Date of Award

5-14-2026

Thesis Type

Masters

Document Type

Dissertation

Divisions

Institute for Advanced Studies

Institution

Universiti Malaya

Abstract

The estuarine and coastal regions of Matang, Perak, Peninsular Malaysia, are vital fishing grounds and recognised biodiversity hotspots, but are increasingly exposed to human activities. Understanding the biodiversity of marine fish and decapods is crucial for effective conservation efforts. Conventional biodiversity monitoring methods face several challenges, including invasiveness, inconsistencies in sampling techniques, reduced taxonomic accuracy, time-consuming processes, high costs, and often only providing approximate estimates. In this study, we evaluated the use of environmental DNA (eDNA) metabarcoding to assess marine fish and decapod diversity in Matang waters and to explore possible associations between fish assemblages and local cetacean occurrence. Water samples were collected across predefined zones between October 2021 and October 2022 and analysed using mitochondrial cytochrome c oxidase subunit 1 (COI) gene metabarcoding. The eDNA survey detected 37 marine vertebrate species and 12 decapod species, representing a total of 39 genera and 28 families, including species not previously recorded in Matang waters. The discrepancy in species detection between eDNA metabarcoding and conventional surveys reflects differences in sampling design, habitat coverage, and taxonomic detectability between the two approaches. Among all predefined zones, zone D (Kuala Trong-Kuala Jarum Mas) recorded the highest observed richness for both marine vertebrates (20 species) and decapods (eight species), whereas effective Shannon diversity was higher in zone B (Kuala Sangga) for marine vertebrates (5.67) and significantly higher (p < 0.05) in zone D (3.68) than in zones B and C for decapods. The highest number of marine vertebrate species was detected in October 2021 (inter-monsoon, 19 species), while decapod richness remained relatively stable across sampling months. Beta diversity analyses showed no significant effects (p > 0.05) of zone, sampling month, salinity or dissolved oxygen concentration on the overall marine vertebrate or decapod community composition. Nonetheless salinity had a marginal influence (p = 0.07) on marine vertebrate assemblages, suggesting that variation in salinity may have contributed to subtle differences in species composition across sites. Binomial logistic regression did not detect a significant association (p > 0.05) between overall fish community structure and cetacean occurrence. However, descriptive comparisons suggested overlap between cetaceans and several fish groups, particularly Siluriformes (catfish), Clupeiformes (anchovies), and Eupercaria incertae sedis (croakers and snappers). As these groups are known prey for cetaceans, the observed overlap may still indicate a possible ecological relationship at biological level. These taxa may therefore have potential as indicators of cetacean occurrence, although further validation is required. In summary, our study shows that eDNA metabarcoding is a useful complementary approach for biodiversity assessment in Matang waters and provides baseline data for future monitoring. Integrating molecular data with detailed morphological identification and improved reference libraries will be important for strengthening species verification, refining biodiversity inventories and supporting fisheries monitoring and conservation planning in the Matang region.

Initial

khm

Additional Information

Dissertation (M.A.) – Institute for Advanced Studies, University of Malaya, 2026.

Download

Share

COinS