Thermal tolerance in embryos and larvae of the bay scallop Argopecten irradians under simulated power plant entrainment conditions

Thermal tolerance was tested in cleavage stages, trochophores and straight hinge larvae of the bay scallop Argopecten irradians. Experiments were designed to simulate larval entrainment in power plant cooling systems. An 11 (temperature) x 8 (time) matrix was used with temperatures ranging from 20.6 to 43.0 oc and exposure times from 1 min to 6 h. Pooled mortality data from triplicate experiments for each larval stage were subjected to stepwise regression analysis (Yarcsine % mortality on temperature and time). Equations derived from these analyses, comprising first, second and third order terms for temperature and time, were used to generate response surfaces relating mortality to temperature and exposure time. In general. higher mortalities were associated with higher temperatures and with longer time exposure at any one temperature. However, there was some evidence of cold shock in trochophore and straight hinge larvae, with elevated mortalities occurring at temperatures lower than the spawning temperature. There was a trend towards increased thermal tolerance in older larvae, although in general A. irradians showed the greatest sensitivity to thermal shock of the estuarine bivalves so far tested in our laboratory

Algunos aspectos de la ecología de nidificación de la tortuga dulceacuícola, tereca y podocnemis unifilis

IP 3253-09-002-91Tortoises and Turtles (1993 Jul. 11-16 : New York) -- Incubationperiods and nest loss due to flooding in;Podocnemis unifilis (Pelomedusidae) in the colombian amazon /Bock B.C ...[et.al]. -- En: Joint meeting The;Herpetologists League (1994 Jul. 28 : Georgia, USA) -- Estudiopreliminarde telemetria en la tortuga;dulciacuicola Podocnemis unifilis en el bajo Caqueta colombiano/ N.F. Perez B. ... [et.al]. -- En: Congreso;Latinoamericano de Ecologia (3 : 1995 oct. 22-28 : Merida,Venezuela) -- Temperature dependent sex;determination in the Pelomedusid turtle Podocnemis unifilis /V.P. Paez, B.C. Bock, O.A. Almanza. -- En: Joint;meeting The Herpetologists League (1994 Jul. 28 : Georgia,USA)'-- Pre- and post-hatching factors affecting;captive juvenile growth rates in the yellow-spotted amazonianturtle, Podocnemis unifilis / V.P. Paez ...;[et.al]. -- En: American Society of Zoologists Annual Meeting(1995 Dec. 26-30 : Washington);PONENCIA(S) EN CONGRESO: Nesting ecology of the yellow-spottedriver turtle in the colombian amazon / Vivian;P. Paez and Brian Bock. -- En: International Conference inConservation, Restoration, and Managment o

Inheritance of nesting behaviour across natural environmental variation in a turtle with temperature-dependent sex determination

Nesting behaviour is critical for reproductive success in oviparous organisms with no parental care. In organisms where sex is determined by incubation temperature, nesting behaviour may be a prime target of selection in response to unbalanced sex ratios. To produce an evolutionary change in response to sex-ratio selection, components of nesting behaviour must be heritable. We estimated the field heritability of two key components of nesting behaviour in a population of painted turtles (Chrysemys picta) with temperature-dependent sex determination by applying the ‘animal model’ to a pedigree reconstructed from genotype data. We obtained estimates of low to non-detectable heritability using repeated records across all environments. We then determined environment-specific heritability by grouping records with similar temperatures for the winter preceding the nesting season, a variable known to be highly associated with our two traits of interest, nest vegetation cover and Julian date of nesting. The heritability estimates of nest vegetation cover and Julian date of nesting were qualitatively highest and significant, or nearly so, after hot winters. Additive genetic variance for these traits was not detectable after cold winters. Our analysis suggests that the potential for evolutionary change of nesting behaviour may be dependent on the thermal conditions of the preceding winter, a season that is predicted to be especially subject to climate change