Digenean diversity of reef fishes in Khanh Hoa province, Viet nam

Journal of Fisheries science and Technology Special issue - 2015 NHA TRANG UNIVERSITY • 23 DIGENEAN DIVERSITY OF REEF FISHES IN KHANH HOA PROVINCE, VIET NAM Dang Thuy Binh1, Tran Quang Sang2, Dang Nguyen Anh Tuan2 ABSTRACT Coral reefs are massive areas of calcium carbonate in the oceans and are among the ecosystems having high biodiversity, including 700 coral species, 600 mollusks, and nearly 4,000 fishes. Research on the parasites that infect Vietnamese coral reef fish are limited. Examinations of 116 individuals of 9 reef fishes have been conducted to date. We have detected 8 digeneans (Bivesicula claviformis, Lecithochirium sp., Allobacciger diplorchis, Cainocreadium labracis, Cholepotes sp., Carneophallus sp., Tubulovesicula sp. and Tetrochetus sp.). Two clownfishes and a goatfish were infected by two species, while only 1 digenean infected all remaining fishes. The highest (63.63%) and lowest (4%) prevalence was for Tubulovesicula sp. and Carneophallus sp. and Cholepotes sp. on Trachinocephalus myops and Parupeneus multifasciatus, respectively. Tubulovesicula sp. on Trachinocephalus myops had a mean intensity of 22, and 1 for Bivesicula claviformis, Carneophallus sp., Cholepotes sp., and Allobacciger diplorchis on Amphiprion perideraion, Amphiprion polymnus, Parupeneus multifasciatus and Scolopsis taeniopterus. As an ecological and economic importance fish species, comprehensive research on parasite infections of coral reefs can help in fisheries management and sustainable development. Keywords: Coral reef, marine fish, parasite, biodiversity, Vietnam 1 Institute for Biotechnology and Environment, Nha Trang University, Email: binhdangthuy@gmail.com 2 Student of Institute for Biotechnology and Environment, Nha Trang University I. INTRODUCTION Coral reefs are massive areas of calcium carbonate in the oceans and are ecosystems having high biodiversity (Vazhiyil, 2009). Currently, the best preservation zones contain over 700 coral species, 600 molluscs, and nearly 4,000 fish species (Spalding et al. 2001; Paulay, 1997). But, in fact, only about one third of all marine fish species live on the coral reefs (Burke et al. 2002). Coral reef fishes are commonly traded in the aquarium industry due to their vibrant colors and high level of biodiversity (Alevizon, 1994). Coral reef fishes are also regarded as food source as well as ecological resources and tourism of more than one billion people worldwide (UNEP, 2004; Burke et al. 2002). Research on parasite biodiversity in coral reefs is often neglected (Justine, 2010; Justine et al. 2012; Justine et al. 2010; Whittington et al. 2003; Poulin, 2004; Bouchet, 2006, Sun et al. 2012). Digenea parasites have been reported on coastal and reef fishes (Cribb et al. 2014; Cribb et al. 1994; Justine et al. 2012; Jacob, 1977). In Vietnam, research focused on zoonotic trematodes occurring on freshwater fish has been published (Pham Cu Thien et al. 2009; Dinh Thi Thuy et al. 2010; Vo The Dung et al. 2008), but few studies have examined parasite diversity on marine fishes (Vo The Dung et al., 2008; Dang Thuy Binh et al., 2013). We here investigate digenean biodiversity on common coral reef fishes in Nha Trang Bay, Khanh Hoa Province, based on morphological characters. Journal of Fisheries science and Technology Special issue - 2015 24 • NHA TRANG UNIVERSITY II. MATERIALS AND METHODS 1. Sampling Reef fishes were collected by fishing or purchased from fisherman at Nha Trang Bay, Khanh Hoa Province, in 2014. A total of 116 individuals belonging to 9 species, of which including 17 pink anemonefish (Amphiprion perideraion), 13 saddleback clownfish (Amphiprion polymnus), 19 yellowtail clownfish (Amphiprion clarkii), 25 manybar goatfish (Parupeneus multifasciatus), 4 Jenkin’s scorpionfish (Scorpaenopsis cacopsis), 10 lattice monocle bream (Scolopsis taeniopterus), 5 golden threadfin bream (Nemipterus hexodon), 11 snakefish (Trachinocephalus myops), and 12 variegated lizardfish (Synodus variegatus). Fish information is presented in Table 1. Fish were transported alive to the laboratory and examined within 24 hrs of capture. Digeneans were preserved in absolute alcohol (99.8%). Table 1. Number and size of the reef fish collected in Nha Trang Bay Coral reef fish Number (n) Length (mm) Weight (g) Amphiprion polymnus 13 86.52 ± 51.81 30.47 ± 29.55 Amphiprion clarkii 19 68.41 ± 32.59 13.49 ± 12.51 Parupeneus multifasciatus 25 191 ± 3.4 95.92 ± 35.33 Scorpaenopsis cacopsis 4 144.5 ± 10.5 64.76 ± 15.09 Scolopsis taeniopterus 10 202.5 ± 75.5 103.01 ± 66.98 Nemipterus hexodon 5 190 ± 6 83.92 ± 12.84 Trachinocephalus myops 11 200.5 ± 55.5 77.44 ± 51.41 Synodus variegatus 12 170 ± 23 50.29 ± 16.97 Presentation value: Mean value ± Deviation 2. Species identification Digenea parasites were collected according to Ha Ky (2007), Cribb & Bray (2010), Bray et al. (2011). Digenea were identified following (Cribb et al. 1994; Justine et al. 2012; Justine 2010; Yamaguti, 1958). The morphological features used to identify each taxa are presented below: Bivescula claviformis, U-shaped excretory gland and eggs distributed into one long array. Tetrouchetus sp., Semicircular shape, pharynx is on the left and the yolk gland scattered bottom body Tubulovesicula sp. , Ventral sucker has big size, two yolk is located in the middle of the body, the large intestinal system and divided into two sides Allobacciger diplorchis, the large testes symmetrical with 7-8 yolk distribution two sides the body Lecithochirium sp., Elongated body with bulging around the ventral sucker and y-shaped glands excrete small at the bottom body Cholepotes sp., Elongated body, ventral sucker nearly with oral sucker and egg distributed mainly inside the body Carneophallus sp., strawberry shape, two intestine are connected together Cainocredium labracis, the yolk gland is distributed in whole body 3. Data analysis 3.1. Prevalence (%) Prevalence was calculated as = No. of infected fish * 100 No. of examinde fish 3.2. Mean Intensity (I) Mean intensity was calculated as = No. of parasites * 100 No. of infected fish Journal of Fisheries science and Technology Special issue - 2015 NHA TRANG UNIVERSITY • 25 III. RESULTS AND DISCUSSION 1. Species identification Seven families were represented: Bivesiculidae (1 species Bivesicula claviformis), Hemiuridae (2 species Lecithochirium sp., and Tubulovesicula sp.), Botulisaccidae (1 species Cholepotes sp.) Microphallidae (1 species Carneohallus sp.), Monorchiidae (Allobacciger diplorchis), Accacoeliidae (Tetrochetus sp.), and Opecoelidae (Cainocreadium labracis). The research detected 8 digenea species belonging 8 genera, of which 5 species were unidentified at the species level, because these have many similar characteristics and different shape, so very difficult to classify. A list of parasites and sites of infection are presented in Figure 1 and Table 2. Bivesicula claviformis, and Lecithochirium sp. commonly infect clownfishes (Amphiprion perideraion, A. polymnus and A. aclarkii). Cainocreadium labracis infected two fishes (Scorpaenopsis cacopsis and Synodus variegatus). The Figure 1. Digenea species on coral reef fish in Nha Trang Bay, Vietnam digeneans commonly infected the gut, and showed morphological variation regarding the host which they infected (Fig. 1). 2. Prevalence and intensity of Digenea species on coral reef fish Prevalence and mean intensity was 4–63.63% and 1–22, respectively (Table 2). The highest (63.63%) and lowest (4%) prevalences were for Tubulovesicula sp., Carneophallus sp. and Cholepotes sp. on Trachinocephalus myops and Parupeneus multifasciatus, respectively. Tubulovesicula sp. on Trachinocephalus myops had a mean intensity of 22 (parasite/infected fish), and 1 (parasite/infected fish) for Bivesicula claviformis, Carneophallus sp., Cholepotes sp., and Allobacciger diplorchis on Amphiprion perideraion, Amphiprion polymnus, Parupeneus multifasciatus and Scolopsis taeniopterus. Two clown fishes and a goatfish species were infected by 2 parasite species, the others had been infected by 1 parasite species. Journal of Fisheries science and Technology Special issue - 2015 26 • NHA TRANG UNIVERSITY Research on the taxonomic diversity of digeneans infecting marine fishes is still limited. Presently, only crustacean have been reported from clownfishes (Ganeshamurthy et al., 2014; Humes, 1982; Manning, 1970; Kokshoorn, 2007; Kent, 1999; Silphaduang et al., 2000). Tetrochetus sp. with high prevalence (>60%) was reported on Diodon hystrix (Radhakrishnan & Nair, 1981); Tubulovesicula sp. infects Serranus sp. and Pomadasys olivaceum in Karachi coast, Pakistan and the Red Sea and Indian Ocean (Shaukat & Bilqees, 2011; Nagaty, 1956). Cribb et al. (1994) detected 4 digeneans species belong to family Bivesiculidae on mullets (Mugilidae). In the current study, Tetrochetus sp., Tubulovesicula sp., Cholepotes sp. and Carneohallus sp. infected Nemipterus hexodon, Trachinocephalus myops, and Parupeneus multifasciatus; whereas, Bivesicula infected clownfish only. Table 2. Prevalence and mean intensity of Digenea species Host Digenean Site in host Prevalence (mean intensity) Amphiprion perideraion Bivesicula claviformis Stomach 5.88(1) Amphiprion polymnus Lecithochirium sp. Stomach/Intestine 30.76(2.25) Bivesicula claviformis Stomach 7.69(1) Amphiprion clarkii Bivesicula claviformis Stomach 4.26(14) Lecithochirium sp. Stomach/Intestine 5.26(2) Parupeneus multifasciatus Cholepotes sp. Intestine 4(1) Carneohallus sp. Intestine 4(1) Scolopsis taeniopterus Allobacciger diplorchis Intestine 5.26(1) Nemipterus hexodon Tetrochetus sp. Stomach 25(3) Scorpaenopsis cacopsis Cainocreadium labracis Stomach 25(6) Synodus variegatus 8.33(2) Trachinocephalus myops Tubulovesicula sp. Stomach/Intestine 63.63(22) Justine (2010) surveyed parasite diversity in New Caledonia and reported 105 parasite species collectively representing Digenea, Monogenea, Copepoda, Isopoda, Nematoda, Cestoda, and Acanthocephala. Of those, Lecithochirium sp. and Cainocreadium sp. infected groupers (Epinephelinae), goatfishes (Mullidae), and snappers (Lutjanidae). Justine et al. (2012) reported 21 digeneans on 207 individual reef fish, including a species of Lecithochirium and Allobacciger infecting lutjanids and caesionids. The present study also detected Lecithochirium sp. and Cainocreadium labracis in 4 fishes (Amphiprion polymnus, Amphiprion clarkia, Scorpaenopsis cacopsis, and Synodus variegatus). Furthermore, Lecithochirium sp was not found on goatfish Parupeneus multifasciatus, while 2 other species Cholepotes sp. and Carneohallus sp. were discovered. The reason could be that Parupeneus multifasciatus lives in a different habitat, e.g. Environment contains many phytoplankton will be infected heavily the digenean of larva stage and flow of water also affect to habitat as well as food souce of them, due to make appearing the other parasite. Cribb et al. (2000) documented the parasites of 386 individual coral reef fish in New Caledonia and showed that the prevalence and intensity of digeneans is relatively low (13% and 23, respectively). Infection status varied according to different parasite species and their hosts. The highest value (both prevalence and intensity) was for Tubulovesicula sp. on Trachinocephalus myops. Journal of Fisheries science and Technology Special issue - 2015 NHA TRANG UNIVERSITY • 27 This is the first characterization of digenean diversity on reef fishes in Vietnam. Clownfishes are highly-valued ornamental fishes; whereas, the remaining fishes are economically and ecologically important species in Vietnam. This information should serve as a useful baseline with which to launch further studies into the ecological interactions between fishes and parasites in Vietnam. IV. CONCLUSION Based on morphological characteristic, the research detected 8 digeneans species of 8 genera, of which 6 are unidentified at the species level. Prevalence and intensity ranged from 4–63.63% and 1–22, respectively. The highest (63.63%) and lowest (4%) prevalence is for Tubulovesicula sp. and Cholepotes sp. and Carneohallus sp., respectively. 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