Dr. William Balch, a senior research scientist at Bigelow Laboratory for Ocean Sciences in Boothbay, will discuss how the Gulf of Maine has changed during the past 20 years, at Watershed School, Free Street, Camden Tuesday, Feb. 5 at 1:45 p.m.

Balch received bachelor's degree from Cornell University and doctorate from Scripps Institution of Oceanography. He has participated in research expeditions in Patagonia, the Southern Ocean and in the north Atlantic. For more than 20 years, he and his research group have gathered data on coastal productivity and how carbon moves in the Gulf of Maine.

For more information, contact jmcmahon@midcoast.com.