A Caribbean seagrass is an important plant producer of carbonate lime mud in the tropics

What is it about?

Seagrass beds contribute to oceanic carbonate lime mud production by providing a habitat for a wide variety of calcifying organisms and acting as efficient sediment traps. Here we provide evidence for the direct implication of Thalassia testudinum in the precipitation of aragonite needles. The crystals are located internally in the cell walls, and as external deposits on the blade, and are similar in size and shape to the aragonite needles reported for modern tropical carbonate factories. Seagrass calcification is a biological, light-enhanced process controlled by the leaf, and estimates of seagrass annual carbonate production in a Caribbean reef lagoon are as significant as values reported for Halimeda incrassata. Thus, we conclude that seagrass calcification is another biological source for the aragonite lime mud deposits found in tropical banks, and that tropical seagrass habitats may play a more important role in the oceanic carbon cycle than previously considered.

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Why is it important?

The high plant productivity of seagrasses invites to hypothesize that this tropical seagrass can be an important contributor to the total carbonate production of Caribbean coral reefs so far ignored in the models and general simulations, which important implications for the global carbon cycle, which will need to consider seagrass contribution to mineral carbon (calcium carbonate) in addition to the organic carbon. This seagrass contribution may be particularly important to generate the fine and white sand that characterizes Caribbean beaches. The total contribution of seagrass meadows to the global carbon cycle

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