The relationships between the distribution of different zooplankton and ichthyoplankton stages an... more The relationships between the distribution of different zooplankton and ichthyoplankton stages and physical and chemical variables were studied using samples and data (CTD profiles, ADCP and current meter measurements, nutrients, mesozooplankton, ichthyoplankton) obtained from different strata during two 24-h cycles at two oceanographic stations in a Chilean Patagonian gulf during the CIMAR 10-Fiordos cruise (November, 2004). A station located at the Chacao Channel was dominated by tidal mixing and small increments in surface stratification during high tides, leading to decreased nutrient availability. This agreed with short periods of increased phytoplankton abundance during slack waters at the end of flood currents. Increases in larval density for all zooplankton and ichthyoplankton taxa corresponded to the flooding phases of the tidal cycle. When the larval density data were fit to a sinusoidal model, the regression coefficients were high, suggesting that tides are important features that modulate short-term variations in plankton abundance. All larvae did not vary synchronously with the tidal phase; rather, time lags were observed among species. The abundances of older individuals of the copepodite Rhincalanus nasutus and all zoea stages of the squat lobster Munida gregaria increased during night flood tides, whereas younger stages increased during daytime flood tides. At a station located at the Queullin Pass, which was dominated by vertical stratification patterns, the variations in peak larval density were better fitted to the semi-diurnal sea level fluctuations. Other evidence indicated internal tides below the pycnocline, which could promote larval transport in deeper layers. In the overall picture that emerges from this study, planktonic organisms from different habitats and phylogenetic origins seem to respond to the local tidal regimes. In some cases, this response might be beneficial, transporting these individuals inshore to areas that are rich in food during the peak biological production season.
Sterechinus neumayeri is an abundant regular sea urchin that lives in the shallow Antarctic water... more Sterechinus neumayeri is an abundant regular sea urchin that lives in the shallow Antarctic waters. This organism has been used as a model system in many fields of the Antarctic biology. Yet, understanding of the evolutionary identity of the species, such as its phylogenetic relationships and divergence time, remains limited. Here, we reconstructed the molecular phylogenies of the species together with two sea urchin species in southernmost South America (Loxechinus albus and Pseudechinus magellanicus), a parechinid species (Paracentrotus lividus) and three strongylocentrotid species (Strongylocentrotus purpuratus, S. intermedius, and Hemicentrotus pulcherrimus) using mitochondrial DNA sequences of 12S rDNA-tRNA(gln) region (877nt) and cytochrome oxidase subunit I (COI, 1079nt). The rate of sequence evolution and the divergence time of the species were then estimated from the trees. The phylogenetic trees reveal that S. neumayeri is a sister group to the lineage of L. albus and P. l...
León, R., Castro, L. R., and Cáceres, M. 2008. Dispersal of Munida gregaria (Decapoda: Galatheida... more León, R., Castro, L. R., and Cáceres, M. 2008. Dispersal of Munida gregaria (Decapoda: Galatheidae) larvae in Patagonian channels of southern Chile. – ICES Journal of Marine Science, 65: 1131–1143. The dispersal of Munida gregaria larvae in Chilean Patagonian channels was assessed in spring 2002 and 2003, and winter 2003. In winter 2003, zoea I was the most abundant stage in all channels and there were no larval stages older than zoea IV. In spring 2002 and 2003, there were six larval stages in all channels, and the greater abundance of older larvae suggested that reproduction takes place in winter and larval development in spring. Further, analysis of spatial distribution by stage revealed that early zoeae moved seawards. Generalized Additive Models analyses showed that most larval stages were temperature-dependent, and that the salinity range of the youngest zoea was wider than that of older larvae and post-larvae, coinciding with an ontogenetic distribution change from estuary to...
Fecundity, egg size, embryo losses and reproductive output (RO) was studied in 84 Austopandalus g... more Fecundity, egg size, embryo losses and reproductive output (RO) was studied in 84 Austopandalus grayi females collected in the channels of the Aysén Region (44º S to 46º S) during the cruises CIMAR 7 Fiordos and CIMAR 8 Fiordos carried out in July 2001 and July 2002. Most of the females carried early stage embryos (68%) and just 6% embryos in final stages. Mean fecundity was higher in 2002, ranging from 185 to 3,200 eggs, than in 2001, when ranged from 48 to 1,329 eggs. The size of the eggs had also higher mean volume in 2002 (0.062 mm 3) that in 2001 (0.037 mm 3). The specimens collected in 2001 came from estuarine areas with lower temperatures and high water dilution that could explain the high interannual differences found. Embryo losses from stage I to stage II was estimated in 25%, and showed a tendency to be higher in smaller size females, although due to the high data variability the differences were not statistically significant. RO was 0.22 in 2001 and 0.24 in 2002 and was not related to female size. Egg water content did not vary significantly among the three stages assessed. Considering a previous study in a population from the Strait Magellan (53º S) the obtained information suggests that A. grayi has an increase in energy investment per egg and a decrease of RO toward higher latitudes.
The relationships between the distribution of different zooplankton and ichthyoplankton stages an... more The relationships between the distribution of different zooplankton and ichthyoplankton stages and physical and chemical variables were studied using samples and data (CTD profiles, ADCP and current meter measurements, nutrients, mesozooplankton, ichthyoplankton) obtained from different strata during two 24-h cycles at two oceanographic stations in a Chilean Patagonian gulf during the CIMAR 10-Fiordos cruise (November, 2004). A station located at the Chacao Channel was dominated by tidal mixing and small increments in surface stratification during high tides, leading to decreased nutrient availability. This agreed with short periods of increased phytoplankton abundance during slack waters at the end of flood currents. Increases in larval density for all zooplankton and ichthyoplankton taxa corresponded to the flooding phases of the tidal cycle. When the larval density data were fit to a sinusoidal model, the regression coefficients were high, suggesting that tides are important features that modulate short-term variations in plankton abundance. All larvae did not vary synchronously with the tidal phase; rather, time lags were observed among species. The abundances of older individuals of the copepodite Rhincalanus nasutus and all zoea stages of the squat lobster Munida gregaria increased during night flood tides, whereas younger stages increased during daytime flood tides. At a station located at the Queullin Pass, which was dominated by vertical stratification patterns, the variations in peak larval density were better fitted to the semi-diurnal sea level fluctuations. Other evidence indicated internal tides below the pycnocline, which could promote larval transport in deeper layers. In the overall picture that emerges from this study, planktonic organisms from different habitats and phylogenetic origins seem to respond to the local tidal regimes. In some cases, this response might be beneficial, transporting these individuals inshore to areas that are rich in food during the peak biological production season.
Sterechinus neumayeri is an abundant regular sea urchin that lives in the shallow Antarctic water... more Sterechinus neumayeri is an abundant regular sea urchin that lives in the shallow Antarctic waters. This organism has been used as a model system in many fields of the Antarctic biology. Yet, understanding of the evolutionary identity of the species, such as its phylogenetic relationships and divergence time, remains limited. Here, we reconstructed the molecular phylogenies of the species together with two sea urchin species in southernmost South America (Loxechinus albus and Pseudechinus magellanicus), a parechinid species (Paracentrotus lividus) and three strongylocentrotid species (Strongylocentrotus purpuratus, S. intermedius, and Hemicentrotus pulcherrimus) using mitochondrial DNA sequences of 12S rDNA-tRNA(gln) region (877nt) and cytochrome oxidase subunit I (COI, 1079nt). The rate of sequence evolution and the divergence time of the species were then estimated from the trees. The phylogenetic trees reveal that S. neumayeri is a sister group to the lineage of L. albus and P. l...
León, R., Castro, L. R., and Cáceres, M. 2008. Dispersal of Munida gregaria (Decapoda: Galatheida... more León, R., Castro, L. R., and Cáceres, M. 2008. Dispersal of Munida gregaria (Decapoda: Galatheidae) larvae in Patagonian channels of southern Chile. – ICES Journal of Marine Science, 65: 1131–1143. The dispersal of Munida gregaria larvae in Chilean Patagonian channels was assessed in spring 2002 and 2003, and winter 2003. In winter 2003, zoea I was the most abundant stage in all channels and there were no larval stages older than zoea IV. In spring 2002 and 2003, there were six larval stages in all channels, and the greater abundance of older larvae suggested that reproduction takes place in winter and larval development in spring. Further, analysis of spatial distribution by stage revealed that early zoeae moved seawards. Generalized Additive Models analyses showed that most larval stages were temperature-dependent, and that the salinity range of the youngest zoea was wider than that of older larvae and post-larvae, coinciding with an ontogenetic distribution change from estuary to...
Fecundity, egg size, embryo losses and reproductive output (RO) was studied in 84 Austopandalus g... more Fecundity, egg size, embryo losses and reproductive output (RO) was studied in 84 Austopandalus grayi females collected in the channels of the Aysén Region (44º S to 46º S) during the cruises CIMAR 7 Fiordos and CIMAR 8 Fiordos carried out in July 2001 and July 2002. Most of the females carried early stage embryos (68%) and just 6% embryos in final stages. Mean fecundity was higher in 2002, ranging from 185 to 3,200 eggs, than in 2001, when ranged from 48 to 1,329 eggs. The size of the eggs had also higher mean volume in 2002 (0.062 mm 3) that in 2001 (0.037 mm 3). The specimens collected in 2001 came from estuarine areas with lower temperatures and high water dilution that could explain the high interannual differences found. Embryo losses from stage I to stage II was estimated in 25%, and showed a tendency to be higher in smaller size females, although due to the high data variability the differences were not statistically significant. RO was 0.22 in 2001 and 0.24 in 2002 and was not related to female size. Egg water content did not vary significantly among the three stages assessed. Considering a previous study in a population from the Strait Magellan (53º S) the obtained information suggests that A. grayi has an increase in energy investment per egg and a decrease of RO toward higher latitudes.
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