Ecology, Diversity and Molecular Studies of Red Seaweed Gracilaria spp. in Lawas, Santubong and Asajaya, Sarawak
Red seaweed Gracilaria (Gracilariaceae, Rhodophyta) is known as ‘Janggut Duyong’ by the local people of Sarawak, widely distributed in both temperate and tropical seawater zones. Gracilaria plays important roles as food materials and income for local people, provide protection and source of foods...
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| Format: | Thesis |
| Language: | English |
| Published: |
2017
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| Subjects: | |
| Online Access: | http://ir.unimas.my/id/eprint/23850/2/Muhammad%20Nur%20Arif.pdf |
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| Summary: | Red seaweed Gracilaria (Gracilariaceae, Rhodophyta) is known as ‘Janggut Duyong’ by the
local people of Sarawak, widely distributed in both temperate and tropical seawater zones.
Gracilaria plays important roles as food materials and income for local people, provide
protection and source of foods for diverse aquatic organisms, one of the primary producer in
marine ecosystem and main contributor of agar worldwide. Despite the importance of
Gracilaria in terms of ecology and socio-economy, little is known about Gracilaria species in
Sarawak. Hence, this study was designed to: (i) assess selected water quality parameters in
Gracilaria habitats, (ii) examine the abundance of Gracilaria in Lawas, Santubong and
Asajaya, Sarawak as well as the aquatic organisms associated with it and (iii) identify species
of Gracilaria using morphological characteristics and molecular approaches. Three field
samplings were conducted in Lawas, Santubong and Asajaya from April 2013 to December
2014. Selected water quality was measured in-situ and ex-situ, whole thallus of Gracilaria and
other aquatic organisms found within it were collected. Identification of Gracilaria using
molecular analysis was done using cytochrome oxidase subunit 1 (CO1) gene marker. Four
species of Gracilaria (Gracilaria blodgettii, G. changii, G. arcuata, G. coronopifolia) were
identified based on morphological characteristics whereas only two species (G. blodgettii,
Hydropuntia edulis) were found using molecular analysis. Both of the data were contradicted
due to: (i) CO1 gene marker may not be suitable to resolve taxanomy of Gracilaria in Sarawak
and (ii) high similarity in terms of morphology between G. coronopifolia and H. edulis. Other
flora (Acanthophora sp. and Padina sp.) and fauna namely bivalves, polychaetes, shrimps,
tunicates, small crabs and brittle stars were found living together in Gracilaria population. The
water quality in Lawas and Santubong were under Class 2 of the Malaysian Marine Water
Quality Criteria and Standard (MWQCS). In contrast, Asajaya’s water qualities fall under Class
iv
E of MWQCS. Overall, the values of water qualities recorded were within normal range of
standard water quality for mangrove water and mariculture in Malaysia. Approximately 80%
to 90% of the cage net in Lawas was covered by seaweeds and pH was the only parameter that
show negative correlation with percentage cover of seaweeds (p= 0.000). In comparison,
percentage cover of seaweeds in Santubong and Asajaya could not be determined due to regular
collection by local people. Healthy population of Gracilaria could be easily found at all the
sampling sites, thus they have the potential for future seaweed aquaculture. It is recommended
that the state government agencies, Department of Fisheries Sarawak and other nongovernmental organisations to introduce and assist the local people embarking in seaweed
culture |
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