Termohaline tolerances of Rapana venosa (Gastropoda: Muricidae) larvae under experimental conditions: implications for range expansions in coastal waters of Argentina

GIBERTO, D. A.; SCHIARITI, A.; MONTOYA, N.; BENAVIDEZ, H.; BRUNO, I.

Congreso; XV Congreso Latinoamericano de Ciencias del Mar COLACMAR; 2013

The gastropod Rapana venosa is one of most conspicuous exotic species inthe Río de la Plata, inhabiting mixohaline and marine waters. The invasion tothe adjacent waters of the region can be boosted by propagule pressure. Theplanktonic larvae of R. venosa iscapable of endure 20 to 80 days in the water column. So to determine thepotential expansion zones of the species we studied the larval survival underdifferent salinity and temperatures values usually recorded in coastal watersof Argentina. Larvae were subjected to different combinations of salinity (5,17, 35, 34), temperature (10°C, 15°C, 20°C) and salinity changes (gradual,abrupt) treatments during 48 hs (72 experimental units in total) and analyzedby an ANOVA. Average survival values for all larvae were 91%. Significantdifferences in survival were found only for temperatures of 20°C (77%), whilesurvival was similar for all salinity conditions, even after being exposed toan abrupt change of 30 units. Larvae with the lowest survival values were thoseexposed to 20°C and salinity of 5 (55.37% ± 16.6). The oceanographic regime ofthe Río de la Plata is characterized by a southern net current during thereproductive period of the species in summer, potentially transporting larvaeto adjacent waters. So larvae must be considered as a potential key responsibleof the dispersion trough coastal waters of Argentina.