García-Fernández, F., J., Gómez-Gutiérrez, R., De Silva-Dávila, D., Gendron-Laniel, B., Lavaniegos & C.J., Robinson (2023). Euphausid abundance shows resilience to warming in the Gulf of California at decadal scale. XXIII Reunión Nacional de la Sociedad Mexicana de Planctología A.C. y XVI International Meeting of the Mexican Society Of Planktology A.C.. Cozumel, Quintana Roo, México, mayo 29 - junio 2, 2023, 46-47.
Franklin García-Fernández 1, Jaime Gómez-Gutiérrez 1, Roxana De Silva-Dávila 1, Diane Gendron-Laniel 1, Bertha Lavaniegos 2 y Carlos J. Robinson 3
The Gulf of California has shown notable ecosystem changes in recent decades such as the decrease of breeding colonies of pinnipeds, the decrease in the capture of sardines, giant squid (decrease in the adult size of the giant squid) and decrease in the biomass of pelagic organisms estimated by hydroacoustic methods. Some of these changes have been explained as dam changes or decreased productivity of the epipelagic ecosystem associated with anomalous increase in surface temperature and decreased chlorophyll-a concentration. The present study hypothesizes that zooplankton have declined in the last six decades associated with global warming. The decadal trends of zooplankton biovolume (proxi of total abundance), and abundance and specific composition of euphausiids comprising about 7% of total zooplankton abundance were analyzed. 1335 samples of zooplankton obtained with Bongo net (500 m light mesh) were analyzed in 27 oceanographic cruises carried out in the Gulf of California between1957–2019. The main modes of variability were seasonal variation (cold season Dec-Jun and warm Jul-Nov) and nictimeral (day-night). The greatest biovolumes and abundance occurred during the cold season and during the night. Separating these two modes of variability, decadal variability was compared, finding that the median biovolume of zooplankton and abundance of euphausiids were not significantly different between decades. That is, there is no evidence that the zooplankton community has a long-term decline trend between 1957 and 2019. However, the proportion of data with extremely high euphausiid abundance was lower during the 2010s than during the 1950s. That is, although the magnitude of the median euphausiid abundance is similar between 1957 and 1984 vs 2005–2019, the proportion of aggregations with extreme abundances has possibly decreased with relevant implications for their predators in the Gulf of California.
Palabras clave: Euphausiids; resilience; Warming
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