Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Species Diversity and Distribution of Cnidarians in Raffles Marina Teo, D. L. E.1 and Chou, L. M.2 Department of Biological Sciences, Faculty of Science, National University of Singapore 10 Kent Ridge Crescent, Singapore 119260 ABSTRACT In Singapore, limited research on Cnidarian biodiversity in semi-enclosed water-bodies like boating marinas has been done. Marina construction leads to changes in water quality due to introduction of pollutants, and modification of hydrodynamics, thus causing habitat degradation, and the resulting loss of many native marine fauna. Bioremediation measures aim to improve and restore water quality. Prior to bioremediation, biological monitoring of the selected area has to be done periodically and one useful way is to use bioindicators. Cnidarians require specific environmental conditions for growth and survival and are sensitive to slight changes. Therefore the objective of this research is to investigate cnidarian biodiversity and distribution in Raffles Marina so as to identify potential bioindicators. A basic visual survey was conducted, in situ photographs were taken and specimens were collected for further identification by comparing differences in morphology, size and color using identification keys and reference pictorial guides. A distribution map was created to represent the occurrences and abundance of various classes in the marina. Up to twelve genera were identified and their distribution in the marina reflects the specific conditions required for them to survive. Among the five marinas in Singapore, Raffles has been observed to have highest cnidarian diversity. INTRODUCTION Marina construction leads to changes in water quality due to the introduction of various pollutants, as well as increases in turbidity due to increased levels of sedimentation. Sedimentation causes the choking up of marina seafloor and reduces dissolved oxygen content, thereby creating an anoxic environment detrimental to living organisms. In addition, there would also be a modification of hydrodynamics, which would cause habitat degradation, and the resulting loss of many native marine fauna. Bioremediation measures aim to improve and restore water quality. Prior to bioremediation, biological monitoring of the selected area has to be done periodically and one useful way is to use bioindicators. The detection of signs of environmental degradation and ecological stresses could be the role of bioindicators, which have to be equipped with high sensitivity to the environment they are placed in. Cnidarians require specific environmental conditions for growth and survival and are sensitive to slight environmental changes. This group of animals coincidentally fit into the criteria of being bioindicators and this includes hydroids, jellyfish, sea anemones, zoanthids, gorgonians, hard and soft corals. In general, cnidarians thrive in tropical waters with warm temperatures, low sedimentation and stable salinity and this area covers Singapore. Therefore the objective of this research is to 1 2 Student Professor 1 investigate cnidarian biodiversity and distribution in Raffles Marina so as to identify potential bioindicators in the local context. MATERIALS AND METHODS To investigate the species diversity of cnidarians in a marina, the following methods were used. A basic visual survey was conducted, in situ photographs were taken and specimens were collected for further identification. It is important to know the exact parts of each specimen to be collected and identified. Each specimen was accompanied with a label that contained relevant information about its characteristics. All specimens collected were placed temporarily in plastic containers in 70% alcohol for preservation. Using identification keys and reference pictorial guides, descriptions and photographs of the specimens were compared for differences in morphology, size and color, verified and identified to the lowest rank possible. A distribution map was created to represent the occurrences and abundance of various classes in the marina. RESULTS AND DISCUSSION The identification of specimens collected at Raffles Marina is listed in Table 1 and the distribution map representing the location and abundance of cnidarians in the marina is illustrated in Figure 1. Up to twelve genera of cnidarians were identified and their distribution in the marina reflects the specific conditions required for them to survive. The species richness of cnidarians in a semi-enclosed estuary such as Raffles Marina can be considered high in comparison with the other four marinas in Singapore, where cnidarians were absent or in very low abundance. The pattern of distribution of the various classes of cnidarians in the marina shows a relation between the physical factors and environmental conditions the organisms require for survival, and the locality and abundance of the species at different sites in the marina. The results from this study on the occurrence and abundance of various classes of cnidarians at Raffles Marina will enable the identification of potential species found within the marina to be used in the biological monitoring and remediation of waters within the marina. CONCLUSION As a holistic approach to understanding and maintaining biological diversity and water quality in semi-enclosed marina waters, it is essential to study the animals found within the marina in relation to the hydrodynamics of the water and marina architectural design. A good understanding of these can help improve the management of marinas, in relation to maintaining a healthy ecological balance. ACKNOWLEDGEMENTS Professor Chou Loke Ming, Karenne Tun and all who have helped and contributed in this project are greatly appreciated. 2 Table 1. List of identified cnidarians found in Raffles Marina. Class Hydrozoa Subclass Hydroidea General group describes Hydroid Anthozoa Alcyonaria or Octocorallia Soft coral Sea fan or gorgonian Zoantharia or Hexacorallia Sea anemone Hard coral Zoanthids Species Sertularia sp. Sertularella sp. Plumularia sp. Undetermined stinging hydroid Dendronepthya sp. Nephthea sp. Stereonepthya sp. Sarcophyton sp. Subergorgia sp. Subergorgia suberosa Heteractis sp. Oulastrea crispata Zoanthus sp. Figure 1. Distribution of cnidarians in Raffles Marina 3 REFERENCES Allen, G.R. and Steene, R. (1994) Indo-Pacific Coral Reef Field Guide. Tropical Reef Research, Singapore. Chou, L.M. (1997) A Guide to the Coral Reef Life of Singapore. Singapore Science Centre. Chou, L.M. (1998) ‘Marinas and Marine Conservation.’ Marinas 5: September 1-4, 1998. Haven Marina Systems. Chou, L.M., Goh, B. and Nayar, S. (2000) ‘The Waters in our Marina: Does Green Really Mean Clean?’ Marinas 6: April 4-6, 2000. Spinnaker International. Chuang, S.H. (1973) Animal Life and Nature in Singapore. Singapore University Press. Colin, P.L. and Arneson, C. (1995) Tropical Pacific Invertebrates- A Field Guide to the Marine Invertebrates Occurring on Tropical Pacific Coral Reefs, Seagrass Beds and Mangroves. Coral Reef Press, U.S.A. Fabricius, K. and Alderslade, P. (2001) Soft Corals and Sea Fans- A comprehensive guide to the tropical shallow-water genera of the Central-West Pacific, the Indian Ocean and the Red Sea. Australian Institute of Marine Science. Fraser, C.M. (1938) Hydroids of the 1934 Allan Hancock Pacific Expedition 4(1). The University of Southern California Press, LA. Fraser, C.M. (1948) Hydroids of the 1934 Allan Hancock Pacific Expedition 4(5). The University of Southern California Press, LA. Rees, W.J. and Vervoort, W. (1987) ‘Hydroids of the John Murray Expedition to the Indian Ocean, with Revisory notes on Hydrodendron, Abietinella, Cryptolaria and Zyophylax (Cnidaria: Hydrozoa).’ Zoologische Verhandelingen 237. Rijksmuseum van Natuurlijke Historie, Leiden, The Netherlands. Friese, U.E. (1972) Sea Anemones. T.F.H. Publications. Glasby, T.M. (1999) ‘Differences Between Subtidal Epibiota on Pier Pilings and Rocky Reefs at Marinas in Sydney, Australia.’ Estuary: Coastal and Shelf Science 48: 281-290 Goh, N.K.C. and Chou, L.M. (1996) ‘An Annotated Checklist of the Gorgonians (Anthozoa: Octocorallia) of Singapore, with a discussion of the Gorgonian diversity in the IndoWest Pacific.’ The Raffles Bulletin of Zoology 44(2): 435-459 Goh, N.K.C. (B.Sc.) (1990) Taxonomy, distribution and ecology of the Gorgonacea (sub-class Octocorallia) of Singapore reefs. (Thesis: Dec 1990) Hinwood, J. (1998) ‘Marina Water Quality and Sedimentation.’ Marinas 5: September 1-4, 1998. Haven Marina Systems. Jaafar, Z. (2001) Marine Ecology of Semi-enclosed waters at Raffles Marina. (Thesis: 2000/2001) Mather, P. and Bennett, I (1993) A Coral Reef Handbook- A guide to the geology, flora and fauna of the Great Barrier Reef. Surrey Beatty and Sons Pty Limited. McAllister, T.L., Overton, M.F. and Brill, E.D.Jr. (1996) ‘Cumulative Impact of Marinas on Estuarine Water Quality.’ Environmental Management 20(3): 385-396 Soule, D.F. and Kleppel, G.S. (1988) Marine Organisms as Indicators. Springer-Verlag NY Inc. Veron, J.E.N. (1986) Corals of Australia and The Indo-Pacific. The Australian Institute of Marine Science. Wee, Y.C. and Ng, P.K.L. (1994) A First Look At Biodiversity In Singapore. National Council on the Environment, Singapore. 4