Parasitic Crustaceans Research Articles

The fate of Lernaeocera branchialis (L.) (Crustacea; Copepoda) in Atlantic cod, Gadus morhua L.

Lernaeocera branchialis, a copepod crustacean parasite of gadoids, represents a potential threat to both wild and farmed cod, Gadus morhua. The pathological changes associated with the early stages of experimental infection have previously been reported in detail, and this article describes the lesions associated with later chronic stages of experimental infection. Chronic infection is characterised by extravascular granuloma formation and proliferation of fibrovascular tissue around intact and fragmented, degenerate parasites within both the gill arch and cardiac region. The majority of parasite granulomas are located within connective tissues of the gill arch or pericardium; however, low numbers are present within the wall of large vessels. The intraluminal parasites and thrombi of early stage infection are largely absent in these later lesions. We propose that organisation and incorporation of the parasite thrombus into the vessel wall with subsequent granuloma formation and extrusion into the surrounding connective tissue leads to the elimination of the parasite from the vascular system. Thus, rather than being a negative consequence of infection thrombosis is protective, allowing the host to survive the substantial initial vascular insult.

The relationship between Feeding type and exposure to infection with some Ectoparasites of Marmarij Mastacembelus mastacebelus in Baghdad

40 Mmermrij fish Mastacembelus mastacebelus were collected from different areas in Baghdad , a total of 20 fish from each area; the first 20 from area near a Al Muthanna bridge, and the second from the old Diyala bridge. stomach contents Were taken from these fish and analyzed by the Gel electrophoresis device results showed abandunce of food protein of animal origin, which was identified with the food samples taken from the real environment of these fish. Also two types of parasitic crustaceans were identified which are considered the most common external parasites infected fish ; these were Leranea worms, type Learnea cyprinacea, and fish lice Argulus, type Argulus foliaceus, this is with respect to Almmermrij fish taken from Al Muthanna bridge region.As for the fish brought from the Jisr Diyala area; they were infected by Leranea and free of infection with Argulus , and the severity of infection with Learnea was lower than the first. which shows the disparity of the spread of parasitic crustaceans on fish in both areas because of the different environments and speed of the flow of water in addition to the different seasons of fishing in these two regions.

Parasitic crustaceans influence social relations in fish

Parasitic crustaceans influence social relations in fish

Shallow water Cirripedia of the northeastern coast of Brazil: The impact of life history and invasion on biogeography

This paper reports on shallow water barnacles listed in inventories carried out by several authors and collected from the northeastern coast of Brazil; it pays particular attention to commensal species and their hosts, as well as their dispersive ocean pathways. The 53 barnacles found were grouped together and classified as non-symbiont (28 species) and symbiont species (25); host type (sponges, corals, crustaceans, turtles and other fortuitous associations) was used to group them. Obligate symbionts included four crustacean parasites and 19 commensals, in addition to six other species reported in two or more animal groups as facultative or incidental commensals. The barnacles' geographic distribution was discussed in relation to anthropogenic pathways of dispersion and close relationships with hosts, in the case of obligate commensals. The species are predominantly cosmopolitan (39.6%), but the distribution of 35.8% is restricted to the Western Atlantic Ocean. The geographic distribution of some species was extended northward or southward, mainly for those that had been observed associated with vessel hulls. Additionally, the bathymetric limits of occurrence of some other species have been modified.

Harmful parasitic crustaceans infecting wild arripids: A potential threat to southern Australian finfish aquaculture

Parasitic crustaceans are responsible for severe disease outbreaks in finfish aquaculture. We provide the first report of five marine ectoparasitic crustacean species including Argulus diversicolor Byrnes, 1985 (Branchiura: Argulidae), Caligus bonito Wilson, 1905, C. longipedis Bassett-Smith, 1898, C. pelamydis Hewitt, 1963, and C. punctatus Shiino, 1955 (Copepoda: Caligidae) on wild arripid hosts, Arripis georgianus (Valenciennes, 1841), A. trutta (Forster, 1801) and A. truttaceus (Cuvier, 1829) (Perciformes: Arripidae) in southern Australian waters. Caligus pelamydis and C. punctatus are new Australian records. All five crustacean species exhibit low host-specificity and Argulus spp., C. longipedis, C. pelamydis and C. punctatus have been associated with mass mortalities in cultured fishes outside Australia. Given the propensity for arripids to aggregate at sea-cage aquaculture sites, awareness of these five parasitic crustacean species may allow health managers to identify and anticipate potential outbreaks on southern Australian fish farms.

A record of a crustacean parasite Argulus matuii (Branchiura: Argulidae) in finfish mariculture in Japan

Four specimens of crustacean parasite were collected from the caudal fin and caudal peduncle of a bastard halibut Paralichthys olivaceus (Temminck and Schlegel) cultured in Saiki Bay, the western Bungo Channel (western North Pacific), off Shirahama, Oh-nyu Island, Saiki, Oita Prefecture, Japan in June 1992. The specimens were lost but one of them was identified as the argulid branchiuran Argulus matuii Sikama, 1938, based on its morphological characters recorded on a photograph of the whole body. This finding represents the first record of A. matuii from farmed marine fishes. P. olivaceus is a new host for A. matuii. A total of 8,165 specimens belonging to 57 species of marine fishes cultured in coastal waters of Oita Prefecture were examined for parasitic diseases for 18 years from 1980-1997, but only three cases of argulid infection, including the present case, were found, indicating that argulids are very rare parasites in finfish mariculture in this prefecture.

Parasitic castration: the evolution and ecology of body snatchers

Castration is a response to the tradeoff between consumption and longevity faced by parasites. Common parasitic castrators include larval trematodes in snails, and isopod and barnacle parasites of crustaceans. The infected host (with its many unique properties) is the extended phenotype of the parasitic castrator. Because an individual parasitic castrator can usurp all the reproductive energy from a host, and that energy is limited, intra- and interspecific competition among castrators is generally intense. These parasites can be abundant and can substantially depress host density. Host populations subject to high rates of parasitic castration appear to respond by maturing more rapidly.

The crustacean parasites Ellobiopsis Caullery, 1910 and Thalassomyces Niezabitowski, 1913 form a monophyletic divergent clade within the Alveolata

The Ellobiopsidae are enigmatic parasites of crustaceans that have been grouped together exclusively on the basis of morphological similarities. Ultrastructural studies have revealed their affiliation within the alveolates, which was confirmed by the phylogenetic analysis of the ribosomal RNA gene (SSU rDNA) sequences of two species of Thalassomyces Niezabitowski, 1913. However, their precise systematic position within this group remains unresolved, since they could not be definitively allied with any particular alveolate group. To better determine the systematic position of ellobiopsids by molecular phylogeny, we sequenced the SSU rDNA from the type-species of the Ellobiopsidae, Ellobiopsis chattoni Caullery, 1910. We found E. chattoni infecting various copepod hosts, Acartia clausi Giesbrecht, Centropages typicus Kröyer and Clausocalanus sp., in the Bay of Marseille, NW Mediterranean Sea, which allowed us to study several stages of the parasite development. A single unicellular multinucleate specimen provided two different sequences of the SSU rDNA gene, indicating the existence of polymorphism at this locus within single individuals. Ellobiopsis Caullery, 1910 and Thalassomyces formed a very divergent and well-supported clade in phylogenetic analyses. This clade appears to be more closely related to the dinoflagellates (including the Syndiniales/Marine Alveolate Group II and the Dinokaryota) and Marine Alveolate Group I than to the other alveolates (Ciliophora, Perkinsozoa and Apicomplexa).

Using length-frequency data to elucidate the population dynamics ofArgulus foliaceus(Crustacea: Branchiura)

This study uses a novel method for discriminating cohorts and investigating the population dynamics of the parasitic crustacean, Argulus foliaceus. Analysis of parasite length-frequency data was carried out in order to elucidate the timings and drivers behind the parasite's life cycle. Up to 6 cohorts of the parasite emerge through the course of 1 year in still-water trout fisheries in England. Recruitment ceases over the winter months; however, 3 cohorts of the parasite over-winter, 2 as eggs and 1 as a hatched stage. The technique, when used in conjunction with temperature data, also allowed for the reliable prediction of growth rates and provided estimates of egg incubation times and the length of hatching periods. These data showed that growth rates increased exponentially between the observed temperatures of 4 to 22 degrees C. The method allowed for the time taken from hatching to egg laying under field conditions to be predicted and produced estimates that were validated against independent laboratory studies on the growth of the parasite.

Parasitic crustaceans as vectors of viruses, with an emphasis on three penaeid viruses

Parasitic crustaceans serve as both hosts and vectors of viruses as well as of parasites and other microbial pathogenic agents. Few of the presumably numerous associations are known, but many can be anticipated. Recently, branchiurans and gnathiid isopods have been documented to host helminths and blood parasites. Because the agents can be observed readily with a microscope, these are better recognized than are the smaller viral, bacterial, and fungal agents. Some agents are harmful to the host of the crustacean parasite and others are not. Viruses probably fit both these categories, since viruses that do not appear pathogenic are often seen in ultrastructural images from a range of invertebrate hosts, including crustaceans. Some viruses have been implicated in causing disease in the host, at least under appropriate conditions. For example, lymphocystis virus may possibly be transmitted to the dermis of its fish hosts by copepods and to the visceral organs by a cymothoid isopod. Similarly, argulid branchiurans seem to transmit the viral agent of spring viremia of carp as well as carp pox, and copepods have been implicated in transmitting infectious hematopoietic necrosis, infectious salmon anemia, and infectious pancreatic necrosis to salmon. Other viruses can be vectored to their hosts through an additional animal. We exposed three viruses, Taura syndrome virus (TSV), white spot syndrome virus (WSSV), and yellowhead virus (YHV), all of which cause mortalities in wild and cultured penaeid shrimps, to crustacean parasites on fish and crabs. Using real-time polymerase chain reaction analysis, we show that TSV in the cyclopoid copepod Ergasilus manicatus on the gill filaments of the Gulf killifish, Fundulus grandis, the acorn barnacle Chelonibia patula on the carapace of the blue crab, Callinectes sapidus, and gooseneck barnacle Octolasmis muelleri on the gills of C. sapidus, can replicate for at least 2 weeks and establish what should be an infective dose. This result was additionally supported by positive in situ hybridization reactions. All three parasites are the first known non-penaeid hosts in which replication occurs. The mean log copy number of WSSV also suggested that replication occurred in E. manicatus. The mean log copy number of YHV gradually decreased in all three parasites and both hosts over the 2-week period. The vector relationships indicate an additional potential means of transmitting and disseminating the disease-causing agents to the highly susceptible and economically valuable penaeid shrimp hosts.

Introduction to the first symposium on the biology of the parasitic Crustacea

The parasitic Crustacea represent a diverse group with members in several classes and orders, including the Cirripedia, Isopoda, Amphipoda, Branchiura, Copepoda, Tantulocarida, and Pentastomida. Their biology is as diverse as their morphological and phylogenetic disparity would indicate, and includes egg mimicry, parasitic castration, host feminization, epigametic sex determination, venomous secretions, and bizarre adaptations of the life cycle. However, convergent adaptations to the parasitic lifestyle are common and must be considered when studying the evolution of the organisms, their behaviors, and morphological modifications. Recently, there have been several important papers on the evolution of parasitic crustaceans, but most of these have covered narrow groups, such as the Rhizocephala (e.g. Hoeg 1995, Schram & Hoeg 1995, Hoeg and Lutzen 1996) and the parasitic copepods (e.g. Huys and Boxshall 1991, Ho 2001, Boxshall 2004). Additional papers have highlighted interesting biological attributes of specific parasitic groups, such as polyandry in sea lice (Todd et al. 2005), host preferences, and ecological effects in nicothoid copepods (e.g. Shields et al. 2006 for a review of those on lobsters), and even the effects of climatic warming on species of Argulus (Hakalahti et al. 2006). Such papers have provided new data and new ways of looking at these organisms that give insights into questions about their broader biology. Given the continued interest in the adaptations of parasitic crustaceans, as well as in the effect of these organisms on important aquaculture and fishery species, we organized a symposium at the Society for Comparative and Integrative Biology (SICB) meeting in Boston for 2009, to provide a reference point for broader discussions on the topic. The symposium was structured with topics in evolution, life history, molecular biology, and pathology. As far as we know, there have been no other symposia devoted entirely to the parasitic Crustacea; thus, the First Symposium on the Biology of the Parasitic Crustacea was held at the SICB Annual Meeting, in Boston, January 4–5, 2009. However, it is important to note that there have been several specialized symposia on diseases of Crustacea (Symposium on Diseases of Commercially Significant Crustaceans, International Crustacean Conference VI, Glasgow, 2005; The Biology of the Rhizocephala, The Crustacean Society Annual Meeting, Williamsburg, 2003; Diseases of Crustacea, National Shellfisheries Association Annual Meeting, Mystic, 2002; as well as several on viral infections in shrimp) and a few symposia on specific taxonomic groups such as the parasitic copepods of fishes (e.g. Symposium on the Parasites of Fishes and Other Aquatic Organisms, IX European Multi-colloquium of Parasitology, Valencia, 2004; V International Symposium on Fish Parasites, Ceske Budějovice, 1999; Sea lice and Other Parasitic Copepoda, 1st European Crustacean Conference, Paris, 1992). Hence, our attempt to encompass a broader view of parasitism across the Crustacea was timely and provided an opportunity for experts in diverse taxa to compare and contrast questions broadly between systems. The program for the symposium was organized around different taxonomic groups. There were 11 primary papers in the symposium and five in a complementary session. Several of the papers were reviews of the existing literature. The papers given were:

ABC transporters in the Daphnia pulex genome: Implications for ecotoxicology and drug resistance in crustacean parasites

ABC transporters in the Daphnia pulex genome: Implications for ecotoxicology and drug resistance in crustacean parasites

Desmozoon lepeophtherii n. gen., n. sp., (Microsporidia: Enterocytozoonidae) infecting the salmon louse Lepeophtheirus salmonis (Copepoda: Caligidae).

BackgroundA microsporidian was previously reported to infect the crustacean parasite, Lepeophtheirus salmonis (Krøyer, 1837) (Copepoda, Caligidae), on farmed Atlantic salmon (Salmo salar L.) in Scotland. The microsporidian was shown to be a novel species with a molecular phylogenetic relationship to Nucleospora (Enterocytozoonidae), but the original report did not assign it to a genus or species. Further studies examined the development of the microsporidian in L. salmonis using electron microscopy and re-evaluated the molecular findings using new sequence data available for the group. Here we report a full description for the microsporidian and assign it to a new genus and species.ResultsThe microsporidian infects subcuticular cells that lie on the innermost region of the epidermal tissue layer beneath the cuticle and along the internal haemocoelic divisions. The mature spores are sub-spherical with a single nucleus and an isofilar polar filament with 5-8 turns in a double coil. The entire development is in direct contact with the host cell cytoplasm and is polysporous. During early merogony, a diplokaryotic nuclear arrangement exists which is absent throughout the rest of the developmental cycle. Large merogonial plasmodia form which divide to form single uninucleate sporonts. Sporogonial plasmodia were not observed; instead, binucleate sporonts divide to form two sporoblasts. Prior to final division, there is a precocious development of the polar filament extrusion apparatus which is associated with large electron lucent inclusions (ELIs). Analyses of DNA sequences reveal that the microsporidian is robustly supported in a clade with other members of the Enterocytozoonidae and confirms a close phylogenetic relationship with Nucleospora.ConclusionThe ultrastructural findings of the precocious development of the polar filament and the presence of ELIs are consistent with those of the Enterocytozoonidae. However, the confirmed presence of an early diplokaryotic stage and a merogonial plasmodium that divides to yield uninucleate sporonts instead of transforming into a sporogonial syncitium, are features not currently associated with the family. Yet, analyses of DNA sequence data clearly place the microsporidian within the Enterocytozoonidae. Therefore, due to the novelty of the copepod host, the ultrastructural findings and the robust nature of the phylogenetic analyses, a new genus should be created within the Enterocytozoonide; Desmozoon lepeophtherii n. gen. n. sp. is proposed.

Tropical Veterinary Parasites at Harvard University's Museum of Comparative Zoology

Tropical veterinary parasites have been maintained by the Museum of Comparative Zoology (MCZ) at Harvard University since the mid 1800s. Most of these are maintained by the Department of Invertebrate Zoology, but many vectors and intermediate hosts are maintained by the Departments of Entomology and Malacology. The largest collections are of avian and mammalian ticks (Acarina) that are important as both parasites and vectors. Nematodes are second in numbers, followed by cestodes, trematodes, and several minor helminth groups, crustacean parasites of fish, and protozoan parasites of various hosts. The MCZ directed or participated in several major expeditions to tropical areas around the globe in the early 1900s. Many of these expeditions focused on human parasites, but hundreds of veterinary and zoonotic parasites were also collected from these and numerous, smaller, tropical expeditions. Host sources include companion animals, livestock, laboratory species, domestic fowl, reptiles, amphibians, exotics/zoo animals, commercially important fishes, and other wildlife. Specimens are curated, either fixed whole in vials or mounted on slides as whole mounts or histopathological sections. The primary emphasis of MCZ's current work with tropical veterinary parasites is on voucher specimens from epidemiological, experimental, and clinical research.

Detection and Discovery of Crustacean Parasites in Blue Crabs ( Callinectes sapidus ) by Using 18S rRNA Gene-Targeted Denaturing High-Performance Liquid Chromatography

Recently, we described a novel denaturing high-performance liquid chromatography (DHPLC) approach useful for initial detection and identification of crustacean parasites. Because this approach utilizes general primers targeted to conserved regions of the 18S rRNA gene, a priori genetic sequence information on eukaryotic parasites is not required. This distinction provides a significant advantage over specifically targeted PCR assays that do not allow for the detection of unknown or unsuspected parasites. However, initial field evaluations of the DHPLC assay suggested that because of PCR-biased amplification of dominant host genes it was not possible to detect relatively rare parasite genes in infected crab tissue. Here, we describe the use of a peptide nucleic acid (PNA) PCR hybridization blocking probe in association with DHPLC (PNA-PCR DHPLC) to overcome inherent PCR bias associated with amplification of rare target genes by use of generic primers. This approach was utilized to detect infection of blue crabs (Callinectes sapidus) by the parasitic dinoflagellate Hematodinium sp. Evaluation of 76 crabs caught in Wassaw Sound, GA, indicated a 97% correspondence between detection of the parasite by use of a specific PCR diagnostic assay and that by use of PNA-PCR DHPLC. During these studies, we discovered one crab with an association with a previously undescribed protist symbiont. Phylogenetic analysis of the amplified symbiont 18S rRNA gene indicated that it is most closely related to the free-living kinetoplastid parasite Procryptobia sorokini. To our knowledge, this is the first report of this parasite group in a decapod crab and of this organism exhibiting a presumably parasitic life history.

Investigations of Internal Interactions between the Parasitic Barnacle Loxothylacus texanus (Rhizocephala: Sacculinidae) and Its Host Callinectes sapidus (Brachyura: Portunidae) using PCR Techniques

We describe techniques that enable the preservation of tissues from the rhizocephalan barnacle, Loxothylacus texanus, inside the body cavities of blue crab hosts, Callinectes sapidus, in a manner that minimizes the degradative activities of hepatopancreatic enzymes. These procedures allow the extraction and amplification of both parasite and host 18S rDNA within the same sample and enable one to distinguish between parasitized and unparasitized crab tissue in as little as two weeks after infection, well before any external manifestations of the parasites. Two PCR-based approaches were taken to identify the presence of L. texanus. In the first approach, a set of primers specific for L. texanus was used to specifically amplify 18S sequence in a background of C. sapidus DNA or the DNA of other barnacle species. In the second approach, a set of general primers was used to amplify 18S sequence from C. sapidus and a variety of barnacle species. The products of this PCR were then digested with an enzyme that recognizes a restriction site present only in the L. texanus PCR product to yield a unique pattern of fragments. With these techniques, we could detect as few as five parasitic cypris larvae in water samples, as well as L. texanus in the tissue of a small crab collected from the field and in the four anterior periopods of a crab bearing the external stage of the parasite. In experiments with potential hosts of varying sizes and molt stages, we confirmed that the parasite was significantly more effective in infecting crabs less than 30 mm carapace width than larger individuals. These techniques will facilitate future investigations of ecological and physiological interactions between these important crustacean parasites and their hosts and will help to determine the economic impact of this parasite on blue crab fisheries.

A checklist of macroparasites of Liza haematocheila (Temminck & Schlegel) (Teleostei: Mugilidae)

BackgroundThe mugilid fish Liza haematocheila (syn. Mugil soiuy), native to the Western North Pacific, provides opportunities to examine the changes of its parasite fauna after its translocation to the Sea of Azov and subsequent establishment in the Black Sea. However, the information on macroparasites of this host in both ranges of its current distribution comes from isolated studies published in difficult-to-access literature sources.Materials and methodsData from 53 publications, predominantly in Chinese, Russian and Ukrainian, were compiled from an extensive search of the literature and the Host-Parasite Database maintained up to 2005 at the Natural History Museum, London.ResultsThe complete checklist of the metazoan parasites of L. haematocheila throughout its distributional range comprises summarised information for 69 nominal species of helminth and ectoparasitic crustacean parasites, from 45 genera and 27 families (370 host-parasite records in total) and includes the name of the parasite species, the area/locality of the host capture, and the author and date of the published record. The taxonomy is updated and the validity of the records and synonymies are critically evaluated. A comparison of the parasite faunas based on the records in the native and introduced/invasive range of L. haematocheila suggests that a large number of parasite species was 'lost' in the new distributional range whereas an even greater number was 'gained'.ConclusionAlthough the present checklist provides information that will facilitate future studies, the interesting question of macroparasite faunal diversity in L. haematocheila in its natural and introduced/invasive ranges cannot be dealt with the current data because of unreliability associated with the large number of non-documented and questionable records. This stresses the importance of data quality analysis in using host-parasite database and checklist data.

Investigations of Internal Interactions between the Parasitic Barnacle Loxothylacus Texanus (Rhizocephala: Sacculinidae) and Its Host Callinectes Sapidus (Brachyura: Portunidae) Using PCR Techniques

We describe techniques that enable the preservation of tissues from the rhizocephalan barnacle, Loxothylacus texanus, inside the body cavities of blue crab hosts, Callinectes sapidus, in a manner that minimizes the degradative activities of hepatopancreatic enzymes. These procedures allow the extraction and amplification of both parasite and host 18S rDNA within the same sample and enable one to distinguish between parasitized and unparasitized crab tissue in as little as two weeks after infection, well before any external manifestations of the parasites. Two PCR-based approaches were taken to identify the presence of L. texanus. In the first approach, a set of primers specific for L. texanus was used to specifically amplify 18S sequence in a background of C. sapidus DNA or the DNA of other barnacle species. In the second approach, a set of general primers was used to amplify 18S sequence from C. sapidus and a variety of barnacle species. The products of this PCR were then digested with an enzyme that recognizes a restriction site present only in the L. texanus PCR product to yield a unique pattern of fragments. With these techniques, we could detect as few as five parasitic cypris larvae in water samples, as well as L. texanus in the tissue of a small crab collected from the field and in the four anterior periopods of a crab bearing the external stage of the parasite. In experiments with potential hosts of varying sizes and molt stages, we confirmed that the parasite was significantly more effective in infecting crabs less than 30 mm carapace width than larger individuals. These techniques will facilitate future investigations of ecological and physiological interactions between these important crustacean parasites and their hosts and will help to determine the economic impact of this parasite on blue crab fisheries.

Temporal partitioning: dynamics of alternating occupancy of a host microhabitat by two different crustacean parasites

Double infection by 2 crustacean parasites was found on the mysid Siriella okadai collected from the Seto Inland Sea, Japan. An epicaridean isopod, Prodajus curviabdominalis, and a siphonostom- atoid copepod, Neomysidion rahotsu, both occupied the lumen of the host marsupium, and fed vora- ciously upon host eggs. Interestingly, adult females of these 2 parasites occurred alternately on the host, with almost no overlap: the copepod occurred from mid-winter to summer when water temperatures were <20°C (with mean prevalence of 7.2%), whereas the isopod occurred exclusively from mid- summer to late autumn when water temperatures exceeded 20°C (with mean prevalence of 9.1%). Pos- sible factors responsible for generating and maintaining this alternation of microhabitat occupancy on the host are discussed on the basis of the life cycles and host-specificities of the 2 parasites. In addition, we explored the possible means by which these obligate parasites survive during the periods when they are not on the mysid host. In the case of the isopod, we hypothesise that survival away from the mysid host involves the utilisation of an intermediate host by an as yet undiscovered microniscus larva, as in other epicarideans. For the copepod, we considered the available evidence in support of a number of hy- potheses. A new pattern of behaviour, unique within the copepod family Nicothoidae, was discovered in N. rahotsu. After the infective female copepodid stage attached to the host, it moulted into an imma- ture female and penetrated the host tissue. It then migrated internally, typically through the dorsal trunk musculature of the host, finally emerging into the host marsupium. This behaviour was observed exclu- sively during the season when copepods occurred within the marsupium. We inferred that this internal migration behaviour in some ways facilitates the synchronisation of the parasite life cycle with the oviposition by the host into the marsupium. It remains uncertain how and where N. rahotsu passes the exclusive occurence of P. curviabdominalis.

Crustacean fish parasites from Segara Anakan Lagoon, Java, Indonesia

The present study is the first investigation on ectoparasites of commercial important fish from Segara Anakan, a brackish water lagoon located at the southern coast of Java, Indonesia. Eight economically important marine fish species (Mugil cephalus, Siganus javus, Scatophagus argus, Caranx sexfasciatus, Lutjanus johnii, Eleutheronema tetradactylum, Johnius coitor, and Epinephelus coioides) were examined for crustacean parasites. Prevalence and intensity data for each parasite species are given, together with an analysis of the origin and possible transmission pathways. A highly divers copepod fauna consisting of 23 different species and two isopods was found. All fish species were at least infested with two copepod species, with the exception of L. johnii, S. argus, and M. cephalus. With seven and six species, respectively, they harboured the most species-rich ectoparasite fauna. The copepods Ergasilus sp. 3 and Caligus acanthopagri on S. argus showed the highest prevalence (78.6) and intensity [17.8 (1-233) and 5.3 (1-22)] of infestation. The recorded parasite fauna is represented by marine, brackish water, and probably also freshwater components. The brackish water environment of Segara Anakan does not prevent disease outbreaks due to parasitic copepods by preventing pathogenic marine or freshwater species to enter the lagoon. This might cause fish health problems if the Segara Anakan Lagoon would be developed for finfish mariculture in future.