Reef Fish Assemblage in Two Insular Zones within the Mexican Central Pacific

Abstract

Reefs fishes are sensitive to environmental changes, particularly in areas such as the Mexican Central Pacific (MCP), which has a high environmental variability favored by currents. This study assesses the temporal variation in ecological indicators of fishes in Marietas (MI) and Isabel islands (II) in the MCP during 2010–2017. Overall, 118 species were recorded at MI and 95 in II. The highest abundance was recorded in 2013 at MI, and in 2015 at II, with an observed sample coverage > 0.79 for all years. MI showed higher annual taxonomic distinctness and richness than II. Annual biomass and assemblages were different between years and islands. The changes in both islands’ community structure were influenced by ENSO events. A high proportion of the dissimilarity among years is represented in 10 species, and the difference among years for each island is given by rare species. Annually, community indicators (Δ+, q = 1, and q = 2) and physicochemical factors were not related except for q = 0 and the chlorophyll concentration; this is due to the inter-annual variation within the area. The variation in fish communities on both islands results from mesoscale phenomena that have a different effect on each island due to the characteristics of their shelf and oceanography.