Abundance, diversity, and dietary preferences of opisthobranchs in reefs around Kota Kinabalu

• Main Author: Fathma Noora Canoy Abbas
• Format: Academic Exercise
• Language: English
• Published: 2015
• Subjects: QH Natural history
• Online Access: https://eprints.ums.edu.my/id/eprint/17491/1/Local%20air%20quality%20management%20in%20Klang%20Valley.pdf; https://eprints.ums.edu.my/id/eprint/17491/

Opisthobranchia is a subclass of gastropod molluscs subdivided into five orders Cephalapsidea, Sacoglossa, Anaspidea, Notaspidea, and Nudibranchia. Order Nudibranchia, forming the major part of sea slugs, is further grouped into suborders Doridina, Dendronotina, Arminina, and Aeolidina. Two hypotheses were tested in this study (1) Opisthobranch abundance and diversity is greater in protected areas than in unprotected reefs off Kota Kinabalu; (2) Opisthobranch dietary preference influences its habitat selection. The study was conducted in the west coast of Sabah, in the South China Sea. The study areas were at Gaya Island, Sapi Island (protected areas), Sepangar Island, and Udar Island (unprotected areas), with four sampling sites at each island. The roving dive technique using scuba gear was used to survey nudibranch species per site. Each site was covered at 2-10 m depth and each dive lasted for about 35-50 min. Once opisthobranchs were spotted, photos were taken in situ. Data was collected over the course of four months, from January to April 2015. Fourteen opisthobranch species were identified, with Cheloclonura amoena as the most dominant species found. Statistical analysis using the Mann-Whitney test showed a significant difference (p=0.043) in the diversity of the number of species between protected and unprotected areas at P<0.05. Cheloclonura amoena was the most dominant in Sapi Island (69.81%), Gaya Island (42.86%), and Udar Island (44.44%). Phyllidiella pustulosa accounted for 31.58% of species in Sepangar Island. Sapi and Gaya Island showed Significant differences in the abundance of opisthobranch species using the Kruskal-Wallis test (p<0.05). Abundance of species between protected and unprotected areas using Mann-Whitney test resulted in a significant difference (p=0.023). Feeding behaviour were observed in Chelidonura amoena and Pteraeolidia ianthina. C amoena was seen feeding on algae while P. ianthina was observed feeding on hydroids. In conclusion, abundance and diversity is significant in protected areas based on the analyses conducted. However, abundance in unprotected areas is insignificant but a variation of species is still notable.