Heilpern S, DeFries R, Fiorella K, Flecker A, Sethi SA, Uriarte M, Naeem S. (2021) Declining diversity of wild-caught species puts dietary nutrient supplies at risk. Science Advances, 7:eabf9967.
Freshwater fisheries provide many globally with a primary sources of essential nutrients, but are increasingly impacted by overharvesting and habitat loss. Although biodiversity’s role in maintaining ecosystem functions is well established, biodiversity is notably absent from consideration on fisheries and food security. Here we analyze how fish biodiversity loss affects the probability of failing to sustain fish-based nutrient supplies, or nutritional vulnerability, in the Amazon, Earth’s most diverse river basin. Non-random biodiversity loss, in which small sedentary species replace large migratory species, increases the potential to meet intake thresholds for several key nutrients (e.g., fatty acids), but decreases others (e.g., zinc, iron). Biodiversity loss, however, often comes at the cost of increased nutritional vulnerability, but the magnitude depends on biomass compensation, how species vary in their functional traits and the ability of people to substitute fish with other animal foods. In contrast to findings from numerous biodiversity studies, functional diversity could either buffer or exasperate nutritional vulnerability depending on the extent to which species are nutritionally unique and vary in their tolerance to river threats. These results imply that prioritizing biomass production together with multiple dimensions of freshwater biodiversity, including taxonomic and functional diversity, may maximize long-term nutritional benefits from fisheries.