Coral Reefs And Marine Benthic Habitat Mapping Using Hydroacoustics Methods

Lee, Wah Tze (2007) Coral Reefs And Marine Benthic Habitat Mapping Using Hydroacoustics Methods. Masters thesis, University Malaysia Sabah.


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The entire fringing reefs of Pulau Baik, off Lahad Datu, Sabah were mapped in March 2001 using a RoxAnnâ„¢ Acoustic Seabed Classification System (ASCS). A total of 53 km track length was surveyed during this fine scale mapping, discriminating 18 distinct benthic classes. Half of these classes were of living coral substrates comprising 3 major coral growth forms, notably massive, foliose and branching. Reef cover in Pulau Baik was good with 20% healthy corals. Thirty-five percent (35%)was a mixture of live corals with other non-coral substrate i. e. sand and algae. Corals of Pulau Baik were mainly found on the north of the island, diverging into 2 extended reef structures. Based on the relatively low abundance of foliose and branching corals, as well as the presence of large algae mats on rubbles, it was postulated that the reefs at Pulau Baik was damaged by storm Greg in 1996 and it is now in its recovery stage. A broad scale mapping using the same system was conducted in the same time frame to discriminate the general substrate types at Darvel Bay. More than 70% of the surveyed areas were of muddy bottom. Small patch reefs were commonly found around the islets within the bay, as well as waters near Kunak. Generally, coral patches nearer to the islets were in better condition, while more dead corals were found adjacent to Kunak. In coastal areas, corals were found in close proximity to the mangrove forest. Seagrass and brown algae were also a common feature in the shallow areas, east of Lahad Datu. An accuracy assessment was performed in October 2001 to evaluate the integrity of the reef habitat map of Pulau Baik. The internal accuracy assessment was performed using ten 10mx50m test plots method and point sampling method. Due to technical limitations, the results of the test plot method were unsatisfactory. However, point sampling method yielded better internal accuracy at 78%. Both U-test and Regression Analysis showed that orientation to shore and depth within the study area do not have any significant influence on the system performance. The resulting Pulau Baik reef habitat map has high repeatability with map accuracy of more than 80%. Therefore such maps can be used confidently for resource management and monitoring purposes.

Item Type: Thesis (Masters)
Keyword: Coral Reefs and Island, Coral
Subjects: Q Science > QL Zoology > QL1-991 Zoology > QL1-355 General Including geographical distribution
Department: INSTITUTE > Borneo Marine Research Institute
Depositing User: ADMIN ADMIN
Date Deposited: 01 Mar 2011 14:15
Last Modified: 14 Nov 2017 15:13

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