Spatial and temporal variability of temperature, salinity and chlorophyll-a in the Magdalena River mouth, Caribbean Sea

Abstract

Variations in the physico-chemical characteristics of estuaries, such as surface water salinity and temperature, lead to the establishment of gradients that are closely related with the distribution of nutrients and suspended sediment. This affects light penetration, which in turn influences Chlorophyll-a (Chl-a) concentration and primary productivity. We used MODIS imagery to identify spatio-temporal patterns of sea surface salinity, temperature, and Chl-a concentrations from 2003 to 2017, to explore relationships between these variables and oceanographic factors, such as streamflows, winds and currents in the mouth of Colombia's Magdalena River, which discharges to the Caribbean Sea. Sea surface salinity (SSS) in the study zone varied in time and space from estuarine to marine. Mean SSS was 10.8 ± 3.4 at Bocas de Ceniza, and 28.4 ± 0.4 in the Caribbean Sea, with the horizontal salinity gradient providing evidence for the existence of a salinity plume. Mean monthly sea surface temperatures (SST) averaged across all years were 27.6 ± 1.5 °C at Bocas de Ceniza, and 27.6 ± 1.3 °C in the Caribbean Sea. A significant, increasing trend in temperature was observed throughout the years of the study period. Average Chl-a values were 3.3 ± 1.4 mg m−3 at Bocas de Ceniza, and 1.5 ± 1.2 mg m−3 in the Caribbean Sea and the calculated average Trophic State Index (TSI) for Bocas de Ceniza indicated that the estuary trophic state varied between oligo-mesotrophic (30 < TSI≤40) and mesotrophic (40 < TSI≤50). The highest concentrations of Chl-a were found in intermediate salinities in the estuarine zone. Outside the saline plume, there is a considerable decrease in Chl-a concentrations (<0.5 mg m−3). Winds played the most important role in influencing spatio-temporal distribution of chemical and physical variables in the study zone. Our results emphasize the importance of physical processes on biological dynamics in the Magdalena River mouth.

Effect of COVID-19 Anthropause on Water Clarity in the Belize Coastal Lagoon

“…It has been observed that these Belize coastal plumes can be comprised of a variety of constituents, including sediments, agricultural runoff, and sewage (Maidens and Burke, 2005;Macintyre et al, 2009;Emrich et al, 2017;Wells et al, 2019), with Soto et al (2009) observing a consistent year-to-year river plume occurrences with coral ecosystems (Soto et al, 2009). Though classified as oligotrophic, river plumes can often cause Caribbean waters to become mesotrophic (Warne et al, 2005;Torregroza-Espinosa et al, 2021). In Belize, New River is known to cause a decline in water quality affecting surrounding corals due to poor farming practices and deforestation (Espinoza-Avalos et al, 2009;Reyes et al, 2019).…”

Assessing Potential Climatic and Human Pressures in Indonesian Coastal Ecosystems Using a Spatial Data-Driven Approach

“…This occurs because ocean-atmosphere climate interactions, such as those resulting from the ENSO, affect the sea level, SST, air temperature, chlorophyll-a, and upwelling intensity. During the El Niño period, the upwelling intensity increased, followed by an increase in the chlorophyll-a concentration; in contrast, during the La Niña period, the upwelling intensity decreased followed by a decrease in the chlorophyll-a concentration [26,[82][83][84][85].…”

Assessing land use and land cover change in Los Molinos reservoir watershed and the effect on the reservoir water quality

“…8) shows two main periodic peaks that were related to warmer water registered in summer (January to March) and spring (September to December) seasons which could lead to algal growth (Bonansea et al, 2019). Although urbanization and agriculture activities have generated an economic development for the region, different studies suggest that watersheds are extremely sensitive to an increase in intensive land use classes with significant impacts on eutrophication and water quality of aquatic environments, including rivers, lakes and reservoirs (Welde and Gebremariam, 2017;Desta and Fetene, 2020;Kiage and Douglas, 2020;Torregroza-Espinosa et al, 2020;Wei et al, 2020). During the process of urbanization, a permeable vegetated land surface is replaced by concrete and other impervious materials which can drastically transform surface hydrological processes altering the balance between infiltration and runoff.…”

“…Advances in remote sensing technology have considerably improved the assessment of a long time-series of LULC change (Huang et al, 2002;Fukushima et al, 2007;Huang et al, 2014;Loveland and Irons, 2016;Gómez et al, 2016;Wei et al, 2020), variations in water quality (Tebbs et al, 2013;Chen et al, 2014;Villa et al, 2014;González-Márquez et al, 2018;Zhou et al, 2018;Bonansea et al, 2019;Elhag et al, 2019;Germán et al, 2020;Kiage and Douglas, 2020;Li et al, 2020, Torregroza-Espinosa, et al 2020) and eutrophication causes (Smith and Schindler, 2009;Mendoza et al, 2015;Padedda et al, 2017;Bhagowati and Ahamad, 2019;Le Moal et al, 2019;Cai et al, 2020). However, to the best of our knowledge, studies that relate LULC change and reservoir water quality are scarce and dispersed, particularly in the Southern hemisphere.…”