Baseline Information Describing Sediment Physicochemistry of Totten Inlet and the Macrobenthos of the Proposed North Totten Inlet Mussel Farm

Background. Healthy shellfish populations are important to the proper function of estuarine ecosystems. Estuaries like Chesapeake Bay once held large numbers of American oysters (Crassostrea virginica). Historically, these oysters filtered the entire bay’s water volume every 3.3 days. Several centuries of over exploitation compounded by diseases such as Perkinsus marinus and MSX, coupled with water pollution, reduced oyster abundance to the point where in 1988 the remnant population filtered the bay only once every 325 days – a one hundred fold decrease (Newell, 1988). The result has been increased turbidity in the water which has reduced light penetration to the point where submerged aquatic vegetation (SAV) has died off, reducing valuable estuarine habitat for fish and other shellfish such as the blue crab (Callenectes sapidus). Several other authors (Cloern, 1982; Officer et al., 1982; Cohen et al., 1984; Peterson and Black, 1991) have demonstrated the importance of bivalves for controlling phytoplankton and increasing water clarity. Haamer (1996) used an empirical model to assert that mussel farms covering 1 to 2.4% of a eutrophic Swedish fjord would result decrease dissolved inorganic nitrogen by 20% and that bivalves would reduce biological oxygen demand (BOD) in deep basin water by 26%. Haamer (1996) cautioned that mussel farms should be located such that feces and pseudofeces could not collect in deep basins where there is no flushing and consequently little oxygen. It should be noted that mussel farms, as proposed in Totten Inlet by Taylor Resources would cover only 0.034% of the inlet or 29 to 71 times less than proposed by Haamer (1996) as a eutrophication control. Unlike natural populations of animals, whose population size tends to be controlled by competition for food, space and predation, intensive aquaculture of bivalves has the potential to exceed the carrying capacity of estuaries (i.e. depleting organic seston to the point where the ecosystem is adversely affected) and to transfer organic matter filtered from the water to sediments in the form of feces and pseudofeces to an extent that sediment chemistry and the macrobenthos are affected. In sediments containing low amounts of organic matter, moderate amounts of added aquaculture waste are seen as food for detritivores and can result in significant increases in both the diversity and abundance of macrobenthic communities. If these waste products exceed the assimilative capacity of sediments for organic carbon, sediment oxygen can be diminished by aerobic bacteria. Facultative anaerobes, like Desulfovibrio bacteria, then strip oxygen from sulfate and excrete sulfides as a metabolic waste product that affects macrobenthic communities. Physicochemical changes in sediment chemistry and their effects on the macrobenthos have been extensively studied in association with salmon farms in the Pacific Northwest by Brooks (2001a, 2001b), Brooks, et al. (2002), Brooks and Mahnken (2003a, 2003b), and Brooks (2003a, 2003b) and are reasonably well understood. Unlike salmon aquaculture, in which organic matter in the form of feed is added to coastal ecosystems, bivalve culture relies on naturally produced food. The net result is that bivalve aquaculture removes nutrients from coastal bays. Rice (unpublished) concluded that for each kilogram of shellfish meats harvested from an aquaculture farm, 16.8 grams of nitrogen were removed from the