Hierarchical dominance structure in reintroduced California condors: correlates, consequences, and dynamics

Populations of reintroduced California condors (Gymnogyps californianus) develop complex social structures and dynamics to maintain stable group cohesion, and birds that do not successfully integrate into group hierarchies have highly impaired survivability. Consequently, improved understanding of condor socioecology is needed to inform conservation management strategies. We report on the dominance structure of free-ranging condors and identify the causes and consequences of rank in condor populations by matching social status with the behavioral and physical correlates of individual birds. We characterized the hierarchical social structure of wild condor populations as mildly linear, despotic, and dynamic. Condor social groups were not egalitarian and dominance hierarchies regulated competitive access to food resources. Absence of kin-based social groups also indicated that condor social structure is individualistic. Agonistic interactions among condors were strongly unidirectional, but the overall linearity and steepness of their hierarchies was low. Although one aggressive male maintained the highest dominance rank across the 3-year observation period, there was considerable fluidity in social status among condors within middle and lower rank orders. Older condors were more dominant than younger birds and younger males supplanted older females over time to achieve higher status. Dominance rank did not predict the amount of time that a bird spent feeding at a carcass or the frequency that a bird was interrupted while feeding. Thus, younger, less dominant birds are able to obtain sufficient nutrition in wild social populations.     

Sexual and asexual reproduction of<Emphasis Type="Italic"> Allostichaster capensis</Emphasis> (Echinodermata: Asteroidea) in Golfo Nuevo

Sexual and asexual reproduction of the fissiparous starfish Allostichaster capensis were examined for 24 months at Bahía Kaiser, Golfo Nuevo, Chubut, Argentina. Gonad indices revealed an annual reproductive cycle, with peak development occurring in late winter (August). Spawning occurred in spring (September). Pyloric caeca indices displayed a clear annual cycle and a reciprocal relationship with gonad indices, showing the storage function of pyloric caeca. The starfish population appears to be largely maintained by fission, as only two females were found. A. capensis also showed an annual cycle of fission, with the highest frequency in spring and summer (from November to January), just after spawning. Incidence of fission was correlated with environmental factors such as photoperiod, seawater temperature, and salinity.Communicated by P.W. Sammarco, Chauvin     

Reproductive biology of <Emphasis Type="Italic">Cosmasterias lurida</Emphasis> (Echinodermata: Asteroidea) an anthropogenically influenced substratum from Golfo Nuevo,Northern Patagonia (Argentina)

The starfish Cosmasterias lurida was sampled from the pier piles of Almirante Storni in the Golfo Nuevo, northern Patagonia, from November 2001 to November 2003. In this anthropogenically modified site there is an unusually abundant food supply of mussels and large aggregations of starfishes. The reproductive cycle was studied by organ indices and histological examination of gonads. The highest gonad index (GI) values were found in the summer (February–March), followed by a drop in GI values, indicating spawning. Histological analyses indicated that gametogenesis takes place from June to January, sexual maturity occurred during the summer and spawning occurred in April. The GI and pyloric caeca index (PCI) tended to have an inverse relationship, but this was only statistically significant in males. However, biochemical analyses of the starfish indicated no transfer of nutrients between pyloric caeca and gonads in either sex. In fact, simultaneous accumulation of carbohydrates was found in the pyloric caeca and gonads of both sexes.     

Evaluation of spatial and temporal variations in marine sediments quality using multivariate statistical techniques

Spatial and temporal variations of sediment quality in Matanzas Bay (Cuba) were studied by determining a total of 12 variables (Zn, Cu, Pb, As, Ni, Co, Al, Fe, Mn, V, CO₃ ^2?, and total hydrocarbons (THC). Surface sediments were collected, annually, at eight stations during 2005–2008. Multivariate statistical techniques, such as principal component (PCA), cluster (CA), and lineal discriminant (LDA) analyses were applied for identification of the most significant variables influencing the environmental quality of sediments. Heavy metals (Zn, Cu, Pb, V, and As) and THC were the most significant species contributing to sediment quality variations during the sampling period. Concentrations of V and As were determined in sediments of this ecosystem for the first time. The variation of sediment environmental quality with the sampling period and the differentiation of samples in three groups along the bay were obtained. The usefulness of the multivariate statistical techniques employed for the environmental interpretation of a limited dataset was confirmed.     

The interplay between exposure to PAHs and MTHFR C677T polymorphism on cardiovascular risk biomarkers in Mexican women

Environmental Science and Pollution Research - Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. Environmental and genetic factors are recognized as risk...