The Amazon river is a major source of terrestrially derived organic carbon to the tropical Atlantic Ocean. Field, satellite and a vertically generalized production model data were used to estimate empirical surface salinity and fit an inverse logit function to investigate the limiting effect of salinity on the productivity in the Amazon river plume. Satellite data included Moderate Resolution Imaging Spectroradiometer, Soil Moisture and Ocean Salinity, and Aquarius missions. Previous empirical surface salinity models have relied on a very narrow range of salinity values and satellite data to estimate the spatial extent of the river plume. The empirical surface salinity model presented here extended the range of salinity values and captures all the main surface mesoscale features, particularly those related to the main path of the low‐salinity water. We also show that it is possible to gain new insights on the spatiotemporal variability of the Amazon river plume by improving the empirical surface salinity and expanding its sampling period with the aid of remote sensing data. The variability of primary productivity is dominated by the subannual (6 month) and annual (12 month) frequency bands. Low‐salinity river water influences surface primary productivity continuously during the year through mechanisms associated with the western tropical Atlantic circulation and vertical mixing.
This first analysis of the marine fish fossil record in the Caribbean region during the Neogene is based on comprehensive new faunal compilation lists at the generic level from basins of nine Central and South American countries during Miocene and Pliocene times. Joint ordination and classification techniques were used to analyze data comprising 236 genera and 346 species. Principal Component Analyses were used to calculate covariance and variance between localities. We identified four subprovinces, representing four different patterns. The subprovince of Venezuela shows distinct and unique features since the Neogene in the diversity of ecosystems represented. The Antillean subprovince has a western orientation and is composed of Jamaica, the Dominican Republic, and the Trinidad islands. The third subprovince combines Panama and Ecuador. It reflects the Pacific faunal influence into the proto-Caribbean and a characteristic benthopelagic fauna. The fourth subprovince is Costarican. Its nektonic fish fauna reflects the overprinting impact over the proto-Caribbean fish fauna mostly due to local paleoenvironmental changes (neritic, estuarine and deep water assemblages), whereby the overall composition of genera is largely not affected (except few lamnids, such as the giant-toothed white sharks and the wide-toothed mako shark). The results of the analyses are concordant with previous ones based on invertebrates and identified regions in need of study (e.g., Colombia, Nicaragua, Honduras, and Brazil).
1 November 2013 in Estuarine, Coastal and Shelf Science