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Surface sediment samples collected from the Salina Cruz Bay in the last twenty years, were analyzed for the total available trace elements (Cr, Cu, Fe, Pb, Ni, V, and Zn) to evaluate metal contamination due to possible anthropogenic inputs. Normalization of metals to iron and fine-grained fraction (< 63 microm) indicated relatively high enrichment factors for lead during the last two decades. Sediment Quality Guidelines suggest that lead must be considered as a chemical of potential concern in the marine and estuarine ecosystem. Concentration levels of lead ranged from 5-124 microg/g, while Ni and V below 70 and 30 microg/g, respectively. Geoaccumulation and enrichment factors for the rest of elements show comparable values to those reported for sites with similar activities in the world. Spatial distribution suggests that in addition to harbor activities, a transboundary source for Pb must account for the observed trends.

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RESUMENLos cambios de temperatura promedio del océano a nivel global tienen el potencial de afectar negativamente los sistemas naturales y socioeconómicos actuales; sin embargo, los registros para proyectar las tendencias de cambio a nivel regional son escasos y, en algunos casos, contradictorios. En este estudio se analizan las señales de cambio de la temperatura superficial en mares mexicanos, y se comparan con otras regiones del planeta y con indicadores climáticos clave, tanto del Pacífico Norte como de la franja tropical en el Atlántico y el Pacífico. Se identificaron ocho regiones con diferente exposición a la variabilidad climática: en el Pacífico, la costa occidental de la península de Baja California no muestra una tendencia clara, el Golfo de California exhibe una tendencia modesta de enfriamiento durante los últimos 20 a 25 años, en la parte más oceánica del Pacífico mexicano se nota una tendencia intensa de enfriamiento, la región más tropical muestra una tendencia intensa de calentamiento, y entre ambas regiones se forma una banda de transición sin tendencia; en el Atlántico, la parte noreste del Golfo de México muestra una tendencia de enfriamiento, en tanto que la parte oeste, junto con el Caribe, se han estado calentando por lo menos durante los últimos 30 años. Se analizan las interacciones potenciales de estas tendencias con algunas pesquerías principales y la presencia de ecosistemas costeros sensibles. ABSTRACTChanges in global mean sea surface temperature may have potential negative implications for natural and socioeconomic systems; however, measurements to predict trends in different regions have been limited and sometimes contradictory. In this study, an assessment of sea surface temperature change signals in the seas off Mexico is presented and compared to other regions and the world ocean, and to selected basin scale climatic indices of the North Pacific, the Atlantic and the tropical Pacific variability. We identified eight regions with 538 S. E. Lluch-Cota et al. different exposure to climate variability: In the Pacific, the west coast of the Baja California peninsula with mostly no trend, the Gulf of California with a modest cooling trend during the last 20 to 25 years, the oceanic area with the most intense recent cooling trend, the southern part showing an intense warming trend, and a band of no trend setting the boundary between North-Pacific and tropical-Pacific variability patterns; in the Atlantic, the northeast Gulf of Mexico shows cooling, while the western Gulf of Mexico and the Caribbean have been warming for more than three decades. Potential interactions with fisheries and coastal sensitive ecosystems are discussed.

[1] Water temperature and fecal indicator bacteria levels covary along the shoreline of Huntington and Newport Beach, California at interannual to tidal periods. During summer, cooler than average waters caused by interannual variability in sea surface temperature (SST), synoptic upwelling, and tidal-period cooling are coincident with elevated levels of microbial pollution in the surf zone. This relationship can be explained by the effects of weakening in stratification on the fate of a waste water plume and the prolonged persistence of fecal indicator bacteria in colder waters. During winter, warmer than average water caused by basin scale oscillations and atmospheric and oceanographic processes that contribute to the Multivariate El Nino Southern Oscillation Index are indicative of elevated total coliform levels in the surf zone. The elevated coliform levels can be ascribed to increased rainfall, and the resultant storm water inflow to the surf zone.