DISEASES OF AQUATIC ORGANISMS Vol. 10: 87-92, 1991 Published April 4 Dis. aquat. Org. l

Dermatological diseases affecting fishes of the Tar-Pamlico Estuary, North Carolina

Edward J. ~oga',James F. Wright2,Jay F. ~evine~,Michael J. ~ykstra~, Jess H. ~awkins~

' Department of Companion and Special Medicine. Department of Microbiology, Pathology, and Parasitology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606, USA North Carolina Division of Marine Fisheries, PO Box 1507, Washington, North Carolina 27889, USA

ABSTRACT: Over the last several years, various epidemic dermatological diseases have been observed in fishes of the Tar-Pamlico estuary. The most important is ulcerative mycosis, an infection associated with oomycete fungi that affects Atlantic Brevoortia tyrannus. In the present report we describe lesions resembling ulcerative mycosis in other estuarine species such as southern lethostigma, hickory shad Alosa medjocrjs, striped bass Morone saxatilis, bluefish Pomatomus saltatrix, Atlantic croaker Micropogon~as undulatus, weakfish Cynoscion regalis, spot Leiostomus xanthurus, silver perch Ba~rdella chrysura, plnf~shLagodon rhomboides, and hogchoker Trinectes maculatus. Less prevalent dernlatological diseases were also ~bserved~includinglymphocys- tis, bacterial dermatitis and myositis, Argulus dermatitis, Henneguya myositis, and various idiopathic dermatopathies. Only one tumor, a fibroma, was seen. The occurrence of many of these diseases is of concern to fisheries managers because of their potential impact upon estuarine fish populations. Many environmental problems (noxious algae blooms, increasing turbidity, anoxic/hypoxic events, loss of submerged aquatic vegetation, etc.) plague the Tar-Pamlico estuary. The relationship of the observed diseases to these environmental problems is presently unknown.

INTRODUCTION UM in naturally affected menhaden (Noga et al. 1988). In this paper, we describe the dermatopathles affecting Skin diseases appear to be an increasingly common other fish species in the Tar-Pamlico estuary. problem in estuarine fishes of the Tar-Pamlico River, North Carolina, USA. The most common disease is ulcerative mycosis (UM), which was first recognized in MATERIALS AND METHODS Atlantic menhaden Brevoortia tyrannus from the Tar- Pamlico estuary (Noga & Dykstra 1986). Skin lesions Most fish were collected from pound nets set on the were concurrently reported in other commercially Tar-Pamlico River during July 1984 through July 1988 important estuarine fishes in North Carolina (Noga & (Levine et al. 1990). Pound nets were usually sampled Dykstra 1986). Recurrent outbreaks of ulcerative skin within 24 h of harvesting by commercial fishermen; diseases in this and other estuarine systems have thus, fish were not iatrogenically traumatized. Some prompted increasing public concern about their impact fish were obtained from trawl samples of the Division of on the productivity of the fishery (Rader et al. 1987, Marine Fisheries and local fishermen. Noga 1988). All fish were alive when captured and most were Our previous studies with Atlantic menhaden have necropsied on site. Some were transported back to the shown that ulcerative mycosis is associated with oomy- laboratory on ice and immediately necropsied. Most cete fungi. Aphanomyces has been most comn~only lesions were preserved in either 10 O/O neutral buffered cultured from UM lesions, but Saprolegnia has also formalin or Bouin's fluid, embedded in paraffin wax, been isolated (Dykstra et al. 1986, 1989). We have and stained with hematoxylin and eosin (H&E).Selected previously described the pathological characteristics of tissues were also stained with Gomori methenamine

O Inter-Research/Printed in Germany 88 Dis. aquat. Org. 10: 87-92, 1991

silver (GMS), periodic acid-Schiff, Giemsa, Brown and sections from 45 fish). Fungal infections were identified Brenn Gram's stain, a modified MacCallum-Goodpas- in 21 fish (Table 1).Most cases were similar to ulcera- ture Gram's stain, Fite-Faraco acid fast or with Mallory's tive nlycosis lesions described in Atlantic menhaden trichrome. Alternatively, some lesions were examined (Noga et al. 1988), being off-white to dark red, deep by preparing wet mounts of fresh material. ulcers (Fig. 1A) that in some cases extended through the body wall. Chronic inflammation (Figs. 1C & 2A) surrounded broad, aseptate hyphae (Figs. 1D & 2B). RESULTS Inflammation and hemorrhage also extended laterally under intact skin.Lymphocytes were common and Forty-nine skin lesions from 11 specles were eosinophilic granular cells were occasionally present. examined (wet mounts from 4 fish and stained tissue Muscle damage was often associated with the fungal

Table 1. Skin lesions observed on fishes in the Tar-Pamlico Estuary. Total numbers of each case. All fish were large juvenile to adult fish

Diagnosis Species Fungal Parasitic Bacterial Bacterial Lympho- Idiopathic Idiopathic Neoplasia myositisd dermatitis dermatitis myositis cystis dermatitisf myositisf

BOTHIDAE 7 CLUPEIDAE Hickory shad Alosa mediocris Gizzard shad Dorosorna cepedian urn White shad Alosa sapidissima PERICHTHYDIAE Striped bass Morone saxa tdis POMATOMIDAE Bluefish Pornatornus saltatrix SCIAENIDAE Atlantic croaker Micropogonias undulatus Weakfish Cynoscion regalis Spot Le~ostornusxanthunus Silver perch Bairdiella chrysuna Hogchoker Trjnectes maculatus SPARIDAE Pinfish 1'- rhomboides * At least one individual of each species had a UM-like lesion (UMLL),defined as a deep ulcer with broad (at least 7.5 pm in diameter), aseptate hyphae. See text for vanations in this response. All fish examined histologically had a chronic inflammatory infiltrate Fish had deep skin ulcers with 7.5-12 pm aseptate hyphae, but histopathology was not performed to determine the type of inflammatory response C Henneguya sp. chronic dermatitis "rgulus sp. mononuclear dermatitis ' Long, thin, gram-variable rods ' Most cases were small lesions with lymphocytic infiltrates g Fibroma 2 I OCL X ,943 (shtoJle) aeqdiiq aleldase .peoiq ~UIMO~S(3) JO UIP~Sianps (a) OC& X '3TH UOIS~[alssnur e ur (g) rsol ho1ewlue~urs~uolq3 (3) TZ X ,ZJ~Ha1ssnur O~UIspualxa leql uorleurure[jur sruoiys alaAas 6u!~eqssew holemweljur pasre8 (g) 'SZ.0 X (uorsa[ ay[[-srso>iiur a~r~eiasln)uorsal alzrlelasln 'daap [esrdhl e jo asueleadde ss013 (v) IapunoIj ulaqlnos ur suorsal 1e6ung ,eruBljsoylal sAqcpr[ered I 613 Fig. 2. Microscopic appearance of skin lesions In spot Leioslomus xanthurus, silver perch Rairdlella chrysura, and weakfish Cynoscion regalis. (A) Flank lesion of a spot with multiple ~nflammatoryfoc~ (arrows) surrounding fungal hyphae. Fungi are not visible. H&E, X 52. (B) Silver staln of (A) showing numerous fungal hyphae (arrows).GMS, X 130. (C) Flank lesion of a s~lverperch showing fragmentation of muscle fibers and myophagia that was associated with a fungal infection. H&E, X 184. (D) Weakfish with Algulus dermatitis. Note the mononuclear infiltrate and hyperplastic epithelium (E) surrounding the ulcer. H&E, X 52 Noga et al.: Dermatological diseases of fish 91

invasion and appeared as necrotic muscle fibers with The relatively low occurrence of UMLL in species loss of striations that were being phagocytized by mac- other than menhaden (Levine et al. 1990) has hindered rophages (similar to that seen in Fig. 2C). attempts to Isolate the fungi. While definitive diagnosis In addition to the deep ulcers described above, some of these lesions must await cult.ure, Oomycetes are fungal lesions in southern flounder were instead, flat, most likely the causative agents because broad asep- shallow ulcers or raised oval lesions up to 10 mm in tate hyphae are virtually pathognomonic for Oomy- diameter (Fig. 1B) having diffuse to organized inflam- cetes (Neish & Hughes 1980). While lchthyophonus matory foci with macrophage-like cells. In some cases, also has broad aseptate hyphae, its other developmen- the lesions were undergoing epithelia1 regeneration. tal (non-hyphal) stages are also present in lesions Many other skin diseases were present in other sam- (Neish & Hughes 1980). pled fish, including virus-, bacteria- and parasite- Fungal skin ulcers have recently affected fishes in associated lesions (Table 1, Fig. 2D). Some cases had numero'us estuarine systems along the Atlantic coast of no histologically detectable pathogens. the USA, including the Tar-Pamlico (Levine et al. 1990), St. Johns Fhver, Florida (Grier & Quintero 1987, Dykstra et al. 1989), Indian River, Florida (Gner & DISCUSSION Quintero 1987), and Chesapeake Bay, Maryland (Har- gis 1985, Dykstra et al. 1989) estuaries. Weakfish Most of the common fish species inhabiting the Tar- Cynoscion regalis, redfish Sciaenops ocellatus, striped PamLico estuary are susceptible to deep fungal infec- mullet Mugil cephalus, and white mullet Mugil curema tions that are similar to those previously described in have been reported with UMLL (Grier & Quintero Atlantic menhaden (Levine et al. 1990), although the 1987). former fishes are much less frequently affected than Deep ulcerative fungal dermatopathies have also menhaden (Levine et al. 1990). Affected species been reported in many freshwater and estuarine fishes occupy virtually all ecological niches, from benthic throughout the world (Hatai et al. 1984, Boonyaratpalin carnivores (e.g. southern flounder Paralichthys lethos- 1985, Callinan et al. 1989). While the relationship of tigma) to pelagic planktivores (e.g.hickory shad Alosa these other fungal diseases to UM is uncertain, the mediocris). All fish with these ulcerative mycosis-like prevalence of such problems on a worldwide scale is of lesions (UMLL) frequent low to moderate salinities. some concern. We have not seen UMLL in freshwater fishes of the Many other dermatopathies were seen in the sam- Tar-Pamlico estuary, nor does it appear to affect pled fishes, including parasitic, fungal, bacterial, and species that are restricted to high salinities. For exam- viral infections (Table 1). The relationship of these ple, while the southern flounder is affected, the diseases to UMLL is uncertain, but they appear to be closely-related Paralichthys dentatus, pathologically distinct from UMLL and probably repre- which is usually restricted to at least 10 ppt salin- sent different diseases. All of these diseases were ity, has never been observed with UMLL in North uncommon compared to fungal infections (Levine et al. Carolina (J. Hawkins unpubl.). Some estuarine species 1990). that frequent low to moderate salinities are not affected Skin ulcers are indicative of polluted environments by UMLL, including longnose gar Lepisosteus osseus, (Sindermann 1990), which suggests that poor water bay Anchoa rnitchilli, and American eel quality may be responsible for the preponderance of AnguiLIa rostrata (Levine et al. 1990, Hawkins unpubl.), sick fish in the Tar-Pamlico estuary. Thus, future although American eels commonly have ulcers due to studies should focus on determining possible linkages Aeromonas salmonicida (Noga & Berkhoff 1990). The between specific environmental conditions and specific reason for some species' resistance to UMLL is un- diseases. While some have lumped these skin diseases known. into a single category such as 'ulcerative disease syn- The invading fungi in UMLL elicited 2 types of drome' (Hargis 1985) or 'red-sore disease' (Esch & chronic inflammatory responses. In southern flounder, Hazen 1980), they differ in host range, infectious etiol- epithelioid granulomas were histologically similar to ogy, and seasonal disti-ibution. Consequently, whether the mammalian epithelioid cell response. These cells they share common environmental inducers 1-en~alnsto had abundant ground-glass cytoplasm, vesicular nuc- be determined. lei, and indistinct cell borders (Fig. 1C). However, most fish responded to fungal invasion by producing inflam- matory cells with more epithelial-like features (Fig. 2A) Acknowledgements.We thank J. Reid and D. Moye for tech- nical assistance. This work was supported by The University (Noga et al. 1989). Whether this represents a difference of North Carolina Water Resources Research Institute Grant in host response or a difference in etiology awaits # 70054 and contract # 5-35718 from the North Carolina further study. Divison of Marine Fisheries. 92 Dis. aquat. Org. 10: 87-92, 1991

LITERATURE CITED altivelis experimentally inoculated and naturally infected with Aphanomyces piscicida. Fish Pathol. 19: 17-23 Boonyaratpalin, S. (1985). Fish disease outbreak in Burma. Levine, J. F., Hawkins, J. H.,Dykstra, h!. J , Noga, E. J., Moye, FAO Special Report. TCP/BUR/4402, 7 p. D. W., Cone, R. S. (1990). Species distribution of ulcerative Callinan, R. B., Fraser, G. C., Vingona, J. L. (1989). Pathology lesions on finfish in the Tar-Pamlico estuary, North of red spot disease in sea mullet, Mugil cephalus L., from Carolina. Dis. aquat. Org. 8: 1-5 eastern Australia. J. Fish Dis. 12: 467-479 Noga, E. J. (1988). Determin~ng the relationship between Dykstra. M. J., Levine, J. F., Noga, E. J., Hawkins, J. H., water quality and infectious disease in fishery populations. Gerdes, P., Hargis, Jr., W. H., Grier, H. J., Testrake, D. Water Res. Bull. 24: 967-973 (1989). Ulcerative mycosis: a senous menhaden disease of Noga, E. J., Berkhoff, H. A. (1990). Pathological and micro- the southeast coastal fisheries of the United States. J. Fish biological features of Aeromonas salmonicida infection In Dis. 12: 175-178 the American eel (Anguilla rostrata). Fish Pathol. 25: Dykstra, M. J., Noga. E. J., Levine, J. F., Hawluns. J. H.. Moye, 127-132 D. F. (1986) Characterization of the Aphanomyces species Noga, E. J., Dykstra, M J. (1986). Oomycete fung~associated involved with ulcerative rnycosis (UM) in menhaden. with ulcerative mycosis in menhaden. Brevoortia tyrannus Mycologia 78: 664-672 (Latrobe). J. Fish Dis. 9: 47-53 Esch, G. W., Hazeri, T. C. (1980). The ecology of Aeromonas Noga, E. J., Dykstra, M. J., Wright, J. F. (1989). Chronic hydrophila in Albemarle Sound, North Carolina. Univer- inflammatory cells of fish possess epithelia1 cell charac- sity of North Carolina Water Resources Research Institute teristics. Vet. Path. 26: 429-437 Final Report # 80-153. 116 p. Noga, E. J., Levine, J. F., Dykstra, M. J., Hawluns, J. H. (1988). Grier, H., Quintero, I. (1987). A microscopic study of ulcerated Pathology ot ulcerative mycosis in Atlantic menhaden Bre- fish in Florida. Florida Bureau of Marine Research Report voortia tyrannus. Dis. aquat. Org. 4: 189-197 WM-164, St. Petersburg Rader, D. N., Loftin, L. F., McGee, B. A., Dorney, J. P., Clements, Hargis, W. H. (1985). Quantitative effects of marine diseases J. T. (1987). Surface water quality concerns in the Tar- on fish and shellfish populations. Trans. N. Am. Wildlife Pamlico kver estuary. Water Quality Technical Report No. and Nat. Res. Conf. 50: 608-640 87-04, N.C. Division of Environmental Management. 113 p. Hatai, K., Takahashi, S., Egusa, S. (1984). Studies on the Sindermann, C. J. (1990). Principal diseases of marine fish and pathogenic fungus of mycotic granulomatosis - IV shellfish. Vol. 1 Diseases of marine fish. Academic Press, Changes of blood constituents in both ayu, Plecoglossus New York

Responsible Subject Editor: T. Evelyn, Nanaimo, B. C., Canada Manuscript first received: May 8, 1990 Revised version accepted: January 7, 1991