Effects of a hurricane on fish parasites.

Hurricanes, also called tropical cyclones, can dramatically affect life along their paths, including a temporary losing or reducing in number of parasites of fishes. Hurricane Katrina in the northern Gulf of Mexico in August 2005 provides many examples involving humans and both terrestrial and aquatic animals and plants. Fishes do not provide much of an indicator of hurricane activity because most species quickly repopulate the area. Fish parasites, however, serve as a good indicator of the overall biodiversity and environmental health. The reasons for the noted absence or reduction of parasites in fishes are many, and specific parasites provide indications of different processes. The powerful winds can produce perturbations of the sediments harboring intermediate hosts. The surge of high salinity water can kill or otherwise affect low salinity intermediate hosts or free-living stages. Both can introduce toxicants into the habitat and also interfere with the timing and processes involved with host-parasite interrelationships. All these have had a major influence on fish parasite populations of fishes in coastal Mississippi, especially for those parasites incorporating intermediate hosts in their life cycles. The length of time for a parasite to become re-established can vary considerably, depending on its life cycle as well as the associated biota, habitat, and environmental conditions, and each parasite provides a special indicator of environmental health.

Parasites from Indo-Pacific hump-backed dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) stranded in Hong Kong.

Between 1993 and 1998, 28 Indo-Pacific hump-backed dolphins (Sousa chinensis) and 32 finless porpoises (Neophocaena phocoenoides) stranded in Hong Kong territorial waters were examined postmortem for parasites. The nematode Halocercus pingi was discovered in the lungs of one hump-backed dolphin and in 10 finless porpoises, typically within abscesses or granulomata, and they were frequently accompanied by a catarrhal exudate and lesions characteristic of pneumonia. Seven of the 10 finless porpoises were calves with substantial lungworm infections, and three were neonates with visible fetal folds and umbilical remnants, suggesting that H pingi is transferred to the neonate before birth or during lactation. Electron micrographs of H pingi should allow the nematode to be identified by other researchers. An ectoparasitic stalked barnacle (Xenobalanus globicipitis) was recovered from a finless porpoise, the first time that this species of barnacle has been recorded in Hong Kong's territorial waters.

A new species of Eimeria (Apicomplexa, Eimeriidae) from the weedy sea dragon Phyllopteryx taeniolatus (Osteichthyes: Syngnathidae).

A new species of intestinal coccidian is described from the weedy or common sea dragon Phyllopteryx taeniolatus housed at the New England Aquarium in Boston and at the Shedd Aquarium in Chicago, USA. Live oocysts of Eimeria phyllopterycis sp. n. are spherical, 30.9 (28.0-34.4) microm, with a thin, single-layered wall. Both a micropyle and oocyst residuum are absent and a large polar granule is sometimes present. Sporocysts are ellipsoidal and elongate, 24.3 x 10.4 (23.4-25.6 x 9.2-11.2) microm, with Stieda and substieda bodies; shape index (length/width) 2.33 (2.14-2.70). A sporocyst residuum is present, consisting of numerous granules of various sizes. Sporozoites each possess 3 refractile bodies. Preliminary evidence suggests that the coccidian may affect the health of sea dragons; however, it could not be determined whether this parasite caused significant morbidity or mortality.

Calicotyle californiensis n. sp. and Calicotyle urobati n. sp. (Monogenea: Calicotylinae) from elasmobranchs in the Gulf of California.

Two new species of Calicotyle (Monocotylidae: Calicotylinae) are described from elasmobranchs in the western Gulf of California. Calicotyle californiensis n. sp. is described from a single specimen collected from a gray smoothhound shark (Mustelus californicus, Carcharhiniformes: Triakidae). It is distinguished from its congeners by the combination of having vaginal pores opening within the intercecal space, distal regions of the vaginae twisting, proximal regions of the vaginae fusing medially to form a kidney bean-shaped structure, and a relatively long male copulatory organ recurving 3 times and passing between the distal penis bulb and the seminal vesicle. Calicotyle urobati n. sp. is described from 16 specimens collected from at least the cloaca and rectum of the round rays Urobatis halleri and Urobatis maculatus (Rajiformes: Urolophidae). It is distinguished from its congeners by the combination of having vaginal pores opening outside the intercecal space and proximal regions of the vaginae terminating at the level of the ceca. Members of Calicotyle have not been reported previously from the eastern Pacific Ocean or from these hosts. In the past, species of Calicotyle have been distinguished based primarily on the shape and length of the male copulatory organ and hamuli. Divisions of the vaginae and the positions of the vaginal pores are also useful in distinguishing members of the genus.

Life cycle of Calyptospora funduli (Apicomplexa: Calyptosporidae).

The taxonomic status of the extraintestinal piscine coccidium Calyptospora funduli is based in part on its requirement of an intermediate host (the daggerblade grass shrimp Palaemonetes pugio). In the present study, grass shrimp fed livers of Gulf killifish (Fundulus grandis) infected with sporulated oocysts of C. funduli exhibited numerous sporozoites suspended in the intestinal contents when fresh squash preparations were examined by light microscopy. Using this method, sporozoites were not seen in intestinal epithelial cells of the grass shrimp or in any other cell types. Ultrastructural examination, however, revealed sporozoites in the cytoplasm of the gut basal cells. Cross-sections of 1-13 sporozoites were seen within a single cell, and those sporozoites each appeared to be situated in individual membrane-bound vesicles, rather than in a single parasitophorous vacuole. These ultrastructural observations indicate that in the grass shrimp intermediate host, sporozoites that develop into an infective stage probably undergo that development in gut mucosal basal cells. Prior studies revealed that these sporozoites modified their structure over 4-5 days and that before that time, they were not infective to the fish host. Following ingestion of an infected shrimp by a killifish, the infective sporozoites apparently reach the liver of their killifish definitive hosts through the bloodstream. Sporozoites were seen in blood smears from the longnose killifish, Fundulus similis, 4 hr after fish were fed experimentally infected grass shrimp. Additionally, coccidian trophozoites and early meronts were seen in hepatocytes from several longnose killifish at 48, 72, and 96 hr postinfection. This study, in conjunction with previous findings, clearly confirms that a true intermediate host is required in the life cycle of C. funduli, that a developmental period of about 5 days in grass shrimp is necessary for sporozoites to become infective to killifishes, and that sporozoites do occur intracellularly in gut basal cells of the grass shrimp.

Otobothrium cysticum (Cestoda: Trypanorhyncha) from the muscle of butterfishes (Stromateidae).

On the basis of the tentacular armature, surface ultrastructure, and morphological measurements of plerocerci obtained from the musculature of butterfishes (Stromateidae), we corroborate an earlier proposal that Otobothrium crenacolle, a commonly reported trypanorhynch cestode from the northwestern Atlantic coast, is a junior synonym of O. cysticum. This action exemplifies at least an Atlantic Ocean and Indian Ocean distribution for O. cysticum. The infection in commercially important butterfishes shows that an otobothriid trypanorhynch may heavily infect fish flesh and influence the market value of some fish species yet also be restricted to the body cavity of other fish intermediate hosts. Infections of O. cysticum in the flesh of Peprilus burti (Gulf butterfish) and P. alepidotus (harvestfish) in the Gulf of Mexico has varied annually since 1970, with samples ranging in prevalence between 20% and 100% and in mean intensity between 1 and 3,500 or more plerocerci per fish. Comparative infections in P. burti from the Gulf of Mexico and P. triacanthus (butterfish) from the Atlantic Ocean demonstrate a present geographic difference in infections. The prevalence and mean intensity in 4 collections of butterfishes ranged from 9% to 98% of the fish and from 1 to 678 plerocerci in a subsample of tissue, respectively, with prevalent and heavy infections being observed in the Gulf of Mexico fish and relatively few individuals being infected with few worms in the Atlantic fish. A slight host response in the butterfishes involving some fatty infiltration and inflammatory infiltration was associated with the metacestode. In some larger fish, encapsulations were yellow, and in a few cases, worms had degenerated. This finding and an increase in intensity with fish weight suggest a continual accumulation of the worms in association with little host resistance.

New records of trypanorhynch cestodes from the Gulf of Mexico, including Kotorella pronosoma (Stossich, 1901) and Heteronybelinia palliata (Linton, 1924) comb. n.

Four trypanorhynchs, Kotorella pronosoma (Stossich, 1901), Nybelinia cf. bisulcata (Linton, 1889), Nybelinia scoliodoni (Vijayalakshmi, Vijayalakshmi et Gangadharam, 1996), and Dasyrhynchus pacificus Robinson, 1965 are reported for the first time from the Gulf, which is now known to harbour at least 34 different species. In addition to the range extension for the trypanorhynchs listed above, 21 new host records are reported involving 13 cestode species. Characters of the genus Kotorella Euzet et Radujkovic, 1989 are emended, Nybelinia narinari MacCallum, 1917 is considered ajunior synonym of Kotorellapronosoma (Stossich, 1901), and Heteronybelinia palliata (Linton, 1924) comb. n. is redescribed. The usefulness of the bulb ratio as a means to distinguish different tentaculariid species is discussed, and the importance of shallow water localities for the life cycle of trypanorhynch cestodes is emphasised.

Emerging marine diseases--climate links and anthropogenic factors.

Mass mortalities due to disease outbreaks have recently affected major taxa in the oceans. For closely monitored groups like corals and marine mammals, reports of the frequency of epidemics and the number of new diseases have increased recently. A dramatic global increase in the severity of coral bleaching in 1997-98 is coincident with high El Niño temperatures. Such climate-mediated, physiological stresses may compromise host resistance and increase frequency of opportunistic diseases. Where documented, new diseases typically have emerged through host or range shifts of known pathogens. Both climate and human activities may have also accelerated global transport of species, bringing together pathogens and previously unexposed host populations.

Margolisianum bulbosum n. gen., n. sp. (Nematoda: Philometridae) from the southern flounder, Paralichthys lethostigma (Pisces: Bothidae), in Mississippi Sound, USA.

A new species of a philometrid nematode, Margolisianum bulbosum, is described from the subcutaneous tissue in the mouth (larvigerous females), head (males, ovigerous, and larvigerous females), and eye (preovigerous females) of the southern flounder, Paralichthys lethostigma, from Mississippi Sound. It is placed in a new genus diagnosed by the combination of 8 large, paired but separate cephalic papillae; no inner cephalic papillae; an esophagus with a separate, muscular anterior bulb; a prominent mononuclear esophageal gland; and variable, irregularly distributed cuticular bosses in the females, as well as a vestigial rectum, particularly in larvigerous females. Some female specimens exhibit rows of lateral grooves and longitudinal ridges near the posterior end. Males have 2 small slightly subequal spicules, a barbed gubernaculum, 4 pairs of small cephalic papillae, and a bipartite hypodermal extension within a membranous cuticle on the posterior end. Males, ovigerous females, and larvigerous females appear to be present year round in this sporadic infection in Mississippi.

Infectivity and pathogenicity of Baculovirus penaei (BP) in cultured larval and postlarval Pacific white shrimp, Penaeus vannamei, related to the stage of viral development.

The infectivity and pathogenicity of the penaeid shrimp virus, Baculovirus penaei (BP), is influenced by the stage of viral development. This study consisted of a preliminary experiment which showed that nonocculuded virus administered per os is infective, followed by two infectivity experiments. In the first phase of each infectivity experiment, mysis stage larvae of Penaeus vannamei were inoculated with BP and samples of infected tissue were collected at various times postinoculation (p.i.). These samples were then used to inoculate either mysis or postlarval stage P. vannamei in the second phase of each experiment. Viral inocula prepared from patently infected tissues consistently produced infections in both mysis and postlarval stage shrimp. Inocula prepared from prepatently infected tissue collected 12-18 h p.i. produced infections in some, but not all replicate cultures, while inocula prepared from tissues collected earlier than 12 h p.i. were not infective. Viral development in mysis stage larvae was substantially delayed and the mortality was significantly lower when the viral inocula were prepared from prepatently compared to patently infected tissues. BP appears to be most pathogenic to larvae that have been exposed to inocula prepared from tissues that had recently developed a high prevalence of patent infections or about 72 h p.i.

Carcinogenic effects of 1,2-dibromoethane (ethylene dibromide; EDB) in Japanese medaka (Oryzias latipes).

The carcinogenicity of 1,2-dibromoethane (ethylene dibromide; EDB) was investigated in the Japanese medaka (Oryzias latipes), a small fish species. EDB was administered in water continuously for 97 days to a low concentration group, for 73 days to an intermediate concentration group, and intermittently for 24 h once each week over 97 days to a high concentration group. Medaka were 7 days old at the beginning of the tests. Mean measured EDB concentrations in the ambient water were 0.13 mg l-1, 6.20 mg l-1, and 18.58 mg l-1 in the low, intermediate, and high concentration groups, respectively. Two control groups, one inside and one outside the exposure apparatus, were used. Samples were examined histologically at 24, 36, and 58 weeks from the beginning of the tests. EDB was clearly carcinogenic to medaka in the intermediate and high concentration groups causing (1) hepatocellular adenomas and carcinomas, (2) cholangiomas, (3) chloangiocarcinomas, and (4) gall bladder papillary adenomas and adenocarcinomas. In separate studies, medaka exposed to 1.0 mg l-1 EDB for 2 to 5 weeks had elevated hepatic glutathione S-transferase activities, possibly indicating induction of a pathway that forms the reactive metabolite of EDB in mammals. SDS-PAGE of hepatic cytosolic fractions of EDB-exposed medaka showed a pronounced increase in a band at 26,000 Da, the expected position for GSH-S-transferase. Although little is known about EDB's mechanisms of action, medaka appear exceptionally sensitive to the carcinogenic effects of EDB and could serve as a model test species for studying similar compounds.

Species of Myxobolus (Myxozoa) from the bulbus arteriosus of centrarchid fishes in North America, with a description of two new species.

Three species of Myxobolus (Myxozoa, Myxosporea) occur in heart tissue of centrarchids. Myxobolus paralintoni Li and Desser, 1985 from Lepomis gibbosus in Algonquin Park and in Lake Erie, Ontario, has subcircular spores (in plane of spore length) in frontal view (11-13 microm long, 9-10 microm wide, and 5 microm thick) with a width-to-length ratio of 1:1.2. Myxobolus jollimorei n. sp. from Lepomis macrochirus in Lake Erie and in the Pascagoula River System, Mississippi, has subcircular spores (in plane of spore width) in frontal view (10.0-11.5 microm long, 12.0-14.5 microm wide, and 6.5-8.0 microm thick) with a width-to-length ratio of 1:0.8. Myxobolus manueli n. sp. from Pomoxis nigromaculatus in Lake Erie has spores (10-11 microm long, 8-10 microm wide, and 6.5-7.0 microm thick) that are nearly circular in frontal view but that have 2 distinct sublateral knobs along the sutural ridge and a width-to-length ratio of 1:1.2. All 3 species occur in the bulbus arteriosus of their hosts where they form small, saucer-shaped pseudocysts. Free spores were found free in the lumen of the heart and bulbus arteriosus, in bile, and in kidney tissue presses.

Cucullanus palmeri n. sp. (Nematoda: Cucullanidae) from the batfish Ogcocephalus nasutus in the Gulf of Mexico.

Cucullanus palmeri n. sp. is described from the shortnose batfish, Ogcocephalus nasutus, in the Gulf of Mexico. This species is anatomically most similar to Cucullanus gendrei but differs from it in having a shorter esophagus and longer tail. Males differ in having a smaller gubernaculum and a different arrangement of a lateral caudal papilla. Cucullanus palmeri is readily distinguished from Cucullanus lophii, also from a lophiform fish host in that the deirids and excretory pore are not posterior to the posterior end of the esophagus like in C. lophii.

Parasitological data as monitors of environmental health.

When an appropriate fish host is selected, analysis of its parasites offers a useful, reliable, economical, telescoped indication or monitor of environmental health. The value of that information increases when corroborated by another non-parasitological technique. The analysis of parasites is not necessarily simple because not all hosts serve as good models and because the number of species, presence of specific species, intensity of infections, life histories of species, location of species in hosts, and host response for each parasitic species have to be addressed individually to assure usefulness of the tool. Also, different anthropogenic contaminants act in a distinct manner relative to hosts, parasites, and each other as well as being influenced by natural environmental conditions. Total values for all parasitic species infecting a sample cannot necessarily be grouped together. For example, an abundance of numbers of either species or individuals can indicate either a healthy or an unhealthy environment, depending on the species of parasite. Moreover, depending on the parasitic species, its infection, and the time chosen for collection/examination, the assessment may indicate a chronic or acute state of the environmental health. For most types of analyses, the host should be one that has a restricted home range, can be infected by numerous species of parasites, many of which have a variety of additional hosts in their life cycles, and can be readily sampled. Data on parasitic infections in the western mosquitofish (Gambusia affinis), a fish that meets the criteria in two separate studies, illustrate the usefulness of that host as a model to indicate both healthy and detrimentally influenced environments. In those studies, species richness, intensity of select species, host resistance, other hosts involved in life cycles, and other factors all relate to site and contaminating discharge.

Experimental infection of Contracaecum multipapillatum (Nematoda: Anisakinae) from Mexico in the domestic cat.

Juveniles of Contracaecum multipapillatum infected the Mayan cichlid (Cichlasoma urophthalmus) and adults infected the olivaceous cormorant (Phalacrocorax olivaceus) and the great egret (Casmerodius albus) in the coastal lagoon at Celestun, State of Yucatan, Mexico. All are new host records, and, even though the geographic locality record of Mexico for the species has not been published, unidentified but presumably conspecific specimens have been reported from there. When juveniles of C. multipapillatum were fed to a kitten, but not rats, ducks, or chickens, they developed into adults. Measurements and morphological data are provided on the specimens from the kitten. Development of an avian ascaridoid in the intestine of a mammal increases the potential of this widespread species to infect other mammals, including humans.

Proteinase activity in the plerocercoid of Proteocephalus ambloplitis (Cestoda).

Host invasion and tissue migration of several helminths have been linked to expression and release of parasite-derived proteinases. The plerocercoid of the cestode Proteocephalus ambloplitis can migrate into the visceral organs or, in the case of bass, from them into the intestinal tract of the same individual fish. It does this within a few hours, aided by secretion of a substance from its apical gland. Proteinase activity in this plerocercoid, obtained from the host liver, was defined by pH optimum, by substrate and inhibitor specificity, and by electrophoretic and chromatographic techniques. Homogenates of plerocercoid contained a metalloproteinase exhibiting a molecular weight of 30,000 determined by gelatin substrate gel electrophoresis. Peak activity of this proteolytic enzyme in gel filtration fractions when azocoll was used as substrate then corresponded to a molecular weight of 31,500. The proteinase showed collagenolytic, haemoglobinolytic and slight elastinolytic activity, and it had a pH optimum at 9.0. Enzyme activity could be inhibited by various chelating agents. The metalloproteinase identified in this study constitutes the only enzyme class present in this larval stage of P. ambloplitis. We suggest that the plerocercoid's metalloproteinase is the substance secreted from the apical organ, necessary for the previously recognized tissue migration phase. This enzyme might also have a nutritional function.

Hepatocarcinogenesis in western mosquitofish (Gambusia affinis) exposed to methylazoxymethanol acetate.

To assess the potential of western mosquitofish (Gambusia affinis) for the detection of environmental carcinogens, laboratory-reared specimens were exposed to methylazoxymethanol acetate 10 mg per 1 for 2 h and then examined periodically for the onset of neoplastic lesions. Approximately 33 per cent of the exposed fish developed liver neoplasms within 25 weeks of exposure and 52 per cent within 40 weeks. The lesions were mostly hepatocellular carcinomas and cholangiocarcinomas. No neoplastic lesions were detected in other organs. The carcinogen sensitivity and the widespread distribution of the mosquitofish suggest that this species would be useful as a warm water sentinel for environmental contamination.