Fish loss in tropical coastal ecosystems can jeopardise nutrient supply to traditional fishing communities: A case study from Northeast Brazil

Fisheries constitute one of the major benefits that oceans provide for people. Yet anthropogenic pressures and global changes are disrupting coastal systems, eroding marine biodiversity and threatening the food security of traditional populations. Although fishes are recognised as fundamental food resources in coastal zones, their specific contribution to human nutrition and how biodiversity loss may affect nutrient supply remains a knowledge gap, particularly in the tropics.

Here, we integrate information on food intake with nutrient composition data of animal-based foods to assess the dietary patterns of fishing families and to evaluate how fish loss may impact nutrient provision for coastal communities in Northeast Brazil.

We found that marine fish account for 30%–40% of animal-based protein consumed monthly by families, with fish diversity consumption influencing nutrient intake patterns. Furthermore, marine fish have the potential to account for up to 71% of the multidimensional micronutrient space available to fishing families, primarily providing calcium, selenium and omega-3 fatty acids.

Simulated species losses indicated substantial risks, with nutrient supply depletion exceeding 70% under the extinction of a quarter of fish species. Scenarios based on body length and vulnerability led to an 80% nutritional space reduction, while the sequential loss of lower-trophic-level species resulted in a 70% decrease. The most severe impacts occurred in scenarios based on species nutrient density, where extinctions led to a greater than 90% depletion of the nutritional space provided by fishes.

Given the escalating threats to marine biodiversity, prioritising nutritionally important species could provide a sustainable strategy to strengthen food security and fisheries systems in coastal regions.