A twenty-year record of carbon isotope values of amino acids from Potamocorbula amurensis

Amino acids were isolated from the muscle tissue of Potamocorbula amurensis, an invasive clam species, collected from two locations in the northern portion of the San Francisco Bay. Clam specimens were collected biannually in 1997, 2002, and from 2009-2017 at both locations. The carbon isotope values of individual amino acids were measured. Clam specimens were collected at USGS Sites 4.1 (Suisun Bay) and 8.1 (Carquinez Strait) in the San Francisco Bay and processed as described in Stewart et al. (2013; doi:10.3354/meps10503). Amino acids were hydrolyzed from P. amurensis, derivatized, isolated and the carbon isotope values were measured following Vokhshoori et al. (2013; doi:10.3354/meps10746). The purpose of this study was to assess long-term changes in dietary sources and/or changes in the baseline carbon isotope value of the estuary's food-web following the invasion of P. amurensis.