Physical, chemical and biological characterization of Sibuti mangrove forest estuary, Sarawak, Malaysia
Estuaries are the areas of complex interaction between fresh and saline water. The mangrove estuaries are claimed to be the most productive and considered as the breeding ground for fishery resources. Though, Malaysia is blessed with number of mangrove estuaries, however not adequate research fin...
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| Format: | Thesis |
| Language: | English |
| Published: |
2015
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/78359/1/FSPM%202015%2010%20ir.pdf |
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| Summary: | Estuaries are the areas of complex interaction between fresh and saline water. The
mangrove estuaries are claimed to be the most productive and considered as the
breeding ground for fishery resources. Though, Malaysia is blessed with number of
mangrove estuaries, however not adequate research findings are reported about
their potentialities. Thus, this study was conducted to investigate the characteristics,
plankton diversity and feeding habit of fishes in Sibuti mangrove estuary. Monthly
sampling for ecological and biological parameters was conducted from January
2013 to December 2013 and data were pooled into seasons viz., intermediate, dry
and wet. The summarised indices from Estuarine Water Quality Index (EWQI),
Shannon- Wiener Diversity Index (SWDI) and Estuarine Resource Importance
Index (ERII) claimed this estuary as high quality (total index 10.83). The hydrobiological
parameters of the estuary followed a seasonal rhythm. The surface water
temperature of the estuary ranged from 27.1 to 32.2οC and revealed mesohaline on
the basis of salinity ranged from 0.3 to 27.1 PSU. Water of the estuary revealed
acidic to alkaline where dissolved oxygen (DO), total dissolved solids (TDS) and
light extinction coefficient (LEC) were observed ranging from 1.94 to 6.71 mgL-1,
0.5 to 43.9 mgL-1 and 1.71 to 6.71 respectively. The chlorophyll a concentration of
the surface water ranged from 0.002 to 0.348 mg m-3. Primary productivity (PP)
ranged from 0.20gCm-3hr-1 to 0.74gCm-3hr-1 (0.53±0.15gCm-3hr-1) with its higher
mean in the intermediate season (0.60±0.08 gCm-3hr-1) and the lower in the wet
season (0.35±0.12 gCm-3hr-1). Nitrate, phosphate, ammonium and silica
concentrations ranged from 0.40 to 3.53 mgL-1, 0.01 to 1.92 mgL-1, 0.06 to 1.24
mgL-1 and 1.7 to 3.47mgL-1 respectively. Seasonality exerted significant variation
in surface water temperature, salinity, TDS, conductivity and ammonium. One
hundred two (102) species of phytoplankton under 43 genera were recorded from
Sibuti mangrove estuary including 6 species of Cyanophyta, 4 species of
Chlorophyta, 63 species of Diatom and 29 species of Dinoflagellate. Mean
abundance of phytoplankton ranged from 5694 to 88890 cellsL-1 over the study
period with its higher value in the dry season. Species recorded from the estuary,
were dominated by Pleurosigma normanii, Coscinodiscus sp, Coscinodiscus
centralis, Coscinodiscus granii, Dinophysis caudata, Ceratium carriense, Ceratium
fusus and Ceratium lineatum. Abundance of phytoplankton demonstrated positive correlation with chlorophyll a (r=0.69, p=0.01), ammonium (r=0.64, p=0.01) and
silica (r=0.64, p=0.01).
A total of 54 forms of zooplankton belonging to diverse groups viz., copepod (35),
chaetognatha (1), decapoda (1), amphipoda (1), mysid (1), cladocera (1), ostracoda
(1), rotifer (1), tintinnid (1), apendicularia (1), doliolid (1), medusa (1), mollusc (2)
and larvae, nauplii and fish eggs (6) were recorded form the estuary. The majority
of zooplankton was occupied by copepod (73.58%) and was dominated by Acartia
spp.(calanoida), Oithona spp. (cyclopoida) and Euterpina spp. (harpacticoida).
Abundance of zooplankton ranged from 1419.58- 3121.59 ind. m-3 and maximum
was observed in the intermediate season while minimum in the wet season. Species
diversity (H́) of zooplankton ranged from 1.62-2.61 and there was revealed no
seasonal or site specific variation. Zooplankton abundance showed positive
correlation with phytoplankton (r=0.66, p=0.01) and chlorophyll a (r= 0.73,
p=0.01).
A total of 997 stomachs of 12 species of fishes under 9 genera namely Arius
maculatus, Arius caelatus, Arius truncatus, Hexanematichthys sagor, Setipinna
melanochir, Setipinna breviceps, Setipinna taty, Coilia dussumieri, Opisthopterus
tardoore, Ilisha elongata, Nibea saldado and Otolithes ruber were investigated for
the purpose of getting insight of feeding habits of the fishes of the estuary. Empty
stomach consisted of the largest portion of investigated stomachs and poor feeding
was common all over the study period. Crustacean dominated by shrimps were
found as the most preferred food of the fishes followed by miscellaneous
(appendages, detritus, plant parts) and molluscs. Feeding habit of fishes was found
different in various length group as well as seasons. A cluster analysis based on
dietary overlaps and dominant food consumption criteria, revealed four feeding
guilds viz., shrimp feeder, gastropod and bivalve feeder, fish and shrimp feeder and
detritus (plant part and sand-mud) and shrimp feeder. The results depicting
estuarine characteristics, diverse primary consumer (phytoplankton), secondary
consumer (zooplankton) and feeding habit of fishes and the correlation among them
exerted an interlocking pattern, which demonstrated the interdependency of the
variables towards functioning of the estuary. |
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