Catherine Johnston, Class of 2012<\/p>\n
Merrymeeting Bay is a freshwater tidal ecosystem in midcoast Maine that experienced\u00a0ecosystem collapse in the mid-20th century. The focus of our study this summer was on two vital\u00a0components of the ecosystem that were negatively impacted by poor water quality, overfishing, and\u00a0other human activities. Submerged aquatic vegetation provides key habitat for a variety of organisms\u00a0present in the bay. Anadromous fish are economically and ecologically important fish that pass\u00a0through the bay before and after spawning. Studying vegetation and fish species can provide details\u00a0on the status of recovery of biological components of the bay.<\/p>\n
Submerged aquatic vegetation (SAV) are rooted aquatic plants and both freshwater and\u00a0marine species are present in our study area. Our work this summer focused on freshwater species of\u00a0Vallisneria and Potomogeton present in Merrymeeting Bay. For the past two summers, a Trimble\u00a0GeoXM GPS unit has been used to map vegetation beds on the ground (Figure 1). This distribution\u00a0data can be added to a graph of area of MMB that is covered by SAV (Figure 2). This can tell us\u00a0whether SAV is continuing to recover from its low densities in the early 1970s.<\/p>\n
Anadromous fish spend most of their life time in marine systems but spawn in freshwater.\u00a0Three species of the genus Alosa play pivotal roles in Maine waters. Alewives, shad, and Blueback\u00a0herring serve as nutrient transporters between freshwater and marine ecosystems. They are food\u00a0sources for important groundfish such as cod and are preferred lobster bait. Passage upriver to\u00a0spawning grounds is vital for anadromous fish in spring and early summer, but dams pose barriers to\u00a0migrating alosids. Fish ladders are effective for some species such as alewives and Atlantic Salmon,\u00a0but ladders are ineffective for shad passage. A study in coordination with the Maine DMR and Florida\u00a0Power and Light initiated this summer to investigate the effectiveness of a fish elevator at the\u00a0Brunswick-Topsham dam. A structure was engineered to simulate the flow generated by a fish lift\u00a0with the goal of monitoring how shad react to the flow. Two underwater cameras were placed in the\u00a0river and a computer program called SalmonSoft FishTick was used to capture and review video of\u00a0when shad passed the cameras. The results can help make a decision about installation of a fish lift.<\/p>\n
To answer questions about alosid activity in Merrymeeting Bay, weekly beach seines\u00a0were conducted at Abby Point. Species and length were recorded for each fish caught and\u00a0alsoids that did not survive were brought back to lab and their stomachs were preserved in\u00a0alcohol. Examining stomach contents of juvenile alosids can provide information on diet,\u00a0which has been previously unexplored for fish in the ecosystem. Diet analyses will answer\u00a0questions such as how diets differ by species and size class and whether diets are composed\u00a0primarily of planktonic or benthic invertebrates.<\/p>\n
Figure 1. Map of MMB vegetation 2010-2011<\/p>\n
Figure 2. Area of MMB covered by SAV<\/p>\n
Faculty Mentor: John Lichter, Biology<\/p>\n
Funded by the University of Maine, Sustainability Solutions Initiative<\/p>\n
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Catherine Johnston, Class of 2012 Merrymeeting Bay is a freshwater tidal ecosystem in midcoast Maine that experienced\u00a0ecosystem collapse in the mid-20th century. The focus of our study this summer was on two vital\u00a0components of the ecosystem that were negatively impacted … Continue reading