Microplastic ingestion by commercial fish from the Pearl River Estuary, South China /

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Student Theses

2021

Lam, Wing Ling

Hong Kong : The Education University of Hong Kong

Thesis

Plastics have penetrated into almost every aspect of human life because they have advantageous features in durability and versatility coupled with lightweight compared to traditional materials. However, the extensive use of plastics, absence of proper waste management in less-developed regions and environmentally irresponsible practices towards plastic disposal have introduced a substantial amount of plastics into the world's oceans. Worse still, plastic items of size smaller than 5 mm, commonly known as "microplastics", pose a more serious threat to the environment due to their small size and ubiquitous presence. To date, over 420 fish species worldwide have been found to consume microplastics. Although microplastic contamination in wild fish is well-documented, information regarding microplastic ingestion by farmed fish is very limited at the present stage. The Pearl River Estuary (PRE), the largest estuary in southern China surrounded by nine highly urbanized cities, is prone to microplastic pollution. Given that the PRE is a vital fishing ground in China, it is imperative to investigate to what extent marine-cultured fish from the PRE are impacted by microplastics.Herein, a total of 180 tiger grouper (Epinephelus fuscoguttatus) × giant grouper (Epinephelus lanceolatus) (hereinafter referred to as "TGGG hybrid grouper") were sampled from fish farms located in Zhuhai of the PRE, directly adjacent to the Pearl River mouth, and eastern Hong Kong, where is unaffected by the Pearl River discharge. Microplastics were first extracted from the stomach and intestine, and then quantified to assess the level of oral intake of this pollutant. Microplastics were also characterized based on their morphotype, size and colour. Microplastic items were detected in all fish samples with an average abundance of 26.63 ± 21.87 n/individual or 0.47 ± 0.35 n/g. Fibres and mini-microplastics (< 1 mm) dominated the samples, making up 61.1% and 73.6% of the total count, respectively. Over 80% of the microplastics analyzed with a micro-Raman spectrometer were high-density polymers. Additionally, this study highlights a significant spatial difference in microplastic abundance in fish between Zhuhai and Hong Kong, with a higher load of microplastics found in fish from Zhuhai. The occurrence of microplastics in fish could be related to fish diet and the availability of microplastics in their feeding habitats. These results indicate that microplastic contamination is widespread in farmed fish from South China

LG51.H43 MPhil 2021eb Lamwl

https://educoll.lib.eduhk.hk/records/2NAQCvbs