Browsing by Author "Jayasinghe, R.P.P.K."

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    Abundance and Diversity of Ichthyoplankton in the West Coast of Sri Lanka, from Kelani River Estuary to Maha Oya Estuary
    (Uva Wellassa University of Sri Lanka, 2019-02) Silva, A.P.R.; Rathnasuriya, M.I.G.; Guruge, K.P.G.K.P.; Jayasinghe, R.P.P.K.
    Fundamental understanding of fish resources has become an urgent need in Sri Lanka for the sustainable management of fish stocks. As studies on ichthyoplankton (fish eggs and larvae) in Sri Lankan coastal waters are scarce, a preliminary study was carried out with the aim to find the abundance, distribution and composition of ichthyoplankton in the west coast. Samples were collected in five stations bordering Kelani river estuary, Negombo lagoon and Maha Oya estuary in the west coast where human interactions are relatively high. Horizontal surface sample and a vertical sample were collected from each station using Working Party 2 (WP2) plankton net (180 µm mesh size) for three months in 2018: March, September and October representing 1st inter-monsoon, Southwest monsoon and 2nd inter-monsoon respectively. Fish eggs and larvae were separated from plankton and identified to the lowest possible taxonomic level under the stereo microscope using the standard keys. A total of 4095 fish eggs and 465 fish larvae belonging to 23 families were collected from the study area. An average abundance of 8772 eggs and 996 larvae per 1000 m3 were recorded. Most abundant taxonomic level in each month were, Family Siganidae in March, Family Blennidae in September and Order Clupeiformes in October. The highest abundance of fish eggs was found in Station 3 (22158 per 1000 m3 in vertical sample and 13934 per 1000 m3 in horizontal surface sample) and larvae was found in Station 4 (1196 per 1000 m3 in vertical sample and 2537 per 1000 m3 in horizontal surface sample) which is located adjacent to Maha Oya estuary, showing estuaries’ ecological services as nursery grounds for early stages of fish. This study infers that there is a high pelagic and demersal fish diversity and abundance in the west coast of Sri Lanka. Since this is a preliminary study, comprehensive studies on the spatial and temporal variation of abundance and diversity of ichthyoplankton in Sri Lankan waters are recommended.
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    Zooplankton Studies in East Coast of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2019-02) Koshika, K.; Wimalasiri, H.B.U.G.M.; Jayasinghe, R.P.P.K.; Guruge, K.P.G.K.P.
    Zooplankton plays a vital role in marine environment by transferring the energy to higher trophic levels through the food web. However, the studies on zooplankton in the coastal water of Sri Lanka especially in the East coast are deficient. The present study was conducted to investigate zooplankton abundance in East coast of Sri Lanka in marine resources survey using the Research Vessel: Dr. Fridtjof Nansen during June to July 2018. Twenty-five samples were obtained from five transects using WP2 plankton net with 180µm mesh size. The samples were collected vertically from 30 m, 100 m and 200 m depths. In the laboratory; zooplankton was identified to the lowest possible taxonomic groups using standard keys and counted. The results revealed that zooplankton are dominated by the Phylum Arthropoda (63%), followed by Chordata (20.6%), Sarcomastigophora (7.4%), Chaetohnatha (4%), Cnidaria (2.5%), Annelida (1%), Echinodermata (0.4%), Mollusca (0.4%) and Ciliophora (0.2%). The highest (13053.57 m-3) and lowest (5747.43 m-3) abundance were recorded at transects near Mullaitivu and Batticaloa respectively. The study showed that there was no significant difference (p>0.05) of the abundance of zooplankton among the sampling stations. However, abundance of the zooplankton between shallow and offshore sampling stations were significantly different (p <0.05). The abundance of zooplankton at the depth of 100 m indicated an increasing trend towards Batticaloa. Offshore (100 m and 200 m) zooplankton abundance (2697 m-3) at 30 m depth was higher than the abundance of nearshore samples (1298 m-3). This study revealed that there are spatial variations of zooplankton in East coast of Sri Lanka and it may affect the fish production in the area. Therefore, further comprehensive studies on zooplankton are recommended to find out the possible reasons for such variations which could be useful in managing the marine environment.