Rev. biol. mar. oceanogr. 51(1): 197-201

Research Note

http://dx.doi.org/10.4067/S0718-19572016000100021

Proliferation of Falcula hyalina and Cylindrotheca closterium (Bacillariophyceae) on copepods in Bahía de La Paz, Gulf of California, Mexico

This email address is being protected from spambots. You need JavaScript enabled to view it.¹ and Gabriela María Esqueda-Escárcega¹

¹Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, Departamento de Plancton y Ecología Marina, Avenida Instituto Politécnico Nacional s/n, Col. Playa Palo de Santa Rita, La Paz, Baja California Sur 23096, México

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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 proliferation of the epizoic diatoms Falcula hyalina and Cylindrotheca closterium occurred, respectively, on the exoskeleton of marine copepods Acartia tonsa and Paracalanus sp. Samples were collected in February and in October 2013 in Bahía de La Paz. Both represent the first proliferations of this epizoic microalgae reported in the Gulf of California. Seawater temperature was 19°C in February and 28°C in October. A short morphological description, cell measurements and distribution of both species are provided. 

Key words: Epizoic diatoms, Cylindrotheca closterium, Falcula hyalina, Bloom, Bahía de La Paz, Gulf of California