The Future of Upwelling
May 21, 2018
One of the main reasons we study seabirds, both on Southeast Farallon Island and on a worldwide scale, is that they provide us with a vital insight into the state of the oceans. If seabirds have a successful breeding season, this tells us that the sea has enough of the right nutrients to support vast blooms of phytoplankton. These phytoplankton provide a key energy source for animals higher up the food chain, such as fish and krill, which in turn are a major food source for a huge range of animals such as marine mammals and seabirds.
This use of seabirds as indicators of the quality of the marine environment is particularly useful on Southeast Farallon Island, due to our situation in an important upwelling region within the Gulf of the Farallones National Marine Sanctuary. Along the west coast of the US, northerly winds cause sea surface waters to move offshore, due to the spinning of the earth (Coriolis effect). As this surface water moves offshore, cold nutrient rich water from below is drawn up to replace it; a process called upwelling that gives the sea in this area the ability to support some of the richest biodiversity in the world. Our seabird research allows us to monitor how the strength, timing, and duration of this upwelling impacts the success and survival of marine predators.
It has been found that climate change has a significant impact on upwelling, as warmer air temperatures cause the sea surface temperature to increase as well. This warmer, less nutrient rich water sits as a blocking layer on the surface, essentially hampering the mixing of colder more nutrient rich water from below. Wind patterns also change as a result of the warming air and sea, so upwelling is not driven as effectively by strong northerly winds. Prolonged periods of warm water years decreases the sea’s capacity to support the wide and varied life we are lucky enough to currently have on and around the Farallon Islands, which is all the more reason to continue to use seabirds as sentinels of the changes yet to come.
By summer intern Holly Pickett