Near shore patchy reef located at the leeward side of the fringing reef at Polhena was surveyed to evaluate spatial patterns of growth rates of Pocillopora damicornis. This study was carried out at three locations of the reef; front, side and back from June to November in 2004. Three sites were selected from each location considering the depth (surface, middle, and bottom). Forty five colonies of P. damicornis which were approximately of the same size were studied. Temperature, dissolved oxygen, BOD5, salinity, pH, soluble reactive phosphorous, turbidity and light intensity of each site were measured fortnightly and their mean values were 28.06 ± 0. ) (n = 36). Growth of coral colonies, which was measured as linear skeletal extension rate (LSER), was 0.15 ± 0.01 mm day -1 . Significant differences in mean light intensity, mean sediment volume, and LSER of coral colonies were observed among different sites. The highest sedimentation rate 94818.2 ± 6981.5 ml m -2 day -1 (5418.2 ± 398.9 g m -2 day -1 ) and the lowest LSER of the colonies (0.05 ± 0.01 mm day -1 ) were observed at back bottom site. The highest LSER was observed at front surface (0.23 ± 0.01 mm day -1). LSER showed a significant negative correlation (R 2 = 0.59) with increased sedimentation rate and low light intensity. Back bottom site of the patchy reef was having comparatively unfavorable conditions for the growth of corals that were subjected to more environmental stress than the corals in other sites of the reefs.
Lack of proper scientific data on the behaviour of cetaceans is a major constraint in managing whale and dolphin watching activities without affecting cetacean populations in marine waters off Mirissa, where it has become a high income generating tourist activity. Therefore a shipboard surveys were conducted using a special whale watching boat for 43 days from January to April 2012 in an area of about 940 km 2 in Mirissa, southern coast of Sri Lanka to identify the environmental parameters that affect the abundance of cetaceans. During this study, 8 cetacean species including 6 toothed whale species (Physeter macrocephalus, Globicephala melas, Peponocephala electra, Orcinus orca, Tursiops truncates and Stenella longirostris) and two baleen whale species (Balaenoptera musculus and Balaenoptera physalus) were identified. Results of the study revealed that relationship between species occurrence and the measured water quality parameters (temperature, salinity and density) was significant (p < 0.05). From the identified species blue whale and melon headed whale can tolerate high density (1.02±0.0) and salinity (blue whale-36.35±0.75; melon headed-35.55±0.51) range while blue whale (28.53±0.89), sperm whale (28.47±0.93) and spinner whale (28.66±1.04) can tolerate widee temperature range.
Dolphin and whale watching has become a blooming activity in the tourism industry in Sri Lanka. Proper scientific data is lacking for the understanding and management of dolphin and whale watching activities particularly in the Southern coast. Based from Mirissa, a shipboard survey was conducted for 43 days from January to May 2012 covering 940 km 2 .The diversity and distribution of cetaceans inhabits in the continental shelf and slope were recorded from shipboard sighting data. Their species composition, pod size, behavioral pattern were observed and the distribution pattern was mapped. Total of 8 species of cetaceans were recorded during the study period. They were spinner dolphin (Stenella longirostris), bottlenose dolphin (Tursiops truncates), melon headed whale (Peponocephala electra), fin whale (Balaenoptera physalus), killer whale (Orcinus orca), short finned pilot whale (Globicephala melas), sperm whale (Physeter macrocephalus) and blue whale (Balaenoptera musculus). Distribution pattern and pod size varied with the species. Out of 6675total sightings, 5382 were spinner dolphins and 843 were bottlenose dolphins. Depth levels showed a significant relationship with different cetacean species (p < 0.05). Spinner dolphins, bottlenose dolphins and melon headed whales were always observed near to the shore at relatively shallow areas around 100m depth contours. Fin whales, killer whales and short finned pilot whales were observed around 500 m to 650 m depth while sperm whales and blue whales were observed around 1000 m depth level located further away from the shoreline. Most of the dolphin groups were consisted with relatively large number of individuals about 160 while, most baleen whales were found solitary or small pods consisted with few individuals. Large toothed whales such as sperm whale pods were observed with intermediate number groups about 20 individuals. Those findings can be directly used to conserve and protect cetaceans and prepare a proper management plan to regulate whale watching industry.
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