Determinants of reef fish assemblages in tropical Oceanic islands

Submitted by editor on 22 November 2018. Get the paper!
Oceanic islands. A. St Paul and St Peter, Brazil, photo: Lucas Nunes, B. Isla del Coco, Costa Rica, photo: Juan J. Alvarado, C. Fernando de Noronha, Brazil, photo: Sergio R. Floeter, D. Isla del Coco, Costa Rica, João P. Krajewski, E. St Paul and St Peter, Brazil, photo: Lucas Nunes, F. Principe Island, Africa, photo: Sergio R. Floeter.​

by Sergio R. Floeter & Juan Pablo Quimbayo

- Our study extends findings from Island Biogeography Theory beyond species richness to include other descriptors of fish assemblages, such as functional dispersion, density and biomass.  
- By using a large data set from isolated oceanic islands and applying an integrative analytical framework for comparing fish assemblage metrics, we confirmed several of our predictions and uncovered several unexpected results.

Seascape at Isla del Coco, Costa Rica, photo: João P. Krajewski.

Did you know that oceanic islands are considered a window to the understanding of more pristine marine environments? Oceanic islands are known to have a large number and diversity of reef fish. However, due to its isolation and its small areas they are highly sensitive to changes induced by environmental, oceanographic and human actions. In this recent study in Ecography, Quimbayo and colleagues explored different measures of diversity of reef fish communities. They noted for example, that fish communities on islands with nearby human populations have lower fish biomass, probably due to fishing. Moreover, this study shows the importance of primary productivity for the maintenance of different aspects of biodiversity such as species richness, functional diversity, number of individuals and fish biomass. Finally, this study expands theoretical concepts for marine environments that will be important for the understanding of species diversity patterns.