Climate change impacts on the atmospheric circulation, ocean, and fisheries in the southwest South Atlantic Ocean: a review

Abstract

We present an interdisciplinary review of the observed and projected variations in atmospheric and oceanic circulation within the southwestern South Atlantic focused on basin-scale processes driven by climate change, and their potential impact on the regional fisheries. The observed patterns of atmospheric circulation anomalies are consistent with anthropogenic climate change. There is strong scientific evidence suggesting that the Brazil Current is intensifying and shifting southwards during the past decades in response to changes in near-surface wind patterns, leading to intense ocean warming along the path of the Brazil Current, the South Brazil Bight, and in the Río de la Plata. These changes are presumably responsible for the poleward shift of commercially important pelagic species in the region and the long-term shift from cold-water to warm-water species in industrial fisheries of Uruguay. Scientific and traditional knowledge shows that climate change is also affecting small-scale fisheries. Long-term records suggest that mass mortalities decimated harvested clam populations along coastal ecosystems of the region, leading to prolonged shellfishery closures. More frequent and intense harmful algal blooms together with unfavorable environmental conditions driven by climate change stressors affect coastal shellfisheries, impact economic revenues, and damage the livelihood of local communities. We identify future modelling needs to reduce uncertainty in the expected effects of climate change on marine fisheries. However, the paucity of fisheries data prevents a more effective assessment of the impact of climate change on fisheries and hampers the ability of governments and communities to adapt to these changes.

Potential changes in the connectivity of marine protected areas driven by extreme ocean warming

“…1b). Our simulations agree with previous studies which suggest that the BC is intensifying and shifting southwards due to a poleward shift of near-surface ocean wind 42,43 . The dynamical downscaling also points to marked changes in surface current velocities in the extreme ocean warming scenario with intense surface flow changes occurring between 5°S and 8°N (Fig.…”

Subsurface Ocean Warming Hotspots and Potential Impacts on Marine Species: The Southwest South Atlantic Ocean Case Study

“…Given the high uncertainty levels associated with predictions of global climate models (Franco et al, 2020), outputs from future regional models with higher horizontal resolution will be necessary to better resolve the potential changes in the circulation over the SWAO shelf and their potential impact on species distributions.…”

“…A key question emerging from our study is how climate change will impact the distribution and thermal tolerance of marine species in the SWAO. To answer this question and to overcome the high uncertainty levels associated with global predictive climate models (Franco et al, 2020), outputs from future regional models with higher horizontal resolution than Coupled Model Intercomparison Project (CMIP5)-class models (1 • × 1 • ) will be necessary to better resolve changes in the circulation over the SWAO shelf and then the changes in marine species distribution. The poleward displacement of warm tropical and subtropical waters of the BC (Figure 7) may have a strong impact on the productivity of SBF and the sustainability of the northernmost scallop beds.…”

“…In the South Atlantic Ocean, a poleward displacement of the subtropical gyre at a rate of 0.11 • /decade has been observed (Yang et al, 2020), and the western boundary current -the Brazil Current (BC) -has been reported as one of the most extensive and intense surface warming hotspots in the global ocean (Hobday and Pecl, 2014). Although changes in the distribution and productivity of marine species have been recorded over faster ocean warming regions worldwide (Burrows et al, 2014;Sunday et al, 2015;Pecl et al, 2017), potential changes remain largely unexplored in the southwest South Atlantic Ocean (SWAO, see Franco et al, 2020).…”

Evolución temporal de la diversidad, abundancia y estructura del ensamble de peces costeros en el área de “El Rincón” (39° S-41° 30′ S), Argentina

“…, incluso este calentamiento es observado en gran parte del ECB. Estos cambios ambientales serían responsables, por ejemplo, del desplazamiento hacia los polos de la distribución de especies pelágicas de importancia comercial en la región (Franco et al 2020). Si bien el comportamiento de las especies representa un componente importante de su capacidad de adaptación frente al cambio climático, y la flexibilidad del comportamiento permite a los organismos hacer frente rápidamente a las condiciones ambientales cambiantes (Beever et al 2017), estos aspectos son muy complicados de observar en el corto plazo.…”