This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new study published in Communications Earth & Environment, with contributions from researchers at the Leibniz Centre for Tropical Marine Research (ZMT), shows that higher seawater temperatures could significantly reduce the long-term ability of underwater plants to store carbon. Scientists from Spain and Germany investigated how higher water temperatures affect the dissolved organic carbon released by seagrasses and marine algae.
The results show that as temperatures rise, the proportion of dissolved organic carbon that persists in the ocean over long periods and therefore contributes to long-term carbon storage declines significantly. The experimental portion of the study included seagrasses and macroalgae. In ZMT's aquarium facility in Bremen, Alba Yamuza-Magdaleno (University of Cádiz), Pedro Beca-Carretero and Hauke Reuter (Spatial Ecology and Interactions Research Group at ZMT) simulated different temperature conditions.
Their findings show that even a modest increase in water temperature alters the composition and characteristics of the dissolved carbon released by the seagrasses studied. Seagrasses and algae absorb carbon dioxide from the atmosphere to support growth and metabolism. Some of this carbon is fixed into structural components, such as leaves and rhizomes.
Part is stored in the seafloor for centuries or millennia, while another portion is released into the water as dissolved organic carbon. Some of these substances are quickly broken down by microorganisms. Others are far more resistant to degradation and can remain in the ocean for weeks, years or even centuries.
It was precisely this long-lasting form of carbon that decreased significantly in the experiments conducted at higher temperatures. With a temperature increase of 4 degrees Celsius, the proportion of carbon that is difficult to break down decreased by an average of about 28%. At the same time, the proportion of carbon compounds that are easily broken down by microorganisms increased significantly.
After 60 days, much of this more readily degradable carbon had already been decomposed. "Seagrass beds and kelp forests are considered natural carbon sinks. If the ocean continues to warm, they could sequester significantly less carbon over the long term than previously thought," explains lead author Yamuza-Magdaleno of the University of Cádiz.
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