84 resultados para Lytechinus variegatus.
Resumo:
About 80 species of spores and pollen grains were recorded during detailed palynological investigations of selected Lower Cretaceous sections from Holes 638B and 638C and the bottom of Hole 641C. Most of them are long-ranging taxa with worldwide distribution. However, on the Iberian margin and in the southern European basins, Trilobosporites canadensis, Trilobosporites bernissartensis, Parvisaccites amplus, Foveosporites subtriangularis, and Ephedripites multicostatus seem to be index species of the Valanginian to late Aptian interval. Clavatipollenites was not recovered in the Barremian marginal marine sediments.
Resumo:
Current water management practices in South Florida have negatively impacted many species inhabiting Florida Bay. Variable and high salinity has been identified as a key stressor in these estuaries. The Comprehensive Everglades Restoration Plan (CERP) includes water redistribution projects that will restore natural freshwater flows to northeastern Florida Bay. My studies focused on the following central theme and hypotheses: Biological performance measures (i.e., growth, reproduction, survival), behavior (i.e., habitat preference and locomotor behavior) and diversity of estuarine fish will be controlled by changes in salinity and water quality that will occur as a result of the restoration of freshwater flow to the bay. A series of acute and subchronic physiological toxicity studies were conducted to determine the effects of salinity changes on the life stages (embryo/larval, juvenile, adult) and fecundity of four native estuarine fish (Cyprinodon variegatus, Floridichthys carpio, Poecilia latipinna, and Gambusia holbrooki). Fish were exposed to a range of salinity concentrations (freshwater to hypersaline) based on salinity profiles in the study areas. Growth (length, weight) and survival were measured. Salinity trials included both rapid and gradual change events. Results show negative effects of acute, abrupt salinity changes on fish survival, development and reproductive success as a result of salinity stress. Other studies targeted reproduction and critical embryo-larval/neonate development as key areas for detecting long-term population effects of salinity change in Florida Bay. Adults of C. variegates and P. latipinna were also examined for behavioral responses to pulsed salinity changes. These responses include changes in swimming performance, locomotor behavior and zone preference. Finally, an ecological risk assessment was conducted for adverse salinity conditions in northeastern Florida Bay. Using the U.S. EPA's framework, the risk to estuarine fish species diversity was assessed against regional salinity profiles from a 17-year database. Based on the risk assessment, target salinity profiles for these areas are recommended for managers.^
Resumo:
Current water management practices in South Florida have negatively impacted many species inhabiting Florida Bay. Variable and high salinity has been identified as a key stressor in these estuaries. The comprehensive Everglades Restoration Plan (CERP) includes water redistribution projects that will restore natural freshwater flows to northeastern Florida Bay. My studies focused on the following central theme and hypotheses: Biological performance measures (i.e., growth, reproduction, survival), behavior (i.e., habitat preference and locomotor behavior) and diversity of estuarine fish will be controlled by changes in salinity and water quality that will occur as a result of the restoration of freshwater flow to the bay. A series of acute and subchronic physiological toxicity studies were conducted to determine the effects of salinity changes on the life stages (embryo/larval, juvenile, adult) and fecundity of four native estuarine fish (Cyprinodon variegatus, Floridichthys carpio, Poecilia latipinna, and Gambusia holbrooki). Fishe were exposed to a range of salinity concentrations (freshwater to hypersaline) based on salinity profiles in the study areas. Growth (length, weight) and survival were measured. Salinity trials included both rapid and gradual change events. Results show negative effects of acute, abrupt salinity changes on fish survival, development and reproductive success as a result of salinity stress. Other studies targeted reproduction and critical embryo-larval/neonate development as key areas for detecting long-term population effects of salinity change in Florida Bay. Adults of C. variegatus and P. latipinna were also examined for behavioral responses to pulsed salinity changes. These responses include changes in swimming performance, locomotor behavior and zone preference. Finally, an ecological risk assessment was conducted for adverse salinity conditions in northeastern Florida Bay. Using the U.S. EPA's framework, the risk to estuarine fish species diversity was assessed against regional salinity profiles from a 17-year database. Based on the risk assessment, target salinity profiles for these areas are recommended for managers.
Resumo:
El Cerro El Potosí es un área prioritaria para la Comisión Nacional para la Biodiversidad (CONABIO) y un Área Natural Protegida por el estado (Anónimo, 2000), debido a la existencia de una gran diversidad de tipos de vegetación y de especies de importancia fitogeografica o su orografía y altitud (3715 msnm) se considera un área promotora de procesos de especiación, registrándose especies endémicas y relictuales como el caso del Pinus culminicola y Nucifraga columbiana , es una de las montañas más altas del noroeste del país, está enclavada en la Sierra Madre Oriental. Con base en la información previa disponible, se presume que esta área ostente una mayor diversidad de flora y fauna. El objetivo principal fue el análisis de la diversidad y distribución de los mamíferos en los diferentes estratos vegetativos y altitudes dentro de los límites del Cerro El Potosí. Con el propósito de realizar las comparaciones de las diversidades de las especies en forma altitudinal, por vegetación, estacional; Se seleccionó la prueba de Chi-cuadrada para determinar dependencia entre especies y la altitud, tipo de muestreo o tipo de vegetación. Se efectuaron 24 salidas (mensuales) de campo, de noviembre del 2006 a octubre del 2008, de 3 a 4 días por salida. Se registraron 27 especies (14 Familias, 24 géneros, 27 especies, y 14 especies no reportadas previamente). De acuerdo al tipo de vegetación la riqueza se concentro en el bosque de pino seguido por el bosque de encino, las especies se distribuyeron en uno, en dos o más estratos de vegetación (patrones), para los diferentes tipos de vegetación se distribuyeron las especies de Silvilagus floridanus, Thomomys bottae, Peromyscus melanotis, Peromyscus levipes ambiguus, Canis latrans y Lynx rufus. Las especies que sólo se encontraron en un solo tipo de vegetación fueron Bassariscus astutus, Conepatus mesoleucus, Corynorhinus townsendii, Didelphis virginiana, Eptesicus fuscus, Puma yagouaroundi, Lasiurus cinereus, Lasiurus ega, Leptonycteris nivalis, Mustela frenata y Sorex milleri, por lo que se aprecia la diversidad encontrada en el sitio, esto en gran medida por la asociación de la vegetación y la altura marcado por la temperatura reportada para el sitio. Las especies que se localizaron en dos o más estratos o patrones de vegetación fueron Myotis thysanodes, Sciurus alleni, Otospermophilus variegatus, Microtus mexicanus, Urocyon cinereoargenteus, Procyon lotor, Puma concolor, Pecari tajacu y Odocoileus virginianus.