Peritrich Ciliate Research Articles

Analysis of the flow field induced by the sessile peritrichous ciliate Opercularia asymmetrica

The feeding mechanism of the sessile protozoon Opercularia asymmetrica (Oligohymenophorea, Peritrichia) relies on the cilia beat generating a flow field that convectively transports suspended particles and dissolved substances to the oral cavity of the organism. By use of optical micro-flow measurement and theoretical methods the flow environment of two neighbouring peritrichous ciliate cells is studied. Both, yeast cells ( Saccharomyces cerevisiae) and artificial flow tracers are used for the visualisation of the flow field. Artificial tracers are rejected by the protozoa and deviate from the fluid path lines, while yeast cells follow the flow almost perfectly. This is shown through a dimensional analysis of the involved hydrodynamic forces on the tracers. The measured flow field exhibits maximum velocities of 25 μm/s at around 20 μm distance ahead of an individual ciliate. The flow field extends 200 μm from the location of the ciliate. A nicking motion of the protozoon is observed and found not to obey any periodic law. Multiples of protozoa exhibit most commonly an alternating cilia beat regime generating a non-stationary flow field. It can be shown through theoretical methods that fluid exchange is enhanced in this alternating regime compared to a flow field generated by a single ciliate. Fluid exchange depends on the distance of the ciliates from each other and on the alteration frequency of the cilia beat. The comparison of an analytical Stokes’ flow solution with the observed fluid flow serves to determine the force required to maintain the flow field against viscous dissipation. The force magnitude is in the order of magnitude of 10–100 pN.

Taxonomy and distribution of the hydrozoan and protozoan epibionts on Pagurus bernhardus (Linnaeus, 1758) (Crustacea, Decapoda) from Scotland

AbstractProtozoan and hydrozoan epibionts on the hermit crab Pagurus bernhardus and its shell, collected near Cumbrae Island (Scotland) were studied. The epibionts found were the following: (1) protozoans: the suctorian ciliates Ephelota plana, Acineta compressa, Conchacineta constricta, Corynophrya anisostyla; the peritrich ciliates Cothurnia mobiusi and Zoothamnium plumula; the chonotrich ciliate Chilodochona quennerstedti; and (2) hydrozoans: the species Leuckartiara sp. and Clytia sp. The morphological characteristics of the epibionts were analysed, as well as their taxonomic position. The distribution of epibionts on the crab surface and its shell was studied, and the density and biomass of epibionts were calculated on each anatomic unit. There was a differential distribution according to the type of epibiont: hydrozoans dominated in biovolume and were present mainly on the shell, meanwhile protozoans represented the highest fraction of density and they were found exclusively on the crab (principally on eyes, antennulae, antennae, maxillipeds, pereopods and uropods). The anterior area of the cephalothorax was the most colonized. On this area, the maxillipeds and second pereopods showed the highest densities. The location of each epibiont species was described. There was a correlation between the length of the crab and the total number of hydrozoans. There was a significant correlation between the right and the left units of the crab, taking into consideration the mean densities of epibionts on each anatomical unit. The shell was colonized by the same species of hydrozoa that appeared on the crab, although in a much higher density (mean 3024.38 per shell; 6.9 per crab). There was a significant difference between both species of hydrozoan epibionts with respect to the mean densities on the different areas of the shell. The zone of the shell more occupied by Clytia sp. was the apical zone of the shell, while the highest densities of Leuckartiara sp. were registered near the aperture of the shell. The hydrozoan and protozoan epibiont species found on P. bernhardus in this study represent the first mention of their presence on this hermit crab.

Redescription of Lagenophrys cochinensis Santhakumari & Gopalan, 1980 (Ciliophora, Peritrichia, Lagenophryidae), an Ectosymbiont of Marine Isopods, Including New Information on Morphology, Geographic Distribution, and Intraspecific Variation

Lagenophrys cochinensis is a peritrich ciliate originally reported as an ectocommensal of the wood-boring isopods Sphaeroma terebrans, Sphaeroma triste, and Sphaeroma annandalei and the tanaidacean Apseudes chilkensis in estuaries of southern India. In the present study, it was found to occur also on Sphaeroma quoyanum, Sphaeroma walkeri, and Exosphaeroma planulum. New material was used to make permanent preparations, allowing a comprehensive description of the morphology of L. cochinensis for the first time. The macronucleus of L. cochinensis was found to have an elongate shape that spans the width of the cell body, unlike the compact macronucleus originally described. In addition, the loricae of all samples examined were subcircular or shorter than wide, not longer than wide as originally described. Polykinetid 3 of the infundibular infraciliature consisted of three rows of kinetosomes, only the third species of Lagenophrys found to have more than two rows in polykinetid 3 so far. Samples of L. cochinensis on S. quoyanum from New Zealand and California appeared to represent a population distinct from others. The species has a cosmopolitan distribution, probably owing to the ease with which its hosts are transported from one estuary to another in drifting wood or on hulls of ships.

Notes on a new marine peritrichous ciliate (Ciliophora: Peritrichida), Zoothamnium xuianum n. sp., with redescription of Z. paraentzii Song, 1991 from northern China

The morphology, infraciliature and silverline system of two marine peritrichous ciliates, Zoothamnium xuianum n. sp. and Z. paraentzii Song, 1991, collected from a shrimp-hatching plant in northern China, were investigated using both in vivo and silver impregnation methods. The new species is recognized by the following characters: colony alternatively branched, zooids in vivo about 45 × 30 μm with single-layered peristomial lip; contractile vacuole apically located; macronucleus band-like and transversely positioned; more than 50 striations from peristomial area to aboral trochal band, about 14 from aboral trochal band to scopula; three equally long kineties in peniculus 3 parallel to each other. Based on both the Qingdao population and the original description, an improved diagnosis for Z. paraentzii is suggested: marine Zoothamnium with irregularly dichotomously branched stalk; zooid 50–80 × 25–45 μm in vivo with single-layered peristomial lip; contractile vacuole apically positioned; macronucleus C-shaped, transversely orientated; number of silverlines between anterior end and aboral trochal band about 75–83, between aboral trochal band and scopula, 28–33; inner row of peniculus 3 displaced from the other two and converges with peniculus 1 at aboral end.

Redescription of Pseudovorticella cylindrica (Dons, 1915) nov. comb. and Zoothamnium hiketes Precht, 1935, two poorly defined marine peritrichs (Ciliophora: Peritrichia) from the north China Sea

The living morphology, silverline system and infraciliature of two marine peritrichous ciliates, Pseudovorticella cylindrica (Dons, 1915) nov. comb. (formerly Vorticella cylindrica) and Zoothamnium hiketes Precht, 1935, collected in Qingdao, China, were investigated. Based on the Qingdao populations, both species are redefined. Pseudovorticella cylindrica is characterized by: cell inverted bell‐shaped, about 45×50 µm in vivo; macronucleus J‐shaped; one apically positioned contractile vacuole; pellicle smooth with inconspicuous, closely spaced striations; the number of transverse silverlines from peristome to aboral ciliary wreath 33–40, from aboral ciliary wreath to scopula 14–19; the inner row of peniculus 3 conspicuously short. An updated and supplementary description of Zoothamnium hiketes is also supplied: size of zooid in vivo 70×35 µm on average, elongate in shape with inconspicuously double‐layered peristomial lip; macronucleus C‐formed; one large contractile vacuole apically located; colony dichotomously branched; the number of striations from peristome to aboral ciliary wreath 89–109, from aboral ciliary wreath to scopula 35–43; rows in peniculus 3 parallel to each other.

Spatial and Temporal Patterns in the Occurrence of Peritrich Ciliates as Epibionts on Calanoid Copepods in the Chesapeake Bay, USA

We investigated temporal and spatial patterns of distribution in two peritrich ciliates (i.e. Zoothamnium intermedium and Epistylis sp.) living as epibionts on calanoid copepods (i.e. Acartia tonsa and Eurytemora affinis) in Chesapeake Bay. Net tow samples collected along the main axis of the Bay were analyzed to estimate the occurrence of epibionts on copepods and to explore relationships among infestation prevalence, host abundance, and environmental variables. Zoothamnium intermedium and Epistylis sp. colonized populations of A. tonsa during spring and summer months, while only Z. intermedium colonized E. affinis during spring. Occurrence of epibionts on copepods showed high interannual variation, marked seasonality, and geographic heterogeneity. Extensive statistical analyses rejected simple scenarios of interactions between epibiosis, environmental variables, and host density, suggesting a more complex dynamics for the system. Analyses of epibiont colonies and zooids per host area (i.e. the sum of width and length of the body including antennae and swimming legs calculated assuming a cylindrical shape) were also performed. Overall, epibiont infestation prevalence (i.e. colonies/host area) and load (i.e. zooids/host area) were higher on copepodites than on adults for both host species, suggesting a preferential attachment to juveniles, or a higher predation pressure on adult stages. Infestation density and loads of both epibiont species were higher on the cephalothorax and abdomen of A. tonsa and E. affinis in comparison to the antennae and swimming legs, suggesting that ciliates can more easily colonize less active parts of the host.

Taxonomic Characterization of Two Marine Peritrichous Ciliates, Pseudovorticella clampi n. sp. and Zoothamnium pararbuscula n. sp. (Ciliophora: Peritrichia), from North China

The morphology, infraciliature, and silverline system of two new peritrichous ciliates, Pseudovorticella clampi n. sp. and Zoothamnium pararbuscula n. sp., have been investigated based on both living and silver-impregnated specimens. Partial sequence of 18S-ITS1-5.8S rDNA of Z. pararbuscula is also determined in order to compare it with the closely related congener, Zoothamnium arbuscula. Zoothamnium pararbuscula can be distinguished from its close form Z. arbuscula by the different habitats, the appearance of the main stalk, the position of the contractile vacuole, and the information derived from 18S-ITS1-5.8S rDNA sequence analysis. Pseudovorticella clampi n. sp. is distinguished from its congeners by its body shape and size, pellicle granules, habitat, and number of transverse silverlines.

Possible artificial introductions of freshwater peritrich ciliates and their implications for assessment of protistan biodiversity

The planktonic, sessiline peritrichs Epicarchesium pectinatum (Zacharias 1897) and Pelagovorticella natans (Fauré‐Fremiet 1924) were collected from different tributaries of the St. Lucie River, Florida. Epistylis procumbens Zacharias, 1897, another planktonic sessiline, was collected near the mouth of the Kissimmee River, Florida. Epicarchesium pectinatum and P. natans were not seen again in the St. Lucie drainage, probably because prolonged drought had increased the salinity of habitats drastically. Epistylis procumbens was absent from other, nearby sections of the Kissimmee River and nearby lakes and streams. Efforts to collect the three species from other bodies of water in Florida and from lakes and ponds in central New York met with no success; however, P. natans was found in two of the many localities sampled in North Carolina, an artificial pond and a natural lake. Pelagovorticella natans was found on only one of several visits to the latter locality. The three species occurred in habitats that were either within or near populated areas and had been extensively modified. This and the disjunct, ephemeral distributions of the peritrichs suggest that they may have been introduced artificially. Artificial introduction of ciliates or other protists is poorly documented but probable, considering their small size and consequent ease of transportation, and peritrichs should be especially suspect because many of them attach to aquatic plants. In the end, research on biodiversity of free‐living protists must include the possibility of artificial introductions and develop methodologies to separate them from natural occurrences or else be reduced to a meaningless exercise.

Redescription of Lagenophrys maxillaris (Jankowski, 1993) (Ciliophora, Peritrichia, Lagenophryidae), an Ectosymbiont of Marine Amphipods

The loricate peritrich ciliate Lagenophrys maxillaris, a highly specialized ectosymbiont of marine gammarid amphipods, was examined and redescribed by using material from museum collections to make hematoxylin and protargol preparations. The infraciliature is described for the first time, and the shape of the macronucleus was found to differ significantly from the shape given in the original description. Lagenophrys maxillaris is one of only four species of Lagenophrys known to occur on the maxillipeds of amphipods or isopods and differs from the others with respect to the structure of the lips of the lorica aperture and pattern of infundibular polykinetids. It appears to prefer attaching to hosts that live in water deeper than that inhabited by hosts of other known marine species of Lagenophrys and was recorded from one sample of Gammarus locusta taken at a depth of 240-250 m. Lagenophrys maxillaris seems to be restricted to G. locusta and G. oceanicus although three other closely related species of Gammarus are available as hosts. Host specificity is possibly the result of trophic differences, possibly related to depth of habitat, between the two hosts and their congeners.

The pelagic community of a gravel pit lake: Significance of Coleps hirtus viridis (Prostomatida) and its role as a scavenger

Coleps hirtus viridis was the dominant species of the planktonic ciliate community of Lake Fühlinger See (Germany) during the study in 1999 and 2000. Total ciliate densities ranged from 120 to 42,000 ind. l −1 in 1999 and up to 8,000 ind. l −1 in 2000. Coleps contributed up to 98% to both total ciliate abundance and biomass and made up an average of 64% of the total ciliate biomass. Oligotrichs (Rimostrombidium, Strobilidium) dominated the epilimnetic zone, whereas peritrich ciliates (Pelagovorticella, Vorticella) were predominantly located in the hypolimnion. The population maximum of Coleps changed locations from the epilimnion in early summer to the hypolimnion (up to 40,000 ind. l −1) during stratification. High growth rates in the hypolimnion, presence of endosymbiontic algae and the ability to ingest detritus seem to be important for the success. Growth rates of Coleps in June were determined by Landry-Hassett dilution experiments in both the epilimnion and the hypolimnion. The instantaneous growth rates were similar in both layers (0.6 d −1), but a distinctly higher instantaneous mortality was estimated for the epilimnion. These high loss rates may be due to grazing pressure by cladocerans. The significance of the histophagous feeding of Coleps was evaluated through an experiment using killed zooplankton. Parts of Daphnia magna were incorporated at rates of about 1,100 μm 3 ind. −1 h −1 by Coleps without endosymbiotic algae and at rates of 500 μm 3 ind. −1 h −1 by Coleps with endosymbionts. These high feeding rates support the conclusion that Coleps can use dead organic matter as an additional food source.

Rediscovery and redescription of the marine peritrichous ciliate Epicarchesium abrae (Precht, 1935) nov. comb. (Protozoa, Ciliophora, Peritrichia)

The morphology, infraciliature and silverline system of the marine peritrichous ciliate, Epicarchesium abrae (Precht, 1935) nov. comb., isolated from an abalone-farming pond off the coast of Qingdao, China, are investigated. E. abrae is characterized by: size of zooid in vivo 68 μm×48 μm on average; macronucleus usually J-shaped; one dorsally-located contractile-vacuole; colony regularly dichotomously branched with 4–16 zooids; total number of transverse silverlines 62–72, from peristome to aboral ciliary wreath 41–47, from aboral ciliary wreath to scopula 21–25; outer kinety of peniculus 3 prolonged and converges with peniculus 1.

Pseudovorticella paracratera n. sp., a new marine peritrich ciliate (Ciliophora: Peritrichida) from north China

A new marine peritrich ciliate, Pseudovorticella paracratera n. sp., was isolated from marine waters off the coast of Qingdao, China. The morphology, infraciliature, and silverline system were studied from living and silver-impregnated specimens. It is characterized by a wide conical or inverted bell-shaped body which measures 40–88 μm in length × 64–144 μm in width in vivo, two ventrally located contractile vacuoles, and a wide peristomial lip with closely-spaced, irregular tubercles. The pellicle is tubercular with conspicuous, widely-spaced striations. There are 15–18 transverse silverlines between the peristomial lip and the aboral ciliary wreath and 9–11 between the aboral ciliary wreath and the scopula. The stalk is 8–10 μm wide and about 5–12 times the zooid length. The spasmoneme has numerous conspicuous thecoplasmic granules.

Chemical modification of contractile 3-nm-diameter filaments in Vorticella spasmoneme by diethyl-pyrocarbonate and its reversible renaturation by hydroxylamine

A peritrich ciliate possesses a zooid and a long stalk consisting of a bundle of 3-nm-diameter filaments. Glycerinated stalks can contract in the presence of free Ca 2+ and re-extend in the absence of free Ca 2+. In the present study, we demonstrated that histidine residue(s) played a critical role in spasmoneme contraction by using glycerinated stalk of Vorticella. Concentration-dependent inhibition of spasmoneme contraction was observed in the presence of reversible histidine-modifying reagent named diethyl-pyrocarbonate (DEPC). In addition, the contractility degree of DEPC-modified spasmoneme could be partially restored by hydroxylamine treatment. The 244 nm absorption of modified spasmoneme protein(s) increased with rising DEPC concentration and decreased following the addition of hydroxylamine treatment. Adding Ca 2+ before DEPC modification could prevent the spasmoneme contraction from inhibition of DEPC. Those results suggested that histidine residues were actively involved in spasmoneme contraction. Ca 2+-binding ability of spasmin was not inhibited by DEPC modification, which suggested that the essential histidine residues were not on the calcium-binding site of spasmin.

Longitudinal changes in protistan bacterivory and bacterial production in two canyon-shaped reservoirs of different trophic status

We studied bacterial production and mortality due to heterotrophic nanoflagellate (HNF) and ciliate grazing on longitudinal transects conducted on two canyon-shaped reservoirs of different trophic status, Řimov and Orlik (Czech republic). Special attention was paid to the changes in these processes related to depth, spatial distribution of sampling points, different periods of planktonic succession and to the taxon-specific bacterivory of ciliates. Bacterial production (BP) in both reservoirs was, on average, reaching similar values (ranging from 1.2 × 106 to 4 × 106 bacteria ml−1 d−1). In Řimov (mesoeutrophic, mean retention time 100 days), when seasonally averaged, total protistan grazing accounted for 35% of BP and was consistantly lower in the layer R (layer with the same temperature and conductivity as the river inflow). On the contrary, the seasonal average for the Orlik reservoir (eutrophic, mean retention time of 23 days) showed roughly two times higher proportion of BP (70% of the total) removed by protists. In both reservoirs, there was little or no difference in contribution of ciliates and HNF to total protistan bacterivory. Overall, oligotrichous ciliates were recognized as the major ciliate bacterivores (accounting for 67% and 48% of total ciliate bacterivory in Řimov and Orlik, respectively) followed by peritrichous ciliates that contributed to total ciliate bacterivory from 23% (Řimov) to 28% (Orlik). A small omnivorous oligotrichous ciliate Halteria cf. grandinella was the major bacterivore within the whole ciliate community in both reservoirs, contributing as much as 48 and 34% to the total ciliate bacterivory, in the Řimov and Orlik reservoirs, respectively.

Description of a Marine Peritrichous Ciliate, Pseudovorticella sinensis n. sp. (Ciliophora, Peritrichia) from China

A new marine peritrich ciliate, Pseudovorticella sinensis n. sp. was isolated from a shrimp-farming pond in the littoral area of Qingdao, China. The morphology, infraciliature, and silverline system were studied based on living and silver-impregnated specimens. This species is characterized by (1) an elongated bell-shaped body that measures 50-60 x 35-45 microm in vivo, (2) one large, ventrally located contractile vacuole, and (3) a pellicle covered by a layer of transparent, cortical vesicles. The number of transverse silverlines from the peristomial area to the aboral ciliary wreath is 26-32, and from the aboral ciliary wreath to the scopula is 12-15. The stalk measures about 160-250 microm long x 5-6 microm wide. The spasmoneme has one row of conspicuous thecoplasmic granules, which are about 0.8 microm in diameter.

Redescription of four species of lagenophryid peritrichs (Ciliophora) from Australia and New Guinea, with descriptions of two new species

Four insufficiently described species of ectosymbiotic peritrich ciliates in the family Lagenophryidae that occur on crustacean hosts in Australia and New Guinea are redescribed. These include two species of Operculigera from phreatoicid isopods, one species of Setonophrys from a phreatoicid isopod, and one species of Lagenophrys from a palaemonid shrimp. Two undescribed species of Operculigera, also found on phreatoicid isopods, are described for the first time. Australian species of Operculigera appear to be restricted to phreatoicid hosts. This is unusual because a diverse array of other lagenophryids occur on parastacid crayfish in Australia. Furthermore, species of Operculigera are conspicuous symbionts of parastacids and various freshwater crabs in Chile and Madagascar. In addition to this peculiarity of distribution, the Australian species of Operculigera appear to comprise a morphologically distinct group within the genus.

Ultrastructure, encystment and cyst wall composition of the resting cyst of the peritrich ciliate Opisthonecta henneguyi.

The cyst wall of Opisthonecta henneguyi has been studied ultrastructurally and cytochemically by light and electron microscopy, as well as by chemical and electrophoretic analyses, to examine the structure of the cyst wall and its composition. The cyst wall consists of four morphologically distinct layers. The ectocyst is a thin dense layer. The mesocyst is the thickest layer and is composed of a compact material. The endocyst is a thin layer like the ectocyst, but less dense. The granular layer varies in thickness and is composed of a granular material. In the resting cyst, kinetosomes of both oral apparatus and trochal band as well as the myoneme system are maintained, and only cilia are resorbed. The sugars present in the cyst wall are predominantly N-acetylglucosamine (90%) and glucose (10%). The mesocyst is composed of chitin, and the endocyst includes glycoproteins and acid mucopolysaccharides. During secretion of the cyst wall, the endocyst and granular layer are secreted from precursors synthesized "de novo". No cytoplasmic precursors of ectocyst and mesocyst have been detected.

Some parasites of the small-eyed rabbitfish, Hydrolagus affinis (Capello, 1867) (Holocephali), caught in deep waters off SW Greenland

Nine parasite species were recorded from the deep-water chimaera Hydrolagus affinis (Capello, 1867) collected at 1300-2100 m depth southwest of Greenland. A peritrich ciliate, Trichodina sp., infected the urinary system and was also found in the cloaca and on the claspers of a male. Metazoan parasites were represented by two monogeneans, Chimaericolidea gen. sp. (gills) and Calicotyle sp. (cloaca); an aspidogastrean Multicalyx sp. (gallbladder and bile ducts); two trematodes, a blood fluke Chimaerohemecus sp. (heart), Gonocerca phycidis Manter, 1925 (stomach and oesophagus); two cestodarians, Gyrocotyle abyssicola Van der Land & Templeman, 1968 and Gyrocotyle major Van der Land & Templeman, 1968 (spiral intestine), and a lernaeopodid copepod, Lernaeopodina longibrachia (Brian, 1912) attached to the eyes. In 118 fish examined for Lernaeopodina longibrachia , the prevalence of female copepods was high (83%), while the intensity rarely exceeded one per eye and hence two females per fish. Data on the parasite...

Flow microenvironment of two marine peritrich ciliates with ectobiotic chemoautotrophic bacteria

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 29:19-28 (2002) - doi:10.3354/ame029019 Flow microenvironment of two marine peritrich ciliates with ectobiotic chemoautotrophic bacteria Kay Vopel1,*, Christian H. Reick1, Günter Arlt2, Martina Pöhn3, Jörg A. Ott3 1Alfred Wegener Institute for Polar and Marine Research, Columbusstr. , 27568 Bremerhaven, Germany 2Institute for Aquatic Ecology, Marine Biology, University of Rostock, Freiligrathstr. 7/8, 18051 Rostock, Germany 3Department of Marine Biology, Institute of Ecology and Conservation Biology, University of Vienna, Althanstr. 14, 1090 Vienna, Austria *Present address: Department of Oceanography, Florida State University, Tallahassee, Florida 32306-4320, USA. E-mail: cvopel@ocean.fsu.edu ABSTRACT: The flow microenvironment of 2 marine peritrich ciliates, Vorticella sp. and Zoothamnium niveum, with ectobiotic sulfur bacteria was studied with frame-by-frame analyses of video sequences and a microsensor for fluid velocity. Both species populate the chemocline above H2S-releasing mangrove peat. Vorticella sp. moves the surrounding seawater up to a horizontal and vertical distance of at least 400 μm with a maximum flow velocity of 18 mm s-1 close to its peristomial edge. The feather-shaped colonies of Z. niveum generate a unidirectional flow of seawater passing the colony perpendicular to the stalk; the convex side of the feather faces upstream. The flow velocity increased exponentially towards the colony, up to 11 mm s-1 at a distance of 100 μm. Contraction of the stalk forces the zooids of Vorticella sp. and Z. niveum towards the substrate at a high velocity of 71 and 520 mm s-1, respectively. During contraction of Vorticella sp., only little seawater is dragged along towards the surface to which the ciliates are attached whereas the contraction of Z. niveum resulted in a clear increase in the velocity of the seawater both surrounding the colony and above the substrate. Extension of the species proceeds 700 to 1000 times more slowly than contraction, and the surrounding seawater sticks to the cells and therefore is dragged along. The measurements given here support our earlier data indicating the importance of the feeding current for the bacteria-ciliate association, i.e. the cilia beat drives H2S- and O2-containing seawater toward the zooid at high velocity and thus, supports the growth of the ectobiotic sulfide-oxidizing bacteria. Rapid movement, shrinkage (Vorticella sp.) and bunching (Z. niveum) of the zooids during stalk contraction apparently cause sufficient shear stress to abrade ectobiotic bacteria that, once suspended, could enter the feeding currents. KEY WORDS: Sulfur ectosymbioses · Chemoautotrophic bacteria · Peritrich ciliates · Vorticella · Zoothamnium niveum · Flow velocity Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 29, No. 1. Online publication date: September 03, 2002 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2002 Inter-Research.

Pathological and Physiological Changes in the South African Freshwater Crab Potamonautes warreni Calman Induced by Microbial Gill Infestations

The impact of microbial gill infestations on the pathology and physiology of the freshwater crab Potamonautes warreni was investigated by comparison of infested and uninfested crab populations from, respectively, a polluted and an unpolluted site along the Mooi River, North West Province, South Africa. Heavy gill infestations by bacteria (70%), peritrichous ciliates such as Lagenophrys sp. (15%), Zoothamnium sp. (10%), and Epistylis sp. (5%), and motile protozoans resulted in species-specific lesions in the gill epithelia of P. warreni and physiological changes in crabs from the polluted site. Bacterial colonies enmeshed in polysaccharide-like films produced indentations of the gill cuticular surfaces and dissociation of microvillous membranes at the basal zone of epithelial cells of gill lamellae of P. warreni. Lagenophrys sp. induced large subcuticular spaces with an unfolding or resorption of the plasma membrane in the gill epithelia. The attachment of stalks of Zoothamnium and Epistylis resulted in dilation of lamellar tissues, the formation of vacuoles, and an increase in subcuticular spaces in the epithelia. Physiological changes in infested crabs included significant differences (P = 0.001) in increments of wet body mass and a reduced growth rate over time compared with uninfested crabs. The specific oxygen consumption (ṀO2) in rested infested crabs significantly increased (31.29 ± 5.8 μmol O2/kg/min) compared with the ṀO2 in uninfested crabs (27.92 ± 5.6 μmol O2/kg/min; P = 0.009). The heart rate of infested rested P. warreni was significantly lower (40.77 ± 13.79 beats/min; P < 0.02) than that in uninfested crabs (61.09 ± 29.02 beats/min) but the heart rate of infested crabs increased significantly with body mass (r = 0.53, P = 0.02). These findings suggest an interrelationship among organic pollution, microbial gill infestations, and specific pathological and physiological responses in the crab host. The role of P. warreni and its microbial gill communities as bioindicators of pollution are discussed.