Functional changes in benthic macrofaunal communities along a natural gradient of hypoxia in an upwelling system

Increasing global concern has been raised about the expansion of hypoxia in coastal waters and its potential to impact benthic ecosystems. Upwelling areas offer opportunities to study the effects of hypoxia on benthic communities under natural conditions. We used a biological trait-based approach and estimated functional di-versity indices to assess macrobenthic community functioning along a depth gradient associated with naturally increasing hypoxia and concentrations of organic matter in the upwelling zone of northern Chile (South-East Pacific) over two years. Our results highlighted the increasing dominance of opportunistic biological traits associated with hypoxia and high organic matter content. Habitat filtering was the main process affecting the studied communities. Functional diversity patterns were persistent overtime despite the occurrence of a pulse of oxygenation. This study contributes to our understanding of how natural hypoxia impacts macrobenthic com-munities, providing useful information in the context of increasing eutrophication due to human influence on coastal areas.

Automated summary

This study utilized a trait-based approach to assess macrobenthic community functioning along a depth gradient in the upwelling zone of northern Chile. The results showed an increasing dominance of opportunistic biological traits associated with hypoxia and high organic matter content, with habitat filtering as the main process affecting the communities. Functional diversity patterns remained consistent over time despite the occurrence of oxygenation pulses, contributing to our understanding of how natural hypoxia impacts macrobenthic communities.