Cryptocotyle Research Articles

Effects of host habitat quality on the viability of Cryptocotyle lingua (Trematoda: Digenea) cercariae

In an earlier study it was shown that Cryptocotyle lingua cercariae, matured in Littorina littorea from a polluted marine lagoon, displayed slower horizontal swimming rates, and reduced longevity compared to cercariae released by periwinkles from a cleaner environment. This work investigated whether the pollution-induced reduction in swimming rates was due to an inefficient swimming action or the adoption of a less direct swimming path. In addition, cercariae from L. littorea that had been transferred from an 'unpolluted' to a 'polluted' site for 1 month provided information on the speed with which pollutants affect cercariae through their intermediate hosts. Results indicated that, in general, horizontal swimming rates were reduced due to slower swimming rather than disorientation and longer swimming pathways. Effects of host transplantation to a polluted site were clearly evident after 1 month. Evidence suggested that the pollutants accumulated by the cercariae via their first intermediate host affected the neuromusculature associated with swimming performance rather than sensory structures. Bearing in mind the reduced viability of C. lingua cercariae in polluted sites it is assumed that high prevalence of this digenean in gastropods (at such sites) must be due to their continual introduction by infected birds attracted to these habitats from other areas.

Four-year monitoring of parasite communities in gobiid fishes of the south-western Baltic

The parasite infracommunity of five goby species (Pomatoschistus minutus, P. pictus, P.microps, Gobiusculus flavescens, Gobius niger) from the south-western Baltic was investigated during spring, summer and autumn of the years 1997-2000. The mean parasite species number in single hosts was high, ranging between 1.1 (P. minutus), 2.1 (P. pictus) to even 3.3 (P. microps). Gobius niger is the only host which lives longer than a year and is infested by almost identical parasites for longer times, i.e. the parasite species composition has greater homogeneity. Most intensity of infestation values peaked in summer and were lowest in autumn; only a few exceptions were found in spring or autumn. Only the Digenea Podocotyle atomon and Cryptocotyle concavum were abundant enough to show a clear seasonal fluctuation in Pomatoschistus minutus, P. pictus and Gobiusculus flavescens. Aphalloides timmi and Apatemon gracilis (Digenea) also attained high intensities in P. microps. These four parasite species and, additionally, Cryptocotyle lingua (Digenea), and Hysterothylacium sp. (Nematoda) can be strongly accumulated from either prey or free-swimming larvae and, thus, decisively influence the structure of the infracommunities. Due to selection by filter mechanisms, rare parasites settle rather by chance after competition with other species. The number of parasite species usually increased significantly with host growth. As many as four parasite species were found at the same time in the intestinal tract microhabitat of Gobius niger and P. minutus; at most three parasite species were present on the skin and fins or in the body cavity. The level of infection is due to the respective life history patterns and the kinds of prey, which harbour different parasites as intermediate hosts. Additionally, it depends on the time of appearance of goby offspring in the course of the year.

Trematode parasite influence on copper, iron and zinc content of polluted Littorina littorea: infection, host sex and time effects

Temporal variations in copper, iron and zinc levels in the periwinkle, Littorina littorea, were investigated to determine whether levels were affected by the sex of the organisms and/or by the presence of two species of trematode parasite. Significant monthly changes in concentrations of all these metals were found, with levels varying according to periwinkle sex and parasite infection. Periwinkles infected by either Cryptocotyle lingua or Renicola roscovita had reduced copper and iron concentrations compared to same-sex uninfected periwinkles, although infected periwinkles generally contained higher concentrations of zinc. Periwinkles infected by the more invasive C. lingua rediae had lower copper concentrations than those infected by R. roscovita sporocysts. These results clearly indicate that in areas of high parasite prevalence L. littorea is not an ideal metal-biomonitor.

Four-year monitoring of parasite communities in gobiid fishes of the south-western Baltic. I. Guild and component community.

The parasite communities of goby species (Teleostei, Percomorphi) from the south-western Baltic Sea were investigated from 1997 to 2000 in three different seasons. In total, 30 parasite species were found in the guild of four goby spp. from Dahmeshöved (Lübeck Bight). The component community of Pomatoschistus minutus comprised 22, Pomatoschistus pictus 20, Gobiusculus flavescens 18 and Gobius niger 14 parasite species, whereas Pomatoschistus microps from the Salzhaff (Mecklenburg Bight) harboured 24 species. The digenean Podocotyle atomon (ingested with prey) and Cryptocotyle concavum (active penetration) were the most common parasites. Cryptocotyle lingua and the nematode Hysterothylacium sp. in Gobius niger as well as the specialists Aphalloides timmi and Apatemon gracilis (Digenea) in Pomatoschistus microps were also very abundant. There were large changes in the parasite communities within the years as well as between the seasons of a year; only Gobius niger presented rather homogeneous communities. The ratio of core parasite species in the hosts was at most 28% ( Gobiusculus flavescens) and at least 9% ( Gobius niger). The core species can attain their maximum values at different seasons, which is not only influenced by the parasite but also by the host species. It is concluded that the composition of parasite communities was predominantly determined by the ways of life of the host as well as of the parasite species. Another important factor is the population density of intermediate hosts.

Health of flatfish from localities in Placentia Bay, Newfoundland, contaminated with petroleum and PCBs.

This study compared the health of flatfish inhabiting two areas in Placentia Bay, Newfoundland, contaminated either with polycyclic aromatic hydrocarbons (PAHs) or polychlorinated biphenyls (PCBs) with samples from reference sites. Initially, four species of flatfish, including American plaice (Hippoglossoides platessoides), yellowtail flounder (Limanda ferruginea), gray sole (Glyptocephalus cynoglossus), and winter flounder (Pleuronectes americanus), were sampled only for external lesions from commercial catches at three offshore sites. Others, captured by scuba divers at inshore sites, were autopsied to compare external lesions, condition (K) factor, hepatosomatic index (HSI), hemoglobin and lymphocyte levels, histological changes in the liver and spleen, and two parasites, metacercariae of Cryptocotyle lingua in the skin and a digenetic trematode, Steringophorus furciger, in the digestive tract. A higher prevalence of lesions occurred in the four species of flatfish caught offshore by commercial fisherman near the oil terminal and the PCB-contaminated dockyard than at a reference site. Lesions were also more prevalent in three species of flatfish captured by scuba divers inshore near the oil terminal and were associated with significantly lower K factor and lymphocyte levels but elevated HSI values and histopathological changes in the liver and spleen than in reference samples. Winter flounder sampled at two locations near the PCB-contaminated dockyard and a PAH-polluted small boat wharf also exhibited more external lesions, liver discoloration, and lower K factor, hemoglobin, and lymphocyte but higher HSI values and hepatic and splenic hemosiderosis than in reference fish. Prevalence of C. lingua in the skin was significantly greater but S. furciger in the digestive tract lower in samples taken from the aforementioned contaminated sites than from the reference locations. These results, based on several bioindicators, suggest that the health of bottom-dwelling flatfish at three sites of this embayment was impaired by chronic exposure to sediment contaminated with PAHs or PCBs.

Parasites and size‐assortative schooling in three‐spined sticklebacks

Recent field studies carried out in lacustrine environments have suggested that fish schools may be assorted with respect to parasite infections, but the generality and strength of parasite‐assortative schooling in fish is unclear. In this study, data are presented on the body size and externally visible macroparasite load of 366 individual three‐spined sticklebacks Gasterosteus aculeatus L. (Gasterosteidae, Teleostei) from six naturally formed schools captured in the Gullmarsfjord on the west coast of Sweden. Length–frequency analysis suggested that two separate year classes (presumed 0+ and 1+) were represented in the sample. Individual schools were assorted by body size, and contained largely fish of a single year class. The number of fish in the school was negatively related to median body size of members. Probability of infection increased significantly with fish length for two parasites (Cryptocotyle lingua (Trematoda) and Glugea anomala (Microsporidia)), and marginally for a third (chalimus larvae of Caligus sp. (Copepoda)). After correcting for body‐size effects, the proportion of school members infected with C. lingua and G. anomala did not differ significantly from a model of random assortment by infection status. However, two of the six schools were found to have significantly more, or significantly fewer, members infected with Caligus sp. chalimus larvae than predicted by the random model. Significant inter‐school differences in the intensity of C. lingua infection were also detected, but these resulted from the combined effects of size‐assortment and a strong correlation between body size and infection intensity. The results of this study provide only limited support for the existence of active parasite‐assortative schooling in marine sticklebacks, and are discussed in relation to recent studies of parasite assortment amongst host fish in other ecosystems.

The parasite fauna of the Norwegian spring spawning herring (Clupea harengus L.)

Tolonen, A., and Karlsbakk, E. 2002. The parasite fauna of the Norwegian spring spawning herring (Clupea harengus L.). ICES Journal of Marine Science, 60: 77–84. We examined 220 Norwegian spring spawning (NSS) herring for parasites. The samples included juvenile herring from coastal nursery areas and young or mature herring from feeding areas in the Norwegian Sea and from the wintering areas in fjords in Northern Norway. We detected 11 parasite species. The coccidian Goussia clupearum infects both young and adult fish, with increasing prevalence with age. Eimeria sardinae, a coccidian infecting the testes of males, is mostly restricted to mature fish. Spores of a myxozoan parasite, Ceratomyxa auerbachi, were only detected in fish from the wintering areas. Adult trematodes, Hemiurus spp., occurred only in young herring from a coastal sample. Adult and larval Hysterothylacium aduncum (Nematoda) infections occur predominantly in immature fish. That H. aduncum is rare in mature fish suggests that infections acquired as young are lost, and that there is virtually no transmission of the parasite in the feeding areas (continental shelf areas post-spawning and the Norwegian Sea). Cryptocotyle lingua metacercarial infections are acquired only by young herring in coastal nursery areas. The only macroparasite increasing in abundance in mature NSS herring is larvae of the nematode Anisakis simplex, this species infecting the fish also in the feeding areas. The parasite fauna of NSS herring is species poor, adult helminths occurring only in juveniles, while adult fish are host only to larvae, chiefly A. simplex. 2003 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd.

Effects of trematode parasitism on the behaviour and ecology of a common marine snail (Littorina littorea (L.)).

Cryptocotyle lingua (Creplin) is a digenean trematode parasite of the littoral prosobranch gastropod Littorina littorea (L.). The literature suggests the snails become infected by grazing guano of the final host, the herring gull, Larus argentatus Pontoppidan. The parasite emerges from the snail as free-swimming cercariae. Interactions between the snail and the parasite at cellular and life-history levels are well established, but little is known of the influences the interaction has on the behaviour and the ecology of the snail. We tested the response of the snail to encounters with cercariae, examined the longevity of the guano on-shore and tested the responses of the snail to encounters with guano. Over half the L. littorea tested were able to detect both cercariae and a filtered homogenate of cercariae in conspecific mucus trails, approximately one-third of animals refusing to cross the treatments. Chemoreception by the mouth or foot is considered the most likely means of detection. Guano samples (mean weight 3.22 g) naturally deposited at approximately mid-tide level were completely washed away by one tidal inundation. We consider this period too brief to allow for ingestion of eggs in guano by the snail. Further, snails would not cross guano placed in conspecific trails. Most snails would not cross guano diluted by 10(3)x(10 mg ml(-1)) and some snails could still detect guano diluted by 10(6)x(10 &mgr;g ml(-1)), though all were prepared to cross it. Detection of guano is again believed to be by chemoreception by the mouth or foot. These results are discussed in terms of the mating and aggregating behaviour of L. littorea. Ingestion of the parasite by L. littorea is likely to take place once the guano has washed away as the eggs are negatively buoyant in seawater and may adhere to rock (biofilm) or algal fronds which may be grazed by the snail.

Respiration rates in Littorina littorea infected with three species of digenean parasite

The gastropod Littorina littorea shows increased mortality in the summer months when infected with digenean parasites. One possible cause of this mortality is impaired respiration in infected hosts. Respiration rates of L. littorea infected with three species of digenea of varying pathogenicity were measured: Cryptocotyle lingua, Himasthla elongata and Renicola roscovita. No evidence of altered respiration rates in infected snails was found.

Digenetic trematodes in four species oflittorinafrom the West Coast of Sweden

Abstract Four species of Littorina (L. littorea, L. obtusata, L. fabalis and L. saxatilis) from the Swedish west coast were examined for infections with digenetic trematodes. Four species of the genus Microphallus, Podocotyle alomon, Renicola roscovita, Himasthla elongata, Cryptocotyle lingua, and Paramonostomum chabaudi were found, in addition to encysted metacercariae of the two genera Himasthla and Renicola. The prevalence of sporocysts and rediae varied substantially among sampled populations (0-44%), as did the prevalence of metacercarial infections (3-100%), and this variation was due both to different microhabitats and to different host species. In L. saxatilis exposed rocky shore populations had lower prevalence than sheltered boulder shore populations. Within the same shores, L. littorea was the host species with highest prevalence of digeneans. The general pattern of distribution of the nine trematode species over host species was similar to what have been reported from other North Atlantic area...

Alien Invaders: Larval flukes as an aid to teaching

Few organisms have life cycles as elaborate or behaviour as complex as parasites. In this paper the biology of digenean trematodes and their larval stages is outlined. Like alien invaders with malevolent intent, these highly adapted organisms encounter and penetrate host tissues. Aspects of their life cycles truly surpass any creation of the Hollywood dream factory, a case of science fact being more bizarre than science fiction. The similarities between reality and the manifestations of the film industry can be employed to stimulate interest among students. Here, the use of non-pathogenic larval flukes in studies of parasite behaviour is encouraged, and a number of investigations suitable for students from GCSE to undergraduate level are suggested. The equipment required is commonly available in school laboratories. As trematode life cycles are quite diverse, the marine parasite Cryptocotyle lingua is used as an exemplar.

Length-mass relationship, histopathology, and parasitism in winter flounder (Pleuronectes americanus) living near a PCB-contaminated naval facility in Newfoundland

A study was conducted to ascertain the health of winter flounder (Pleuronectes americanus) sampled near a naval facility contaminated with polychlorinated biphenyls (PCBs), using length-mass relationship, hematological values, histopathology, and parasitism as bioindicators of stress. Samples were collected by SCUBA divers about 2 km (Broad Cove) and 5 km (Fox Harbour) down-current from the dockyard and a reference site (Fox Island) 5 km offshore in Placentia Bay, Newfoundland. Length, mass, and condition factor were significantly greater in both sexes sampled at the reference site than at the two contaminated sites, whereas macroscopic anomalies, including fin necrosis, infestation with ectoparasitic metacercariae of the digenean Cryptocotyle lingua, and histopathological lesions in the liver, kidney, spleen, and gills, were more frequent at the latter locations. A greater variety of prey were consumed by fish taken at Fox Island than at Fox Harbour, while food was absent in several samples from Broad Cove. Three endoparasites, Ceratomyxa acadiensis, Echinorhynchus gadi, and Steringophorus furciger, were less prevalent and abundant in flounder sampled at Broad Cove than at the other two sites. These results suggest a connection between PCB contamination and impaired fish health. In addition, anomalies were more prevalent in samples collected nearest to the contaminated site than in those collected farther away.

Anthropogenic influences on the infestation of intertidal gastropods by seabird trematode larvae on the southern Barents Sea coast

In this study we examined how the variation in the distribution of six species of seabird trematodes was influenced by human activities along the subarctic Barents Sea coast of northern Norway. This was done by comparing the prevalence of the parasites in two species of intermediate host (Littorinasaxatilis and Littorina obtusata) on seashores near fishing industry complexes, fish farms and at control sites. In L. saxatilis there were higher prevalences at sites influenced by human activities for three out of five trematode species (Microphallus piriformes, M. similis, Cryptocotyle lingua) which have gulls (Larus spp.) as their predominant final hosts, while in L. obtusata, only M. similis was more common at sites with human activity. For M. pygmaeus, a trematode which has the common eider (Somateria mollissima) as its most predominant final host, the prevalence in L.␣saxatilis tended to be higher at sites with fishing industry, but differences were not significant. No such tendency was found in L. obtusata for this trematode. The overall prevalence in L. obtusata was lower than in L.␣saxatilis. This indicates that the vulnerability to trematode infection differs between the two snail species depending on the variation in the distribution patterns in the intertidal zone. Gulls tend to concentrate in areas near fishing industry and fish farms to feed on fish offal, which leads to an increase in the transmission between hosts, and to a higher level of parasite infection, locally.

Diseases and parasites of Baltic cod (Gadus morhua) from the Mecklenburg Bight to the Estonian coast

During the 1994 BMB/ICES Sea-going Workshop “Fish Diseases and Parasites in the Baltic Sea”, the prevalences of skin ulcers, pseudobranchial swellings (X-cell disease), skeletal deformities, and the parasites Cryptocotyle lingua and Lernaeocera branchialis were recorded in cod in 11 areas from the Mecklenburg Bight in the southwest to the Estonian coast in the northeast of the Baltic Sea. Prevalences were highest in the western part, except for skeletal deformities, which were highest in the central part. The spatial distribution of pseudobranchial swellings, C. lingua and L. branchialis appeared to be restricted to areas with salinity above 8. Skin ulcers were mainly observed in German waters, while skeletal deformities were most abundant in the Polish, Russian, and Lithuanian coastal zones.

Digenean metacercariae (Timoniellaspp.,Labratrema minimusandCryptocotyle concava) from the flounder,platichthys flesus, in the tidal Thames

A detailed examination of the abundant flatfish speciesPlatichthys flesus, the flounder, in the tidal Thames has revealed the presence of four digenean metacercarial parasites,Cryptocotyle concava(Creplin, 1825),Timoniella imbutiforme(Molin, 1859),T. praeterita(Looss, 1901) andLabratrema minimus(Stossich, 1887). Flounders were recorded as a new second intermediate host forT. praeteritaandL. minimus. They were also recorded as second intermediate hosts for the first time in British waters forT. imbutiforme. The temporal and spatial characteristics of these infections were examined and were believed to provide indirect parasitological evidence of the movement patterns of flounders during their utilization of the Thames Estuary as a nursery ground. From these data it was also surmised that the first intermediate host ofT. imbutiforme,T. praeteritaandC. concavawas probably the molluscan speciesHydrobia ulvaein the lower Thames Estuary, whereasL. minimuswas most likely to occur in the molluscan hostCerastoderma edule, also present in the lower estuary.

Digenean metacercariae (Timoniella spp., Labratrema minimus and Cryptocotyle concava) from the flounder, platichthys flesus, in the tidal Thames

A detailed examination of the abundant flatfish species Platichthys flesus, the flounder, in the tidal Thames has revealed the presence of four digenean metacercarial parasites, Cryptocotyle concava (Creplin, 1825), Timoniella imbutiforme (Molin, 1859), T. praeterita (Looss, 1901) and Labratrema minimus (Stossich, 1887). Flounders were recorded as a new second intermediate host for T. praeterita and L. minimus. They were also recorded as second intermediate hosts for the first time in British waters for T. imbutiforme. The temporal and spatial characteristics of these infections were examined and were believed to provide indirect parasitological evidence of the movement patterns of flounders during their utilization of the Thames Estuary as a nursery ground. From these data it was also surmised that the first intermediate host of T. imbutiforme, T. praeterita and C. concava was probably the molluscan species Hydrobia ulvae in the lower Thames Estuary, whereas L. minimus was most likely to occur in the molluscan host Cerastoderma edule, also present in the lower estuary.

HIGH PERFORMANCE THIN-LAYER CHROMATOGRAPHIC ANALYSIS OF NEUTRAL LIPIDS IN THE MARINE SNAILS ILYANASSA OBSOLETUS AND LITTORINA LITTOREA INFECTED WITH LARVAL TREMATODES

High performance thin-layer chromatography analysis was used to analyze neutral lipids in the digestive gland-gonad (DGG) complex of the marine snails Ilyanassa obsoletus and Littorina littorea infected with larval trematodes. The results were compared with the DGGs of snails not infected with larval trematodes. The most abundant neutral lipid in both infected and non-infected snails was triacylglycerols, with percentages ranging from 2.8% in I. obsoletus snails infected with unidentified armatae cercariae to 24.7% in I. obsoletus snails infected with Zoogonius rubellus. L. littorea snails infected with an unidentified armatae cercaria contained 6 to 7 times the amount of cholesteryl ester than uninfected snails or those infected with Cryptocotyle lingua cercariae. I. obsoletus snails infected with Z. rubellus or an unidentified armatae cercaria contained 2 to 3 times more free sterol than the uninfected controls. Larval trematode parasitism was found to alter the neutral lipid profiles of the marine snails I. obsoletus and L. littorea.

Transmission of Cryptocotyle lingua cercariae in natural environments: a field experiment

Atlantic cod were kept at two different depths in three cages placed at increasing distance from a rocky shore where natural infections of the digenean Cryptocotyle lingua occurred in the snail Littorina littorea. During a 6‐month period the fish kept at 0–2 m accumulated significantly more parasites than those kept at 2–4 m. Distance from the shore did not affect infection rates. We conclude that host location behaviour of cercariae influences the infection pattern under natural conditions, and that transmission from snail to fish can take place over large areas of coastal waters.

Reactions of sera from immunised and experimentally infected thick-lipped grey mullet, Chelon labrosus(Risso, 1826), with isolated proteins of Cryptocotyle lingua(Creplin, 1825)

The reactions of sera from thick-lipped grey mullet, Chelon labrosus(Risso, 1826), experimentally infected with metacercariae of the digenean Cryptocotyle lingua(Creplin, 1825) were compared with those from mullet and rabbits immunised with sonicated cercariae using Western blotting. SDS-PAGE revealed 35 proteins from the redia and cercaria respectively and 20 from the metacercaria of C. lingua. Antisera from rabbits reacted most strongly and with the greatest number of proteins. Common antigens exist between all three stages of the life cycle. Cross-reactivity was also detected between C. linguaand the first intermediate molluscan host, Littorina littorea. The failure of sera from fish exposed to metacercarial infection to react with some parasite proteins may suggest a role for the metacercarial cyst wall in evasion of the host response.

Threatened fishes of the world: Eucyclogobius newberryi Girard, 1857 (Gobiidae)

Distribution:Tidewater gobies are confined to shallow, brackish portions of coastal streams, marshes, lagoons and estuaries between the Smith River to the north and Agua Hedionda Lagoon to the south California (Swift et al. 1989). Abundance: Where found, they are often one of the most abundant fish species (densities peak in summer). Habitat and ecology: They feed on benthic invertebrates such as ostracods, amphipods, and insect larvae. Potential predators include birds and other fishes. Wading and diving birds often forage in areas where tidewater gobies are abundant. Larger native fishes such as Oncorhynchus mykiss, Cotfus aspeu, Leptocotrus armatus and Gil/ichthys mirabilis may be important predators. Introduced fishes such as Tridentiger trigonocephalus, 7: bifasciatus, Acanthogobiusflavimanus, Morone saxatilis, Micropterous salmoides and other centrarchids may also adversely affect goby populations. Tidewater gobies rarely occur where predatory fishes are abundant. In addition, trematode metacercariae (probably Cryptocotyle lingua) infect some populations. Reproduction: Males excavate 10-20 cm mucus lined burrows in coarse sand and care for one clutch of 300-500 eggs. Embryos hatch in about 10 days. Females, which are more strikingly patterned, aggressively compete with other females for breeding males. Both sexes spawn several times. Spawning occurs almost year-round, with spring and fall peaks (Brown & Swenson 1994). Mortality appears to increase after spawning, and fish typically live only one year. Some may overwinter upstream. Threats: Habitat loss and degradation is associated with land use practices such as conversion of coastal wetlands to marinas, highway and railroad construction. freshwater diversions, grazing, breaching of coastal lagoons, and flood control practices. Drought conditions in recent years have compounded these effects. The number of known populations has declined by half since 1900 (less than 50 populations currently exist) (Swift et al. 1989). Reductions have been most striking in Southern California and San Francisco Bay. The loss of this many populations is impressive in light of the broad physical tolerance of this species. The lack of a marine phase has led to genetically divergent populations with limited capacity for re-colonization following local extinctions (Crabtree 1985). Small populations continue to be found, suggesting that the total number of populations lost might be higher than presently estimated. Conservation action: Gobies were successfully re-introduced into Malibu Lagoon (Swift et al. 1993) and Waddell Creek in 1991 (Brown & Swenson 1994). Its recent listing as a federally endangered species (7 March 1994) should increase protection. Conservation recommendations: Reducing eutrophication, maintaining the quality of freshwater flows, and allowing the natural development of barrier sand berms which close stream mouths and enhance lagoon formation will help protect habitats. In addition, introductions of exotic species to goby habitats should be prevented.