New paper assesses how dams alter the ratios of macronutrients (nitrogen, phosphorus and silicon) delivered to the world’s oceans

Monday, August 3, 2020

The damming of rivers is one of the most impactful modifications of the flows of water and associated materials from land to sea. Included in these materials are nutrient elements like nitrogen and phosphorus, which are elements required by all life on Earth, and silicon, which is required by diatoms, the algae that account for the largest fraction of biological productivity of the oceans. Past studies have shown that changes in the ratios in which these nutrient elements enter the coastal oceans affect plankton communities, even causing harmful algal blooms or “red tides” to occur. In a new paper published in Geophysical Research Letters, (former) ERG researchers Taylor Maavara, Zahra Akbarzadeh and Philippe Van Cappellen use models of nitrogen, phosphorus, and silicon cycling in dam reservoirs to determine how the damming of rivers change the nutrient ratios delivered to coastal zones worldwide. The results predict that by mid-century, more than half of the rivers flowing to the sea will experience greater removal of silicon over nitrogen and phosphorus, in response to ongoing construction of many new hydroelectric dams. This will impact the role of diatoms in nearshore marine production, as they are increasingly outcompeted by other, potentially harmful, algae that do not need silicon to grow.

To access the paper, click here.