Reproduction and Population Structure of Corbicula fluminea in an Oligotrophic Subalpine Lake

ABSTRACT Reproductive effort and population structure of the nonnative clam Corbicula fluminea were studied in an oligotrophic subalpine lake. Three shallow sites (5 m) and one deeper site (20 m) were studied between May 11, 2010, and November 5, 2010, to determine spatial variation and the influence of environmental conditions (e.g., temperature and food availability as determined by total organic carbon (TOC) and sediment particulate organic matter (SPOM) on reproductive effort. The clam C. fluminea exhibited a univoltine spawn cued by increases in temperature. Reproductive effort calculated for adult clams (13.67 ± 0.03 mm (SE), n = 1,875) across sites was not influenced by TOC and SPOM concentrations, and overall reproductive effort was less than more productive ecosystems, which may be a result of Lake Tahoe's ultraoligotrophy. All 3 shallow sites had similar levels of reproductive effort. Once veligers were observed, of the 603 clams then dissected, there were 10 ± 2 veligers per clam (±SE), 25 clam...