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. 2022 Jan 29;11(2):188.
doi: 10.3390/pathogens11020188.

First Molecular Identification of Caligus clemensi on Cultured Crimson Snapper Lutjanus erythropterus on Jerejak Island, Penang, Peninsular Malaysia

Zary Shariman Yahaya  1 , Mohd Nor Siti Azizah  2 , Luay Alkazmi  3 , Rajiv Ravi  1 , Oluwaseun Bunmi Awosolu  1   4
Affiliations

First Molecular Identification of Caligus clemensi on Cultured Crimson Snapper Lutjanus erythropterus on Jerejak Island, Penang, Peninsular Malaysia

Zary Shariman Yahaya et al. Pathogens. .

Abstract

Fish parasites such as Caligus clemensi are a serious concern for cultured fish in many regions of the world, including Malaysia. This study was designed to elucidate the parasites' prevalence and intensity coupled with the morphology and molecular identification of C. clemensi on cultured Lutjanus erythropterus in Jerejak Island, Penang, Peninsular Malaysia. The study was carried out on 200 fish specimens of cultured L. erythropterus obtained from the GST group aquaculture farm. Parasites were collected from the infested part of L. erythropterus fish, and their prevalence and intensity were determined. The parasites were identified morphologically using a field emission scanning electron microscope. Molecular studies were performed through PCR amplification and sequencing. MEGA 5 was used to construct a phylogenetic tree using the pairwise distance method. The results showed that only the C. clemensi parasite was found prevalent on L. erythropterus fish with a prevalence and mean intensity (S.D) of 198 (99%) and 36.4 ± 12.2, respectively. The prevalence varied significantly with respect to fish length (p < 0.05). The nucleotide BLAST sequence for 18S ribosomal RNA partial sequences showed 97% with 100% query similarity, E-value 0 with C. clemensi with the accession number DQ123833.1. Conclusively, C. clemensi remains a major parasite of L. erythropterus in the study area.

Keywords: aquaculture; aquaculture industry; fish parasites; morphological identification; phylogenetic tree.

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Conflict of interest statement

All the authors declare that there is no conflict of interest in this paper.

Figures

Figure 1
Figure 1
Caligus clemensi ventral view with the aid of optical microscope, magnification 50X.
Figure 2
Figure 2
Caligus clemensi viewed under SEM. (A): Ventral view of adult female with egg sacs; (B): leg 2 measured as 0.3 mm; (C): genital complex measured as 1.0 mm; (D): tip of labium detailed; (E): leg 4 detailed; (F): furca detailed. Magnifications (A) = 35X, (B) = 40X, (C) = 40X, (D) = 80X, (E) = 50X and (F) = 80X.
Figure 3
Figure 3
Caligus clemensi. in ventral view. A: lunule; B: mouth tube; C: 3-segmented antenna which consists of basal segment (=coxa), middle segment (=basis) and terminal segment (=endpod); D: 1-segmented hook-like post antennal process; E: maxillae; F: sternal furca that has tapering tines; G: leg 1; H: leg 2. Magnification at 50X.
Figure 4
Figure 4
Caligus clemensi in ventral view. I: Leg 3; J: leg 4 with 5 setae; K: genital complexes which attach to the posterior portion of the fourth leg-bearing segment without the posterolateral processes; L: 1st abdominal somite that leads to anal somite where caudal ramus originates from it; M: egg sac. Magnification at 22X.
Figure 5
Figure 5
Verification of the obtained sequence of 18S ribosomal RNA partial sequences’ comparison with Caligus clemensi (DQ123833.1) using ClustalW, multiple sequence alignment software. There is an indication of 97% similarity between both sequences.
Figure 6
Figure 6
MEGA 5 generated neighbor-joining tree based upon the 18S ribosomal RNA partial sequences of specimens analyzed in this study.
See this image and copyright information in PMC

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