Diversity of Heterocapsa (Dinophyceae) and the algal bloom event in the mariculture areas of Johor Strait, Malaysia

Razali, Roziawati Mohd and Mustapa, Nurin Izzati and Yaacob, Ku Kassim ku and Yusof, Fadzilah and Teng, Sing Tung and Hanafiah, Afiqah Hamilton and Hii, Kieng Soon and Mohd Din, Monaliza and Gu, Haifeng and Leaw, Chui Pin and Lim, Po Teen (2022) Diversity of Heterocapsa (Dinophyceae) and the algal bloom event in the mariculture areas of Johor Strait, Malaysia. Plankton & Benthos Research, 17 (3). pp. 290-300. ISSN 1880-8247, DOI https://doi.org/10.3800/pbr.17.290.

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In November 2020, a high biomass multi-species algal bloom caused heavy water discoloration in the fish and mussel farm areas of the Johor Strait, Malaysia. A total of 19 microalgal taxa were identified from the plankton samples collected during the bloom event. Eleven genera were diatoms, and eight genera were dinophytes. The mi-croalgal composition was dominated by the diatom Guinardia sp., with an average cell density of 1.7X10(6 )cells L-1, making up 65-80% of the phytoplankton composition. Concomitantly, high densities of the dinophytes Heterocapsa minima (3.8-5.3X10(5) cells L-1) and Karlodinium spp. (3.5-6.6X103 cells L-1) were found. This is the first record of the occurrence of H. minima in Malaysian waters. Detailed morphological observations of H. minima based on scanning electron microscopy are presented in this study. To have a better insight into the Heterocapsa species assemblages in the Johor Strait, the diversity of Heterocapsa species assemblages along the strait was investigated based on a me-tabarcoding approach. Environmental DNA collected between 2018 and 2019 was used for high throughput amplicon sequencing targeting the small subunit (SSU) ribosomal RNA gene marker. The metabarcoding analysis detected three rare Heterocapsa species in the waters, H. niei, H. rotundata, and H. steinii. The results showed that Heterocapsa species assemblages varied temporally across the strait, with higher species diversity and amplicon sequence variant (ASV) read abundances detected in the Eastern Johor Strait. Although no fish/shellfish kills were sighted during the 2020 bloom event, the presence of harmful microalgal species, such as Heterocapsa minima and Karlodinium spp., urged the need for a comprehensive HAB monitoring program in the Strait to safeguard the aquaculture industry in the areas.

Item Type: Article
Funders: Malaysian Government through the Ministry of Higher Education, Malaysia, Long-term Research Grant Scheme (LRGS) [LRGS/1/2020/UMT/01/1/3], Higher Institution Centers of Excellence (HiCOE) [IOES-2014C], 11th Malaysia Plan Development Fund
Uncontrolled Keywords: Diatom; Dinoflagellates; Harmful algal bloom; Heterocapsa; Shellfish
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions: Deputy Vice Chancellor (Research & Innovation) Office > Institute of Ocean and Earth Sciences
Depositing User: Ms. Juhaida Abd Rahim
Date Deposited: 13 Sep 2023 08:10
Last Modified: 13 Sep 2023 08:10
URI: http://eprints.um.edu.my/id/eprint/41213

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