Trends in the study and impacts of brine discharge on benthic communities

Abstract

The increasing global demand for potable water has led to a growing reliance on desalination technologies. However, these processes produce hypersaline brine as a byproduct, which is typically discharged into the marine environment. The ecological consequences of such discharges have become an important area of research, particularly with regard to the protection of sensitive coastal habitats. Among the most affected are benthic communities-organisms living on or near the seabed-which serve as reliable bioindicators due to their sensitivity to environmental change. Despite rising interest in this topic, empirical data on benthic responses to brine exposure remain limited, especially in regions with extensive desalination infrastructure but insufficient ecological monitoring. Benthic fauna are commonly categorized into macrofauna and meiofauna based on size, yet research has predominantly focused on macrofaunal communities. This review synthesizes findings from 100 peer-reviewed scientific articles to assess the effects of brine discharge on benthic abundance, species richness, and diversity. The analysis reveals that while both macrofauna and meiofauna generally exhibit reduced abundance in response to brine exposure, their species richness and diversity often increase, possibly due to shifts in community composition favouring more tolerant taxa. Furthermore, the spatial extent of these ecological impacts correlates with the concentration of discharged brine. To substantiate these patterns and address existing knowledge gaps, particularly concerning meiofauna, further site-specific studies and enhanced long-term monitoring are essential. These efforts will be critical for improving our understanding of brine-induced stress on marine ecosystems and for guiding the development of more sustainable desalination practices.