Diversity patterns of reef fish along the Brazilian tropical coast.

Causal mechanisms for broad-scale reef fish diversity patterns are poorly understood and current knowledge is limited to trends of species richness. This work compared the effects of ecological drivers on components of fish diversity across reefs spanning over 2.000 km of the tropical Brazilian coastline. A quarter of communities' diversity is accountable to common and dominant species, while remaining species are rare. Low-latitude sites were more diverse in rare species. Communities along the coast share common and dominant species, which display high densities across all reefs, but differ in rare species that show abundance peaks in particular reef morphotypes. The disproportionate distribution of rare species reveals a higher vulnerability of these communities to impacts and stochastic density fluctuations. Uneven conservation efforts directed to these morphotypes pose a threat to the maintenance of a paramount component of the reef fish diversity represented by rare species.

Mixed-species schooling behavior and protective mimicry involving coral reef fish from the genus Haemulon (Haemulidae)

The present study analyzed heterotypic schooling behavior and protective mimicry relationships involving species of the genus Haemulon and other coral reef fishes on coastal reefs at Tamandaré, Pernambuco State, Northeastern Brazil. The work was performed during 35 hours of direct observation using the "focal animal" method. The observed events involved 14 species of reef fish in eight different families. The phenomenon of mixed schooling appeared to be related to the large number of individuals of the genus Haemulon present in reef environments and to the tendency of individuals with limited populations to try to aggregate in schools (e.g. genus Scarus).

O presente estudo analisou o comportamento de formação de cardumes mistos e mimetismo de proteção envolvendo espécies do gênero Haemulon e demais peixes recifais nos recifes costeiros de Tamandaré, estado de Pernambuco, Nordeste do Brasil. O trabalho foi realizado utilizando observações subaquáticas e incluiu 35 horas de observação direta utilizando o método animal focal, durante as quais foram registradas associações com 14 espécies pertencentes a oito famílias diferentes. Os fenômenos registrados possivelmente estão relacionados à grande quantidade de indivíduos do gênero Haemulon presentes nos ecossistemas recifais e também à tendência de indivíduos com reduzidas populações a permanecerem em cardumes (e.g. gênero Scarus).