Seagrass meadows support more nutritious fisheries than nearby coral reefs

Stockholm University researchers find fish from seagrass meadows contained more key nutrients than those from nearby coral reefs off African coast

Seagrass meadows play a major overlooked role in feeding and nourishing coastal communities, according to a study led by researchers at Stockholm University.

The research, published in Cell Reports Sustainability, found that fisheries associated with seagrass meadows provide higher levels of essential nutrients than those linked to neighboring coral reefs.

Although coral reefs are widely recognized for supporting coastal fisheries, the researchers found seagrass meadows may be just as important, and in some cases even more important, for the fish people catch and eat.

The research team studied fish from 20 seagrass meadows and 20 coral reefs along a 1,864-mile stretch of coastline from Kenya to Mozambique. They looked at six key nutrients that people need to stay healthy, like calcium, iron, zinc, selenium, vitamin A and omega-3 fatty acids. Instead of looking at each nutrient one by one, the scientists treated fish more like natural multivitamins.

“Fish don’t nourish people one nutrient at a time,” said Benjamin Jones, who carried out the research as a Ph.D. student at Stockholm University and is now Chief Conservation Officer at Project Seagrass. “They come as a package. A single fish contains iron, zinc, calcium, selenium, vitamin A and omega-3s. We wanted to understand which habitats produce fish with the best mix of these nutrients.”

After accounting for differences in fish biomass, the team found that for the top three most important food fish species, nutrient support was over eight times higher in seagrass meadows than coral reefs. On average, seagrass fish communities were 1.6 times more nutritionally rich than coral reef fish communities.

Two important food fish prized in the region, rabbitfish and parrotfish, were also far more common in seagrass meadows. In terms of biomass, they were five times and 65 times more abundant in seagrass than on coral reefs.

“We know that coral reefs have more fish overall, but seagrass meadows had more of the fish that really matter for local food,” said Jones. “This changes how we should think about these habitats. Seagrass isn’t just a fish nursery, nor just a carbon stock, it’s food infrastructure, nature’s own supermarket.”

The researchers estimated that an average fish associated with seagrass meadows could provide about 5 percent of a young child’s daily iron needs, 70 percent of selenium needs and 21 percent of zinc needs.

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The study measured the nutrients available in fish rather than what people actually consume. Still, the findings suggest seagrass meadows could make an important contribution to nutrition in tropical coastal communities, where millions of people rely on fisheries for food and income.

The researchers said the findings highlight the need to consider seagrass meadows in marine conservation and fisheries management. Like coral reefs, seagrass ecosystems face pressures from climate change, coastal development, pollution and other human activities, but they have received comparatively less conservation attention and funding.

“Our results really underscore the need to protect seagrass meadows, which are often overlooked in the shadow of more well-known habitats such as coral reefs and mangrove forests, while at the same time avoiding fishery closures, as these could jeopardize one of the most important sources of nutritious food for local communities along tropical coastlines,” said Johan Eklöf, professor in marine ecology at Stockholm University and co-author of the study.

The researchers said the findings do not suggest seagrass meadows should replace coral reefs as a conservation priority. Instead, the study found the two ecosystems play complementary roles and should both be considered in conservation and fisheries management.

While coral reefs support greater fish biomass, seagrass meadows provide access to key food fish that are particularly rich in nutrients, highlighting their importance for coastal food security.

“Reefs and seagrass meadows work together,” said Jones. “If we want coastal fisheries to feed people, we need to protect the whole seascape.”

Read the full study.

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