Gray snappers and a jellyfish visible among the roots of a mangrove forest.
Mangroves are groups of trees and shrubs that grow on tropical coasts. They ‘dip’ their tangled roots into the water, causing sand to collect and creating safe places for marine animals to live and hide.
The strategic positioning of mangroves on coastlines also makes them essential for stabilizing shorelines. Since mangrove forests pour-over into the adjacent ocean, their roots hold down coastal land right where the ocean and land meet - a role that is particularly important during storms.
A mangrove forest in the Bahamas during a low tide, showing how much sediment these plants hold, ... [+]
Mangrove ecosystems are notoriously lacking in nutrients. To compensate, mangroves are already among the most efficient plants when it comes to nutrient resorption. However, according to a new study by the University of Michigan, two tropical fish may be mangrove’s ‘most valuable players’ in the pursuit of nutrients - by providing the mangroves with their nutrient-rich urine.
University of Michigan marine ecologist Jacob Allgeier measures one of the gray snappers used to ... [+]
The researchers radio-tracked tropical fish near a mangrove on Abaco Island in the Bahamas. Of all the fish tracked, the gray and cubera snappers spent the most time in the mangrove’s underwater root systems swimming, foraging, and urinating. In fact, the excretory contributions of these two active fish species nearly doubled the total amount of nitrogen that would otherwise be in the water in their absence.
In total, the study radio-tracked 33 gray snappers and 25 cuberas over two years, but the group plans to track as many as 500 fish using recently-awarded grant funding from the Packard Foundation. The researchers hope to dive deeper into the potential for fish excretion to function as a natural renewable source of fertilizer, and perhaps improve food security for people living in tropical areas.
