![]() ![]() By contrast, stronger upwelling may increase nutrient input, but at the same time increase offshore transport ( Cury and Roy, 1989 Botsford et al., 2006 Bakun et al., 2010, 2015). For example, weaker upwelling may limit nutrient enrichment of the photic zone with potentially negative impacts on primary production ( Chhak and Di Lorenzo, 2007). ![]() Understanding how these winds will change is of vital importance. Recent observations ( Sydeman et al., 2014a) generally support this notion, and global model projections suggest intensification of regional coastal winds during the twenty-first century ( Rykaczewski et al., 2015 Wang et al., 2015). ![]() In particular, it is predicted that global warming will impact atmospheric pressure gradients and hence the coastal winds that cause upwelling ( Bakun, 1990 Bakun et al., 2015). Overall, the “bottom-up” drivers of nutrient enrichment, advection and retention, coupled with the transfer of carbon and energy up the food web make EBUS “hotspots” of productivity and upper-trophic-level biodiversity ( Arístegui et al., 2009 Block et al., 2011), providing substantial economic value to coastal communities.īecause the mechanisms underpinning upwelling originate from large-scale atmospheric-oceanographic coupling, the amplitude and timing of upwelling-favorable winds are sensitive to climate variability ( Montecinos et al., 2003 Macias et al., 2012), and are highly likely to be affected by global warming ( Barros et al., 2014 Bakun et al., 2015). These “upwelling shadows” are sites of the highest chlorophyll concentrations in EBUS ( Vander Woude et al., 2006), contrasting with lower productivity in areas with strong advection this variability may influence zooplankton and higher trophic levels ( Santora et al., 2011). In embayments and other wind-protected inshore areas and in places where local circulation patterns may favor retention of local water masses, primary production can be intense and sustained ( Graham and Largier, 1997). However, multi-trophic level, end-to-end (i.e., “winds to whales”) studies are needed to resolve the resilience of EBUS to climate change, especially their response to long-term trends or extremes that exceed pre-industrial ranges. Although predictions of ecosystem responses are uncertain, EBUS experience considerable natural variability and may be inherently resilient. ![]() There is low confidence regarding the future effects of climate change on coastal temperatures and biogeochemistry due to uncertainty in the countervailing responses to increasing upwelling and coastal warming, the latter of which could increase thermal stratification and render upwelling less effective in lifting nutrient-rich deep waters into the photic zone. Although evidence is weak in data that are presently available, future projections show that this pattern might be driven by changes in the positioning of the oceanic high-pressure systems rather than by deepening of the continental low-pressure systems, as previously proposed. We find that model and observational data suggest coastal upwelling-favorable winds in poleward portions of EBUS have intensified and will continue to do so in the future. We use these recent studies to develop a new synthesis describing climate change impacts on EBUS. The IPCC AR5 provided an overview of the likely effects of climate change on Eastern Boundary Upwelling Systems (EBUS), stimulating increased interest in research examining the issue. 6Environmental Research Division, National Oceanic and Atmospheric Administration Southwest Fisheries Science Center, Monterey, CA, USA.5Department for Biodiversity and Conservation Biology, University of the Western Cape, Bellville, South Africa.4Marine Science Institute, University of Texas at Austin, Port Aransas, TX, USA.3Department of Biological Sciences and Marine Science Program, University of South Carolina, Columbia, SC, USA.2School of Science and Engineering, University of the Sunshine Coast, Maroochydore, QLD, Australia.1Farallon Institute for Advanced Ecosystem Research, Petaluma, CA, USA. ![]()
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