Comparative Biogeography of Benthic and Mid-Water Coastal Fish Communities of the Galapagos: Stereo-BRUVs Surveys Support the Use of Bioregions for Management

Abstract

Aim

Biogeographical frameworks inform effective marine spatial planning, assessing ecological patterns across taxa and environments. In the Galapagos Archipelago, benthic bioregions guided marine reserve zoning, yet their representation of the mid-water environment remains unassessed. Our study aimed to strengthen the understanding of patterns in marine biogeography in Galapagos by assessing whether the currently accepted benthic bioregions also represent mid-water reef fish communities.

Location

Galapagos Archipelago.

Taxon

Marine fish species.

Methods

We used baited remote underwater stereo-video systems to conduct archipelago-wide surveys of benthic and mid-water fish communities. Locations were sampled during the cold and warm seasons, yielding 598 deployments which were analysed to compare multivariate patterns between bioregions and environments.

Results

Bioregion partitioning based on benthic fish community data was more distinct than in previous studies with the Far-North, North, Centre-Southeast and West bioregions displaying significantly different community compositions. The main Galapagos bioregions displayed less distinct coastal mid-water fish communities suggesting three subdivisions may be more representative, namely the Far-North, West and the Centre-Southeast plus North combined. When compared with benthic communities, mid-water communities displayed higher heterogeneity, lower species richness and were dominated by species with extensive distribution ranges.

Main Conclusions

Our study builds upon previous biogeographic studies in the Galapagos Islands by considering previous limitations and assessing both benthic and mid-water environments. Our results support the currently accepted bioregion scheme but suggest that the coastal mid-water environment could be divided into three, not four bioregions. Mid-water stereo-BRUVs represent a useful tool to study mid-water biogeographical patterns, and we recommend their application in other regions of the world to improve our understanding of biogeography in this understudied environment.