A bloom of Karlodinium australe (Gymnodiniales, Dinophyceae) associated with mass mortality of cage-cultured fishes in West Johor Strait, Malaysia

Hong, Chang Lim and Chui, P.L and Toh, Hii Tan and Nyuk, Fong Kon and Leh, Hie Yek and Kieng, Soon Hii and Sing, Tung Teng and Roziawati, Mohd Razali and Gires, Usup and Mitsunori, Iwataki and Po, T.L (2014) A bloom of Karlodinium australe (Gymnodiniales, Dinophyceae) associated with mass mortality of cage-cultured fishes in West Johor Strait, Malaysia. Harmful Algae, 40. pp. 51-62. ISSN 1568-9883

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Abstract

A recent (February 2014) mass mortality of fishes was observed in the cage-farming region of the West Johor Strait of Malaysia, involving over four different species of cultured fishes, numbering ∼50,000 fish. A field investigation at six stations along the West Johor Strait collected water samples and examined for the presence of harmful species. Dead fishes were collected for necropsy. The phytoplankton composition was dominated by a species of Karlodinium, at a considerably high cell concentration (0.31–2.34 × 106 cells l−1), and constituting 68.8–98.6% of the phytoplankton relative abundance at all stations. Detailed morphological assessment by light and scanning electron microscopy revealed that the species was Karlodinium australe de Salas, Bolch and Hallegraeff. This was supported by molecular evidence of the nuclear encoded large subunit ribosomal gene (LSU rDNA) and the second internal transcribed spacer (ITS2) via single-cell PCR. The sequences of LSU rDNA yielded 3.6–4.0% divergence when compared to the sister taxon, K. armiger; and >6.5% when compared to other Karlodinium species. Fish necropsy showed symptoms similar to those affected by karlotoxin ichthyotoxins. This is the first report of a mass mortality of cage-cultured and wild fishes attributed to the unarmored dinoflagellate K. australe.

Item Type: E-Article
Uncontrolled Keywords: Dinoflagellate, Fish mortality, Harmful algal bloom, Karlodinium australe, West Johor Strait, unimas, university, universiti, Borneo, Malaysia, Sarawak, Kuching, Samarahan, ipta, education, research, Universiti Malaysia Sarawak
Subjects: S Agriculture > SH Aquaculture. Fisheries. Angling
Divisions: Academic Faculties, Institutes and Centres > Institute of Biodiversity and Environmental Conservation
Depositing User: Karen Kornalius
Date Deposited: 07 Sep 2016 22:30
Last Modified: 07 Sep 2016 22:30
URI: http://ir.unimas.my/id/eprint/13409

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