Spatio-temporal variations of benthic communities along the coast

The distribution of benthic fauna and their community structure varies spatially and temporally in response to variations in environmental and ecological factors. Such variations may occur as spatial (e.g., latitudinal and bathymetric) gradients in physical factors, or as a result of periodic (diurnal, seasonal, etc.) or episodic phenomena in marine systems. However, considering the vastness of the marine system and the uniqueness of its component ecosystems, the relationships between spatiotemporal patterns in benthic communities and the causative factors are still being unraveled. A proper understanding of these causes and effects is key to developing predictive capabilities for effective ecosystem management. Spatial gradients in environmental factors often result in the zonation of benthic communities, for example, upstream-downstream horizontal patterns in estuaries, vertical zonation in intertidal habitats, and latitudinal or bathymetric gradients in subtidal habitats. Temporal trends may be on a diurnal scale (e.g., in response to tidal fluctuations in intertidal habitats), seasonal (e.g., in response to precipitation, freshwater discharge, or sediment/organic matter deposition in estuaries) or episodic (e.g., upwelling or ice scour in polar subtidal habitats). In recent decades, climate change, overexploitation of coastal resources, offshore oil-related activities, and coastal development have caused substantial and sometimes irreversible changes in benthic communities. This chapter describes the spatial patterns and temporal variations in coastal benthic communities, among which three distinct habitats, namely estuarine, intertidal and subtidal, are presented separately.