FARMINGTON — Western Maine Audubon will host a lecture by Dr. William “Barney” Balch, a senior research scientist at Bigelow Lab for Ocean Sciences in East Boothbay at 7 p.m. Wednesday, April 12, at the Roberts Learning Center at UMF, in Classroom 101.

Bigelow Lab’s mission is to investigate the microbial drivers of global ocean processes, essential to the conservation and responsible use of the ocean. A major part of the research at the Lab is on climate change and ocean health.

The Gulf of Maine is a shallow sea surrounded by land on three sides, which promotes strong interactions between the Gulf and its surrounding watersheds. For the last 18 years, Balch has run the Gulf of Maine North Atlantic Time Series, a scientific study that includes regular collection and analysis of samples along the same transect across the Gulf.

Using data gathered from ships, autonomous gliders (undersea robots) and satellites, GNATS helps scientists understand how the Gulf works and how it is changing — from the fundamental carbon cycle to a whole suite of optical, chemical, biological and physical properties. It also provides essential on-the-water data to NASA, which helps validate the ocean color measurements taken from NASA satellites.

One of the most striking observations of the project was an eighty percent decline in the primary production of the Gulf’s marine phytoplankton — the vital organisms at bottom of the marine food web, upon which all sea-life depends — that occurred after an anomalous increase in precipitation in the mid-2000s. Balch and his team have two main hypotheses about why this may have happened, both strongly tied to land-ocean interactions.

They have also observed a “yellowing” of the Gulf of Maine, after comparing their results to those of the legendary oceanographer, Henry Bigelow, who made basic ocean color measurements more than a century ago on the same transect. Balch believes that the decline in productivity and the yellowing may be related to each other and a testament to how complex land-ocean systems react to a changing world.

This lecture is sponsored by the Western Maine Chapter of Maine Audubon and is free and open to the public.

William Balch