Annual cycle of microphytoplankton from the coasts of the tropical Mexican Pacific

Despite the length of littorals, studies of annual cycles for phytoplankton in the Mexican Pacific are rare, especially in tropical areas. A study of the phytoplankton (basically microphytoplankton) was realized in six locations off the States of Jalisco and Colima, from June, 2001 to May, 2002. A total of 286 taxa belonging to the taxonomic groups diatoms, dinoflagellates, cyanophyceae and silicoflagellates were identified. The best represented groups were dinoflagellates (157 taxa) and diatoms (119 taxa). Moreover, the study included a small fraction (15-25 %) of the diatom planktonic flora and 43% of the dinoflagellate flora from the Mexican Pacific. The flora showed a strong tropical-subtropical affinity. Dinoflagellate species appeared to be more important in late spring and early summer, whereas relative abundance of diatoms was higher most of the year of study. Five new records of dinoflagellates for the Mexican Pacific are annotated: Amphisolenia palmata, Amphisolenia truncata, Gonyaulax jollifei, Kofoidinium splendens and Protoperidinium divaricatum, from which only one is a non-thecate form; these findings may be due to the lack of previous detailed floristic studies in the area. No clear relation existed between microplankton and other variables found in the literature, such as chlorophyll a and nutrients. However, several patterns of phytoplankton succession were detected during our study: three stages were recognized, although they did not correspond with the diversity index values calculated

Annual cycle of microphytoplankton from the coasts of the tropical Mexican Pacific

Despite the length of littorals, studies of annual cycles for phytoplankton in the Mexican Pacific are rare, especially in tropical areas. A study of the phytoplankton (basically microphytoplankton) was realized in six locations off the States of Jalisco and Colima, from June, 2001 to May, 2002. A total of 286 taxa belonging to the taxonomic groups diatoms, dinoflagellates, cyanophyceae and silicoflagellates were identified. The best represented groups were dinoflagellates (157 taxa) and diatoms (119 taxa). Moreover, the study included a small fraction (15-25 %) of the diatom planktonic flora and 43% of the dinoflagellate flora from the Mexican Pacific. The flora showed a strong tropical-subtropical affinity. Dinoflagellate species appeared to be more important in late spring and early summer, whereas relative abundance of diatoms was higher most of the year of study. Five new records of dinoflagellates for the Mexican Pacific are annotated: Amphisolenia palmata, Amphisolenia truncata, Gonyaulax jollifei, Kofoidinium splendens and Protoperidinium divaricatum, from which only one is a non-thecate form; these findings may be due to the lack of previous detailed floristic studies in the area. No clear relation existed between microplankton and other variables found in the literature, such as chlorophyll a and nutrients. However, several patterns of phytoplankton succession were detected during our study: three stages were recognized, although they did not correspond with the diversity index values calculated

Marine planktonic dinoflagellates of the order dinophysiales (Dinophyta) from coasts of the tropical Mexican Pacific, including two new species of the genus Amphisolenia

Despite a recent revision of the dinoflagellates of the order Dinophysiales on Mexican coasts and a checklist of dinoflagellates from the Mexican Pacific, many records still need to be confirmed, for there are very few reliable illustrations and/or descriptions. In this paper, species composition and distribution of dinoflagellates belonging to the Dinophysiales, the product of the analysis of net phytoplankton material collected from coasts of the tropical Mexican Pacific (Jalisco to Chiapas) are presented. The material has been studied using light microscopy, although a few species were also studied by scanning electron microscopy (SEM). Forty-one species from five genera were identified, with two new records annotated for the Mexican Pacific: Amphisolenia thrinax and Metaphalacroma skogsbergii, and two new species of the genus Amphisolenia, Amphisolenia fusiformis sp. nov. and Amphisolenia michoacana sp. nov. Illustrations, dimensions and distribution data are provided for each species, and descriptions of the new species are also given. Amphisolenia palmata, A. rectangulata, A. truncata, Dinophysis apicata, D. hindmarchii, Histioneis biremis, H. crateriformis, H. pulchra, Ornithocercus cristatus, O. heteroporoides and O. orbiculatus arc illustrated for thefirst time in the waters of the Mexican Pacific. The number of species found in this study is relatively low. The species Dinophysis norvegica and D. sacculus, reported in previous papers, do not seem to occur in Mexican waters, as their distribution is rather limited to the Mediterranean Sea and the North Atlantic, respectively. Finally, the identity of certain species of Dinophysis and the nature of the new species described here are discussed