Ecological Studies on Zooplankton from the Straits of Malacca With Special Reference to Copepods
The purpose of this study was to analyze the zooplankton composition and distribution in relation to spatial and temporal variations in the Straits of Malacca. The distribution of zooplankton, was determined using samples collected from 13 to 20 stations during four oceanographic expeditions alon...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2002
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/9396/1/FSAS_2002_25_A.pdf |
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| Summary: | The purpose of this study was to analyze the zooplankton composition and
distribution in relation to spatial and temporal variations in the Straits of Malacca. The
distribution of zooplankton, was determined using samples collected from 13 to 20
stations during four oceanographic expeditions along the Straits in different periods
between 1998 to 2000. Monthly zooplankton samples were also collected from two
stations at nearshore and offshore waters off Port Dickson from July 2000 to June
2001.
Copepods comprised an average of 71.3%, 71.2%, 70.9% and 57.9% of the total
zooplankton populations during consecutive cruises and were the main group of
zooplankton during each sampling period. Total zooplankton densities were higher in
the near-coastal area than the offshore area. A spatio-temporal variation of
zooplankton standing crop both in terms of biomass and density was not significant.
Higher mean density estimates of total zooplankton (mean of 12,918 ± 5,635 indo m·3)
and that of adult copepods (mean of 2,927 ± 1,085 indo m·3) were recorded during cruise II (pre-SW monsoon) compared to other cruises. However. variation of
copepods was temporally insignificant but spatially significant. Higher zooplankton
densities were obtained at 10-20 m depth stratum than any other depth strata.
Maximum peak of copepod densities collected off Port Dickson waters coincided with
NE and pre-SW monsoons when samples were collected horizontally and vertically,
respectively. Depth and salinity in associations with other factors explained the
distributional patterns of copepods in the studied area.
A total of 119 species of pelagic copepods belonging to calanoids (76), cyclopoids
(9), harpacticoids (6) and poecilostomatoids (28) were determined during the course
of the present investigation. Of these, nine species are new records for the Straits of
Malacca. Two characteristic copepod communities in the northern and southern parts
of the Straits were distinguished. The shallow southern part was characterised by
high-density values and low species diversity (H' = 2.967), and the dominance of few
coastal species such as Oithona simplex and Paracalanus parvus. The deeper waters
of the northern part were characterised by low-density values, relatively high species
diversity index (H' = 3 .632).
The heavy metal concentrations in mixed zooplankton were relatively low: ranging
from 1.19-1013.70 µg gol wet weight for copper, 1 6.54-235.78 µg gol wet weight for
zinc, 3.92-36.08 µg gol wet weight for lead and from 0.32-4.09 µg gol wet weight for
cadmium. Concentrations of copper and zinc were higher in near-coastal than offshore
areas, whereas those of lead and particularly cadmium were higher in offshore areas |
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