An Unfriendly Dinoflagellate Appears in the Gulf of Maine

By Hannah McGrath

Some species of phytoplankton produce harmful toxins that have consequences for the environment and ecosystems. One example of a phytoplankton that produces harmful toxins is a species called Karenia mikimotoi. When this species grows a lot it produces harmful algae blooms which causes issues like massive fish deaths, gill damage, and prevents the clams and oysters from filtering seawater. 

Photo credit: Zaie Nursey

Historically K.mikimotoi has been recorded in european and asian waters. However, currently we’re having problems with this species in the Gulf of Maine. In 2017, Maine experienced its first bloom causing clam populations to die off. Then 2 years later, a second bloom occurred in Casco Bay alarming the local residents and Maine’s fishing industry. Unfortunately, this species has not been studied since it’s relatively new to the GOM. Since the GOM continues to rapidly warm faster than 99.9% of all global oceans, we don’t know how this will impact their patterns, which may harm Maine’s ecosystem and economy. Therefore, it is important to understand the conditions that cause large increases in their population in our changing climate. 

To gain a better understanding of this species in the Gulf of Maine we went out on cruises from August to late October of 2020 and collected water samples to take back to the lab. In the lab, we looked for evidence of K.mikimotoi that may have left behind in the water at one point in time called environmental DNA or eDNA. eDNA is like following breadcrumbs that were left behind from the main culprit. This gives us a better understanding of where they like to hang out in the water column. I am working with Senior Research Scientist Pete Countway to investigate how K. mikimotoi abundance and distribution is influenced by a rapidly changing climate in the Gulf of Maine. 

Hannah McGrath is a Colby College student in the 2020 Sea Change Semester Program at Bigelow Laboratory. This intensive experience provides an immersion in ocean research with an emphasis on hands-on, state-of-the-art methods and technologies.

An Unfriendly Dinoflagellate Appears in the Gulf of Maine