Parasitic Copepod Research Articles

Redescription of two parasitic copepods belonging to Chondracanthidae and Hatschekiidae, recovered from Japanese fishes (Actinopterygii)

Abstract Acanthochondria uranoscopi Ho & Kim, 1995 (Copepoda, Cyclopoida, Chondracanthidae) and Laminohatschekia synaphobranchi Boxshall, 1989 (Siphonostomatoida, Hatschekiidae) are redescribed based on specimens of the female, recovered from Uranoscopus japonicus Houttuyn, 1782 (Perciformes, Uranoscopidae) and Synaphobranchus affinis Günther, 1877 (Anguilliformes, Synaphobranchidae), respectively.

Chafing behaviour of great barracudas on sea turtles triggers escape response of external parasites

If chafing behaviours on the bottom or rocks are common, interspecific events are rare and usually involve smaller ray-finned fishes rubbing on larger sharks or manta rays. Reports on interspecific chafing between fishes and reptiles are even less common, with just one report of great barracudas (Sphyraena barracuda) using swimming hawksbill (Eretmochelys imbricata) and green turtles (Chelonia mydas) as chafing surfaces in the Southwestern Atlantic. Here, we describe a chafing interaction between a great barracuda and a hawksbill turtle in the Red Sea. Our observation provides evidence that this interaction is probably not localised but may represent a more widespread behavioural pattern than previously thought. This chafing behaviour is suggested to remove external parasites, and our observation documents the behaviour of the scraper and the scraped animal, as well as the reaction of the parasites during the same event, clearly demonstrating that chafing behaviour aims at the removal of parasitic copepods (Caligidae). We also report the evasive behaviour of the copepods during the event, providing novel information on parasite removal in reef fishes.

Description of Boylea inflata sp. nov. (Cyclopoida: Bomolochidae), a new parasitic copepod from sea catfishes (Siluriformes: Ariidae) in the Brazilian Amazon Coast, with amended diagnosis of this rare genus

Description of Boylea inflata sp. nov. (Cyclopoida: Bomolochidae), a new parasitic copepod from sea catfishes (Siluriformes: Ariidae) in the Brazilian Amazon Coast, with amended diagnosis of this rare genus

Correction: Osorio et al. Parasitic Copepods as Biochemical Tracers of Foraging Patterns and Dietary Shifts in Whale Sharks (Rhincodon typus Smith, 1828). Fishes 2023, 8, 261

The authors wish to inform readers of an error that was overlooked during the proof-reading of the original article [...]

A new genus of Herpyllobiidae (Copepoda: Cyclopoida) from a deep-living annelid (Polychaeta: Sigalionidae).

A taxonomic study of deep-sea polychaetes collected at a depth of 2,805 m off the northern coast of California revealed a scaleworm of the family Sigalionidae with an attached parasitic copepod. The copepod represents an undescribed genus of the family Herpyllobiidae, comprising mesoparasitic copepods chiefly recorded from polychaetes of the family Polynoidae. Blakerius gen. nov. diverges from the other herpyllobiid genera by its possession of 1) a chalice-shaped ectosoma with several protuberances along the posterior margin and a long cylindrical shaft with a hyaline coating and integumental sculpturing, a short stalk with a small, anteriorly placed sclerotized ring, 2) a relatively large, discoid-shaped endosoma with digitiform process, and 3) attached male copepodids with 3-segmented antennules, containing limbless sac-like males. The new genus is compared with other herpyllobiids. This discovery increases the number of known herpyllobiid genera to six and is the first record of a herpyllobiid parasitizing a sigalionid polychaete.urn: lsid: zoobank.org:pub:5E31FEED-D3EB-460E-AEA4-02A9D3A778D6.

Morphology, DNA barcoding and seasonal occurrence of Ergasilus lizae Krøyer, 1863 (Copepoda: Ergasilidae) parasitizing mullets from northwestern Mexico

Ergasilus lizae Krøyer, 1863 is a parasitic copepod known to infect mullets (Mugilidae) in different parts of the world. It was originally reported from the east coast of North America, but the original description lacks enough detail, making identification with this information difficult. In this study, we provide a redescription of E. lizae found on Mugil curema Valenciennes and M. cephalus Linnaeus, caught in two coastal lagoons of northwestern Mexico during two climatic seasons: warm/rainy and cold/dry. The prevalence of this parasite was higher in the warm season than in the cold season. To facilitate the species identification, new sequences of the barcoding gene (COI mtDNA) of E. lizae were generated and compared against unpublished sequences of E. lizae available in the Barcode of Life Database (BOLD). Our results suggest that the sequences of BOLD possibly belong to a species misidentified as E. lizae.

Prevailing parasitic diseases affecting Oreochromis aureus in Lake Burullus.

Lake Burullus is an important source of fish production in Egypt; it produces 20.5% of the Egyptian fisheries' production. There is intense controversy about the heavy metal pollution in Burullus water and its effects on fish health and safety for human consumption. Heavy metals represent a major concern for aquatic life and could negatively affect fish health. Agricultural and industrial water drainage represents a considerable part of the lake water supply. The present work was conducted to determine heavy metal concentrations in lake water and blue tilapia Oreochromis aureus musculature. Water samples were collected from six locations to determine cadmium, copper, lead, zinc and iron. Sixty O. aureus fish samples were also collected from the same sampling points to assess the prevalent parasites infesting fish and to determine the heavy metal (Cd, Cu, Pb, Zn and Fe) concentrations in fish musculature then study the relationship between heavy metals concentration and prevailing fish parasites. Results indicated that 53.34% of the examined fish were infested with encysted metacercaria. Centrocestus formosanus, Prohemistomum vivax, and Euclinostomum heterostomum were retrieved from gills, musculature, hepatopancreas and the posterior kidney. The parasitic intensity in fish tissues was between 1 and 9 cystg-1. Centrocestus formosanus was identified using the polymerase chain reaction in the gill tissues of 16 fish. The gill parasitic copepod Lamproglena monodi was identified in one fish. Degenerative changes such as thickening, corrugation, and destruction of gill filament are the most dominant pathological changes in infested fish gills. Heavy metal concentrations in water samples were at normal levels, except for copper and iron in the southern part of the lake. All heavy metals in fish musculature were below the permissible limits. The parasitic infestation was more dominant in the northern part of the lake than in the southern region; this could be due to elevated copper concentration in the southern part of the lake that could negatively affect the survival of the first intermediate host and parasite cercaria. In conclusion, captured fish from Lake Burullus were safe for human consumption, and heavy metal pollution in lake water does not represent a severe risk.

Peracetic acid treatment of squid eggs infected with parasitic copepod (Ikanecator primus gen. et sp. nov.)

Having been successfully bred in semi-intensive and intensive aquaculture systems, oval squids of the Sepioteuthis lessoniana species complex are emerging as promising candidates for research and industry. Nevertheless, information about pathogens and diseases that may affect squid aquaculture remains sparse. In this study, we identify new parasitic copepod species that causes squid mortality and decreases squid hatching rates, and we also offer a solution to eliminate the pathogen during incubation of squid eggs. The newly discovered copepod Ikanecator primus gen. et sp. nov. was identified on oval squid eggs for the first time using both morphological and molecular diagnostic markers. In the genomes of the copepod and associated microbiome, we identified multiple genes for enzymes involved in cephalopod eggshell degradation in genomes of the copepod and associated microbiome. Furthermore, we conducted experiments to assess efficacy of peracetic acid in inhibiting the I. primus gen. et sp. nov. both in vitro and in vivo using immersion treatment. We established that a 2-min exposure to a concentration of 250 μl/L of peracetic acid containing product (PAA-product; 35 mg/L PAA and 15 mg/L H2O2) inhibited the development of nauplii in vitro. All parasites exposed to a concentration of 500 μl/L of PAA-product (70 mg/L PAA and 30 mg/L H2O2) were eliminated within two minutes. On top of this, the immersion treatment with 500 μl/L of PAA-product (70 mg/L PAA and 30 mg/L H2O2) improved survival of squid embryos and increased size of squid hatchlings compared with control and the immersion treatment with 125 μl/L of PAA-product (17.5 mg/L PAA and 7.5 mg/L H2O2) and the immersion treatment with 250 μl/L of PAA-product (35 mg/L PAA and 15 mg/L H2O2). These findings suggest that PAA holds a great potential as inhibitor and controller of parasitic copepod infections and for overall health management in cephalopod culture.

Distribution and host range of a highly invasive parasitic copepod

AbstractThe parasitic copepod Neoergasilus japonicus (Ergasilidae), native to East Asia, has spread rapidly around the world over the past half-century and now represents a clear example of successful parasitic invader. The species is now found in western Asia, Europe, America and Africa, with aquaculture and fish introductions identified as the primary vectors of dispersal. Regional field investigations have revealed surprisingly high number of affected localities, indicating potentially wider distribution than currently recognised. Neoergasilus japonicus exhibits low host specificity, parasitising a diverse range of freshwater fishes. This study updates the global fish host species list to 132, spanning 27 families across 15 orders, with Cypriniformes identified as the most susceptible host species. Under experimental conditions in this study, however, N. japonicus avoided its natural host, topmouth gudgeon Pseudorasbora parva, suggesting a level of resistance to its native parasite. Piscivorous and demersal fish were less infected by copepods than planktivorous, benthivorous, pelagic and benthopelagic species, reflecting the ecology of both the parasite and its hosts. An ability to re-attach to another host, though limited, was confirmed under experimental conditions. Recognising the ecological impacts and potential consequences associated with the introduction of non-native parasites emphasises the need for continuous monitoring and research globally.

Warming effects on the life cycles of two parasitic copepods with different invasion histories.

Climate change may exacerbate the impact of invasive parasites from warmer climates through pre-existing temperature adaptations. We investigated temperature impacts on two closely related marine parasitic copepod species that share the blue mussel (Mytilus edulis) as host: Mytilicola orientalis has invaded the system from a warmer climate <20 years ago, whereas its established congener Mytilicola intestinalis has had >90 years to adapt. In laboratory experiments with temperatures 10-26°C, covering current and future temperatures as well as heat waves, the development of both life cycle stages of both species accelerated with increasing temperature. In the parasitic stages, the growth of the established invader increased evenly from 10°C to 22°C, whereas the recent invader barely grew at all at 10°C and grew faster already at 18°C. In contrast, temperature had little effect on the transition success between life cycle stages. However, the highest temperature (26°C) limited the egg development success of the established invader and the host entry success of both species, whereas the infection success of the established invader increased at 18°C and 22°C. In general, our experiments indicate that the main effect of temperature on both species is through development speed and not life cycle stage transition success. Based on regional long-term temperature data and predictions, the numbers of completed life cycles per year will increase for both parasites. The established invader seems better adapted for low current temperatures (around 10°C), whereas the more recent invader barely develops at these temperatures but can cope in high temperatures (around 26°C). Hence, pre-existing temperature adaptations of the recent invader may allow the species to better cope with heat waves.

Specifics of &lt;i&gt;Anisakis simplex&lt;/i&gt; larvae infection in the Pacific herring &lt;i&gt;Clupea pallasii&lt;/i&gt; Valenciennes, 1847 from Lake Tunaicha

The purpose of the research is to analyze specifics of Anisakis simplex larvae infection in the body cavity of the lake Pacific herring in Lake Tunaicha (from materials of 1980 to 1995).Materials and methods. Conventional parasitological methods were used for collecting the material. The dissection recorded the number of nematodes in the fish. Parasitological studies of the herring from Lake Tunaicha (southern Sakhalin) were conducted from 1980 to 1995. A total of 4,438 fish caught in the Krasnoarmeyskaya channel and Lake Tunaicha were examined.Results and discussion. The parasite fauna in the herring from Lake Tunaicha included six parasite species of which two nematode species (Anisakis simplex l., Hystorethylacium aduncum l.), one acanthocephala species (Corynosoma strumosum juv.), one trematode species (Brachyphalus crenatus) and two parasitic copepod species (Ergasilus wilsoni and E. hypomesi). Among all the above species, A. simplex larvae were of greatest interest for study. The helminth is a typical species of the Pacific herring and poses a threat to human and animal health. The results of the studies found no difference in the infection of herring females or males in Lake Tunaicha. A change in the infection rate was demonstrated in the herring by age and linear dimensions depending on the fish life cycle (spawning and wintering migration periods). The first cases were recorded for herrings infected with Anisakis sp. larvae sized from 14 cm.

On finding of an abundant population of free-living stages of ergasilids (Copepoda, Cyclopoida) in the Lyutoga river of Southern Sakhalin

In the littoral zone of the oxbow of the Lyutoga River (Southern Sakhalin), which remains connected to the main channel, a high population density of parasitic copepods was found (103 ind./m2). Ergasilus briani Markewitsch, 1933, widely distributed in Eurasia, but not previously recorded in South Sakhalin and noted only for one water body in northwestern Sakhalin (Lake Sladkoe), demonstrated the highest population density (98 ind./m2). The abundance of the second species, Thersitina gasterostei (Pagenstecher, 1861) was significantly lower (5 ind./m2). T. gasterostei has previously been noted in South Sakhalin, but the present finding is the first for the Lyutoga River. The high abundance of free-living stages of ergasilids is presumably related to the reproductive peak and the hydrological nature of the collection site (littoral area with a slow current and strong overgrowing with macrophytes).

Community science informs movement and reproductive ecology of sand tigers Carcharias taurus off North Carolina, United States of America

Sand tigers are frequently observed at shipwrecks and other artificial reef habitats off North Carolina (USA), but data about occupancy, movement ecology, and site fidelity are lacking. Spot A Shark USA researchers used Wildbook© photoidentification software to spot map sand tigers in images provided by recreational SCUBA divers, or collected from remotely operated vehicles, and an offshore live-streaming camera. We uniquely identified 1837 sand tigers, 101 of which were resighted on more than one date between 2005–2021. Sand tigers of both sexes and various ages were found year-round along the northern, central and southern coast. We identified shipwrecks or artificial reef sites with consistently high numbers of shark encounters reported, sometimes with seasonal occupancy patterns. Resighted sharks were often encountered at the same or nearby locations, confirming high levels of residency and site fidelity to specific locations. Together, the mating scars seen on 121 female sand tigers and 202 females documented with rotund abdomens consistent with pregnancy highlight the importance of NC waters for reproduction. We also quantified other characteristics of the sand tigers visible in the photographs including wounds, parasitic copepods, and attached fishing gear. Our results reflect the importance of habitats off the NC coast to the movement and reproductive ecology of sand tigers at multiple life history stages. Sand tiger populations have declined in the Northwest Atlantic, so information about residence at specific locations, seasonal patterns of occupancy, and sex-dependent behaviors associated with migration and reproduction are important to future management and conservation of the species.

First occurrence of the family Botryllophilidae Sars G.O., 1921 (Copepoda, Cyclopoida) in Sicily, central Mediterranean Sea

Abstract A female copepod specimen belonging to the family Botryllophilidae Sars G.O., 1921 was retrieved for the first time in December 2023 from nautical ropes of the tourist marina in Palermo (Cala Marina), near the commercial port of the city. The individual lacks many of the distinctive morpho-anatomical characteristics of the class Copepoda, as usual in cyclopoid parasites. In this group, females typically carry paired multiseriate egg sacs, which are extruded from the genital openings and lead to taxonomic identification. The family is commonly associated with tunicates. There are few reports of commensal and/or parasitic copepods associated with sea squirts in the Mediterranean Sea. This record cannot be treated as a new non-indigenous species for the Italian coasts yet, as there are no extensive studies on the distribution of the taxon.

Molecular characterization of Lernathropus kroyeri from intensive aquaculture and pathophysiology of infested sea bass

The copepod Lernathropus kroyeri constitutes one of the major parasites for the Mediterranean aquaculture, infesting the sea bass Dicentrarchus labrax causing thus disruptions of growth performance and occasionally mortalities. Despite the large spread and the high frequency of this parasite in mariculture farms of Eastern Mediterranean, L. kroyeri genetic profile from aquaculture as well as the pathophysiological response of D. labrax have not been studied so far. Keeping this in mind, in the present study we investigated the L. kroyeri infestation on D. labrax from two farms in Greece, examining both healthy and heavy parasitized individuals. Assays included histopathology, phylogenetic reconstruction of the parasite and physiological response of the fish by the means of antioxidant, inflammatory metabolic and stress related gene expression analysis at both mRNA and protein levels. Genetic analysis indicated that L. kroyeri composes a monophyletic group, highly phylogenetically distant from other congeneric groups. Heavy infested D. labrax witnessed a significantly increased immune response that further led to oxidative stress and metabolic alterations. Overall, our results demonstrate the, seasonally independent, high infestation of this parasitic copepods, which continue to affect Mediterranean intensive aquaculture systems.

A new species of Sarcotaces (Copepoda: Cyclopoida: Philichthyidae) from Antimora rostrata (Actinopterygii: Gadiformes: Moridae)

Parasitic copepods of the genus Sarcotaces occur in galls inside the skeletal musculature of fishes. The gall, hosting a highly metamorphosed drop-shaped female contains also a black fluid capable of staining the fish tissues during filleting. Their marine fish hosts are globally distributed and until recently, eight nominal species have been described from fish hosts representing eight fish families. Females are quite similar in their morphology, therefore the males are used for the species determination. The aim of this study was to provide a detailed morphological characterization of the Sarcotaces specimens found in muscles of the blue antimora, Antimora rostrata (Günther, 1878) originating from deep open waters of the Atlantic. The present paper describes and illustrates Sarcotaces antimorisp. nov. The new species differs from its congeners in the shape of the cephalothorax, relative proportions and structure of the caudal rami, and in the setal formula of the antennulae of the male.

Two New Genera and Species of the Parasitic Copepod Family Chondracanthidae Milne Edwards, 1840 (Copepoda: Cyclopoida) from Deep-Sea Fishes Off Suruga Bay, Japan

PurposeThe present paper describes two new genera and species of the parasitic copepod family Chondracanthidae Milne Edwards, 1840 based on specimens collected from two species of deep-sea fishes at a depth of 212 m off Suruga Bay, Japan. Avatar nishidaigen. et sp. nov. is described from the host fish Chaunax abei Le Danois, 1978 (Chaunacidae). Kokeshioides surugaensisgen. et sp. nov. is described from the host fish Setarches longimanus (Alcock, 1894) (Setarchidae).MethodsFresh specimens of chondracanthids were collected from the buccal cavity of two species of deep-sea fishes (fish hosts were frozen), Chaunax abei Le Danois, 1978 (Lophiiformes: Chaunacidae) and Setarches longimanus (Alcock, 1894) (Perciformes: Setarchidae), caught at a depth of 212 m in Suruga Bay, Japan (34° 37′48.87″ N, 138° 43′2.958″ E). Both the species are described and illustrated based on ovigerous females.ResultsThe genus Avatargen. nov. can readily be distinguished from all other chondracanthid genera by the following combination of features: cephalothorax slightly wider than long with anterior pair of large and posterior pair of small lateral lobes, and two pairs of ventro-lateral processes; the very posteriormost part of the first pedigerous somite contributes to the neck; cylindrical trunk with two pairs of blunt proximal fusiform processes; antennule with small knob terminally; antenna bearing distal endopodal segment; labrum protruding ventrally; two pairs of biramous legs each with 2-segmented rami. Kokeshioidesgen. nov. has the following combinations of features that distinguish it from other chondracanthid genera: body flattened, without lateral processes; cephalothorax much wider than long, with paired anterolateral and posterolateral lobes, folded ventrally; the very posteriormost part of the first pedigerous somite contributes to the neck; mandible elongate; legs unique, heavily sclerotized, represented by two pairs of acutely pointed processes.ConclusionWith the addition of two new genera presently reported, the family Chondracanthidae currently includes 52 valid genera. Among the described genera Avatargen. nov. seems to be very primitive, while Kokeshioidesgen. nov. is highly advanced. The deduced evolutionary history of chondracanthid genera is also discussed.

Systematic Status of Copepods Infecting the Rosy Goatfish (Parupeneus rubescens)

Fish represent one of the most important sources of protein. All fish species are vulnerable to great hazards due to infection with various parasitic taxa and other disease agents. The rosy goatfish (Parupeneus rubescens) is one of the most widely distributed and edible species. Little information about the copepod parasites infecting this fish remains. This review included all related published scientific articles in the electronic databases NCBI, ScienceDirect, Saudi digital library and GenBank database. Relevant studies were reviewed through the generic features and molecular analysis of copepods. Parasitologists use many scientific tools to classify copepods and the morphological and morphometric levels are a basic key to identifying copepods. The presence of many copepod species makes it difficult to confirm their taxonomic status. Therefore, scientists focused on the molecular tools to identify each copepod species based on nuclear ribosomal genes as markers to discriminate copepodid species. Scientists can confirm the parasite species’ systematic status by combining fundamental and innovative identification tools.

Comprehensive molecular characterisation of the complete mitogenome of Ergasilus tumidus and phylogenetic relationships of Copepoda inferred from mitogenomes.

Although parasitic copepods of the genus Ergasilus von Nordmann, 1832 are globally distributed parasites of fish, their phylogenetic relationships with other Copepoda are not clear, and the characteristics of their mitochondrial genomes (mitogenomes) are not thoroughly understood. The objective of this study was to address these knowledge gaps by sequencing the complete mitogenome of Ergasilus tumidus Markevich, 1940. The complete mitogenome (GenBank Acc. No. OQ596537) was 14,431 bp long and it comprised 13 protein-coding genes (PCGs), 22 tRNAs, two tRNAs, and two control regions (CRs). Phylogenetic analyses, conducted using concatenated nucleotide and amino acid sequences of 13 protein-coding genes, produced two partially incongruent topologies. While the order Calanoida was consistently resolved as the sister lineage to the other three orders, topological instability was observed in the relationships of the orders Cyclopoida, Siphonostomatoida and Harpacticoida. Siphonostomatoida clustered with Cyclopoida in the nucleotide-based phylogeny, but with Harpacticoida in the amino acid-based phylogeny. The latter topology conforms to the widely accepted relationships, but we speculate that the former topology is more likely to be the correct one. Our study provides a complete mitogenome sequence of E. tumidus, which helps us better understand the molecular evolution of the genus Ergasilus. Additionally, we suggest a different perspective on the controversial phylogenetic relationships among Siphonostomatoida, Cyclopoida and Harpacticoida, diverging from previously accepted views.

Ergasilus lyraephorus n. sp. (Copepoda: Cyclopoida: Ergasilidae) parasitic on the Longtail Knifefish Sternopygus macrurus (Bloch & Schneider, 1801) (Actinopterygii: Sternopygidae) from Northeast Brazil.

The cyclopoid family Ergasilidae Burmeister, 1835, is the most common group of parasitic copepods infesting fish in Brazil, and the type-genus Ergasilus von Nordmann, 1832 comprises the highest number of species. During a survey of freshwater fish in Northeast Brazil, a new species of Ergasilus was found on the gills of the Longtail Knifefish Sternopygus macrurus (Bloch & Schneider) (Actinopterygii: Sternopygidae) in the Viana lake system, State of Maranhão. Ergasilus lyraephorus n. sp. can be distinguished from its closest congeners mainly because it has a lyre-shaped ornamentation on the ventral surface of first pedigerous somite, a feature that has never been reported in the family. In addition, the new species differs from closely related congeners by having a maxillule bearing three elements, by the large spinules on the interpodal plates of legs 1, 2 and 3, and by having leg 5 reduced to a single seta of moderate size. The present study is the first report of an ergasilid parasitizing S. macrurus, as well as the first parasitic copepod found on a host belonging to the family Sternopygidae Cope.