Project: Changes in Baseline Conditions in Gulf of Maine Coastal Ecosystems Over the Last 4000 Years

Description from NSF award abstract:
Predicting the responses of marine ecosystems to natural and anthropogenic perturbation remains one of the greatest challenges to oceanography. In order to assess the significance of current changes in these systems and to predict possible future changes, oceanographers need to understand the ecological history of the ecosystem. The aim of this study is to create long-term records for the Gulf of Maine (GoM), a marginal shelf basin in the northwest Atlantic. Current knowledge of the resilience of the GoM ecosystem is based largely on studies focused on the last 70+ years. In this project, investigators will develop an understanding of ecosystem processes in the GoM extending back 4000 years by analyzing stable carbon (C), nitrogen (N) and sulfur (S) isotopes preserved in tissues of modern and ancient marine organisms to assess long-term trends in nearshore primary production, trophic connectivity, and food web dynamics.

The investigators will employ a combination of field, analytical, and modeling techniques to:
(1) determine the spatial scale over which organic matter derived from seagrasses, microalgae, and macroalgae is currently transferred into coastal food webs, and
(2) determine the timing, magnitude, and spatial extent of changes in nearshore primary production and trophic connectivity among organisms living in the GoM through the last 4000 years.

Tissue samples will be obtained from different coastal settings, museum collections, and three coastal archaeological sites in the GoM. The bulk organic fractions of primary producers and consumers will be analyzed for C, N, and S isotopes. The C isotope composition of essential amino acids (e.g., phenylalanine) will be measured, allowing for determination of the carbon source at the base of the food web. Nearshore food web interactions will be modeled by using the C, N and S isotope data and non-steady state equations that include competition-dependant changes in the consumers prey choice.