Number Of Epibionts Research Articles

Infestation by Octolasmis species (Lepadiformes, Poecilasmatidae) of the marine crab Lupocycloporus gracilimanus (Decapoda, Portunidae) from India

Abstract The portunid crab Lupocycloporus gracilimanus from Digha, Bay of Bengal, India was investigated for an infestation by the lepadomorph cirriped Octolasmis spp. About 93% of the epibionts examined were found attached to the surface of the carapace, abdomen and legs, and these were identified as Octolasmis warwicki (EOW). Only 7% of the epibionts were attached to the branchial lamellae, and these were identified as Octolasmis angulata (EOA). Twenty-seven O. warwicki were also found to have conspecific dwarf males (CDM) attached to the scutum: probably an adaptive strategy to maximize the total insemination. Both the epibionts and the CDM showed spatial preference for the posterior mesobranchial region of the carapace. Most of the CDM (27%) were seen as a single attachment on the epibiont. The distance between the epibiont and its nearest neighbour (DNN) was found to be strongly and negatively correlated (, ) with the number of epibionts, indicating its preference to stay in an intermediate-sized group rather than remain solitary, which probably would have facilitated the evolution of dwarf males (CDMs). A higher percentage of epibionts were observed to have attached CDMs when the DNN increased, and above the 25 mm DNN, all epibionts were having CDM attachments, which is believed to be a strategy to maximize the fertilization success of CDMs by reducing sperm competition. A strong, positive correlation (, ) was observed between the carapace width of the host crab and the numbers of the infesting epibionts, proving that the larger crabs are more susceptible to the infestation compared to the smaller ones. The sex ratio of the host crab was 1 : 5.5 (Male : Female), nevertheless, only the females were infested by the epibionts. The percentage of the prevalence, relative abundance and mean intensity of EOW infestation were recorded as 46.15%, 182.05% and 394.44%, respectively. None of the crabs had serious external or internal infestations that seemed to hinder the activities of the animal. This is the first report of the infestation of these Octolasmis species on the portunid crab Lupocycloporus gracilimanus from India.

The polychaete Histriobdella homari and major groups of epibionts on the European lobster, Homarus gammarus and other decapods

Abstract The quantitative biology and ecology of epibiotic communities on decapods are only vaguely known. An analytic method revealed close to 100% of metazoan epibionts among the eggs and gills of some decapods in Swedish waters. High abundances of the epibiotic polychaete Histriobdella homari were found (100% prevalence) and European lobsters, Homarus gammarus, with a carapace length of 100 mm have, as a mean, approx. 6700 H. homari among their old eggs, underlining the importance of these epibiont polychaetes as cleaners of lobster eggs (and gills). For the first time, a nematode (Pontonema sp.) was found feeding on H. homari. Gills of American lobsters, Homarus americanus, caught in Swedish waters were infested with the European parasitic copepod Nicothoe astaci (80% prevalence). This study shows that on decapods a number of epibionts (Ciliophora, Nematoda, Hydrachnidia, Copepoda, Ostracoda, Amphipoda and Kinorhyncha) can be quantified, using the method adopted here, which will enable a better understanding of epibiotic communities.

Epibionts on the krill (Euphausia pacifica) from the E coast of Japan

Fernandez-Leborans, G. 2011. Epibionts on the krill (Euphausia pacifica) from the E coast of Japan. —Acta Zoologica (Stockholm) 00: 1–10. Specimens of Euphausia pacifica collected from shallow waters of the E coast of Japan showed ciliate epibionts belonging to two suctorian species: Ephelota plana and Gymnodinioides sp. The epibionts were present in a total of 27 anatomical units of E. pacifica, in numbers fluctuating between 8 and 80 individuals per basibiont. Gymnodinioides showed the highest mean number of epibionts. The presence–absence of epibionts indicated some specificity of the species by different locations on the basibiont body, which is corroborated by the analysis of the colonization throughout the longitudinal axis of the basibiont. Ephelota plana was recorded by the first time on E. pacifica, while Gymnodinioides sp. extended its geographical area with respect to previous studies. Morphological, taxonomical features of the species and the statistical analysis of their spatial distribution on E. pacifica are included.

Epibiotic protozoan communities on juvenile southern king crabs (Lithodes santolla) from subantarctic areas

In this study, we describe for the first time the composition of epibiotic protozoan communities on juvenile southern king crabs Lithodes santolla. Basibionts were collected in subantarctic bays near Santa Ana Point (Magellan Strait, Chile). Seven epibiotic protozoan ciliates were found: Ephelota gemmipara, Ephelota gigantea, Podophrya fixa, Acineta tuberosa, Zoothamnium duplicatum, Chilodochona quennerstedti and Gymnodinioides sp. The mean number of epibionts per crab was 99 (maximum 897). Both Ephelota species were the most abundant and most widely distributed epibionts on the crab examined. The lengths of basibionts were correlated with the number of epibionts, indicating a relationship between the age of the crab and the state of epibiosis. Epibionts differed in their distribution patterns along the anteroposterior axis of the crab. Less abundant species tended to occupy sites that are not colonized by the predominant Ephelota species. Maxillipeds and pereiopods were most densely colonized by epibionts. The behaviours of epibionts and basibionts related to epibiosis are discussed. The recent studies about invasive lithodids in Antarctic areas enhance the interest for the epibiotic communities colonizing these crustaceans, which can illustrate changes in biodiversity and state of these environments.

Comparative Distribution of Protozoan Epibionts on Mysis Relicta Lovén, 1869 (mysidacea) from Three Lakes in Northern Europe

Specimens of Mysis relicta from three lakes in northern Europe had protozoan epibionts belonging to three genera of ciliates: Vorticella, Dendrosoma, and Tokophrya. The epibionts were present on a large part of the mysid's surface: antennulae, antennae, eyes, mandibulae, maxillulae, maxillae, pereiopods, pleopods, uropods, telson, carapace, and abdomen. The density of epibionts on each anatomical unit was measured, and these densities were compared in mysids from different geographical areas. The number of epibionts per individual mysid fluctuated between 1 and 1,587. The mean number of epibionts on each anatomical unit was 22.62. Antennae, pereiopods, and carapace were the areas with the highest densities of epibionts. The degree of colonization on the various anatomical units varied among the geographical sites monitored. Statistical analysis performed using data of epibiont densities on all colonized regions of the mysids showed that there was a significant difference in epibiosis among mysids from different geographical areas. In addition, epibiotic relationships at each geographical site were calculated with respect to the morphology and sex of the basibionts, and with respect to the differential presence of the epibionts on the anatomical areas of the mysids.

Distribution of the protozoan epibiont Ophryodendron mysidacii (Ciliophora, Suctoria) on the mysid Schistomysis parkeri (Crustacea)

The Schistomysis parkeri population is one of the most important components of the suprabenthic community of the ‘swash zone’ at Hendaye Beach (Bay of Biscay, Atlantic Ocean, France), near the mouth of the River Bidasoa. In samples containing this mysid, a suctorian epibiont of the genus Ophryodendron was found, showing two types of forms: tentaculate and vermiform and a resistant stage. The number and distribution of these epibionts on the surface of the mysid was analysed, taking into account the sex and age group of the crustacean. The data showed a significant correlation between the size and maturity state of the mysid, and the number of epibionts. The tentaculate forms were generally located on the uropods, penian lobes, abdominal segments, telson and eyes. The vermiform individuals were located on the bristles of the uropods, on the eyes, and on the basal area of the antennae and antennulae.

The ecological niche of the consortium " Pelochromatium roseum "

A dense accumulation of the phototrophic consortium "Pelochromatium roseum" in a small, eutrophic, freshwater lake (Dagowsee, Brandenburg, Germany) was investigated. Within the chemocline, the number of epibionts of the consortia represented up to 19% of the total number of bacteria. Per "P. roseum" a mean value of 20 epibionts was determined. Similar to other aquatic habitats, consortia in the Dagowsee were found only at low light intensities (< 7 &mgr;mol quanta m-2 s-1) and low sulfide concentrations (0-100 &mgr;M). In dialysis cultures of "P. roseum", bacterial cells remained in a stable association only when incubated at light intensities between 5 and 10 &mgr;mol quanta m-2 s-1. Intact consortia from natural samples had a buoyant density of 1046.8 kg m-3, which was much higher than that of ambient chemocline water (995.8 kg m-3). Under environmental conditions and without motility, this density difference would result in rapid sedimentation of consortia toward the lake bottom. Our results indicate that (1) consortia are adapted to a very narrow regime of light intensities and sulfide concentrations, (2) motility and tactic responses must be of ecological significance for the colonization of the free water column of lakes, and (3) phototrophic growth of consortia can be explained only by a cycling of sulfur species in the chemocline, possibly within the consortia themselves.

EPIBIONTS OF THE TANNER CRAB CHIONOECETES BAIRDI IN THE REGION OF KODIAK ISLAND, ALASKA

ABSTRACT We examined the epibionts on 98 legal male Tanner crabs (Chionoecetes bairdi) of varying, known shell ages, which were tagged in the region of Kodiak Island, Alaska, and recovered in the commercial fishery. We found 39 species or collective taxa of organisms on C. bairdi, a conservative estimate of the number of species involved. Seven species or collective taxa occurred on the exposed outer surface of ≥50% of all crabs examined: Alcyonidium sp., Balanus spp., a tube-dwelling amphipod, Spirorbis spp., Serpula spp., a lichenoporid bryozoan, and the fungus Trichomaris invadens.At least 12 species occurred in the branchial chamber. Of these, Triticella sp., Alcyonidiumsp., and mucoid-tube polychaetes were found in ≥50% of 25 branchial cavities examined. Three species (Triticella sp.; a small, white flatworm; and Hiatella arctica) were found only in the branchial chamber. Our data showed trends of increasing frequency of occurrence and increasing mean number of epibionts with increasing shell age. Crab-shell age was a significant factor in determining the number of epibiotic species on crabs; the area of origin was not a significant factor. Epibionts are likely to be of limited use as a management tool, because of difficulties in accurately assessing the age composition of commercial samples and the likelihood of temporal and geographic variation in recruitment of epibiont organisms. However, epibionts are probably a significant factor in the population dynamics of C. bairdi and, hence, worthy of further investigation.

A study of the natural antifouling mechanisms of the green musselPerna viridisL. (Mytilidae)

The green mussel Perna viridis L. (Mytilidae) is commonly found on hard substrata in the littoral zone of the upper Gulf of Thailand. Mussels appeared to be less densely colonized by epibionts than other artificial and natural hard substrata. The number of epibionts (bacteria, diatoms, protozoa, fungi, macroorganisms) on Perna viridis shells and their potential defence mechanisms were studied. The number of epibionts on isolated mussels and those in patches were compared. Densities of protozoa and macrofauna were much higher on isolated specimens than on aggregated (patch forming) mussels. Among possible antifouling mechanisms which were studied sloughing, shell surface tension and surface‐pH proved to be non effective in preventing fouling. Toxicity assays of shell extracts showed limited activity against bacteria and fungi. Grazing by two different gastropod species (Planaxis sulcatus, Thais sp.) reduced the number of protozoa and macroorganisms on isolated and aggregated mussels. Diatoms were restricte...