Identification And Distribution Of Marine Dinoflagellates At Sebatu And Sungai Rambai, Malacca, Malaysia

Phytoplan11on is an important organism in the aquatic ecosystem as a primary producer. However, some species of phytoplankton also causes red tides or harmful algal blooms (HAB) which lead to negative impacts on human health, economics, aquaculture, fisheries and tourism. In this study, dinoflagellates, the main causative organism of red tides, were identified and enumerated from samples taken at Sebatu and Sungai Rambai, Malacca. In the identification of dinoflagellates, thecal plate tabulation and morphological characters of the cells were observed by light and electron microscopy.Thirty four species of dinoflageRates were identified, which consists of 10 potential HAB species viz

Identification of marine sand-dwelling dinoflagellates in Dinawan Island, Sabah

Identification of marine sand-dwelling species is important due to the toxin-producing abilities of some species that may harm human beings. In this study, sand samples were collected for 12 months at Dinawan Island, Sabah. Samples were identified using light microscopy (LM) and Scanning Electron Microscopy (SEM). Sixteen dinoflagellates species have been identified including 4 potential toxic species i.e. Prorocentrum arenarium, P. lima, P. rhatymum and Amphidinium carterae. Prorocentrum norrisianum is morphologically very similar to P. cassabicum. List of sand-dwelling dinoflagellates species especially toxic species provides important knowledge for monitoring and management of harmful algal bloom

Comparison on the cell abundance of benthic dinoflagellates in macrophytes and water column collected from open coastal waters and semi-enclosed lagoon

Benthic dinoflagellates are known to occur in the water column. The reason they can be found in different parts of the ecosystem is not clear. This study aims to determine the species and the cell abundance of benthic dinoflagellates in the water column and macrophytes collected from two different locations i.e. semi-enclosed lagoon and open coastal waters. The physico-chemical parameters (temperature, salinity, pH, dissolved oxygen) and nutrients (nitrate and phosphate) were determined. Results showed that in the lagoon, the most abundant dinoflagellate species on the macrophytes was also the most abundant dinoflagellate species in the water column. The species that dominated the water column and marophytes in the lagoon was Bysmatrum caponii. In the coastal area the trend was not clear. Coolia dominated the macrophytes whereas Peridinium quinquecorne dominated the water column. The physico-chemical parameters determined were similar at both sites except for nutrients. Results show that type of substrates and different geomorphology effects benthic dinoflagellates cell abundance in the macrophytes and water column

Effects of pH and water turbulence on the growth of harmful algae pyrodintum bahamense var. compressum

Pyrodinium, a red tide causing dinoflagellates are often related to toxicity cases particularly paralytic shellfish poisoning (PSP). Study on the effects of specific parameter on the growth it fy*ai"iin is essential to determine the potential factors r-esponsible for thek occurrences. The effects or iH ana turbulence on the growth of Pyrodinium bahamense var. compressun was conducted in laboratory under controlled conditions. P bahamense was cultured in nine different pH levels under two conditions; with and without water turbulence. The experiments were conducted under constant light intensity 100 pmolm-2s{ at 25"C with photoperiod of 12h'light:12 h dark bycle. Cells were incubated for two weeks'and **pri"gr *";;;;" for growth deterrnination every day at interval. This study shows thatP bahamenseattained the highest cell density (616 cells mT:t; when grown at pH 8-5 without water motion. However, in the presence of Ilow water turbulence or water motion, the cell density is relatively low (128 cells ml,-r) at pH 8.5. These different outcomes might be due to the growth inhibitory effect of water motion to P bahameise. Celldensities of p. bahamensewere also found significantly lower at acidic conditions ( 9.0