Rev. biol. mar. oceanogr. 51(1): 175-179

Nota Científica

http://dx.doi.org/10.4067/S0718-19572016000100017

Floración de Trichodesmium erythraeum en la región costera tropical de Brasil

This email address is being protected from spambots. You need JavaScript enabled to view it.^1,2, Taiara A. Caires^2,3, Eduardo M. da Silva¹ y José Marcos de C. Nunes^1,3

¹Universidade Federal da Bahia, Instituto de Biologia, 40170-115, Salvador, Bahia, Brasil

²Laboratório de Algas Marinhas, Instituto de Biologia, Universidade Federal da Bahia, Salvador, Bahia, Brasil 

³Universidade Estadual de Feira de Santana, Departamento de Ciências Biológicas, 44031-460, Feira de Santana, Bahia, Brasil

  This email address is being protected from spambots. You need JavaScript enabled to view it.

The southwestern Gulf of California has high-value commercial fisheries; however, there are few studies of the taxonomic diversity of fish in this area. Surveys of taxonomic diversity of the fish assemblage at 8 localities near the shore of Bahía de La Paz were undertaken from March 2002 to April 2003. Seasonal changes in diversity of rocky reef fish were analyzed, including taxonomic distance among fish species, using the alpha, alpha average, beta, and gamma diversity indices, the taxonomic distinctness index (TD D*), and the average taxonomic distinctness index (AvTD D+). Submarine visual censuses were carried out along 48 transects measuring 100 × 5 m (500 m2) at 5 m average depth from 09:00-16:00 h. Two seasons were studied: winter with an average temperature of 22.57°C, and summer with an average temperature of 27.09°C. 24,633 fishes, belonging to 92 species and 67 genera were recorded. According to the alpha average, beta, and gamma diversity indices, August had the highest diversity (19.5, 40.5, and 60 species, respectively), and December had the lowest diversity (20.6, 27.4, and 48 species, respectively). Spatial analysis of TD and AvTD were not significantly different, and analysis by season of these indices was not significant different. Greater anthropogenic impact would cause differences in TD and AvTD found at El Guano compared with other locations.

A bloom of Trichodesmium erythraeum with average densities of 3.5 x 106 trichomes L^-1 was recorded in February 2014, in an extensive range of beaches on the northern coast of Bahia, Brazil. High water temperatures and rainfall, associated with wind frequency and intensity may have triggered the bloom, which lead to a strong odor and change in the color of the water, it obliged the authorities to shut down the affected beaches. These blooms negatively affected tourism and fishing, the main economic activities in the region, highlighting the importance of monitoring these events in the area.

Key words: Cyanobacteria, bloom, harmful species, Brazil beaches