Growth changes of the stout razor clam Tagelus plebeius (Lightfoot, 1786) at different salinities in SW Atlantic estuaries

ADDINO M.,; ALVAREZ F.,; BREY T.,; IRIBARNE O.; LOMOVASKY BETINA J.

JOURNAL OF SEA RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2019 vol. 146 p. 14 - 23

1385-1101

Estuarine abiotic characteristics vary with the tidal water influence and the fresh water input, both driven by climatic conditions and cyclical climatic events. These are very productive areas where bivalves often represent the major proportion of the biomass with an important ecological role. Salinity fluctuation is often the key environmental factor affecting the shell growth parameters and individual condition index (CI), which may demonstrate the performance of one population in a given environmental setting. The stout razor clam Tagelus plebeius is a euryhaline filter-feeder species that inhabits sandy-silt tidal flats within a wide salinity range. The objective of this study was to evaluate, by survey sampling and in situ transplant experiments among sites with different salinity, whether shell growth and CI of T. plebeius vary with the salinity regime. We hypothesize a higher growth and CI related to the intermediate salinity. Clams and abiotic parameters were sampled in three estuaries of the northern Argentinean coast with different salinity regimes, and in three sites along the salinity gradient of the Mar Chiquita coastal lagoon (MC, 37º32?S) where the manipulative experiments were also conducted. Shells were more elongated in sites with lower salinity; but the growth rate (k) and the CI were higher in sites with intermediate salinity. Further, clams transplanted from intermediate salinity sites to those with higher or lower salinity showed a disadvantage in shell growth. Then, a better performance in sites with intermediate salinity was found. Considering the scenario of climatic driven salinity changes in these estuaries and given that T. plebeius is the only native bivalve species in those intertidals, having a relevant ecological role and conspicuous fossil presence in Holocene outcrops, the findings presented in this study highlight the relevance of this clam as a valuable target for future studies on biology and paleobiology conservation.