Changes of larval fish feeding ecology in the anthropogenic-impacted Klang strait (Malaysia) between the time periods 1985-86 and 2013-14

Quah, Wei Chiang (2020) Changes of larval fish feeding ecology in the anthropogenic-impacted Klang strait (Malaysia) between the time periods 1985-86 and 2013-14. Master dissertation/thesis, UTAR.

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Abstract

Between time periods 1985-86 and 2013-14, Klang Strait was heavily impacted by anthropogenic activities such as the operation of Kapar Power Station (KPS), shipping, removal of mangroves for industrial and coastal development, housing, agriculture and shrimp farming. This environmental change had collectively caused a shift in the zooplankton community structure, in which large-bodied zooplankton were replaced by small-bodied zooplankton. In order to access KPS impact on fish larvae growth and feeding, fish larvae in the Klang Strait were compared using archived samples collected from this two time periods, 1985-86 and 2013-14. Zooplankton samples were also collected in parallel with fish larvae sampling. A total of 761 fish larvae belonging to seven dominant families (Bregmacerotidae, Callionymidae, Cynoglossidae, Engraulidae, Gobiidae, Leiognathidae and Sciaenidae) were examined in this study. Fish larvae were categorized according to their life history stages: preflexion, flexion and postflexion. Gut content analysis and Index of Relative Importance were used to gain insight of diet composition and rank importance of prey in the diet. Copepods dominated the diet of all fish larval families except Leiognathidae. Three types of feeding habits of fish larvae were identified through Principal Component Analysis; zooplanktivorous, planktophagous and detrivorous. Callionymidae, Cynoglossidae and Sciaenidae showed a diet preference over small-bodied copepods whereas Bregmacerotidae preferred large-bodied copepods. Gobiidae preferred the younger nauplii compared to adult stages of copepods after 30 years. Engraulidae are planktophagous because copepods and detritus are both important in their diet. Leiognathidae are benthic detrivorous feeders because detritus and polychaete larvae are found to be the main food items in the gut. As shown by Redundancy Analysis, diet of fish larvae was highly correlated with the zooplankton community abundance in the environment. Specialised (Bregmacerotidae and Leiognathidae) or opportunistic (Callionymidae, Cynoglossidae, Engraulidae, Gobiidae and Sciaenidae) feeding behaviour may be a feeding strategy to reduce dietary overlap or to adapt to the changing environment. Understanding the feeding habit of larval fishes in anthropogenic-impacted areas are crucial in fisheries management and conservation to ensure sustainable fish stocks. This study may possibly be the first dietary study comparing time series in dietary composition of larval fishes in the tropics.

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