RANGIA CUNEATA IN THE LOWER NECHES RIVER, REVISITED: THE EFFECT OF A PERMANENT SALTWATER BARRIER ON A BRACKISH INDICATOR SPECIES
The estuarine clam, Rangia cuneata, invaded the upper reaches of the lower Neches River as it was dredged in the early to mid-1900s. Adult clams are tolerant of a wide range of disturbances, but require a salinity pulse to spawn. The construction of the Lower Neches River salt water barrier in 2003 eliminated salinity pulses in a portion of the river. We surveyed the Neches River above and below the barrier in 2016 and compared our results to rangia data collected in the 1950's, 1980's and 1990's, when rangia beds dominated the lower river, with few other bivalves present. The lack of salt-water pulses lead to drastic decreases in clam abundance above the barrier. The few individuals present were large and old, likely settling during pre-barrier spawning events. We developed a salinity-flow model broken-stick regression model and estimated when salinity conditions would facilitate spawning, which corresponded with cohort ages in rangia beds below the barrier. The loss of rangia above the barrier has allowed other freshwater unionid species to become established in areas that they may not have inhabited for over 100 years.
Matthew Pyne (Primary Presenter/Author), Lamar University, firstname.lastname@example.org;
Ana Christensen (Co-Presenter/Co-Author), Lamar University, email@example.com;