Resumen del producto

The main effects of El Niño and La Niña on fish are increases in mortality rates, abundance and recruitmentvariation, and expansion/restriction in the range of distribution and spawning areas. Potentially, the interactionswith seasonal effects can further exacerbate or dampen fluctuations in these parameters. The objective of thiswork, therefore, was to characterize the possible differences in the reef fish community structure in two seasons ofthe year (warm/cold) and between years (2010/2012) following El Niño-La Niña events. There were no significantdifferences in mean species richness between years. Furthermore, although more than twice the number of in-dividuals was observed in the year after La Niña (2012) compared to the year following El Niño (2010), there wereno significant differences with respect to mean abundance per transect. The total number of species recorded wasslightly higher in the cold season, with 68 species across both years. In contrast, the total abundance was higher inthe warm season. However, differences between seasons were neither significant for mean species richness nor formean abundance. Neither season nor year exhibited a significant effect on community composition. The coldseason in the Gulf of California is characterized by intense winds which generate a greater mixed layer; this, inturn, increases productivity, with cascading effects on higher trophic levels. In contrast, the presence of nitrogen-fixing picocyanobacteria which increase the levels of primary production may be a factor leading to maintaining asimilar fish abundance in the warm season. Fluctuations between seasons and years of study were observed forsome individual species, which may be related to oceanic productivity and reproductive periods. The results ob-tained in this work indicate that seasonality and climatic phenomena such El Niño and La Niña do not have amarked effect on community attributes of rocky reef fish in the southern Gulf of California, which apparently forma seasonally stable community, despite some fluctuations in individual species.

Palabras clave: rocky reef; ENSO; Gulf of California; primary production

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