Examining the diversity, stability and functioning of marine fish communities across a latitudinal gradient. Issue 1 (9th November 2022) - Yan, Helen F.
Abstract: Aim: As anthropogenic stressors on the biosphere intensify, understanding how communities respond to disturbances is critical. Biodiversity is often thought to promote the stability of communities over time and enhance ecosystem functioning. However, results have been inconsistent, and the multifaceted linkages among diversity, stability and functioning under acute disturbances remain poorly understood. We experimentally tested the responses of marine fish communities to disturbance (i.e., acute habitat loss) across a diversity gradient spanning 35 degrees of latitude in the western Atlantic Ocean to assess the diversity–stability relationship and the interplay between diversity, stability, and fish biomass recovery (as a proxy for function) in marine fish communities. Location: Western Atlantic Ocean [Maine, Massachusetts, North Carolina, Florida (USA), Belize and Panama]. Time period: 2016–2017. Major taxa studied: Small, bottom‐dwelling ('cryptobenthic') fishes. Methods: We experimentally tested the response of marine fish communities to disturbance across a diversity gradient on human‐made dock pilings. We holistically sampled cryptobenthic fish communities, then we imposed a severe disturbance by removing all benthic epifauna. We then compared the community stability, defined as the constancy in community composition, on disturbed and undisturbed pilings after one year. Results: Diversity showed a negative effect on community stability at both the regional (across docks) and local (within docks) scales. Similarly, local diversity was negatively correlated with ecosystem function. These effects are exacerbated by the habitat loss imposed via our experimental treatment. Main conclusions: Our results suggest that habitat loss may re‐shuffle diverse, tropical communities more intensively than species‐poor, temperate communities, which impacts biomass recovery, our proxy of functioning. Contrary to ecological theory, in small‐bodied, benthos‐associated vertebrate communities, biodiversity may neither promote stability nor functioning, suggesting that human disturbances may be particularly impactful in tropical, high‐diversity ecosystems.