Vertical and horizontal distribution of marine sand-dwelling dinoflagellates in Dinawan Island, Sabah
A study on marine sand-dwelling dinoflagellates was carried out for duration of one year covering Southwest Monsoon (SWM) and Northeast Monsoon (NEM) in Dinawan Island, Sabah. Sand samples were collected from two sampling areas (coastal, and lagoon) to determine the vertical and horizontal distribu...
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| 格式: | Thesis |
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2012
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| 总结: | A study on marine sand-dwelling dinoflagellates was carried out for duration of one year covering Southwest Monsoon (SWM) and Northeast Monsoon (NEM) in Dinawan Island, Sabah. Sand samples were collected from two sampling areas
(coastal, and lagoon) to determine the vertical and horizontal distribution of sand dwelling dinoflagellates. The aim of this study was to describe the distribution of
marine sand-dwelling dinoflagellates in intertidal sandy beach area particularly in tropical area. In order to analyze the vertical distribution, sand samples were collected using the modified PVC tube at 12 cm depth of sand and were divided into 0-2 cm, 2-4 cm, 4-6 cm, 6-8 cm and 8-10 cm of sand layers. While for horizontal distribution, sand samples were collected along a transect line which
were divided into 6 stations with 10 m interval from beach face (0 m) toward sea (50 m). Dinoflagellate cells were identified via light and scanning electron microscopy. Overall, there were sixteen dinoflagellate species from four Orders identified. Most of the cells belong to Order Prorocentrales. There were also five harmful dinoflagellates viz. Amphidinium Carterae, Bysmatrum caponii, Peridinium
Quinquecorne, Prorocentrum lima and Prorocentrum rhatymum. The number of sand-dwelling dinoflagellates were higher in the lagoon area (1496 cells gâ»Â¹) compared to number of cells in the coastal area (1283 cells gâ»Â¹)). At the coastal
area, the number of dinoflagellate cells was significantly high at 2 cm depth of sand and low at the 8 cm depth of sand. Furthermore, dinoflagellate cell abundance also significantly correlated (p<0.05; r²=0.234) with the horizontal distance. Number of dinoflagellates increased from the station at 0 m (147 cells g-1) to station 50 m (252 cells g-1). In the lagoon area, however, no significant
difference was found between sand-dwelling dinoflagellate abundance and depth of sand. The granulomentric composition of sand sample was similar at all sand layers and stations (0m-S50m). In both study areas where the fine particles (0.250-0.125 mm) were dominated the granulometric composition of sand samples. Composition of fine partides were significantly different (p<0.05) with coarse
particles (2.0-0.5 mm) and very fine fraction (0.063 mm). Two peaks of dinoflagellate abundance were observed 330 cells gâ»Â¹)in August 2009 (SWM) and 439 cells gâ»Â¹)in February 2010 (NEM). Sand-dwelJing dinoflagellates positively
correlated with seawater nitrate concentration and temperature but had a negative correlation with phosphate concentration. However, no correlation was found between cell abundance (cell gâ»Â¹)) with sand Total Phosphorus (µM), sand Total Nitrogen (µM) and sand pH.
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