The role of temperature and oxygen availability on the distribution ofCorbicula largillierti

Abstract

The invasiveness of Corbicula largillierti has been underestimated, but this bivalve is currently receiving more attention. The first study of the distribution of this species along one of the major basins of central Argentina showed that it was completely absent in the major central reservoir, but was present along its tributary and effluent rivers. Ten years later, this discontinuous distribution has not changed, despite the bivalve's high dispersion capacity. The main environmental differences between the reservoir and the rivers are that the former has finer sediment grain size, higher temperatures, and lower oxygen concentration during summer months. This study aimed to evaluate whether one of these factors could be limiting the distribution of C. largillierti. We assessed the metabolic response and burial behavior (under different grain sizes) of C. largillierti over 8 weeks at 30°C against a control condition at 20°C. We also analyzed the oxygen consumption (vO2) as a function of environmental oxygen concentration (pO2) at 25°C, estimating its metabolic regulation capacity (R). This showed the existence of an environmental oxygen concentration threshold (Pt) that could be an indicative of physiological limiting concentrations that compromise species survival and settlement. After 8 weeks at 30°C, the metabolic rate of individuals of C. largillierti increased and their burial behavior was slightly compromised but mostly for coarser sediments. Concerning environmental oxygen availability, C. largillierti is an oxyconformer with a low R (39.9%), a clear pattern of negative regulation, and a low Pt (48.4% air saturation). The lack of any regulation capacity of C. largillierti under environmental oxygen limitations and the extremely low pO2 at the bottom of the reservoir during summer months may explain its failure to colonize and survive there.

FIRST RECORD OF THE ASIAN CLAM Corbicula largillierti (PHILIPPI, 1844) IN THE LOWER SÃO FRANCISCO RIVER, NORTHEASTERN BRAZIL

“…Although both species may be sympatric, C. largillierti appears to be a less effective competitor than C. fluminea, and this interspecific competition for space and food has resulted in a decrease in population size and even displacement of the C. largillierti (DARRIGRAN, 1992;RESHAID et al, 2017;REYNA et al, 2018). Furthermore, C. largillierti is more sensitive to lower oxygen levels, limiting the species' ability to colonize and survive at the bottom of the reservoir (RODRIGUEZ et al, 2020). Indeed, C. largillierti seems to be better adapted to streams and brook environments RESHAID et al, 2017).…”