No abstract

Five benthic species of the genus Gambierdiscus (Dinophyceae) were observed for the first time in the coastal waters of Pakistan, Northern Indian Ocean. The morphology of the epiphytic, ciguatera-related toxic species G. toxicus, G. belizeanus, G. polynesiensis, G. australes and G. cf. yasumotoi are presented here, described by the Kofoid system of thecal plates Po, 3΄, 7˝, 6c, 8s, 5˝΄, 1p, 2˝˝ with differences in cell shape, cell size, plates, pores around the apical pore plate by using light and scanning electron microscopy. The occurrence of these potentially toxic dinoflagellate species in Pakistani coastal areas of Manora Channel and Balochistan during high temperatures of 28-32ºC is cause of concern for human health impacts from ciguatera fish poisoning.

Tintinnid community structure was investigated by plankton net (20 µm) sampling in the water column (0−200 m) at 33 stations during the spring inter-monsoon (10 March to 9 April 2012) in the eastern equatorial Indian Ocean. A total of 126 species belonging to 32 genera were recorded. Tintinnid abundance and biomass in the range of 193−2983 ind. m −3 and 0.99−14.75 µg C m −3 were positively related to integrated chlorophyll a (chl a) concentration. Taxonomic and morphological diversity were not significantly related to integrated chl a concentration and size diversity, estimated by size-fractionated chl a concentration in the water column of 0−200 m, but were negatively correlated to the depth of the deep chlorophyll maximum. Species abundance distributions at most stations (31 of 33) and in the 3 zones -the northern zone of the equator, the southern zone of the equator (SEQ) and the equator (EQ) -followed a typical lognormal distribution. The geometric distribution gave the best fit for the distribution of lorica oral diameter sizeclasses in the NEQ and SEQ. Our results suggest that the community structure of tintinnids is governed by the underlying water column environment rather than by the neutral theory of random colonization from a large species pool.

No abstract

No abstract