Freshwater exchanges and surface salinity in the Colombian basin, Caribbean Sea

Abstract

Despite the heavy regional rainfall and considerable discharge of many rivers into the Colombian Basin, there have been few detailed studies about the dilution of Caribbean Surface Water and the variability of salinity in the southwestern Caribbean. An analysis of the precipitation, evaporation and runoff in relation to the climate variability demonstrates that although the salt balance in the Colombian Basin overall is in equilibrium, the area south of 12°N is an important dilution sub-basin. In the southwest of the basin, in the region of the Panama-Colombia Gyre, Caribbean Sea Water is diluted by precipitation and runoff year round, while in the northeast, off La Guajira, its salinity increases from December to May by upwelling. At the interannual scale, continental runoff is related to El Niño Southern Oscillation, and precipitation and evaporation south of 12°N are related to the Caribbean Low Level Jet. During El Niño years the maximum salinification occurs in the dry season (December-February) while in La Niña years the maximum dilution (or freshening), reaching La Guajira Coastal Zone, occurs in the wet season (September-November).

Dynamics of physicochemical variables of the northern Colombian Caribbean coastal waters

“…2-6). All recorded values were similar to those found in other studies for the dry and rainy season [4,7,8,21,25,30,34,38].…”

“…The characteristics of the first water mass, only for the August and November assessments, coincide with the Caribbean Surface Waters (CSW) that have temperatures between 27 and 30 °C and salinities between 34.5 and 36.0 [4,26,29,31,32,41]. These waters with high temperatures and low salinities are the result of the seasonal displacement of the ITCZ, oceanatmosphere events and the contribution of river runoff in the rainy season [8,29,31].…”

“…Additionally, it provides important information for environmental emergency responses. The characteristics of oceanographic conditions in the northern Colombian Caribbean have been widely described [2,4,8,20,28,29,32,37,38] but few investigations have been carried out on a wide spatial scale. Also, most studies have focused solely on the department of Magdalena [5,7,21,22,23,25,30] and the information has not recently been updated.…”

The impact of upwelling on the intensification of anticyclonic ocean eddies in the Caribbean Sea

“…Over the past 2 decades, a weak decreasing trend has been observed in the coastal wind stress and upwelling strength (Campbell et al, 2011;Lima and Wethey, 2012;Torres and Tsimplis, 2013). Not only does this have severe ecological impacts (Villamizar and Cervigón, 2017), but it also impacts mesoscale variability.…”

Steady Decline of Corals and Other Benthic Organisms in the SeaFlower Biosphere Reserve (Southwestern Caribbean)

“…The 1997-1998 El Niño Southern Oscillation led to mass coral bleaching and subsequently coral mortalities as well as the appearance of numerous diseases affecting corals (Weil, 2004), which most likely also impacted the two Banks. In terms of direct external effects, these reefs face the Caribbean current, NW direction, and at least part of the year receive diluted waters influenced by fresh-water runoff from the continental coast (Beier et al, 2017). Coastal waters coming from the Colombian coast are increasingly polluted with nutrients coming from rivers, which promotes coral degradation and harmful algae blooms (Restrepo et al, 2006;Coronado-Franco et al, 2018).…”