Tropical Biomedicine 31(2): 362–369 (2014) Seasonal occurrence and habitat of two pennellids (Copepoda, Siphonostomatoida) infecting marine ranched black scraper and Korean rockfish in Korea Venmathi Maran, B.A.*, Oh, S-Y., Choi, H-J. and Myoung, J-G. Marine Ecosystem Research Division, Korea Institute of Ocean Science & Technology, 787, Haean lo, Ansan 426-744, Seoul, Korea *Corresponding author email: [email protected]; [email protected] Received 16 November 2013; received in revised form 8 January 2014; accepted 10 January 2014 Abstract. The seasonal occurrence and habitat of two parasitic copepods, Peniculus minuticaudae (Shiino, 1956) and Peniculus truncatus (Shiino, 1956) (Siphonostomatoida, Pennellidae) infecting the fins of black scraper Thamnaconus modestus and Korean rockfish Sebastes schlegelii, respectively were investigated. The fishes were collected from Tongyeong marine living resources research and conservation center, southern coast of Korea as five per month for two years from July 2011 to June 2013. In total, 391 copepods of P. minuticaudae were collected in two years, in contrast to P. truncatus. Prevalence was 85%, mean intensity was 3.25, and maximum intensity was 33. Season wise, the infestation was observed as the highest in autumn (September-November) season, and the lowest in winter (December- February). It was infested only on fins of black scrapers. Abundance of P. minuticaudae was found on the pectoral fin (43.5%), followed by anal (22.5%), second dorsal (20.5%) and caudal fins (13.5%). Statistically significant interactions were observed between season, infestation and infected regions (P<0.001). It is also reported for the first time in Korea from the fins of wild threadsail filefish Stephanolepis cirrhifer from Busan, Jeju, Tongyeong and Yeosu fish markets. It can be a new record on its host and localities. A total of 51 P. truncatus were collected with the prevalence of 37.5%, mean intensity of 0.37 and maximum intensity of 6. Season wise, infestation was observed as the highest in summer (June-August), and the lowest in winter. Attachment site was the dorsal fin and not found from any other fins of rockfish. Statistically significant interaction was observed between season and infestation (P<0.05). This is the first report on the ecology of these two pennellids. INTRODUCTION originally described by Shiino (1956) from wild fishes of Japan, but recently P. The genus Peniculus (von Nordmann, 1832) minuticaudae was reported from farmed (Siphonostomatoida: Pennellidae) is one of T. modestus and threadsail filefish the parasitic copepods frequently reported Stephanolepis cirrhifer (Yamaguti, 1963; from Korea and Japan and it consists of Fukuda, 1999; Nagasawa et al., 2011; Ismail 14 valid species (Venmathi Maran et al., et al., 2013), aquarium fishes, unicorn 2012a). In Korea, two species of Peniculus leatherjacket filefish Aluterus monoceros have recently been reported with their (Linnaeus, 1758), hairfinned leatherjacket complete redescription such as Peniculus Paramonacanthus japonicus (Tilesius, 1809) minuticaudae (Shiino, 1956) from black and brown-banded butterflyfish Roa modesta scraper Thamnaconus modestus (Günther, (Temminck & Schlegel, 1844) in Japan 1877) and Peniculus truncatus (Shiino, (Okawachi et al., 2012). The severity of 1956) from Korean rockfish Sebastes P. minuticaudae infection is high in both schlegelii (Hilgendorf, 1880) (Venmathi- Korea (Venmathi Maran et al., 2012a) and Maran et al., 2012a). Those two species were Japan (Nagasawa et al., 2011) and it has so 362 far not been reported from elsewhere. The Tongyeong (Gyeongsangnamdo), Yeosu complete life cycle of P. minuticaudae was (Jeollanamdo) in Korea. revealed recently in Japan (Ismail et al., Few specimens were used for scanning 2013), but the ecological studies on both electron microscope analysis to show some pennellids are lacking in either countries. general features. The copepods were Hence, in this study, we report the ecology of transferred to 70% ethanol and then both pennellids and a new host and localities dehydrated through a graded series of records on P. minuticaudae. ethanol (90%, 99.5% and 100%) and finally by Black scrapers have been cultured at a isoamyl alcohol. The samples were critical few localities of the southern coastal regions point-dried using CO2 gas and ion-sputtered of Korea. At Tongyeong marine living for observation with a scanning electron resources research and conservation center microscope (Hitachi S-4700, Tokyo). (TMRC), several commercially important fishes were ranched under the marine ranching program (MOMAF, 2007). Recently, RESULTS we studied the symbiotic organisms associated with ranched fishes and their life Peniculus minuticaudae (Figure 1B, C) cycle at TMRC (Venmathi Maran et al., A total of 391 pennellids of P. minuticaudae 2012a; b; 2013). Threadsail filefish culture is was collected from the soft fin rays of T. uncommon in Korea, because of the small modestus for two years. Prevalence was 85%, size and low growth rate of this fish, in contrast mean intensity was 3.25, and maximum to Japan (Fukuda, 1999). Korean rockfish is intensity was 33. Seasonwise, the infestation cultured at several localities around the was observed as highest in autumn southern coastal region of Korea due to its (September-November), and lowest in winter high commercial value (Froese & Pauly, (December-February) (Figure 3). In two years 2013). In order to control the increasing threat period, infestation was found as high in of parasites in aquaculture, the ecology of September, followed by October, however, in these two pennellids P. minuticaudae and December it was low. The habitats of P. truncatus are studied. infestation were only fins of black scrapers, not on body surface, gills and they were severely damaged. Abundance of pennellids MATERIALS AND METHODS was found on the pectoral fin (43.5%), followed by anal (22.5%), second dorsal The collection of ranched (TMRC, (20.5%) and caudal fins (13.5%). Significant Gyeongsangnamdo, Korea) fish hosts T. interactions were observed between season modestus (T= 18-32 cm) (Figure 1A) and S. and infected regions (P<0.001), season and schlegelii (T= 15-30 cm) (Figure 2A) (five infestation (P<0.001). The same pennellid per month) were carried out for two years was also found for the first time in Korea from July 2011 to June 2013. The seasonal from the fins of wild threadsail filefish study of both parasitic copepods was carried Stephanolepis cirrhifer (Monocanthidae) out. In addition, their habitats (infested site), from Busan, Jeju, Tongyeong and Yeosu fish prevalence, mean intensity were carefully markets. It can be considered as a new record analysed and investigated. Infested sites on its host and localities in Korea. were microphotographed (Figure 1B, 2B). One-way and Two-way ANOVA analyses were Peniculus truncatus (Figure 2B) applied for the statistical interpretation for A total of 51 P. truncatus was collected from season and infestation and also with infected the dorsal fin of S. schlegelii for two years regions. The common and scientific names (Figure 4). Prevalence was 37.5%, mean of host fishes follow Froese & Pauly (2013). intensity was 0.37 and maximum intensity The infection of pennellids was also studied was 6. Season wise, infestation was observed in the wild fish S. cirrhifer collected at fish as highest in July 2012 (summer), and lowest markets located at Jeju (Jejudo), Busan, in winter. In 2011, summer and autumn 363 Figure 1. A. Marine ranched host black scraper Thamnaconus modestus; B. Severe infestation of pennellids on the fin (arrowed); C. Adult female Peniculus minuticaudae Shiino, 1956 with eggs Figure 2. A. Marine ranched host Korean rockfish Sebastes schlegelii; B. Infestation of adult female Peniculus truncatus Shiino, 1956 with eggs (arrowed) 364 Figure 3. Seasonal occurrence of Peniculus minuticaudae Shiino, 1956 infesting the all fins of Thamnaconus modestus from July 2011 to June 2013 at Tongyeong, Korea Figure 4. Seasonal occurrence of Peniculus truncatus Shiino, 1956 infesting the dorsal fin of Sebastes schlegelii from July 2011 to June 2013 at Tongyeong, Korea 365 Figure 5. Scanning electron micrographs of a pennellid showing: A. oral region with maxilla (arrowed); B. enlarged oral cone (arrowed); C. legs (arrowed) seasons were found with more number of from the soft fin rays of fish hosts. In general, pennellids than 2012. The infestation pennellids are having host specificity in both decreased (Aug-Oct) after July in 2012 wild and farmed fishes (Ho, 1966; Boxshall & (Figure 4). Attachment site was the dorsal Halsey, 2004). While, fish live in aquarium, fin (100%) and not found from any other fins, the infestation of pennellids can become in body surface or gills of rockfish. Significant extensive range to many fish hosts due to interaction was observed between season conserved and restricted areas (Okawachi and infestation (P<0.05). et al., 2012). However, in the ranched locality at Tongyeong (TMRC), seven different Scanning electron microscope fish hosts are ranched, the infestation of The oral region (Figure 5A) of pennellid was P. minuticaudae was restricted only to black observed with the enlarged oral cone (Figure scraper and P. truncatus only to Korean 5B). Around the oral region, maxilla (arrowed rockfish. It shows the high host specificity Figure 5A) was located. The legs (Figure 5C) of Peniculus in farming areas. However, have been found located near the end of the one pennellid species, Haemobaphes neck and the beginning of cylindrical body. disphaerocephalus (Grabda, 1976), was reported as an accidental infection from farmed Atlantic salmon Salmo salar DISCUSSION (Linnaeus, 1758) in Canada (Kent et al., 1997; Johnson et al., 2004). Thus, our finding from A total of 391 P. minuticaudae and 51 P. Korea of P. minuticaudae and P. truncatus truncatus were collected for two years from is only the second country record after Japan. July 2011 to June 2013 from sea ranched We have also revealed a new record on locality. Both pennellids were collected only localities in Korea such as Busan, Jeju, 366 Tongyeong and Yeosu.