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Vol. 9: 185–192, 2010 AQUATIC BIOLOGY Published online May 12 doi: 10.3354/ab00250 Aquat Biol Microparasite ecology and health status of common bluestriped snapper Lutjanus kasmira from the Pacific Islands Thierry M. Work1,*, Matthias Vignon2, 3, Greta S. Aeby4 1US Geological Survey, National Wildlife Health Center, Honolulu Field Station, PO Box 50167, Honolulu, Hawaii 96850, USA 2Centre de Biologie et d’Ecologie Tropicale et Méditerranéenne, UMR 5244 CNRS-EPHE-UPVD, avenue Paul Alduy, 66860 Perpignan Cedex, France 3Centre de Recherches Insulaires et Observatoire de l’Environnement (CRIOBE), USR 3278 CNRS-EPHE, BP 1013 Papetoia, Moorea, French Polynesia 4Hawaii Institute of Marine Biology, PO Box 1346, Kaneohe, Hawaii 96744, USA ABSTRACT: Common bluestriped snappers Lutjanus kasmira were intentionally introduced into Hawaii from the South Pacific in the 1950s and have become well established throughout the archipelago. We examined health, prevalence and infection intensity of 2 microparasites, coccidia and epitheliocystis-like organisms (ELO), in L. kasmira from their introduced and native range including the islands where translocated fish originated (Tahiti and Marquesas Islands, French Polynesia) and from several other islands (American Samoa, Fiji and New Caledonia). In addition, we did a longitu- dinal survey of these parasites in the introduced range. Coccidia and ELO were widely distributed and were found on all islands except for New Caledonia. Health indices, as measured by overall organ lesions, body condition and parasite intensity, indicated that fish from Samoa were the least healthy, and fish from Midway (Hawaiian Archipelago) were the healthiest. Microparasite diversity was highest on Midway and Hawaii and lowest on New Caledonia. Infection of coccidia followed an asymptotic size–prevalence curve, whereas that of ELO peaked at larger size classes (27.8 cm). Prevalence and aggregation of both parasites in the host varied dynamically over 8 yr, with prevalence and aggregation of coccidia being consistently higher and lower, respectively, than ELO. We hypothesize that these parasites are enzootic to the Hawaiian Islands and were not introduced with fish from Tahiti or the Marquesas Islands. Host response and aggregation parameters suggest that coccidia exert a negative effect on their host and probably have an indirect life cycle, whereas ELO appears less pathogenic and has a direct life cycle. KEY WORDS: Common bluestriped snapper · Lutjanus kasmira · Coccidia · Pathology · Epitheliocystis-like organism · Prevalence · Pacific Islands Resale or republication not permitted without written consent of the publisher INTRODUCTION fisheries. Since its introduction to Oahu, L. kasmira has become extremely abundant and has successfully The common bluestriped snapper Lutjanus kasmira spread throughout the entire Hawaiian Archipelago, (Forsskål, 1775) (Lutjanidae) is a reef fish found from Midway in the northwest to the island of Hawaii throughout the Indo-Pacific (Randall 2005). Because of in the southeast (Friedlander et al. 2002). Since its the lack of highly commercially valuable fish species introduction, this snapper has become the focus of con- such as groupers and snappers (Oda & Parrish 1981, siderable attention in the scientific and fishing commu- Randall 1987), this fish was intentionally introduced off nity because of its possible deleterious effects on local the island of Oahu, Hawaii, from the Marquesas marine communities. However, evidence is scant for Islands and Tahiti in the 1950s to enhance local coastal dietary overlap or competition between L. kasmira and *Email: [email protected] © Inter-Research 2010 · www.int-res.com 186 Aquat Biol 9: 185–192, 2010 native fish, nor have they been incriminated in con- helminth surveys, for example, host response to the sumption of native fish (Oda & Parrish 1981). In con- parasite is often not examined, although exceptions to trast, L. kasmira are often found schooling with native this exist (Rigby & Dufour 1996). In contrast, histologic goatfish, and asymmetrical competition occurs with examination of tissues for microparasites usually in- one species, Mulloidychthies vanicolensis, the latter cludes documentation of host response and patholo- being displaced higher into the water column, possibly gies that may not be evident from routine gross exam- making the native goatfish more susceptible to preda- ination of tissues. tion (Schumacher & Parrish 2005). The objectives of the present study were to document: In general, animals that colonize remote islands are (1) the geographic extent of microparasites in Lutjanus thought to have a low probability of introducing para- kasmira from both the native range, where the fish orig- sites from their native range, in part because only the inated (Tahiti and the Marquesas Islands in French Poly- fittest animals are thought capable of long-distance nesia), and the introduced range (Hawaiian Archipel- migrations (Torchin et al. 2003). The case of the Lut- ago); (2) the general health status of L. kasmira in these janus kasmira in Hawaii is different in that this species islands; (3) the spatio-temporal epidemiological variabil- was deliberately and repetitively introduced in large ity in L. kasmira within the introduced range; and (4) the numbers (Randall 1987), thus presumably enhancing potential effects of microparasites on the health of L. kas- the likelihood of parasite introductions into Hawaii mira in their introduced range. (Randall 1987). Several reports exist on investigation of potentially invasive nematodes in L. kasmira from Hawaii (Rigby & Font 1997, Font & Rigby 2000), and a MATERIALS AND METHODS recent comprehensive study of overall macroparasite fauna of L. kasmira from South Pacific islands suggests Fish from Oahu and Maui were collected by hook that most of the macroparasites found in L. kasmira and line or by pole spear at depths ranging from 15 to from Hawaii were introduced (Vignon et al. 2009). 80 m. For the temporal study, an equal number of fish In contrast, relatively less information exists on were caught at the same 5 locations off Oahu each year microparasites in L. kasmira (and tropical wild marine between 2001 and 2008 as part of a long-term water fish in general) in part because these are more difficult quality study carried out by the City and County of to detect. One report documented a high prevalence of Honolulu. We measured whole weight (0.1 g) and total merozoites of a coccidian parasite and a relatively and fork length (0.1 cm). Body condition index (whole lower prevalence of infections of epitheliocystis-like weight/total length3) was calculated as described by organisms (ELO) in L. kasmira from Oahu where the Le Cren (1951) because it is a good indicator of the fish were initially introduced (Work et al. 2003). How- general well-being of a fish (Bolger & Connolly 1989). ever, the role of L. kasmira in introducing potential All fish underwent a systematic external and internal microparasites into Hawaiian marine ecosystems is examination, and representative tissues including gill, unclear, and it is unknown how widespread these skin, muscle, brain, liver, spleen, cranial and caudal microparasites are in fish populations within the kidney and swim bladder were preserved in 10% neu- Hawaiian Archipelago or the Pacific. In addition, we tral buffered formalin, embedded in paraffin, sec- do not have data on the potential effects of these para- tioned at 5 µm and stained with hematoxylin and sites on the host. eosin. Parasites were identified as belonging to one of Unless parasites can be documented to cause signif- the following groups: (1) coccidia, (2) ELO, (3) hel- icant mortality (epizootics), determining whether or minths, (4) myxosporea or (5) microsporea. not they have an adverse impact on hosts based on Microscopic lesions for each organ were assigned a cross-sectional age–prevalence surveys can be diffi- score according to a scheme simplified from Bernet et al. cult because their effects can be subtle (McCallum & (1999). Briefly, lesions were characterized as atrophy, in- Dobson 1995). Controlled experimental studies expos- flammation or necrosis and assigned a score of 1, 2 or 3, ing hosts to parasites are ideal to document effects, respectively. These scores were a modification of Bernet but for marine ecosystems the life cycles of many para- et al. (1999), whereby the magnitude of the score re- sites are unknown, precluding their use. However, flected the reversibility of damage (e.g. atrophy is a re- clues to effects of parasites on hosts can be gained versible process, necrosis is not). Lesions were further as- from cross-sectional surveys. For example, decreasing signed a subjective severity score: mild (1), moderate (2) prevalence of parasites with age can be caused by or severe (3). Lesion type multiplied by lesion severity parasite-induced host mortality or successful host im- was summed for each organ to arrive at a lesion score for mune response and clearance of parasites (Wilson et that organ. An average lesion score was then computed al. 2001). Sorting this out in absence of knowledge on for each fish by dividing the sum total lesion score for all immune status of the host can be difficult, and for most organs by the number of organs examined. Work et al.: Parasites in Pacific common bluestriped snapper 187 To ensure a sufficient sample size for meaningful sta- hood estimates of k (Bliss & Fisher 1953); the former tistics, we evaluated the effects of parasites

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