Fall Field Guide for the Gulf of Maine

At the microscopic level, fall is an exciting time with different larval species out and about in the water column. Many marine organisms reproduce in the spring and summer; for broadcast spawners that generally spawn in late summer, such as Placopecten magellanicus, the Atlantic sea scallop, and Mercenaria mercenaria, the quahog clam, their larvae stay in the water column traveling with ocean currents for weeks before they settle and start their next life phase.

Kelp species such as Saccharina latissimia, or sugar kelp, spawn later in the year and are preparing to release their spores in the fall. If you find yourself around sugar kelp this fall, notice how the middle of the blade appears very defined and dark. This is the sorus tissue that contains the spores for reproduction. After reproduction and settlement, sugar kelp will enter its fastest-growing phase throughout the winter. 

In the intertidal zone, the number of molting European green crabs, Cancer maenas, starts to drop. While most of the males will have stopped molting at the end of the summer, there is usually the occasional soft-shell female who snuck one last molt cycle into the season. Take a trip to the intertidal zone and keep an eye open for tiny, newly settled green crabs scurrying among the rocks. 

These seasonal patterns are rooted in the Gulf of Maine’s annual biological cycle; however, the impacts of climate change are shifting some of those patterns. Partner fishers have recently reported Callinectes sapidus, or blue crabs, in lobster traps both in the New Meadows River and off of Georgetown. The blue crab is most commonly thought of as a mid-Atlantic species, but with warming temperatures, their range is shifting north and are now an emerging species along the coast of Maine. Other species including Selene vomer, the lookdown fish, were also found in lobster traps off of Georgetown this fall. The lookdown fish is not a common find off of coastal Maine and is more commonly found in tropical Atlantic Ocean waters. In the coming years, these species may become part of our established seasonal rhythms in Maine waters.

The intertidal and shallow subtidal are an extreme habitat for species to call home. At all times of the year, these environments are presented with twice-daily tides and temperature fluctuations. Species must be specially adapted to survive both in and out of the water, as well as the different predator threats of each tide. Fall brings the added challenges of drastic temperature fluctuations, increased wave action from the coming winter storms, and even sea ice on the coldest days. Let us know what you find along your section of the Gulf of Maine coast by sharing a photo or video and tagging us on Facebook, Twitter, or Instagram!