Jiménez Rosenberg, S.P.A., G., Aceves Medina & R., Durazo (2023). How extreme cold and warm oceanographic events influence larval fish assemblages in the southern region of the California Current off Mexico. 46th Annual Fish Larval Conference. Lisboa, Portugal, mayo 7 - 11, 2023, 79.
Sylvia Patricia Adelheid Jiménez Rosenberg 1, Gerardo Aceves Medina 1 y Reginaldo Durazo 2
The fish larvae community in the southern region of the California Current (CC) was analyzed to test the hypothesis of a northward expansion of tropical species for the summer–fall seasons of La Niña (LN) 2010–2011, The Blob 2014 and El Niño (EN) 2015–2016. Interannual temperature anomalies (–5 °C to 2 °C), as well as a decrease in Chl–a (68%), and zooplankton density (71%), translated into drastic changes in the larval fish community, such as an unprecedented reduction of 82% in larval fish density previously unseen in the CC. The tropical species richness increased in the north by 46% and temperate species decreased by 65% in the south. The mesopelagic species richness increased in the north by 53%, as well as their relative abundance (92%). In the south, the species richness of the demersal component increased up to 39%, but they were codominant with mesopelagic species, accounting for 49% of the relative abundance vs. 47% of the demersal species. The magnitude of the changes in the community were unprecedented when compared with other warming events, such as EN 1983-1984 or EN 1997-1998. The differences were probably related to the presence of The Blob, which favored the transport of oceanic species into the neritic region of the CC region. In both cold and warm years, fronts and mesoscale eddies in the middle part of the Peninsula represented barriers to the latitudinal distribution of species, even during intense tropicalization processes since no latitudinal extensions in species distribution occurred.
Palabras clave: Fish larvae; California Current; El Niño, The Blob
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