Horseshoe Crabs and Climate Change

Alice Noyes

Last year Frank Dorsey noticed a trend in the first arrivals of horseshoe crabs for mating. In 2021, horseshoe crabs (HSC) arrived earlier than each of the previous two years. First arrivals were on June 6 in 2019, on May 23 in 2020, and May 16 in 2021. This year, they again arrived on May 16.

Josh Cook and Kazu Temple, two graduate students in the Marine Biology program at U. Maine—Orono, have recently begun to study what the effects of warming waters and ocean acidification are on the development and survival of marine invertebrates, using horseshoe crabs as a model.  Since Taunton Bay is home to the northernmost populations of Limulus polyphemus, and the Gulf of Maine is one of the most rapidly heating bodies of water on Earth, they want to find out if the changes to Maine’s environment will exert pressure on our northern horseshoe crabs. 

They were able to collect a few eggs from live horseshoe crabs here at Shipyard Point this spring.  If they are successful in obtaining fertilized eggs, they will grow them in the laboratory and expose the eggs and embryos to different pH and temperature ranges that are predicted to affect the Gulf of Maine over the next 25, 50, and 100 years.  They will compare the stress indicators of those exposed to the higher temperatures and pH to those of eggs developing under optimal conditions.