Day and Night in the Gulf of Maine

Molly transferring a zooplankton net tow sample into a secure container for future analysis off the Bigelow Laboratory dock.

This summer, I had the opportunity to conduct research under the mentorship of Senior Research Scientist David Fields at Bigelow Laboratory. The Fields laboratory primarily focuses on research pertaining to zooplankton, predominantly copepod, behavior in their global and local distribution. This lab dedicates its research concerning small-scale interactions in the zooplankton community structure to better understand their large-scale distribution patterns.

My REU was focused on the variability of day-time and night-time zooplankton abundance and diversity within the water column off of Bigelow’s pier. A water column is the conceptual column of water from the surface of a body of water to the bottom sediment, but more specifically, we are ascribing it as the vertical space through which marine organisms vertically migrate (ascend and descend) throughout.

Zooplankton exhibits a migration pattern known as DVM (Diel Vertical Migration), which is the synchronized movement up and down in the water column over a daily cycle. Zooplankton normally ascend towards the surface at dusk and descend back to deeper water before dawn, but reverse patterns can also occur. It is unclear whether it is predation, light availability, lipid storage, or environmental/abiotic factors that influence this migration, but our research is specifically intended to analyze exactly what populations and abundance of zooplankton species are seen within the water column pertaining to light availability.

Our study seeks to determine if there is a significant difference in the volume or species  of zooplankton that inhabits the waters of the Damariscotta River in reference to the time of day; in other words, what areas of the water column are zooplankton inhabiting when there’s daylight, and what area are they occupying when there is no light. This analysis was important to investigate due to the very limited research done on zooplankton DVM in the shallow waters within the Gulf of Maine. Identifying this gap of knowledge was surprising to me due to the importance of this particular marine animal’s behavioral patterns, which provide so much of the basal energy for our water’s secondary and tertiary consumers – and carry essential information for our aquaculture sector. The sheer population biomass of this marine organism supplies a plethora of food-energy for inhabitants within any marine ecosystem, including many species of commercial value in Maine; Atlantic cod, Herring, and Lobster. The areas which these organisms occupy within a water column can be detrimental for secondary-consumer population health and stability.

This research has the potential to inform our aquaculture sector of feeding patterns that are critical in prey-predator dynamics within the Gulf of Maine, and how temporal migration of zooplankton could be affecting patterns seen within commercial fishing.

Molly Spencer is a University of Southern Maine student in Bigelow Laboratory for Ocean Science’s Research Experience for Undergraduates program. This intensive experience provides an immersion in ocean research with an emphasis on state-of-the-art methods and technologies.

Day and Night in the Gulf of Maine