Copepod Mytilicola Intestinalis Research Articles

Mikrocytos mytilicoli n.sp. (Cercozoa, Mikrocytida, Mikrocytiidae) infecting the copepod Mytilicola intestinalis (Arthropoda, Cyclopoida, Mytilicolidae), a symbiont of Mytilus galloprovincialis in Galicia (NW Spain)

During a histopathological survey of Mytilus galloprovincialis in Galicia (NW Spain), microcells were observed infecting several organs of the symbiont copepod Mytilicola intestinalis. Positive results of PCR assay with specific primers for genus Mikrocytos and a clear signal of in situ hybridization with MACKINI-1 digoxigenin- labelled DNA probe (DIG-ISH) indicated a protozoan parasite of Mikrocytos genus. The ultrastructural study revealed intra and extracellular locations, polymorphic nuclei, intracellular round vesicles in the cytoplasm and absence of mitochondria. The present paper reports the characterization of the Mikrocytos sp. infecting M. intestinalis and proposes a novel species in the genus: Mikrocytos mytilicoli n. sp. A sequence of 18S-28S rDNA was obtained with 95.6% maximum identity (query cover 100%) with Mikrocytos mackini. Phylogenetic analysis showed that M. mytilicoli n. sp. and M. mackini share a common ancestor. However, comparison of the ITS1 rDNA region showed low similarity (75.8%) with M. mackini, which, combined with differences in ultrastructural details, host and geographic location, support the designation of a new species. This is the first description of a microcytid parasite of the genus Mikrocytos from a non-bivalve host.

An Evolutionary Perspective of Dopachrome Tautomerase Enzymes in Metazoans.

Melanin plays a pivotal role in the cellular processes of several metazoans. The final step of the enzymically-regulated melanin biogenesis is the conversion of dopachrome into dihydroxyindoles, a reaction catalyzed by a class of enzymes called dopachrome tautomerases. We traced dopachrome tautomerase (DCT) and dopachrome converting enzyme (DCE) genes throughout metazoans and we could show that only one class is present in most of the phyla. While DCTs are typically found in deuterostomes, DCEs are present in several protostome phyla, including arthropods and mollusks. The respective DCEs belong to the yellow gene family, previously reported to be taxonomically restricted to insects, bacteria and fungi. Mining genomic and transcriptomic data of metazoans, we updated the distribution of DCE/yellow genes, demonstrating their presence and active expression in most of the lophotrochozoan phyla as well as in copepods (Crustacea). We have traced one intronless DCE/yellow gene through most of the analyzed lophotrochozoan genomes and we could show that it was subjected to genomic diversification in some species, while it is conserved in other species. DCE/yellow was expressed in most phyla, although it showed tissue specific expression patterns. In the parasitic copepod Mytilicola intestinalis DCE/yellow even belonged to the 100 most expressed genes. Both tissue specificity and high expression suggests that diverse functions of this gene family also evolved in other phyla apart from insects.

Infection by invasive parasites increases susceptibility of native hosts to secondary infection via modulation of cellular immunity.

Parasite spillover from invasive aliens to native species increases the risk of disease emergence within native biota-either by direct harm to the new host or by indirect effects like increased risks of secondary infection. One example for such a detrimental effect is the parasitic copepod Mytilicola intestinalis that infected blue mussels Mytilus edulis after being introduced into the North Sea in the early 20th century. Since 1949, the parasite was blamed for multiple mass mortalities of infested blue mussels but evidence for a direct causal involvement of M.intestinalis remained circumstantial. Here, we now examine the potential effects of primary infections by the invasive parasite on the susceptibility to secondary infections with virulent bacteria (Vibrio spp.) in a full factorial infection experiment combining parasite infection (control vs. infected) with different Vibrio infection treatments (control, bath challenge, injection) in environmental conditions that either favoured the host (ambient temperature) or the bacterium (elevated temperature). The influence of primary and secondary infections on cellular immunity (phagocytosis) and Vibrio load in the haemolymph was used to correlate these results to host survival. Our results suggest that the rate of secondary Vibrio infection is increased due to lower efficiency of the cellular immune response. As a consequence, the failure of clearing Vibrio from the haemolymph might increase mortality of mussels infected by M.intestinalis. This demonstrates that indirect effects of parasite invasions can outweigh direct effects of the infection highlighting the need for a more integrative approach to understand and predict the consequences of parasite invasions.

Histopathology of mussels ( Mytilus sp.) from the Tamar estuary, UK

This study assessed numerous histological parameters as markers of health status in mussels ( Mytilus spp.) collected from several locations along a contamination gradient on the River Tamar and two coastal sites on the north and south coast of Cornwall, UK. Twenty-seven health parameters were assessed including the presence of pathogens, inflammatory lesions, non-specific pathologies and reproductive condition. Logistic regression showed that reproductive condition and inflammatory lesions showed changes indicative of a contamination gradient response. Mussel populations further upstream within the Tamar were relatively less developed compared to mussels situated downstream in the estuary. Compared to coastal locations, mussels sampled within the Tamar also exhibited a higher prevalence of inflammatory lesions that increased at locations situated furthest upstream. Similarly, levels of lipofuscin within the kidney epithelium were highest in mussels sampled within the estuary and Whitsand Bay compared to Trebarwith Strand. The most prevalent pathogens observed during this survey included Rickettsia/ Chlamydia-like organisms (R/CLO), gill ciliates including Ancistrum mytili, the copepod Mytilicola intestinalis, Ciliophora-like organisms and Marteilia sp. Marteilia sp. was observed in 31% of the mussels sampled from the Cremyll Ferry site. Generally, the range and prevalence of pathogens was highest from the two estuarine locations at Cremyll Ferry and Wilcove. No significant differences were observed between estuarine sampling sites and Whitsand Bay with respect to median epithelial cell height of digestive tubules, however mussels from Trebarwith Strand did exhibit a reduced median epithelial cell height compared to mussels sampled from other sampling sites. Species genotyping was also undertaken during this study in order to consider any histological differences in relation to species. Results are discussed in relation to histopathology health parameters and biological effects monitoring.

Histopathological lesions of molluscs in the harbour of Norderney, Lower Saxony, North Sea (Germany)

During a combined research project at several stations along the Lower Saxony coast (German North Sea) antifouling biocides were analysed in water, sediment and biota. Pathological alterations in blue mussel, Pacific oyster and periwinkle found in the harbour of Norderney and a reference station are presented here and discussed on the background of chemical analyses. The molluscan species from the reference station Borkum East flat did not show any pathological effects in central organs, except those provoked by an infestation in the gastro-intestinal tract by the copepod Mytilicola intestinalis and trematode larvae. In most animals, the metacercaria were found in the interstitial tissue without any inflammatory reaction. In a minor number of specimens, an inflammatory reaction in the mucosa and sub-mucosa of the intestine occurred in association with Mytilicola infestation. These reactions may be evoked through mechanical irritation of the gut epithelium, metabolic products of the parasites or invading bacteria. In contrast to the observed pathological changes of mussels, oysters and periwinkles in Norderney harbour were not found to be associated with parasitic infestation. The most prominent pathological alterations were observed in the digestive system and in the gonad. In the gastro-intestinal tract inflammatory reactions, atrophy and necrosis of tubules in the mid gut gland were most pronounced in spring at the beginning of the pleasure boat season in the Pacific oyster and to a minor degree in the blue mussel and the periwinkle. The latter displayed additional inflammatory and necrotic processes in the gills. Especially in the gonad, an elevated resorption rate of gametes was present in the Pacific oyster and in the periwinkle. In addition, impact of organotin compounds was reflected in an intersex index of up to 1.4 in Littorina littorea in coincidence with masculinization of the reproductive organs.

Diversity of metazoan parasites of the introduced oyster species Crassostrea gigas in the Exe Estuary

Temporal patterns in metazoan parasite community diversity of Crassostrea gigas, (Lamellibranchia: Ostreidae) were studied in the Exe Estuary at monthly intervals over one year and in relation to host age-classes. A total of four metazoan species was found to parasitize C. gigas in the Exe Estuary: the turbellarian Paravortex sp., cercaria Lepocreadiidae, metacercariae of Renicola roscovita and the copepod Mytilicola intestinalis. Only R. roscovita and M. intestinalis were present in all months throughout the year and in all host age-classes. Analysis of the metazoan parasite community at individual host level revealed little variation in community structure with respect to season or host age, as only a slight increase in diversity values was observed during the summer months. However, community diversity does vary from year to year, as shown by comparison between host age group samples in three consecutive years. None of the parasites are specialist to oysters but all appear to be widespread and abundant parasite of other lamellibranch species.

Symbionts and diseases of farmed mussels Mytilus galloprovincialis throughout the culture process in the Rías of Galicia (NW Spain)

DAO Diseases of Aquatic Organisms Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials DAO 31:127-139 (1997) - doi:10.3354/dao031127 Symbionts and diseases of farmed mussels Mytilus galloprovincialis throughout the culture process in the Rías of Galicia (NW Spain) Antonio Villalba, Susana G. Mourelle, María J. Carballal, Carmen López Centro de Investigacións Mariñas, Consellería de Pesca, Marisqueo e Acuicultura, Xunta de Galicia, Aptdo. 13, E-36620 Vilanova de Arousa, Spain None Mediterranean mussels Mytilus galloprovincialis were experimentally cultured from 5 rafts located in 4 Galician Rías, following the established industrial procedure. Cultures were sampled monthly until mussels exceeded market size. Observation of histological sections of sampled mussels by light microscopy demonstrated symbionts which could be classified into 3 groups according to their pathogenicity. The first group consisted of symbionts with unnoticeable pathogenic effects including: prokaryotic inclusion bodies (PIB) in digestive gland and gills, an unidentified protistan in digestive primary ducts, a kidney coccidian, intracytoplasmic ciliates in digestive tubules, gill ciliates and a turbellarian in the intestinal lumen. The second group comprised symbionts that could damage the host, although unlikely to be lethal, including: the microsporidian Steinhausia mytilovum, the flatworm Urastoma cyprinae, and the copepod Mytilicola intestinalis. The third group included the protistan Marteilia refringens and the trematode Proctoeces maculatus, potentially lethal pathogens. In addition, mussels with haemocytic infiltration of tissues and granulocytomas and a few cases of disseminated neoplasia were detected. The qualitative composition of mussel symbiont community was similar at the 5 study sites, except for 3 symbionts which were not detected at some sites. Quantitatively, symbiont loads were higher and histological signs of stress more abundant in Moaña and Vilagarcía (the most inner sites in the Rías), intermediate in Illa de Arousa and Muros, and lower in Lorbé. Symbionts increased in prevalence as mussels grew. Some of the symbionts were detected in mussel seed at the beginning of the experimental cultures. Mytilus galloprovincialis · Symbionts · Parasites · Prokaryota · Protista · Metazoa · Pathological conditions · Neoplasia Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in DAO Vol. 31, No. 2. Publication date: November 20, 1997 Print ISSN:0177-5103; Online ISSN:1616-1580 Copyright © 1997 Inter-Research.

Mussel ( Mytilus edulis) treatment against the red copepod Mytilicola intestinalis

Mytilicola intestinalis, a copepod parasite of the gut of mussels, is endemic along European coasts. It has been responsible for heavy mortalities, especially in Mont Saint-Michel's Bay (Northern Brittany) between 1982 and 1984. From laboratory screening of seven drugs, an organophosphorate Dichlorvos appears to be the most efficient. Dichlorvos treatment for 2 h at 30 mg/l concentration frees mussels from Mytilicola without any mortality. Later field trials showed an equal efficiency if the drug is used properly.

Diseases and parasites of rafted mussels (Mytilus galloprovincialis Lmk): preliminary results

A detailed histopathology-based survey of a total of 330 cultured mussels collected from three locations on mussel rafts in the Ria de Arosa (NW, Spain) was carried out over a 1-year period between 1985 and 1986. The populations were “healthy” at the time of sampling. The commonest parasites found in histology were Rickettsiae (up to 50% of histological samples demonstrated clear “inclusions”), the AscetosporanMarteilia (possiblyM. maurini) (up to 35%), and the “redworm” copepodMytilicola intestinalis (up to 80%). A gill ciliate similar toAncistrum mytili was found on all samples examined, ranging in frequency from 60–95%. Specific host-tissue reponses were detected in association with the plasmodial and spore stages ofMarteilia sp. infections, as well as with ovarian infection by the microsporidian parasiteSteinhausia mytilovum, and there was a marked haemocyte encapsulation response to tissue penetration by a copepod. No tissue responses could be detected in association with the other parasites observed.

Mytilicola Intestinalis (Copepoda: Cyclopoida): A Ten Year Survey of Infested Mussels in a Cornish Estuary, 1978–1988

The progress of the copepod Mytilicola intestinalis Steuer from obscurity in Mediterranean mussels, Mytilus galloprovincialis, to notoriety as the scourge of European blue mussels, M. edulis, has been well documented (e.g. Lauckner, 1983). However, a reputation as a pest in a commercially important species is not easily overturned and operators in the economic sphere must be expected to proceed with circumspection where their livelihoods are.at stake. In the UK, Parliamentary Orders still control the deposition and movements of seed shellfish in the attempt to contain the spread of the copepod.

The susceptibility of seed oysters of Ostrea edulis L. and Crassostrea gigas Thunberg to natural infestation by the copepod Mytilicola intestinalis Steuer

Ostrea edulis and Crassostrea gigas seed of 5–45 mm length were exposed to Mytilicola intestinalis during the main (autumn) infestation season in the Lynher and Teign Estuaries, south-west England. C. gigas proved to be far less susceptible than O. edulis to infestation. In Ostrea edulis the numbers of copepodites acquired during 2 months were positively correlated with host size; no such correlation was apparent with C. gigas. C. gigas smaller than 25 mm were so rarely infested that the risk of them transmitting the parasite is considered to be negligible. Some juvenile parasites overwintered in larger C. gigas but grew more slowly than in O. edulis hosts of similar size and their survival to breed seemed unlikely. O. edulis as small as 5–10 mm acquired parasites but juveniles and adults overwintered only in larger seed (> 35 mm) and with 87% mortality. Female Mytilicola grew to 6 mm by early winter, thus suggesting that breeding can occur in larger seed in spring. O. edulis should be regarded as a potential vector, although the risk may be considered slight with seed smaller than 15 mm.

Enzyme extraction of the parasitic copepod Mytilicola intestinalis Steuer from mussels, Mytilus edulis L.

Enzyme extraction of the parasitic copepod Mytilicola intestinalis Steuer from mussels, Mytilus edulis L.

Seasonal cycles in the carotenoid content in Mytilus edulis

The carotenoid content of Mytilus edulis was studied over a period of 3 years from 1965 to 1967; a seasonal cycle was observed which appeared to be controlled by the spring bloom of phytoplankton, and the sexual cycle of the mussel. Infestation by the copepod Mytilicola intestinalis and hours of exposure in the tidal cycle were found to contribute to variations in carotenoid content. Maturation of the gonads and spawning occurred in the late spring and early summer of the period studied. In addition, a second sexual phase was recorded in October 1967. The possible effect of exposure on the time of spawning is discussed. Lack of food affects both carotenoid content and the maturation of the gonads. M. edulis kept at 10 °C with little food showed no seasonal variation in the carotenoid content when compared with animals fresh from the shore. Lack of food resulted in regression in gonadal tissue after a period of time, and an absence of mature and spawning individuals.

The Influence of Polydora ciliata (Johnst.) on the Degree of Parasitism of Mytilus edulis L. by Mytilicola intestinalis Steuer

Polydora ciliata (Johnst.) is a tubicolous polychaete, generally free-living, but also found burrowing in the shells of molluscs, especially mussels and oysters (Lebour 1907; Wilson 1928). At Whitstable it is abundant both in the London Clay on the beach (Dorsett 1961) and in oyster shells (Newell 1954). The parasitic copepod Mytilicola intestinalis Steuer is widespread in this country (Hepper 1955) and nearly every mussel at Whitstable is infected (Waugh 1954; Williams 1967). During a survey of seasonal variation in the Mytilicola population at Whitstable it was noticed that there appeared to be a relationship between the numbers of copepods inhabiting a mussel and the presence of Polydora. Numbers of copepods found in individual mussels varied tremendously, from nil up to thirty, but when shell valves were grossly affected by the polychaete, numbers of Mytilicola rarely exceeded fifteen and were often below five. It was decided to keep records both of numbers of copepods in a mussel's intestine and of the presence of signs of Polydora activity in its shell, to determine if this observation was statistically significant, and if so, to ascertain the reasons for this phenomenon.

On the Ecology and Distribution of the Parasitic Copepod Mytilicola Intestinalis Steuer

Critical appraisal of the literature data on Mytilicola intestinalis, combined with personal experience in this field, led to formulation of answers on a series of questions re the ecology and distribution of the parasitic copepod Mytilicola intestinalis Steuer. It is confirmed that Mytilicola has been the causative agent in extensive mussel mortalities. The explosion of Mytilicola in several places on the coastlines of North Sea and Atlantic Ocean should be explained in terms of Mytilicola, being a new intruder in these waters. There is no ground for the view that a special set of ecological conditions saw to the explosive development of the autochthonous species Mytilicola intestinalis, normally existing in small numbers only. Mytilicola intestinalis has a wide ecological range in all phases of its life cycle. The number of hosts living in a given volume of water, together with the amount of flushing of that water, is the main factor governing the number of parasites per host. Since two individuals of opposite sex have to meet in the intestinal tract of one and the same host, some scattered pelagic larvae cannot easily lead to establishment of a new focus of infection. Stretches of coast devoid of mussels form an almost unsurmountable barrier against the natural spreading of this parasite. It is usually man, through his multiple activities, who should be held responsible for the invasion of mussel areas previously devoid of Mytilicola intestinalis.