Date of Graduation

Spring 5-2011

Level of Access

Open Access

Degree Name

Bachelor of Arts

Department or Program

Biology

Second Department or Program

Geology

Number of Pages

117

Abstract

Changes to nearshore systems and food web dynamics over the past 2,400 years were assessed using stable carbon and nitrogen isotope analysis of fish bone collagen recovered from archaeological middens in Penobscot Bay, Maine. The stable isotope composition of Atlantic cod (Gadus morhua), Winter flounder (Pseudopleuronectes americanus), and Longhorn sculpin (Myoxocephalus octodecemspinosus) from seven coastal middens was compared to two modern samples: one nearshore in Penobscot Bay anrisd one 20-30km offshore on Georges Bank, Gulf of Maine. The δ13C of flounder decreased by 4‰ from 2,400 BP to the present and may reflect a prehistoric loss of eelgrass (Zostera marina) along Maine’s coast. The δ15N of cod, an apex predator, decreased by 2‰ from 2,400 BP until the present, suggesting the trophic level of cod declined. This may indicate the population was under constant fishing pressure by indigenous people. The δ15N of sculpin and flounder, both mesopredators, increased between 2,400 BP and 1,000 BP, suggesting an increase in trophic level. These populations may have been released from cod predation and permitted to increase in size and abundance, allowing them to feed at higher trophic levels. The δ15N of all species decreased between 500 BP and the present likely indicating increased fishing pressures instigated by the arrival of Western Europeans to Maine’s coast. The magnitude of offsets among the δ13C and δ15N study species at each time period also decreased over time, possibly indicating the ecological niches of omnivorous fish are smaller and may overlap in the modern Penobscot Bay system.

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