Abstract
Fishing is widely considered a leading cause of biodiversity loss in marine environments, but the potential effect on ecosystem processes, such as nutrient fluxes, is less explored. Here, we test how fishing on Caribbean coral reefs influences biodiversity and ecosystem functions provided by the fish community, that is, fish-mediated nutrient capacity. Specifically, we modelled five processes of nutrient storage (in biomass) and supply (via excretion) of nutrients, as well as a measure of their multifunctionality, onto 143 species of coral reef fishes across 110 coral reef fish communities. These communities span a gradient from extreme fishing pressure to protected areas with little to no fishing. We find that in fished sites fish-mediated nutrient capacity is reduced almost 50%, despite no substantial changes in the number of species. Instead, changes in community size and trophic structure were the primary cause of shifts in ecosystem function. These findings suggest that a broader perspective that incorporates predictable impacts of fishing pressure on ecosystem function is imperative for effective coral reef conservation and management.
Highlights
Fishing is widely considered a leading cause of biodiversity loss in marine environments, but the potential effect on ecosystem processes, such as nutrient fluxes, is less explored
The productivity of many ecosystems depends on the nutrient capacity of the ecosystem; here defined as the total nutrients stored within, and the rate at which nutrients are recycled between the constituents of the system[4,5]
One mechanism by which species richness could be maintained despite selective fishing is through functional redundancy, whereby high levels of richness within trophic groups distributes the effect of fishing pressure across species[1,15,21]
Summary
Fishing is widely considered a leading cause of biodiversity loss in marine environments, but the potential effect on ecosystem processes, such as nutrient fluxes, is less explored. Changes in community size and trophic structure were the primary cause of shifts in ecosystem function These findings suggest that a broader perspective that incorporates predictable impacts of fishing pressure on ecosystem function is imperative for effective coral reef conservation and management. Richness, evenness and size structure of species within the community drive variation in fish nutrient capacity across relatively unimpacted coastal fish communities in the Caribbean[15]. It is unknown how fishing pressure, through selective exploitation of certain species, alters fish nutrient capacity of coral reef ecosystems
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