Hydrozoan and protozoan epibionts on two decapod species, Liocarcinus depurator (Linnaeus, 1758) and Pilumnus hirtellus (Linnaeus, 1761), from Scotland

Crabs of the species Liocarcinus depurator and Pilumnus hirtellus, collected on the west coast of Scotland, showed hydrozoan and protozoan epibionts. The epibionts of Liocarcinus depurator were the protozoan Ephelota plana and the hydrozoans Clytia gracilis and Leuckartiara sp. The epibionts of Pilumnus hirtellus were the protozoans E. plana and Zoothamnium sp. For Liocarcinus depurator the number of Ephelota per crab fluctuated between 0 and 47 and the greatest number of suctorians were located on the chelipeds, carapace and anterior pereiopods. The hydrozoans, for Liocarcinus depurator, showed densities of 0-20 (Clytia gracilis on the second pereiopod) and 0-507 individuals per crab (Leuckartiara sp., principally on chelipeds, carapace and the fourth right pereiopod). For Pilumnus hirtellus, Ephelota plana showed densities between 3 and 56 individuals per crab, the greatest number of suctorians being located on the same areas as on Liocarcinus depurator. There was a density of 10-69 individuals per crab of Zoothamnium sp. on Pilumnus hirtellus (located on the carapace). Ephelota plana has not been observed previously as an epibiont on crustacea, nor had Zoothamnium sp. as an epibiont on Pilumnus hirtellus. Both hydrozoans, Leukartiara and Clytia, have not been previously described as epibionts on Liocarcinus depurator. Data about the morphological characteristics and distribution of these epibionts are included.     

Morphology and SSU rRNA gene‐based phylogeny of two Diophrys‐like ciliates from northern china,with notes on morphogenesis of Pseudodiophrys nigricans (Protozoa,Ciliophora)

Two free‐living marine euplotid ciliates, Pseudodiophrys nigricans and Diophrys japonica, collected from the coastal waters off Qingdao, northern China, were investigated using live observations and protargol impregnation methods. The cortical development of P. nigricans was observed during binary division. Although its general pattern of morphogenesis is similar to that of other Diophrys‐like species, three unusual features are noteworthy: 1) the frontoventral transverse cirral anlagen develop in the secondary mode, similar to that of Euplotes; 2) the undulating membrane anlage migrates far from the cytostome and does not split into two membranes; and 3) the parental adoral zone of membranelles remains nearly intact throughout the entire morphogenetic process. Diophrys japonica is redescribed based on a Chinese population and can be recognized by having one left marginal cirrus, densely arranged cortical granules, and a fragment kinety with three dikinetids. Phylogenetic analyses based on the small subunit rRNA (SSU rRNA) gene sequence data indicate that D. japonica is placed within the Diophrys clade and is most closely related to the well‐known D. apoligothrix. © J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.     

Description de Quelques Espèces de Ciliés Hyménostomes des Genres Sathrophilus Corliss, 1960, Cyclidium O. F. Müller, 1786, Histiobalantium Stokes, 1886

RESUME. Les structures buccales de Sathrophilus vernalis Dragesco & Grolière, 1969 sont détaillées. La morphogenèse buccale de l'opisthe, semi-autonome, avec participation du scuticus et d'une cinétie postorale droite, s'accompagne d'une re-constitution de l'appareil buccal du proter. La morphologie buccale de Cyclidium sphagnetorum Šràmek-Hušek, 1949 est comparée à celles de Cyclidium citrullus Cohn, 1865 et Cyclidium glaucoma O. F. Müller, 1786. La stomatogenèse Histiobalantium majus Kahl, 1933 débute par une prolifération du scuticus vers la gauche.
SYNOPSIS. Buccal structures of Sathrophilus vernalis Dragesco & Grolière, 1969 are described. The semiautonomous buccal morphogenesis of the opisthe, involving the participation of the scuticus and the right postoral kinety, is accompanied by the reconstitution of the buccal apparatus of the proter. The buccal structure of Cyclidium sphagnetorum Šràmek-Hušek, 1949 is compared to those of Cyclidium citrullus Cohn, 1865 and Cyclidium glaucoma O. F. Müller, 1786. Stomatogenesis of Histiobalantidium majus Kahl, 1933 starts with a proliferation of the scuticus towards the left.     

Contribution of biofilm‐dwelling consumers to pelagic–benthic coupling in a large river

1. Over the course of this 17‐month study, we assessed the potential loss of plankton (bacteria, algae, heterotrophic flagellates) to consumers (ciliates and rotifers) within mature biofilms established on natural substrata exposed to the main current of the River Rhine (Germany). Once a month, in flow cells in a bypass system to the River Rhine, we measured the clearance rates of the biofilm‐associated consumers on the different groups within the natural plankton. 2. Ciliates were the most dominant consumers, among which planktivorous groups, particularly peritrichs and (in spring and summer) heterotrichs dominated. Consumer biomass varied with season, with the highest density occurring directly after the appearance of the phytoplankton spring peak. 3. Clearance rates on plankton ranged from 96 to 565 L m^?2 d^?1 for bacteria and 66–749 L m^?2 d^?1 for algae, with a preference for algae in summer and for bacteria in winter. This pattern coincided with seasonal changes in the structures of the grazer communities. The consumers (both ciliates and rotifers with total standing stocks ranging between 19 and 572 mg C m^?2) imported a substantial amount of organic matter (between 15 and 137 mg C m^?2 d^?1) into the biofilm. 4. These results highlight the potential importance of consumers in the biofilm as a trophic link between the plankton and the benthos, a function that has hitherto mostly been attributed to filter‐feeding bivalves. In contrast to bivalves, the biofilm‐dwelling consumers show a more dynamic response towards the plankton density and composition. Such dynamic components need to be considered when estimating total plankton consumption by the benthos.     

Allelopathy of diterpenoids on three species of soil ciliates

Allelopathy of diterpenoids extracted from plants of the genus Robdosia on three common species of soil ciliates, Colpoda inflata, Colpoda cucullus and Euplotes muscicola, was studied by acute toxicity test, sub-lethal effect test and morphological observation. Acute toxicity test showed that there was remarkable toxicity of the diterpenoids on the individuals of the three soil ciliate species, and there was close correlation between toxicity and concentration of the diterpenoids. 12 h-LC₅₀ values of the diterpenoids on the individuals of C. inflata, C. cucullus and E. muscicola were 161.40 mg L^?1, 94.80 mg L^?1 and 83.70 mg L^?1 respectively, and 24 h-LC₅₀ values were 114.90 mg L^?1, 92.30 mg L^?1and 65.80 mg L^?1 separately. Sub-lethal effect test of soil ciliates suggested that there existed significant inhibition of the diterpenoids on population growth of the three ciliates with dose-dependant relationships, population density and growth rate of the test group was obviously lower than that of the control group. Morphological observation indicated that diterpenoids affected the body shapes of the three ciliates and made them shorter and thicker, and the higher the concentration of diterpenoids, the greater the affection. The results are of great significance for understanding the functions of ciliates and their relationships to other organisms, and for the application of allelopathy in biological pest control in the soil ecosystems.     

Reducing horizontal and vertical diversity in a foodweb triggers extinctions and impacts functions

Species loss can result in secondary extinctions and changes in ecosystem functions at distant trophic levels. Such effects of species loss are predicted to be affected by both the number of species lost within a trophic level (horizontal diversity) and the number of trophic levels lost (vertical diversity). We experimentally manipulated horizontal and vertical diversity within an aquatic insect community, and examined responses throughout the food web. Horizontal and vertical diversity both impacted ciliates: reduction of detritivorous insect diversity resulted in secondary extinctions and decreased density of ciliates, but only when an insect predator was simultaneously absent. Horizontal and vertical diversity differed in their effect on other foodweb processes, including detrital processing, predator growth, and densities of rotifers, flagellates and flatworms. These results caution that foodweb effects of multitrophic species loss may not be reliably predicted from manipulations of just one dimension of diversity.     

The Secondary Metabolite Euplotin C Induces Apoptosis-Like Death in the Marine Ciliated Protist Euplotes vannus

ABSTRACT. The sesquiterpenoid euplotin C is a secondary metabolite produced by the ciliated protist Euplotes crassus and provides a mechanism for damping populations of potential competitors. Indeed, E. crassus is virtually resistant to its own product while different non-producer species representing an unbiased sample of the marine, interstitial, ciliate diversity are sensitive. For instance, euplotin C exerts a marked disruption of different homeostatic mechanisms in Euplotes vannus . We demonstrate by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay that euplotin C quickly decreases viability and mitochondrial function of E. vannus with a very high efficacy and at micromolar potency. In addition, euplotin C induces apoptosis in E. vannus as 4,6-diamino-2-phenylindole and terminal transferase dUTP nick end labeling staining show the rapid condensation and fragmentation of nuclear material in cells treated with euplotin C. These effects occur without detectable permeabilisation or rupture of cell membranes and with no major changes in the overall morphology, although some traits, such as vacuolisation and disorganized microtubules, can be observed by transmission electron microscopy. In particular, E. vannus show profound changes of the mitochondrial ultrastructure. Finally, we also show that caspase activity in E. vannus is increased by euplotin C. These data elucidate the pro-apoptotic role of euplotin C and suggest a mechanism for its impact on natural selection.