) to evaluate the influence of SAV vertical structure, biomass and macrophyte species richness (includingmacroalgae) and filamentous mat biomass on epifaunal community properties as well as on those of key grazer species. Diversity,vertical structure and biomass of SAV were positively associated with higher total epifaunal abundance and greater abundancegastropod grazers. In contrast, filamentous mats only increased gastropod abundance and biomass. In addition to introducinga rapid tool for quantifying vegetation structural complexity, this study highlights the selective effects of different habitat typeson invertebrate communities in a relatively understudied region of the Baltic Sea. As warming temperatures and eutrophicationpromote filamentous mat growth, reducing nutrient pollution and protecting SAV will be crucial for sustaining abundant anddiverse epifaunal communities.
Keywords: benthic vegetation, coastal zone, Gotland, macrophytes, SAV, Sweden, vegetation structure
