The linkage between spatial and temporal variations in epifaunal and primary producer communities in eelgrass (Zostera marina) beds

Environmental variability within estuaries and lagoons creates environmental gradients. Spatial variations in environments associated with environmental gradients shape spatial variations in primary producer and invertebrate communities. However, whether larger spatial variations are linked to greater temporal variations in the communities remained unclear. To understand the linkage between spatial and temporal variations in the communities and the factors shaping these variations, we targeted various functional groups of primary producers and invertebrates (epifauna) in eelgrass (Zostera marina) ecosystems in lagoons with and without distinct salinity gradients. We tested the following hypotheses: 1) larger spatial variation in the primary producer biomasses and epifaunal community structures (abundance, biomass, and species richness) are associated with greater temporal variation in the structures, and 2) salinity would be a more pronounced factor than water temperature and biomasses of primary producers in shaping the community structures in the lagoon with a salinity gradient. Our results showed that temporal and spatial variations in the primary producer biomasses and community structures of epifauna were larger in the lagoon with a salinity gradient. Moreover, salinity, water temperature, and the biomasses of primary producers affected the spatio-temporal variations in the community structures of epifauna, regardless of the presence of the gradients. We present from these results the connection between spatial and temporal variations of the primary producer and epifaunal community structures and the effects of abiotic and biotic factors shaping the communities.