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The spatial and temporal abundance of epiphytic dinoflagellates associated with ciguatera was studied over two annual cycles (March 1999 to March 2000 and March 2001 to March 2002) in the northwestern coast of Cuba. From 14 species of macroalgae (Phaeophyta, Chlorophyta, and Rhodophyta), 1340 samples were obtained identifying seven species as potentially noxious; five of them are new reports for Cuba's phytobenthos: Prorocentrum belizeanum Faust, P. concavum Fukuyo, P. mexicanum Tafall, Coolia monotis Meunier, and Ostreopsis lenticularis Fukuyo. ANOVA/MANOVA analysis showed significant spatial differences: lower cell abundance near the shoreline adjacent to a river inlet and higher cell abundance in the deepest area. Prorocentrum lima (Ehrenberg) Dodge 1975 was found mainly on Phaeophyta followed by Chlorophyta and Rhodophyta. Gambierdiscus toxicus was found mainly on Phaeophyta followed by Rhodophyta and Chlorophyta. All the species reported in the study area were mainly on Padina spp. (Phaeophyta). Acanthophora spicifera (Rhodophyta) did not host dinoflagellate species. Environmental conditions in summer (higher temperature, more nutrients, greater water transparency, and low wind intensity) are suitable for macroalgae development, which serves as a substrate for potentially harmful dinoflagellates, and possibly the main vector for spreading ciguatera along the coast of Cuba. Rev. Biol. Trop. 54(2): 299-310. Epub 2006 Jun 01.

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If one wishes to distinguish chromatic effects from irradiance effects on metabolism. it is technically invalid to expose cells lo irradiances of equal photosynthetically available radiation (PAR) unless PAR is absorbed in totality. Therefore, the effects of blue light on growth and cellular concentrations of carbon, protein and carbohydrate of the diatom Chaetoceros protuberans Lauder, (in semi‐continuous cultures), were studied by exposing the cells to irradiances of equal photosynthetically usable radiation (PUR), of white (PURw) and blue (PURb) light. Three average levels: PURw=PURb=56, 125 and 13 μ m−2.s−1 were used in the stated sequence. With increasing PUR the relative concentration of carbohydrate increased in both types of light. The efficiency of this increase was not modified by blue light. The relative concentration of protein remained constant in white light out the efficiency of net protein production improved at the lowest blue light irradiance. The saturation threshold of this chromatic effect was higher in C. proluberans than in the Chlorophyceae. The chromatic change did not affect the average cell doubling rate, calculated over (5 or 6 days) an observation which does not agree with recently published work.

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