Experimental infections of Orchitophrya stellarum (Scuticociliata) in American blue crabs (Callinectes sapidus) and fiddler crabs (Uca minax) (original) (raw)
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Marine Biology Research - MAR BIOL RES, 2006
Crabs infected by rhizocephalans usually do not moult. Because moulting is the ultimate defence against fouling epibionts, infected as opposed to uninfected crabs can be expected to harbour a diversity of hard-bottom organisms on their cuticula. Here we provide unequivocal evidence that this is the case in the Carcinus maenas ÁSacculina carcini association. In a Danish sample of shore crabs, 75% of sacculinized individuals harboured macroscopic epibionts, whereas only 29% of the uninfected crabs were colonized. The mean numbers of fouling barnacles and serpulid tubeworms per individual were 7.7 and 47.3 for uninfected and infected crabs, respectively, corresponding to coverage of the cuticula by 0.7 and 5.4%. Infected crabs were 12% lower in tissue dry weight than uninfected individuals, which may be a factor causing the moult of sacculinized crabs to be postponed. Finally, a laboratory experiment suggested that infected crabs are less likely to bury than uninfected specimens. Because burying is an important fouling defence, such a parasite-induced behavioural change will favour the colonization by epibionts. It is argued that rhizocephalans infecting crabs from soft-bottom communities may indirectly affect the structure of the free-living benthic community by adding hard-bottom species that otherwise would be absent.
Some histopathological alteration of the infected blue crab Portunus pelagicus with parasites
Egyptian journal of aquatic biology and fisheries, 2020
The blue crabs are valuable sea food of great demand, both in domestic markets and in the export industry. They are intertidal species with low migration that can be found throughout the year (Robert et al., 2014 ; Zairon et al., 2015). P. pelagicus inhabits the Middle eastern coast of Mediterranean sea, Red sea and Suez Canal (Mehanna, 2005 & Mehanna and El-Aiatt, 2011). It lives in sandy mud habitat until shallow water down to 50 m (Fazrul et al., 2015). Vogan et al. (2001) stated that crabs have been known to have parasites that caused histopathological alterations to their organs and tissues. Histology is the standard method for the examination of crab tissues to identify the presence of parasites and their related pathologies (Bojko et al., 2013). ARTICLE INFO ABSTRACT Article History: Received: June 6, 2020 Accepted: July 3, 2020 Online: July 7, 2020 _______________
The blue crab Callinectes sapidus is an invasive alien species in the Mediterranean Sea. In native habitats, it suffers mortalities determined by different pathogens, including viruses, dinoflagellates, and bacteria. In invaded habitats, scant information is available on the occurrence of parasites in blue crabs, and no comparisons have been made with native brachyuran species. Here, a preliminary screening of the hemolymph of C. sapidus hemolymph as well as of three indigenous crabs (Eriphia verrucosa, Carcinus aestuarii and Pachygrapsus marmoratus), captured in the Acquatina Lagoon (Salento Peninsula, SE Italy), evidenced the presence of unidentified protozoans in more than 70% of the analyzed specimens, with a low number of suspected infections due to dinoflagellates of the genus Hematodinium. In C. sapidus, the occurrence of parasites was accompanied by a decrease of hemocyte functionality, interfering with the role of the cells in innate immunity (i.e. phagocytosis or DOPA production). More studies are necessary in order to verify the impact of this alien brachyuran on invaded ecosystems as mediated by the spread of its parasites and other pathogens.
A parasitic scuticociliate infection in the Norway lobster (Nephrops norvegicus)
Journal of Invertebrate Pathology, 2005
A histophagous ciliate infection was discovered in a number of Norway lobsters (Nephrops norvegicus) from the Clyde Sea Area, Scotland. Silver-carbonate staining of cultured ciliates revealed an oral apparatus and additional structural features that are morphologically similar to scuticociliates in the genus Mesanophrys, which are known to parasitize crustaceans. However, ribosomal DNA sequences (ITS1/5.8S/ITS2) of the ciliate were identical to Orchitophyra stellarum, a parasitic scuticociliate of sea stars with a diVerent morphology from Mesanophrys spp. and to the ciliate from N. norvegicus. Associated pathology included degeneration and necrosis of the myocardial heart muscle, and large numbers of ciliates in the gill Wlaments.
Journal of Experimental Marine Biology and Ecology, 2013
Parasites generally influence the feeding behavior of their host and may therefore indirectly impact ecosystem structure and functioning if the host plays an ecological key role. The ecologically important shore crab (Carcinus maenas) is commonly infected by the rhizocephalan parasite Sacculina carcini that aside from inflicting behavioral change, castration and ceased molting, also feminizes its male host morphologically. The latter results in reduced cheliped size, and, together with the other parasite-induced effects, this may potentially impact host feeding behavior. In two separate laboratory experiments, we offered infected and uninfected adult male crabs respectively ad libitum small, easy-to-handle blue mussels (Mytilus edulis) (10-15 mm in shell-length), and a limited, size-structured prey population (15-45 mm in shell-length; seven size-classes, ten mussels per class) during 10-15 days. Corrected for carapace width, the per capita consumption rate of the infected and uninfected crabs was similar in either experiment, both regarding number of mussels and amount of tissue dry-weight consumed. Also, the median mussel size preyed upon when exposed to the size-structure prey population was unaffected by infection. However, infected crabs preyed less frequently (26%) on intermediate mussel sizes (25-30 mm) than uninfected crabs. For both infected and uninfected crabs the median prey size increased linearly with maximum claw height. Host dry weight was significantly reduced by infection, assumed to be the result of the morphological feminization (reduced appendage size) rather than reflecting poorer general condition of infected individuals. Infected crabs were nonetheless subjected to a higher mortality rate than uninfected crabs during the experimental period. We conclude that Sacculina infection has a very limited effect on its host crabs' feeding biology and that any measurable ecosystem ramifications of the host-parasite association must originate from other processes; for instance reduced mean size (infection inhibits molting) and density (infection increases mortality) of the crab population where parasitism is high.
PeerJ, 2017
Two digging decapod crustaceans, the sand crab species Lepidopa benedicti and the mole crab species Emerita benedicti, both live in the swash zone of fine sand beaches. They were examined for two parasites that infect decapod crustaceans in the region, an unidentified nematode previously shown to infect L. benedicti, and cestode tapeworm larvae, Polypocephalus sp., previously shown to infect shrimp (Litopenaeus setiferus). Lepidopa benedicti were almost always infected with both parasite species, while E. benedicti were rarely infected with either parasite species. This difference in infection pattern suggests that tapeworms are ingested during sediment feeding in L. benedicti, which E. benedicti avoid by filter feeding. Larger L. benedicti had more Polypocephalus sp. larvae. The thoracic ganglia, which make up the largest proportion of neural tissue, contained the largest numbers of Polypocephalus sp. larvae. Intensity of Polypocephalus sp. infection was not correlated with how long L. benedicti remained above sand in behavioural tests, suggesting that Polypocephalus sp. do not manipulate the sand crabs in a way that facilitates trophic transmission of the parasite. Litopenaeus setiferus may be a primary host for Polypocephalus sp., and L. benedict may be a secondary, auxiliary host.
Crustaceana, 2009
Batches of 100 female cypris of the rhizocephalan, Loxothylacus texanus Boschma, 1933 were selected and put into contact with megalopae of crabs of the genus Callinectes. Contacts lasted for 12 h and the organisms infected were then kept individually in plastic containers, and their growth was followed. At the same time, megalopae free of parasites were kept as controls. The infected organisms were monitored daily until the externae of L. texanus emerged. The time interval for emergence of the externae in male hosts was 79-110 days; and the growth rates were 0.19-0.29 mm day −1 with an average of 0.24 ± 0.037 mm day −1 . In females, the emergence interval of externae was 78-100 days; the growth rate was 0.18-0.23 with an average of 0.20±0.023 mm day −1 . The mortality of the cypris is high (50-90%), which ensures that in the natural environment a high percentage of larval stages of Callinectes rathbunae Contreras, 1930 is recruited to the healthy population. Some crabs infected in the first stages die, which also ensures that the population of L. texanus is maintained relatively low in the natural environment. L. texanus infects the first stages of C. rathbunae, because this gives the parasite the time necessary to complete its life cycle. The emergence interval of the externa of L. texanus obtained in this study for C. rathbunae, is similar to that reported for the blue crab, Callinectes sapidus Rathbun, 1896, in other studies.
Diseases of Aquatic Organisms, 2008
We studied the effect of parasitic invasion by the barnacle Sacculina carcini on shore crabs Carcinus maenas collected from the Menai Straits in North Wales, UK. A significant reduction in serum protein and circulating granular, semi-granular and hyaline blood cells was observed in parasitised individuals, while serum ammonium and glucose concentrations were significantly increased. No difference in hepatopancreatic glycogen concentration was found between healthy and parasitised crabs. Histological analysis showed the apparent removal of fibrillar protein from infected muscle by the parasite. Hepatopancreas tubule necrosis was also routinely observed in infected individuals. Parasitisation by S. carcini dramatically affects the haemocyte population and serum chemistry of infected crabs.