Trophic Status of Casco Bay, Maine, as Delineated by Seaweed Diversity and Tissue Analysis
Casco Bay is the second largest bay in Maine and, because of its size, complexity and habitat diversity, provides a variety of critical environments for juvenile and adult fish and birds. Unfortunately, the Bay has experienced diverse sources of toxic pollution (polyaromatic hydrocarbons, heavy metals, sewer discharges, etc.), which have degraded wildlife habitats and diminished water quality.
A number of organizations have come together to develop a Casco Bay Plan designed to reverse this degradation. This research will contribute to that effort by characterizing seaweed populations from estuarine and open coastal sites in the Bay and evaluating possible long-term changes, by evaluating several recent changes in seaweed communities due to human introductions and/or anthropogenic effects, and by analyzing seaweed tissue for PAH, trace metals and nutrient pollution in order to compare polluted and pristine sites.
The primary objectives of our proposed studies are three-fold:
1) Characterize seaweed populations from estuarine and open coastal sites in Casco Bay and evaluate possible long term changes (early 1900s versus present-day) of seaweed biodiversity (i.e., species richness and composition) from a variety of "natural" and "stressed" environments using historical records by F. S. Collins
2) Evaluate several recent changes (50 years or less) in seaweed communities due to human introductions and/or anthropogenic effects, plus identify indicator species for polluted and "pristine" areas that can be monitored by coastal managers
3) Analyze tissue contents in two broadly cosmopolitan seaweed taxa (i.e., Ascophyllum nodosum and Ulva lactuca) for PAH, trace metal (Pb, Hg and chromates) and nutrient pollution (cf. Hardwick-Witman & Mathieson 1986; Levine 1984; Lyngby 1990; Phillips 1977; Rueness 1973; Whitton 1984) that will be used to compare indicator species from polluted and more "pristine sites." Transplants of A. nodosum from clean to polluted sites will also be analyzed in order to assess the speed of metal and nutrient uptake. Similar assessments of tissue contents in historical herbarium samples will be made in order to provide a timeline for pollution events.
Seasonal collections of the dominant seaweed populations at approximately 20 sites within Casco Bay will be made from the summer of 2001 through the spring of 2003. Seaweed samples will be obtained from diverse coastal, estuarine and riverine sites that are currently being sampled by the Friends of Casco Bay and previously evaluated by F. S. Collins, including various sites on the Fore, Harraseeket, New Meadows, Presumscot and Royal Rivers.
Seaweed samples from different substrata types (rock outcrops, boulders, breakwaters and sandy-muddy areas) at each site will be obtained, as well as at habitats with varying hydrographic conditions (temperature and salinity). Both of these physical factors are of critical importance in determining estuarine algal populations (Hardy et al. 1993; Mathieson and Fralick 1973; Mathieson and Hehre 1986; Mathieson and Penniman 1986b; Wilkinson 1980).
Overall, the methods of collection, identification and processing of samples will be similar to those outlined by Hehre and Mathieson (1970) and Mathieson et al. (1981, 1996, 1998), with representative samples of all conspicuous intertidal and subtidal specimens being collected at each site. A complete set of herbarium voucher specimens (i.e., each taxon/site) will be prepared and deposited at the University of New Hampshire (NHA) in order to document these biodiversity patterns. Although Taylor (1957) will be the primary source of identification, other recent monographs will be employed for nomenclatural changes (cf. Bird and McLachlan 1992; Burrows 1991; Dixon and Irvine 1977; Fletcher 1987; Irvine 1983; Irvine and Chamberlain 1994; Maggs and Hommersand 1993; Mathieson et al. 1981, 1993; Mathieson and Hehre 1986; Prud'homme van Reine 1982; Schneider and Searles 1991; Sears 1998; South and Tittley 1986; Villalard-Bohnsack 1995).
The study will evaluate whether present-day seaweed biodiversity within Casco Bay, Maine, has changed significantly since earlier (1911) assessments by F.C. Collins, particularly within the "industrial corridor" of the Fore River. The use of biodiversity and bioassay data will allow coastal managers to identify anthropogenic impacts. Bioassay evaluations of in situ, transplanted, and historical herbarium samples of Ascophyllum nodosum and Ulva lactuca will evaluate patterns of spatial and historical pollution within Casco Bay.
Available from the National Sea Grant Library (use NHU number to search) or NH Sea Grant
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