Ecological Recovery in the Kennebec Estuary and Nearshore Marine Environment

Claude Patrick Millet’14 (Environmental Studies and Biology).  Bowdoin College. “Ecological Recovery in the Kennebec Estuary and Nearshore Marine Environment.” John Lichter, advisor.

Project Summary:
Alewives (Alosa pseudoharengus) and blueback herring (Alosa aestivalis), which are collectively called river herring, constitute an important part of coastal Maine’s aquatic ecosystem, both inshore and offshore. As anadromous fish, they constitute an ecological link between rivers and the ocean and were once greatly abundant in Maine waters. Stocks have been historically depleted due to pollution, habitat destruction and overfishing, and are currently rebounding. The Sustainability Solutions Initiative (SSI), a collaborative project uniting Bowdoin College, Bates College and University of Southern Maine, aims at studying the fish populations and their environment in order to improve recovery efforts, especially in Merrymeeting Bay (MMB). MMB is a unique estuarine system in which 6 rivers (including the Androscoggin and Kennebec rivers) converge. As a member of Professor John Lichter’s lab, and an SSI fellow, I took part in this effort by helping to conduct censuses of fish populations in MMB and to map vegetation in the estuary. The purpose of the censuses was to track the presence of river herring juveniles in Merrymeeting bay, as well as to determine what other fishes occur in the system and potentially interact with the former. To this end, our team collected fish from 3 plots each at Abbagadasset point and on the Eastern River on a weekly basis using a seine net. Various water parameters such as pH and temperature were also collected on location.

Submerged aquatic vegetation (SAV) is of concern in restoration efforts because vegetation provides habitat for fish and their prey, as well as water oxygenation and improved water clarity. SAV had also been historically depleted in the estuary, and our mapping efforts were aimed at determining where patches of SAV occurred in MMB. We completed the enterprise, which had been started two summers ago. Mapping was conducted using the Trimble GeoExplorer 2008 GPS device which collects data that can be projected unto a map of the region in ArcMap, a GIS software. Data was collected by circling the patches on foot at low tide.

In addition to taking part in these projects, I assisted another student in collecting Alosid fish for his genetic studies, and initiated a research project of my own, which stems from the group project. I decided to investigate the effects of vegetation (its presence and diversity) on fish and benthic macroinvertebrate populations in MMB. Studies have shown that different species of plants harbor different invertebrates, which affects the biodiversity of the area (Strayer et al, 2003). I hypothesized that invertebrate diversity would increase with plant diversity, and that the distribution of fish would differ as vegetation characteristics varied within the system. I collected data on fish species by beach seining at various vegetated and unvegetated locations in the estuary, and data on invertebrates by using an invertebrate net, as well as by collecting plant samples. The invertebrate net samples were inspected to isolate all macroinvertebrates, which were then classified. I have yet to go through the plant samples, which I intend to do during the school year. In addition, I will perform the statistical analyses that will allow me to test my hypothesis.

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