Copepod species assemblage and carbon biomass during two anomalous warm periods of distinct origin during 2014–2015 in the southern Gulf of California

Seasonal variability of gelatinous zooplankton during an anomalously warm year at Cabo Pulmo National Park, Mexico

“…The anomalous warm conditions caused a lower Chl-a concentration than those expected during colder previous years (Hidalgo-González & Alvarez-Borrego, 2004;Espinosa-Carreón & Valdez-Holguín, 2007). The mean sea surface Chl-a concentration (0.48 mg m -3 ) observed during 2014 was about half lower the historical average observed between 1997-2016 (1 mg m -3 ) (Ahern et al, 2018;Beltrán-Castro et al, 2020), which could negatively influence the prey availability for carnivores and herbivores zooplankton decreasing their abundances (Alldredge, 1984). The relative abundance of siphono-phores and thaliaceans increased, concerning the other taxonomic groups, from 2% in 2005 to 10% in 2006 in response to anomalous cold and high sea surface Chl-a concentration conditions in the Gulf of California (Jerónimo-Balcázar, 2011).…”

“…The last four warming events (2009,2011,2014,2015,2016) were the warmest (Ahern et al, 2018-2020. This unusual regional heatwave was simultaneous, but independent of the warm winter event of 2013-2014 in the North Pacific known as the "The Blob," generating an increase of the SST of 1-4°C above the average (Kintisch, 2015;Leising et al, 2015;Peterson et al, 2015Peterson et al, , 2017Beltrán-Castro et al, 2020). Boero et al (2016) showed an increase in the medusae population size associated with warm conditions.…”

“…However, the presence of "The Blob" in the southern Gulf of California is still under debate. The 2014 warm event is currently considered a regional heatwave simultaneous, but independent from "The Blob" (Peterson et al, 2015(Peterson et al, , 2017Beltrán-Castro et al, 2020). The regional 2013-2014 heatwave was followed by the Equatorial El Niño 2015-2016, causing prolonged warming conditions in the Gulf of California (Robinson et al, 2013(Robinson et al, , 2016Robinson, 2016;Beltrán-Castro et al, 2020).…”

“…The 2014 warm event is currently considered a regional heatwave simultaneous, but independent from "The Blob" (Peterson et al, 2015(Peterson et al, , 2017Beltrán-Castro et al, 2020). The regional 2013-2014 heatwave was followed by the Equatorial El Niño 2015-2016, causing prolonged warming conditions in the Gulf of California (Robinson et al, 2013(Robinson et al, , 2016Robinson, 2016;Beltrán-Castro et al, 2020). The increase in temperature in the southern Gulf of California promotes changes in the zooplankton community structure numerically dominated by tropical species (Brinton et al, 1986;Badan, 2003).…”

“…Purcell (2008) reported that jellyfish' blooms have become problematic, especially after 1980, likely associated with global warming that promotes north-ward shift distribution range of tropical zooplankton. Therefore, considering the prolonged warm conditions prevailing in the Gulf of California during the 2009-2016 periods (Robinson et al, 2016;Ahern et al, 2018;Beltrán-Castro et al, 2020) and the fast response of gelatinous zooplankton to these conditions, we hypothesize that the assemblage of gelatinous zooplankton will have high abundance and influence the rest of the zooplankton community due to the anomalously warm conditions observed at CPNP during 2014. The of the present study goal was to investigate the seasonal abundance and composition of gelatinous zooplankton taxonomic groups during the anomalous warm conditions recorded during 2014 in the tropical Cabo Pulmo National Park, Gulf of California.…”