Seafood is an important, sometimes essential, source of sustenance for many communities around the world, but not just because of the protein it contains. New research has found that an aquatic diet can provide a comprehensive swath of micronutrients with just one catch—the ecosystem it came from needs to have a high level of biodiversity.
Researchers know that biodiversity in, for example, fish populations can improve their productivity and resilience to environmental changes. But the relationship between aquatic biodiversity and human nutrition hasn’t received as much attention. Researchers from Yale University and the University of British Columbia decided to investigate this relationship both globally and locally.
To understand nutritional distribution, the researchers analyzed the levels of five micronutrients and essential fatty acids—calcium, iron, zinc, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)—in 7,245 samples from 801 aquatic finfish and invertebrates. They also assessed levels of common contaminants. Then, they simulated how nutrient levels in seafood diets would change if the number of species increased.
Because different aquatic species tend to have higher amounts of one nutrient and lower amounts of others, the researchers found that more diverse ecosystems consistently led to an increase in the amount of nutrients packed into a given portion size. This means that multiple species can complement each other in terms of their nutritional benefit.
However, toxin contamination in diets also increased with heightened levels of aquatic biodiversity. How much it rose depended on the contaminant. The authors found that an increase of 10 in the number of species types led to a 10 percent jump in lead but a 50 percent jump in methylmercury in seafood. But the study also found that, due to an increase in nutrients in the edible portion of species, the minimum portion size needed to meet nutritional targets decreased, pointing to the complicated need to find a balance between the risks and benefits of seafood biodiversity and consumption.
“While we have known that biodiversity on land is important for benefits such as forest production, this study provides new evidence that the benefits of biodiversity in oceans and freshwaters are as great as on land,” said Joey Bernhardt, lead author and G. Evelyn Hutchinson Postdoctoral Fellow, in a press release. “Ecological concepts of biodiversity can deepen our understanding of nature’s benefits to people and unite sustainability goals for biodiversity and human well-being.”
Source: Bernhardta, J.R. and O’Connor, M.I. Aquatic biodiversity enhances multiple nutritional benefits to humans. Proceedings of the National Academy of Sciences. 2021
Image: Joey Lecky, NOAA Fisheries