Nutrient shift occurring in the Gulf of Maine could affect planktonic ecosystem

August 26, 2010

(PhysOrg.com) -- The Gulf of Maine waters are cooler, fresher and lower in nitrate than they were 30 years ago, causing a nutrient shift that has potential implications for the structure of the planktonic ecosystem, according to oceanographers at the University of Maine.

Based on recent oceanographic observations, coupled with a 50-year analysis of nutrients and hydrography, the UMaine research team hypothesizes that accelerated melting in the Arctic and freshening of the Labrador Sea have likely caused the Labrador Current to bring colder, fresher deep shelf waters into the gulf.

Until now, it was generally thought that the gulf’s high was fed by an influx of nutrient-rich deep slope water through the Northeast Channel between Georges Bank and Nova Scotia. The warm offshore slope water is higher in nitrate than silicate, helping determine the species composition of phytoplankton.

The UMaine data analysis, lead by David Townsend, showed that from the 1960s to the 1970s, the deep waters of the eastern were saltier and warmer as a result of the slope water. But since the 1970s, the gulf’s deep waters have become significantly fresher and cooler, and had lower nitrate and higher concentrations.

The resulting altered nutrient regime may change the abundance of diatoms and dinoflagellates in the gulf, including the red tide dinoflagellate Alexandrium fundyense that grows best in high nitrate conditions, according to the researchers, writing in the journal Continental Shelf Research.

Explore further: Gulf of Maine census surprises scientists

Related Stories

Recommended for you

New studies take a second look at coral bleaching culprit

December 7, 2016

Scientists have called superoxide out as the main culprit behind coral bleaching: The idea is that as this toxin build up inside coral cells, the corals fight back by ejecting the tiny energy- and color-producing algae living ...

Cosmic dust found in city rooftop gutters

December 7, 2016

(Phys.org)—A small team of researchers with Imperial College London, the Natural History Museum in London, Project Stardust in Norway and Université Libre de Bruxelles in Belgium, has found samples of cosmic dust in the ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.