Heavy Metals in Seaweeds from a Polluted Estuary in Coastal Maine

Seaweeds (macroalgae) accumulate heavy metals from seawater and can therefore serve as biological monitors of marine pollution. In this paper, we present data on the tissue chemistry of seaweeds from the area of Callahan Mine, an intertidal copper and zinc mine in Brooksville, ME, USA, abandoned in the 1970s and now designated as a Superfund site. The mine is located on the Goose Pond estuary, which drains into the ocean via a tidal waterfall at Goose Falls. Seaweed tissue samples from this estuary had the same relative concentrations of metals as had been reported previously in water samples from this location, with Zn > Cu > Pb > Cd. Ascophyllum nodosum, the most common macroalgal species in the area, had comparatively high levels of all four metals in samples from Goose Pond itself, while samples from Goose Falls tended to have substantially lower metal concentrations statistically indistinguishable from samples collected in nearby unpolluted sites. At Goose Falls, where seaweed diversity was highest, Fucus distichus subsp. evanescens tended to accumulate the highest levels of Zn, Cu, Pb, and Cd. We discuss the implications of these results for the Callahan Mine environment and, more generally, for using seaweeds as biological monitors of metal pollution in coastal Maine. In an online appendix, we also provide historical and modern floristic data on the seaweeds of the Callahan Mine. The floristic and tissue chemistry data are baseline information which may be useful for the future assessment and remediation of the mine.