Temporal and spatial ecological community structure along metropolitan beaches

Context The South Australian metropolitan coastline is a highly managed complex environment, yet our understanding of intertidal ecological communities is lacking. Information regarding intertidal macroinvertebrates and meiofauna as important components of beach ecosystems, and their relationships to environmental dynamics, is limited on modified beaches globally. Aims To determine variability in beach environments along the Adelaide metropolitan coastline, and how environmental variability influences intertidal macroinvertebrate and meiofauna communities. Methods Surveys across a year included morphological and biogeochemical beach parameters, macroinvertebrates and meiofauna along the 28-km metropolitan coastline of Adelaide, Australia. Distance-based linear models were conducted to determine how environmental variability influences intertidal communities. Key results Beaches varied from flat, fine sand beaches in the north to steeper, coarser beaches in the south. Variation in beach environment was reflected in macroinvertebrates, with higher abundances coinciding with finer sands. Meiofauna changed with monthly changes in water temperatures, shifting community structure in winter. Conclusions Although metropolitan coastlines are modified, sandy beach ecological communities persist. Size of invertebrate taxa influences the ecological response, with macroinvertebrates responding to beach condition, whereas meiofauna follow temperature-driven trends. Implications Establishing an understanding of modified metropolitan beaches and habitat influences on sandy beach intertidal communities will better inform stakeholders to potential impacts of ongoing modifications on the intertidal ecology of coastlines.