Somatic growth is an integrated, individual-based response to environmental conditions, especially in ectotherms. Growth dynamics of large, mobile animals are particularly useful as bio-indicators of environmental change at regional scales. We assembled growth rate data from throughout the West Atlantic for green turtles, Chelonia mydas, which are long-lived, highly migratory, primarily herbivorous mega-consumers that may migrate over hundreds to thousands of kilometers. Our dataset, the largest ever compiled for sea turtles, has 9690 growth increments from 30 sites from Bermuda to Uruguay from 1973 to 2015. Using generalized additive mixed models, we evaluated covariates that could affect growth rates; body size, diet, and year have significant effects on growth. Growth increases in early years until 1999, then declines by 26% to 2015. The temporal (year) effect is of particular interest because two carnivorous species of sea turtles-hawksbills, Eretmochelys imbricata, and loggerheads, Caretta caretta-exhibited similar significant declines in growth rates starting in 1997 in the West Atlantic, based on previous studies. These synchronous declines in productivity among three sea turtle species across a trophic spectrum provide strong evidence that an ecological regime shift (ERS) in the Atlantic is driving growth dynamics. The ERS resulted from a synergy of the 1997/1998 El Niño Southern Oscillation (ENSO)-the strongest on record-combined with an unprecedented warming rate over the last two to three decades. Further support is provided by the strong correlations between annualized mean growth rates of green turtles and both sea surface temperatures (SST) in the West Atlantic for years of declining growth rates (r = -.94) and the Multivariate ENSO Index (MEI) for all years (r = .74). Granger-causality analysis also supports the latter finding. We discuss multiple stressors that could reinforce and prolong the effect of the ERS. This study demonstrates the importance of region-wide collaborations.

No abstract

No abstract

Los Islotes is the southernmost breeding site of the California sea lion (Zalophus californianus californianus) in the Northern Hemisphere and represents one of the principal tourist attractions for the city of La Paz, Mexico. The tourism has been growing without control and could be the cause of perturbation in the reproductive and haul-out patterns of the sea lion. The aim of the present study was to determine the effect of tourism activities on the behavior of sea lions, in order to help design regulations to assure better use and conservation of the site. The nature and intensity of tourism activity and sea lion behavior were determined based upon monthly sampling over a one-year period (May 2000-April 2001. Tourist activity was higher during autumn and winter, with visits by "panga" boats being the most numerous. A total of 112 disturbances were recorded, the majority of which being non-anthropogenic causes. A quarter of disturbances were triggered by human activity within 20m of the rookery and with harassment reaction (animals going into the water) in 32% of the anthropogenic disturbances.Principal component analysis (PCA) described the conditions under which disturbance was generated (74% of the variation explained). Using three factors (47% of the total variation) the major contributing variables were month, tidal level, relative humidity, Beaufort number, total number of boats and number of powerboats and sailboats. In Los Islotes, the perturbation occurs mostly in autumn and winter coinciding with the highest frequency of tourism, large number of adult and subadult males and unfavorable environmental conditions for haul-out, such as high tide level and strong winds. The lowest number of disturbances occurred in summer, during the breeding season of the sea lion. Most of these, however, were caused by human activity. RESUMEN:Los Islotes es el sitio más sureño de reproducción del lobo marino de California (Zalophus californianus californianus) en el Hemisferio Norte y representa la principal atracción turística de la ciudad de La Paz, México. El turismo ha crecido sin ningún control y puede ser causa de perturbación de los patrones reproductivos y de descanso del lobo marino. El objetivo de este trabajo fue determinar el efecto de la actividad turística en el comportamiento del lobo marino con la finalidad de generar información útil para el diseño de acciones que garanticen un mejor aprovechamiento y conservación del sitio. Se caracterizó y cuantificó la actividad turística y se realizó un seguimiento del comportamiento con muestreos mensuales a lo largo de un año (Mayo 2000 -Abril 2001. La actividad turística fue mayor los meses de otoño e invierno, siendo la embarcación con motor tipo "panga" la más numerosa. Se registraron 112 disturbios, la mayoría de los cuales fueron generados por causas no antropogénicas. Un cuarto de los disturbios fueron ocasionados por causas humanas generándose a distancias menores de 20m de la lobera y ocasionando un efecto intenso (animales se van al agua) en el ...

No abstract

No abstract

No abstract

No abstract