Sargassum, a problem?
Massive Sargassum flow has become a major challenge for tourism-dependent countries. Across the Caribbean and in Mexico, officials have been forced to mobilize to counter excessive blooms of these algae, which in concentrated mats prove not just a problem for tourists, but also for wildlife, coral beds and sea turtles.
While the causes include warming ocean temperatures and divergences in ocean currents due to climate change, some researchers believe the profusion is primarily due to increased land-based nutrients and pollutants washing into the water, including nitrogen-heavy fertilizers and sewage waste that fuel the blooms.These sources reach the sea from rivers such as the Amazon.
A continent away, winds from the Sahara and the Sahel sweep fine mineral dust into the high atmosphere. This is then deposited on the Amazon basin’s vegetation, contributing concentrations of phosphorous, among other nutrients, which then wash into the sea. But, of course, increased deforestation is also to blame as it further accelerates the process. Sargassum proliferations are expected to continue.
This article in Geophysical Research Letters explains the mineral dust phenomenon.