ENSO-induced co-variability of Salinity, Plankton Biomass and Coastal Currents in the Northern Gulf of Mexico

Abstract

The northern Gulf of Mexico (GoM) is a region strongly influenced by river discharges of freshwater and nutrients, which promote a highly productive coastal ecosystem that host commercially valuable marine species. A variety of climate and weather processes could potentially influence the river discharges into the northern GoM. However, their impacts on the coastal ecosystem remain poorly described. By using a regional ocean-biogeochemical model, complemented with satellite and in situ observations, here we show that El Niño - Southern Oscillation (ENSO) is a main driver of the interannual variability in salinity and plankton biomass during winter and spring. Composite analysis of salinity and plankton biomass anomalies shows a strong asymmetry between El Niño and La Niña impacts, with much larger amplitude and broader areas affected during El Niño conditions. Further analysis of the model simulation reveals significant coastal circulation anomalies driven by changes in salinity and winds. The coastal circulation anomalies in turn largely determine the spatial extent and distribution of the ENSO-induced plankton biomass variability. These findings highlight that ENSO-induced changes in salinity, plankton biomass, and coastal circulation across the northern GoM are closely interlinked and may significantly impact the abundance and distribution of fish and invertebrates.

Hurricanes, El Niño and harmful algal blooms in two sub-tropical Florida estuaries: Direct and indirect impacts

“…Among these climatic threats are increases in the intensity and duration of hurricanes and El Niño periods [4][5][6] . High rainfall and winds associated with storms and elevated rain during El Niño periods in certain regions of the world can impact a range of processes relevant to phytoplankton dynamics and HAB development, including nutrient loads, physical disruption of ecosystems and ecosystem flushing rates [7][8][9][10] . These impacts can be exacerbated by human influences on nutrient loads and hydrology 11,12 .…”

Zooplankton summer composition in the southern Gulf of Mexico with emphasis on salp and hyperiid amphipod assemblages

“…The influence of water discharge during this period was evidenced by the lower salinity values at the surface and the shallower peak in fluorescence values in the southernmost station (station X4-H48) of transect 2. Additionally, high plankton productivity in the Bank of Campeche and adjacent shelf break can result from coastal upwelling (Salas-de-León et al ., 2004; Zavala-García et al ., 2016; Gomez et al ., 2019). This process could explain the high zooplankton abundance at station X4-G44, which is located just off the western Yucatan platform, and associated changes in the temperature and fluorescence profiles.…”

El Niño Southern Oscillation (ENSO) effects on fisheries and aquaculture

“…Consequently, El Niño (La Niña) events tend to be followed by a larger (smaller) than usual Atlantic warm pool (Figure 6.24; Enfield, Lee and Wang, 2006). The interannual variability of plankton biomass in the northern Gulf of Mexico during winter and spring is also largely controlled by ENSO, which could impact the reproductive success and biological condition of upper trophic levels, including commercially important species (Gomez et al, 2019). This response is also asymmetric, with much larger and broader impact (biomass increase) during El Niño compared to La Niña events.…”