Bioaccumulation of Microcystins by Freshwater Mussels in Mystic Lake and Middle Pond, MA

The UNH Center for Freshwater Biology investigated a possible relationship between a cyanobacteria bloom and a large-scale die-off of freshwater mussels in Mystic Lake and Middle Pond (Barnstable, MA). Four mussel species, Elliptio complanata (Eastern Elliptio), Pyganodon cataracta (Eastern Floater), Leptodea ochracea (Tidewater Mucket), and Lampsilis radiata (Eastern Lampmussel) (Nedeau, 2008), along with water samples, were collected from these lakes on August 9, 2010 (during bloom) and again on September 29 and October 8, 2010 (post-bloom). Hepatopancreas tissue, foot tissue, and water samples were tested for the cyanobacteria toxins, microcystins (MC), using ELISA techniques. MC concentrations in the hepatopancreas were generally higher (171.2 ng MC g-1 dry weight (dw)) than in the muscle (foot) tissue (55.8 ng MC g -1 dw) for each species. Average microcystin concentrations in mussels sampled during postbloom tissues were slightly lower (161.6 ng MC g-1 dw) than those collected during the cyanobacteria bloom (171.2 ng MC g1 dw). Live mussels were also subjected to a depuration experiment to determine the release of MC from mussels into the water. Mussels that were placed in cyanobacteria-free water depurated 61-90% MC within the first few days demonstrating their ability to release free MC-cyanotoxins into the lake water