A research team from the Marine Research Institute (INMAR) at the University of Cádiz (UCA) discovered that climate change and alterations in the interactions between plants and animals are modifying carbon cycles in marine ecosystems. These changes not only affect marine biodiversity, but also compromise the ability of seagrasses to act as carbon sinks.
The study, focused on a meadow of Cymodocea nodosa in the Bay of Cádiz, was funded by several national and regional projects, including initiatives from the Ministry of Universities, Research and Innovation of the Andalusian Government, and the Ministry of Science, Innovation, and Universities.
Seagrasses, recognized as the main carbon sinks on the planet, are essential for protecting coastal ecosystems. However, human activity is causing excessive nutrient enrichment, such as nitrogen and phosphorus, from fertilizers, wastewater, and other pollutant sources. This phenomenon leads to algae overgrowth, ammonia toxicity, alteration of biological communities, and accelerated organic matter decomposition, profoundly altering the dynamics of these ecosystems.
In an article published in Marine Pollution Bulletin, titled Nutrient enrichment and herbivory alter carbon balance in temperate seagrass communities, researchers highlight that nutrient excess and herbivore pressure affect both carbon production and the physical structures and biodiversity of marine communities. These alterations, along with sediment erosion, compromise the ability of seagrasses to protect coasts and capture carbon.
Seasonal Responses and Ecological Consequences
The behavior of seagrasses in response to nutrient enrichment varies depending on the season. In winter, low temperatures and lack of light turn these ecosystems into net carbon consumers, while in summer, increased light and heat boost the growth of plants and photosynthetic organisms, increasing the carbon flux into the water. However, stress caused by herbivores and nutrient excess can reduce carbon production and destabilize sediments, resulting in the release of stored carbon.
The studied species, Cymodocea nodosa, stands out for its adaptability and rapid growth, becoming a key model to understand how marine plants respond to environmental stress. The results highlight how interactions between nutrient enrichment and herbivore consumption not only threaten the resilience of seagrasses but also amplify the effects of climate change in coastal areas.
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Towards Sustainable Management of Blue Carbon
This work emphasizes the need to continue researching how seasonal and climatic factors, such as temperature and light, interact with these stressors. Furthermore, long-term studies are proposed to assess impacts on biodiversity and global carbon cycles, which could guide strategies for the sustainable management of these ecosystems.
The research, funded by the Ministry of Universities and Innovation, reinforces the importance of protecting seagrasses against climate change to maintain their essential role in carbon capture and the conservation of coastal biodiversity.
Marine biodiversity.
What Are Seagrasses and What Is Their Function?
Seagrasses are underwater ecosystems formed by angiosperm plants that grow in shallow waters and have many important functions:
Water Filtration
Seagrasses filter water, removing pathogens, bacteria, and pollution.
Oxygen Production
Seagrass photosynthesis produces large amounts of dissolved oxygen.
Coastal Protection
Seagrasses reduce the impact of waves and coastal erosion.
Habitat for Many Species
Seagrasses are a breeding, shelter, and feeding ground for many fish species, invertebrates, turtles, and other animals.
Contribution to Food Security
Seagrasses are breeding grounds for over 20% of the world’s major fishing grounds.
Contribution to Climate Change Mitigation
Seagrasses are a blue carbon ecosystem, as they sequester and bury carbon in the ocean.
Seagrasses are found in all the world’s oceans, except Antarctica. They thrive in sandy, muddy, or sandy-muddy bottoms and in shallow-depth areas.
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