Stock structure of blue threadfin Eleutheronema tetradactylum on the Queensland east coast, as determined by parasites and conventional tagging

Blue threadfin Eleutheronema tetradactylum (Polynemidae) were examined from four areas (Princess Charlotte Bay, Trinity Inlet, Halifax Bay and Upstart Bay) in eastern Queensland covering a distance of c . 950 km of coastline. Parasites were used as biological markers to infer stock structure of E. tetradactylum . Parasites designated as 'temporary' biological markers were the copepod Thysanote eleutheronemi , the acanthocephalan Neoechinorhynchus topseyi , the nematode Philometra rajani and hemiurid trematodes. The larval nematodes Anisakis sp. Type 1 and Terranova sp. Type 2; and the larval cestodes Pterobothrium pearsoni and Callitetrarhynchus gracilis were considered 'permanent' biological markers. Both univariate and multivariate analyses demonstrated that there was little difference in temporary parasite abundance between the four areas. In contrast, the same analyses revealed that most areas had two or more significant differences in permanent parasite abundance, with the exception of Halifax Bay and Upstart Bay, which were significantly different only in the multivariate analysis. Biological markers predicted that Princess Charlotte Bay and Trinity Inlet consisted of distinct populations, whereas Halifax Bay and Upstart Bay were not clearly differentiated. Tag recapture data supported this hypothesis; the majority of recaptures were within 100 km of the initial tagging location. Geographical movement of E. tetradactylum may be limited due to their biology and ecology, as well as the distances and oceanographic boundaries that separate habitats. Contrary to current management definitions, the stock structure of E. tetradactylum on the east coast of Queensland appears to be geographically differentiated at a small spatial scale.     

Stock discrimination and movements of narrow‐barred Spanish mackerel across northern Australia as indicated by parasites

The parasite fauna of Spanish mackerel Scomberomorus commerson from 10 sites across northern Australia and one site in Indonesia, was examined to evaluate the degree of movement and subsequent stock structure of the fish. Kupang fish (Indonesia) had very few Terranova spp., Grillotia branchi , Otobothrium cysticum or Pterobothrium sp. compared to Australian fish, indicating that no Australian fish enter the Kupang fishery. Univariate and discriminant function analysis of four 'temporary' parasite species, the copepod Pseudocycnoides armatus and the monogeneans Gotocotyla bivaginalis , Pricea multae and Pseudothoracocotyla ovalis , demonstrated little similarity between areas of northern Australia, indicating minimal short‐term exchange between neighbouring groups of S. commerson . Analyses of five 'permanent' parasite species, the larval helminths G. branchi , O. cysticum , Pterobothrium sp., Callitetrarhynchus gracilis and Paranybelinia balli , also revealed large differences between areas thus indicating long‐term separation. There are at least six parasitological stocks across northern Australia: Fog Bay/Bathurst Island, Cape Wessel, Groote/Sir Edward Pellew, Mornington Island, Weipa, and the Torres Strait. The occurrence of a few irregular fish in the samples suggested that up to 5% of fish moved between stocks during their lifetime. The similarity of within‐school variability to that between schools showed that the fish do not form long‐term school associations.     

Parasite community structure in Pimephales promelas (Pisces: Cyprinidae) from two converging streams

Parasites of the fathead minnow, Pimephales promelas, were examined in fish collected from Elk Creek (40.88534 degrees N, 96.83366 degrees W) and West Oak Creek (40.90821 degrees N, 96.81432 degrees W), Lancaster County, Nebraska. These 2 streams are part of the Salt Valley watershed and flow together approximately 2 km downstream from the collection sites to form Oak Creek. This study examined the extent to which the 2 tributaries constitute a continuous habitat with respect to fish hosts. The parasite community included Trichodina sp., Myxobolus sp., Dactylogyrus simplex, D. bychowskyi, and D. pectenatus (all on gills); Gyrodactylus hoffmani (gill and body surface); Posthodiplostomum sp. (neascus, body cavity); and Uvulifer ambloplitis (encysted in skin). Among 46 fish from Elk Creek and 56 fish from West Oak Creek taken on 5 dates during April-July 1998, U. ambloplitis was found in Elk Creek fish at prevalences of 44-100% but in only 2 West Oak fish on 1 date. Prevalence and mean abundance of D. simplex also differed between the 2 sites. On the basis of these observations, fish populations in the 2 streams were considered to be distinct, with little or no fish movement between the tributaries.     

Metazoan parasite communities of sentinel bluegill caged in two urbanizing streams, San Antonio, Texas

Urbanization has deleterious effects on water quality and biota in stream systems. This project used caged bluegill (Lepomis macrochirus) to assess metazoan fish parasite communities in 2 urbanizing streams of the upper San Antonio River Basin, Bexar County, Texas. Field studies on Leon and Salado creeks were conducted during late summer in 1999 and 2000. Juvenile bluegill, obtained from a local aquaculturist, were held in cages for 10-22 days at middle and lower watershed sites to expose them to in-stream conditions and to allow parasite communities to establish. After removal from cages, fish were examined for metazoan parasites. In 2000, wild Lepomis spp. also were collected at study sites for parasite assessment. In both years, physical and chemical water properties were monitored at each site. Of the 120 fish examined for parasites, 96.7% were infected by at least 1 organism from among the 11 parasitic taxa observed. For caged fish, both diversity and equitability of parasite communities tended to be lower at the more eutrophic downstream sites; accordingly, parasite diversity and equitability were inversely correlated with nitrate concentrations. Ectoparasites were more prevalent in caged fish and endoparasites were more abundant in wild fish. An Ergasilus sp. copepod and a Posthodiplostomum sp. trematode dominated the ecto- and endoparasite faunas, respectively. This study suggests that assessment of watershed health can benefit from comparative cage studies of parasite community development involving sentinel fish species.     

Redescription of the fish parasite Lernanthropus polynemi Richiardi, 1881 (Copepoda: Siphonostomatoida) and relegation of two congeners to synonymy

Lernanthropus polynemi Richiardi, 1881 is described, for the first time since its original discovery, based on the type-material found in the Museum für Naturkunde in Berlin, Germany. Morphological features of this parasite, which infects the commercially-caught fish Eleutheronema tetradactylum (Shaw), are described and illustrated, including those of the male, which is described for the first time. The types of another species from the same host, L. lappaceus Wilson, 1912, and deposited in the National Museum of Natural History in Washington DC, are also examined based on the type-specimens. The types of a third congener, L. trifoliatus Basset-Smith, 1898, also from the same host, are not available, but the original illustrations are studied. It is considered that the three nominal species described from E. tetradactylum represent a single taxon, and that L. lappaceus and L. trifoliatus be relegated to synonymy with L. polynemi.     

The distribution of the introduced tapeworm Bothriocephalus acheilognathi in Australian freshwater fishes

Native and exotic fishes were collected from 29 sites across coastal and inland New South Wales, Queensland and Victoria, using a range of techniques, to infer the distribution of Bothriocephalus acheilognathi (Cestoda: Pseudophyllidea) and the host species in which it occurs. The distribution of B. acheilognathi was determined by that of its principal host, carp, Cyprinus carpio; it did not occur at sites where carp were not present. The parasite was recorded from all native fish species where the sample size exceeded 30 and which were collected sympatrically with carp: Hypseleotris klunzingeri, Hypseleotris sp. 4, Hypseleotris sp. 5, Phylipnodon grandiceps and Retropinna semoni. Bothriocephalus acheilognathi was also recorded from the exotic fishes Gambusia holbrooki and Carassius auratus. Hypseleotris sp. 4, Hypseleotris sp. 5, P. grandiceps, R. semoni and C. auratus are new host records. The parasite was not recorded from any sites in coastal drainages. The only carp population examined from a coastal drainage (Albert River, south-east Queensland) was also free of infection; those fish had a parasite fauna distinct from that of carp in inland drainages and may represent a separate introduction event. Bothriocephalus acheilognathi has apparently spread along with its carp hosts and is so far restricted to the Murray-Darling Basin. The low host specificity of this parasite is cause for concern given the threatened or endangered nature of some Australian native freshwater fish species. A revised list of definitive hosts of B. acheilognathiis presented.     

Parasites of fishes in the Colorado River and selected tributaries in Grand Canyon, Arizona

As part of the endangered humpback chub (HBC; Gila cypha ) Adaptive Management Program, a parasite survey was conducted from 28 June to 17 July 2006 in 8 tributaries and 7 adjacent sections of the main stem of the Colorado River, U.S.A. In total, 717 fish were caught, including 24 HBC. Field necropsies yielded 19 parasite species, 5 of which (Achtheres sp., Kathlaniidae gen. sp., Caryophyllaidae gen. sp., Myxidium sp., and Octomacrum sp.) are new records for Grand Canyon, Arizona, U.S.A. Spearman's correlation coefficient analyses showed no correlations between parasite burden and fork length for various combinations of fish and parasite species. Regression analyses suggest that no parasite species had a strong effect on fish length. The most diverse parasite community (n = 14) was at river kilometer (Rkm) 230, near the confluence of Kanab Creek. The most diverse parasite infracommunity (n = 12) was found in the non-native channel catfish (CCF; Ictaluris punctatus). Overall parasite prevalence was highest in CCF (85%) followed by that in HBC (58%). The parasite fauna of humpback chub was mainly composed of Bothriocephalus acheilognathi and Ornithodiplostomum sp. metacercariae.     

Downstream changes in the composition of the parasite community of fishes in an Appalachian stream

The spatial distribution of 6 parasite species (Myxobolus sp., Dactylogyrus sp., Sterliadochona ephemeridarum, Plagioporus sinitsini, Allopodocotyle chiliticorum, Allocreadium lucyae) was studied in 5 species of fishes (Oncorhynchus mykiss, Clinostomus funduloides, Notropis chiliticus, Rhinichthys atratulus, Semotilus atromaculatus) in Basin Creek, an Appalachian stream in North Carolina. Nonmetric multidimensional scaling and vector fitting were used to determine if the proximity of sampling sites was related to community similarity. Position along Basin Creek was significantly related to parasite community structure. Breaks in parasite community composition were imposed by waterfalls at upstream areas of Basin Creek that restricted distributions of C. funduloides, N. chiliticus, and S. atromaculatus and at the downstream limit of the study area by a break in the distribution of S. ephemeridarum coincident with the existence of a dam but were independent of suitable piscine host distributions. These discontinuities in parasite community composition imply that the relationship between proximity of sites and community similarity is predictive because distance between sites is related to the probability that fish at different sampling sites recruit parasites from different species pools. This relationship is not the same for all component communities.     

The association between parasite infection and growth rates in Arctic charr: do fast growing fish have more parasites?

Trophically transmitted parasites are known to impair fish growth in experimental studies, but this is not well documented in natural populations. For Arctic charr [Salvelinus alpinus (L.)], individual growth is positively correlated with food consumption. However, increased food consumption will increase the exposure to trophically transmitted parasites. Using a correlative approach, we explore the association between parasite abundance and the individual growth of Arctic charr from five lakes within the same watercourse. The studied parasite species differ in their life cycles and cost to the host. We predicted a positive association between parasite abundance and fish growth for parasites of low pathogenicity reflecting high consumption rates, and a negative association at higher parasite abundances for more costly parasites. We found no direct negative associations between parasite abundance and fish growth. The relationship between parasite abundance and growth was linearly positive for the low costly Crepidostomum sp. and concave for the more costly Eubothrium salvelini. In natural fish populations, the negative effects of parasites on fish growth might be outweighed by the energy assimilated from feeding on the intermediate host. However, experimental studies with varying food consumption regimes are needed to determine the mechanisms underlying our observations.

     

Spatial variation in parasite abundance: evidence of geographical population structuring in southern garfish Hyporhamphus melanochir

Southern garfish Hyporhamphus melanochir were examined for metazoan parasites from nine sites in three regions (Spencer Gulf, Gulf St Vincent and northern Kangaroo Island) in South Australia to document parasite assemblages, identify candidate species suitable for use as biological tags and investigate spatial variation in parasite abundance. Four ectoparasite and 10 endoparasite species were identified representing Cestoda, Trematoda, Monogenea, Nematoda, Acanthocephala, Copepoda and Isopoda. Lernaeenicus hemirhamphi, Micracanthorhynchina hemirhamphi, Mothocya halei and Philometra sp. were suggested for 'permanent' biological markers. Multivariate discriminant function analysis showed that most sites could be distinguished based on differences in parasite abundance. Four endoparasites (Conohelmins sp., Hysterothylacium sp., M. hemirhamphi and Philometra sp.) were most important for site characterization. Limited spatial variation in permanent endoparasite abundance among localities in northern Spencer Gulf provided evidence for a distinct northern Spencer Gulf population with little interregional mixing. In contrast, considerable spatial variation in permanent endoparasite abundance between localities sampled off Kangaroo Island implied limited local movement and suggested H. melanochir may comprise a metapopulation structure. These results largely align with recent evidence from otolith chemistry that indicates fine-scale geographical population structuring in South Australian waters.     

Spatial heterogeneity in the parasite communities of creek chub (Semotilus atromaculatus) in southeastern Nebraska

The intestinal helminth communities of creek chub (Semotilus atromaculatus) were studied in the streams of southeastern Nebraska to characterize spatial variation, to determine whether drainages act as regional species pools, and to examine the spatial patterning of individual parasite species within and among drainages. Creek chub were sampled in the summer of 2003 and the spring of 2004 at each of 12 sites distributed evenly among 3 drainages in the Big Nemaha River watershed. Four intestinal helminths were recovered: Allocreadium lobatum, Proteocephalus sp., Rhabdochona canadensis, and Paulisentis missouriensis. Host size had little or no effect on the composition of the parasite communities of creek chub, either among individual fish or among samples. In contrast, drainage and sample date explained 82% of the variation in mean infracommunity species richness among samples, and 62% of the variation in mean infracommunity abundance among samples. Drainage differences were determined by the distributions of P. missouriensis and R. canadensis; whereas, A. lobatum and Proteocephalus sp. were more uniformly distributed among drainages. Each drainage was characterized by a unique pattern of species diversity at infracommunity, component community, and drainage levels of organization.     

Pomphorhynchus heronensis and restricted movement of Lutjanus carponotatus on the Great Barrier Reef

Samples of Lutjanus carponotatus (Lutjanidae) from reef flat (shallow) and reef slope (deep) sites around Heron and Wistari reefs on the southern Great Barrier Reef were examined for Pomphorhynchus heronensis (Acanthocephala). Individual fish from the reef slope had 0-9 (2.6) worms as compared with 1-122 (39.6) worms for individuals from the reef flat (P < 0.0001). Other variables (year, season, size of fish) made little contribution to the variation. Reef flat and reef slope sites were separated by as little as 300 m. These results imply both that the fish have very limited local movement and that transmission of the parasite is concentrated locally.     

Communities of parasites of freshwater fish of Jersey, Channel Islands

The parasite faunas of 12 species of freshwater fish from 17 localities on the island of Jersey were examined. Comparison of the species composition, number, diversity and equitability of the parasite fauna of each species of fish in each locality revealed that community diversity was always low, that most communities were dominated by a single species of parasite, and that community similarity between host species, and often between sites, was generally low. This was not related to unavailability or distribution of potential, invertebrate, intermediate host species, but appeared to be due to chance colonization events. With two exceptions, little exchange of parasites took place between host species, despite vacant niches in the parasite communities and the absence of competitors, and normal parasite specificity was maintained. Comparison of the parasite communities with those on other oceanic islands suggests that they are poorer than would be predicted by island biogeographical theory, and that this is not a very good predictor of parasite community richness on oceanic islands.     

Trophic Structure of One Deep-sea Benthic Fish Community in the Eastern Canadian Arctic: Application of Food, Parasites and Multivariate Analysis

Synopsis As new arctic marine fisheries develop there is need for a comprehensive ecosystem approach to long-term management. This approach recognizes the importance of community interactions such as food web structure and trophic patterns. We determined whether hierarchical clustering (guild formation) is an effective method of trophic evaluation in deep-sea Artic fish communities using stomach content and parasite data with size class, and evaluated the application of endohelminth communities (parasite species transmitted in the food) as indicators of trophic status. Cluster analysis using food group abundance with size class of fish revealed the presence of 11 guilds within the community, however the same analysis using parasite data showed little correlation between food and parasites. Redundancy analysis (RDA) within the 11 guilds also revealed no significant correlations between food group and parasite abundance suggesting that this type of ordination is not suited for environments containing mainly generalist feeders. RDA of individual taxa without a priori guild designation found that taxa in benthic deep-sea communities are defined by their ability to exploit prey species in more than one habitat zone. Benthic fish species were significantly correlated with benthic food groups and parasites that utilize benthic intermediate hosts whereas benthopelagic–pelagic species fed on a higher diversity of prey species and were infected by a larger number of non-host specific parasites. Eigenanalysis and Monte Carlo results showed that parasites and food groups are highly correlated, indicating that parasite community analysis is an effective tool for predicting feeding strategies in Arctic marine environments. It also suggests that in most cases endoparasite infections alone could be used for trophic evaluation in the absence of stomach content data.     

Extreme habitats as refuge from parasite infections? Evidence from an extremophile fish

Living in extreme habitats typically requires costly adaptations of any organism tolerating these conditions, but very little is known about potential benefits that trade off these costs. We suggest that extreme habitats may function as refuge from parasite infections, since parasites can become locally extinct either directly, through selection by an extreme environmental parameter on free-living parasite stages, or indirectly, through selection on other host species involved in its life cycle. We tested this hypothesis in a small freshwater fish, the Atlantic molly (Poecilia mexicana) that inhabits normal freshwaters as well as extreme habitats containing high concentrations of toxic hydrogen sulfide. Populations from such extreme habitats are significantly less parasitized by the trematode Uvulifer sp. than a population from a non-sulfidic habitat. We suggest that reduced parasite prevalence may be a benefit of living in sulfidic habitats.     

Limited ecological population connectivity suggests low demands on self-recruitment in a tropical inshore marine fish (Eleutheronema tetradactylum: Polynemidae)

The diversity of geographic scales at which marine organisms display genetic variation mirrors the biophysical and ecological complexity of dispersal by pelagic larvae. Yet little is known about the effect of larval ecology on genetic population patterns, partly because detailed data of larval ecology do not yet exist for most taxa. One species for which this data is available is Eleutheronema tetradactylum, a tropical Indo-West Pacific shorefish. Here, we use a partial sequence mitochondrial cytochrome oxidase subunit 1 (COI) marker and five microsatellite loci to survey the genetic structure of E. tetradactylum across northern Australia. Structure was found throughout the range and isolation by distance was strong, explaining approximately 87 and 64% of the genetic variation in microsatellites and mtDNA, respectively. Populations separated by as little as 15 km also showed significant genetic structure, implying that local populations are mainly insular and self-seeding on an ecological time frame. Because the larvae of E. tetradactylum have lower swimming performance and poor orientation compared with other tropical fishes, even modest larval abilities may permit self-recruitment rather than passive dispersal.     

Parasites of freshwater resident and anadromous Arctic charr (Salvelinus alpinus) in Greenland

Twenty-one metazoan parasite species were found in Arctic charr at three coastal sites in west Greenland, including Neascus sp. and the nematode Pseudoterranova decipiens , new records for Arctic charr. Twelve species are new records for Arctic charr in Greenland. The quantitative composition of the parasite communities varied, but the freshwater species ( Diphyllobothrium ditremwn, Eubothriutn salvelini, Proteocephalus longicollis, Crepidostotnutn farianis ) were usually numerically dominant, even in anadromous fish. The absence from Greenland of Mysidacea, Amphipoda, Ephemeroptera and Odonata excludes parasites requiring such organisms as intermediate hosts, including the cestode Cyathocephalus truncatus , nematodes of the genus Cystidicola , and freshwater acanthocephalans.     

Beyond Symbiosis: Cleaner Shrimp Clean Up in Culture

Cleaner organisms exhibit a remarkable natural behaviour where they consume ectoparasites attached to “client” organisms. While this behaviour can be utilized as a natural method of parasitic disease control (or biocontrol), it is not known whether cleaner organisms can also limit reinfection from parasite eggs and larvae within the environment. Here we show that cleaner shrimp, Lysmata amboinensis, consume eggs and larvae of a harmful monogenean parasite, Neobenedenia sp., in aquaculture. Shrimp consumed parasite eggs under diurnal (63%) and nocturnal (14%) conditions as well as infectious larvae (oncomiracidia) diurnally (26%). Furthermore, we trialled the inclusion of cleaner shrimp for preventative parasite management of ornamental fish, Pseudanthias squamipinnis, and found shrimp reduced oncomiracidia infection success of host fish by half compared to controls (held without shrimp). Fish held without cleaner shrimp exhibited pigmentation changes as a result of infection, possibly indicative of a stress response. These results provide the first empirical evidence that cleaner organisms reduce parasite loads in the environment through non-symbiotic cleaning activities. Our research findings have relevance to aquaculture and the marine ornamental trade, where cleaner shrimp could be applied for prophylaxis and control of ectoparasite infections.     

High frequency of leaf swallowing and its relationship to intestinal parasite expulsion in "village" chimpanzees at Bulindi, Uganda

Self-medication by great apes to control intestinal parasite infections has been documented at sites across Africa. Chimpanzees (Pan troglodytes) swallow the leaves of certain plant species whole, without chewing. Previous studies demonstrated a relationship between chimpanzee leaf swallowing and expulsion of nematode worms (Oesophagostomum sp.) and tapeworms (Bertiella sp.) in dung. We investigated the relationship between leaf swallowing and parasite expulsion in chimpanzees inhabiting a fragmented forest-farm mosaic at Bulindi, Uganda. During 13 months whole undigested leaves occurred in chimpanzee dung at a considerably higher frequency (10.4% of dungs) than at other sites (0.4-4.0%). Leaf swallowing occurred year-round and showed no pronounced seasonality. Chimpanzees egested adults of multiple species of Oesophagostomum (including O. stephanostomum) and proglottids of two tapeworms-Bertiella sp. and probably Raillietina sp. The latter may not be a true infection, but the byproduct of predation on domestic fowl. Compared to previous studies, the co-occurrence of whole leaves and parasites in chimpanzee dung was low. Whereas the presence of leaves in dung increased the probability of adult nematode expulsion, no association between leaf swallowing and the shedding of tapeworm proglottids was apparent. Anthropogenic habitat changes have been linked to alterations in host-parasite interactions. At Bulindi, deforestation for agriculture has increased contact between apes and people. Elevated levels of leaf swallowing could indicate these chimpanzees are especially vulnerable to parasite infections, possibly due to environmental changes and/or increased stress levels arising from a high frequency of contact with humans. Frequent self-medication by chimpanzees in a high-risk environment could be a generalized adaptation to multiple parasite infections that respond differently to the behavior. Future parasitological surveys of apes and humans at Bulindi are needed for chimpanzee health monitoring and management, and to investigate the potential for disease transmission among apes, people, and domestic animals.