Can greater biodiversity lead to increased food security?

Theoretically, more biodiverse ecosystems are healthier and more productive. But are there direct links between biodiversity and ecosystem services, particularly in terms of food security?

Emma Brooks, a researcher from the University of Southampton in the UK, thinks the answer is yes—at least when it comes to freshwater fisheries. In the first-ever large-scale study of the relationship between fishing yield and biodiversity in the world’s rivers and lakes, she and her colleagues found that the two go hand in hand.

Two billion people depend on freshwater fish for food. And inland water ecosystems are some of the most species-rich habitats on Earth. They cover less than one percent of the earth’s surface but are home 10 percent of all species and a third of all vertebrates, a disproportionate amount of which are highly threatened as compared to terrestrial species.

Brooks and her co-authors crunched a decade’s worth of data on freshwater fish landings from the Food and Agricultural Organization. In addition, they analyzed the International Union for the Conservation of Nature’s species maps for 100 countries in Africa, Europe, and Asia. They looked at six different factors (and the 64 possible combinations of these factors) that could affect fishing yields, including species richness, waterside human population, surface area of the water, and climate related factors.

They found that species richness had a statistically significant effect on the mean annual yield of 3 to 5 percent. It was the second most influential factor behind the 6 to 7 percent effect of waterside human population (a proxy for fishing effort). A second analysis looked at stability of landings over three decades and found that in Africa (though not in Europe), high biodiversity was associated with more stable yields.

The authors note that the results might be skewed to some degree because species-rich ecosystems tend to have dominant species. And if these dominant species are the ones being harvested, yields will look subsequently larger. However, Brooks believes the findings reflect a complementarity effect, in which greater biodiversity creates a more functional ecosystem that in turn supports higher yields.

The limitations of the study, she says, are only more reason to continue to study dynamics of freshwater ecosystems, which are not only understudied, but are also undervalued for their contributions to food security. –Catherine Elton | 11 March 2016

Source: Brooks, E. G. E., Holland, R. A., Darwall, W. R. T. and Eigenbrod, F. (2016). Global evidence of positive impacts of freshwater biodiversity on fishery yields. Global Ecology and Biogeography. DOI: 10.1111/geb.12435.

Photo by Kirk Winemiller, via the Sabo Lab at Arizona State University

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