Phytoplankton and zooplankton as indicators of water quality in Discovery Bay,Jamaica

Several investigations exist which use planktonic communities as indicators of water quality in Jamaican and Caribbean Bays, however, few are conducted before there are obvious effects of eutrophication. Therefore, most of our ‘baseline’ data are for bays already severely affected by pollution. This study was conducted to assess water quality in Discovery Bay, Jamaica, before there were severe signs of eutrophication. The bay was monitored over a 12-month period (October 1995–September 1996) using 10 stations. Physicochemical data indicated a well mixed upper 5 m of water column, below which discontinuities in temperature/salinity profiles indicated the influence of colder, more saline waters associated with deep offshore currents. Physicochemical variables were within the range for oligotrophic systems with a tendency towards mesotrophic in localized areas close to the shoreline. Signs of anthropogenic stress were associated with the eastern, southwestern and western sections of the bay. Of the over 120 species of phytoplankton found in the waters of Discovery Bay, most were neritic/oceanic and diatoms dominated while 11 were found to be potentially harmful species. While these harmful species occurred at all stations they occurred most frequently at stations on the eastern side of the bay. About 107 zooplankton species were identified, 52 of which were copepods. The species also represented a mix of neritic and oceanic taxa and mean abundances for the area ranged from 1077 m⁻³ at the mouth of the bay to 3794 m⁻³ close to the south shore (station 6). Generally stations closest to shore had greater zooplankton abundances than centrally located bay stations and stations close to oceanic influence. Acartia tonsa and Lucifer faxoni showed greatest densities at shoreline areas of the bay while Oithona plumifera, Undinula vulgaris and Temora stylifera were important at stations closest to oceanic influences. These species were thus considered as indicators of these different areas within the bay. From physicochemical data and the planktonic assemblage, Discovery Bay cannot be considered polluted, it is still more accurately classified as generally pristine with mesotrophic zones in the eastern and southeastern sections of the bay. These data therefore provide a real baseline of conditions for similar tropical coastal embayments.     

Morphological and Molecular Redefinition of Euplotes platystoma Dragesco & Dragesco‐Kernéis, 1986 and Aspidisca lynceus (Müller,1773) Ehrenberg, 1859, with Reconsideration of a “Well‐known” Euplotes Ciliate,Euplotes harpa Stein, 1859 (Ciliophora,Euplotida)

We documented the morphology, infraciliature, silverline system, and molecular data of two euplotid species isolated from China, including two populations of the poorly known Euplotes platystoma Dragesco & Dragesco‐Kernéis, 1986 and the previously well described Aspidisca lynceus (Müller, 1773 ) Ehrenberg, 1830. Based on the information available, an improved diagnosis of Euplotes platystoma is given, including: a narrow adoral zone with 44–68 membranelles, 10 frontoventral, 5 transverse, 2 left marginal and 2 caudal cirri, 11–13 dorsal kineties with 17–25 dikinetids in the mid‐dorsal row, and dorsal silverline system of the double‐eurystomus type. The Chinese population of Aspidisca lynceus closely resembles previously described populations. Phylogenetic analyses inferred from SSU rDNA sequences show that E. platystoma is closely related with E. neapolitanus, and the internal position of A. lynceus within this genus is still not robust. A reconsideration of the “well‐known” Euplotes harpa and a comparison of all SSU rDNA sequences of E. harpa in GenBank are provided. We speculate that the sequences available from GenBank under the name of E. harpa are very likely from misidentified materials, that is, the identity of the species currently associated with the SSU rDNA of this “well‐known” form in molecular databases requires further confirmation.     

Benthic ciliates in Adriatic Sea lagoons

Sediment samples were collected from four sandy and muddy bottom sites at both Sacca di Goro lagoon (northern Adriatic Sea) and Lesina lagoon (southern Adriatic Sea) on one occasion in May and one occasion in July in order to make a comparative study of ciliate abundance and diversity. The temperature, pH, dissolved oxygen, and redox potential were measured at the time of collection, the water content of the sediments was determined, and samples subjected to granulometric analysis. The ciliated protozoa in sub-samples from the top centimeter of sediment were identified to genus and species level and enumerated. Ciliates belonging to 38 and 33 species were found in the sediment of Sacca di Goro and Lesina, respectively, the diversity of ciliates varying widely between stations. Total ciliate numbers ranged from 32 to 759 cm(-2) and from 2 to 256 cm(-2) at Sacca di Goro and Lesina, respectively; the ciliate biomass ranged from 1.1 to 30.3 microg C cm(-2) in the samples collected at Sacca di Goro, and from 0.01 to 157 microg C cm(-2) in the samples collected at Lesina lagoon. Aspidisca lynceus, Aspidisca steini, Chilodonella uncinata, Frontonia marina, Pleuronema marinum, Strombidinopsis minimum, Strombidium sp., and Urotricha sp., were observed at the two lagoons but not in all stations; Keronopsis flavicans and Trachelostyla pediculariformis were often numerous at Goro lagoon, A. lynceus, Condylostoma patulum and Tracheloraphis teissieri were the most abundant ciliates observed at Lesina lagoon.     

Signal-induced Defensive Phenotypic Changes in Ciliated PProtists: Morphological and Ecological Implications for Predator and Prey1

ABSTRACT. Survival of a potential prey organism depends on the effectiveness of its physical, chemical, behavioral and life history responses to the appearance of a predator. Inducible defenses are flexible responses in which predator (or competitor)-released substances stimulate potential prey organisms to transform into predator-resistant phenotypes. Induced defenses may be highly protective. Benefits however are often balanced by fitness costs such as decreased growth rates or reduced reproductive potential. Here I discuss inducible defenses in ciliates with particular attention to the hypotrich genera: Aspidisca, Euplotes, Onychodromus, Sterkiella, and an undescribed hypotrich genus. I isolated Sterkiella sp. and the undescribed genus from vernal woodland pools on Saint Anselm College campus. Experimental evidence shows that a signal-induced defensive transformation occurs in these ciliates within hours after exposure to a predator cue and results in a significant decrease in susceptibility to predation. Deployment of ciliate antipredator structures such as spines, keels, ridges and other protuberances requires a large investment of cytoskeletal elements, primarily microtubules, and incurs an evolutionary cost in the form of significantly reduced growth rates. Onychodromus quadricornutus exhibits an extraordinary degree of phenotypic plasticity. In response to different environmental conditions individuals within a clone may express one of three general phenotypes: basic, lanceolate, or giant cells. The predacious giant phenotype releases a morphogenetically active signal substance, Onychodromus-factor, that triggers defensive phenotypic transformation in both intraspecific and interspecific prey. Enzyme degradation and ultrafiltration experiments indicate that Onychodromus-factor is a peptide with a molecular weight below 10,000 Da. Conspecifics develop hypertrophied dorsal spines when exposed to Onychodromus-factor. Sterkiella cells develop two defensive dorsal keels and transform to an enlarged ovoid cell in response to Onychodromus-factor as well as inducing signals released by Stylonychia, Urosyla, and Lembadion. Field studies of two vernal pools show that defensive phenotypic transformation in Sterkiella cells coincides with the appearance of Lembadion magnum during vernal pool succession. An undescribed hypotrich genus also expresses its defended phenotype when Lembadion is present in these pools. Aspidisca turrita (Ehrenberg, 1838) Claparede and Lachmann 1858, closely resembles Aspidisca lynceus (Müller, 1773) except for the possession of a dorsal thorn-like structure. Experimental evidence shows that the dorsal thron is a defensive structure induced by signals released by the predacious ciliates Urostyla grandis and Lembadion magnum. Thus, A. turrita and A. lynceus are alternate phenotypes of the same species. I speculate that inducing signals function in predacious ciliates as lectin-like, carbohydrate-binding adhesion proteins during prey recognition and that prey species have evolved specialized cell surface receptors that allow detection of different predator proteins. I consider consequences for both predator and prey.     

Morphology of two marine euplotids (Ciliophora: Euplotida), Aspidisca fusca and A. hexeris,with notes on their small subunit rRNA gene sequences

We investigate the living morphology, infraciliature, and small subunit rRNA gene sequences of two poorly known marine euplotids, Aspidisca fusca Kahl, 1928 and A. hexeris Quennerstedt, 1869, isolated from intertidal sewage outfall, northern China and sandy sediments, southern China, respectively. Improved diagnoses and morphometric data are provided for both species. Aspidisca fusca is characterized by having a peristomial spur, seven frontoventral cirri in a “polystyla-arrangement”, and two oval macronuclear nodules. Aspidisca hexeris can be recognized by having an elliptical body shape, a peristomial spur, seven membranelles in the anterior portion of adoral zone and 11–13 in the posterior part, as well as seven frontoventral cirri arranged in two oblique rows. In addition, the presence and degree of projections along the left margin of A. hexeris are highly variable among populations. Phylogenetic analyses based on small subunit rRNA gene sequence data support the validity of both A. hexeris and A. fusca as distinct species, and indicate that A. fusca is most closely related to A. aculeata and A. steini, whereas A. hexeris shows a close relationship with A. magna.     

The Distribution of Hydrobiids and the Effects of Sediment Characteristics on the Population Dynamics of Hydrobia ventrosa in a Coastal Region of the Southern Baltic

The composition of the hydrobiid fauna in a coastal water of the southern Baltic was studied in 1990/91 at three stations with different sediment characteristics (grain size, organic content). Four species were found (Hydrobia ventrosa, H. ulvae, H. neglecta and Potamopyrgus jenkinsi). H. ventrosa was dominant at all stations. The mean hydrobiid abundances were 4,000 (stn. C), 18,000 (stn. B) and 40,000 (stn. A) ind./m² respectively. Abundance was found to correlate with the organic content of the sediment. The reproduction and growth of H. ventrosa was studied. Two reproduction phases were observed, one in summer and the other in late autumn. The autumn reproduction peaks were staggered owing to the different growth rates at the various stations. Possible correlations between the differences in shell size of H. ventrosa at the various stations and both sediment characteristics and abundance are discussed.     

Offshore cephalopods (Mollusca: Cephalopoda) collected off the west coast of Mexico during the TALUD cruises

Deep-sea cephalopods are still poorly studied worldwide. In the case of the Mexican Pacific there is a general lack of basic information concerning their distribution and biology. A series of 132 specimens of pelagic and benthic deep-water cephalopods was obtained during the TALUD project. Samples were mostly obtained with benthic sampling gear that operated as mid-water trawls during the ascent of the nets. Micronekton and Isaacs-Kidd samplers were also occasionally used. The specimens (77 lots in total) were obtained at localities off western Mexico at depths between 122 m and 2200 m and belong to 31 species. Considering material identified to species level only, a total of 13 species were found only at a single station, while five others occurred in 5–6 stations (i.e., Leachia dislocata, Abraliopsis [Pfefferiteuthis] falco, Pterygioteuthis giardi, P. holeyi and Benthoctopus robustus). The most widespread species was Japetella diaphana, collected in 11 stations. Twenty-two of the 31 species are strictly pelagic, eight strictly benthic and one is benthopelagic. Significant new distribution records were obtained for seven species: Doryteuthis opalescens, Gonatus berryi, Todarodes pacificus, Opistoteuthis californiana, Benthoctopus leioderma, B. robustus and Graneledone boreopacifica.     

The influence of fundamental design parameters on ciliates community structure in Irish activated sludge systems

The protozoan community in eleven activated sludge wastewater treatment plants (WWTPs) in the greater Dublin area has been investigated and correlated with key physio-chemical operational and effluent quality parameters. The plants represented various designs, including conventional and biological nutrient removal (BNR) systems. The aim of the study was to identify differences in ciliate community due to key design parameters including anoxic/anaerobic stages and to identify suitable bioindicator species for performance evaluation. BNR systems supported significantly different protozoan communities compared to conventional systems. Total protozoan abundance was reduced in plants with incorporated anoxic and anaerobic stages, whereas species diversity was either unaffected or increased. Plagiocampa rouxi and Holophrya discolor were tolerant to anoxic/anaerobic conditions and associated with high denitrification. Apart from process design, influent wastewater characteristics affect protozoan community structure. Aspidisca cicada was associated with low dissolved oxygen and low nitrate concentrations, while Trochilia minuta was indicative of good nitrifying conditions and good sludge settleability. Trithigmostoma cucullulus was sensitive to ammonia and phosphate and could be useful as an indicator of high effluent quality. The association rating assessment procedure of Curds and Cockburn failed to predict final effluent biological oxygen demand (BOD₅) indicating the method might not be applicable to treatment systems of different designs.     

A comparison of the zooplankton of Lake Kainji and of the Rivers Niger and Swashi

Seventy-nine taxa of periphyton were collected on Plexiglas plates at seven stations in the three streams between March, 1975, and February, 1976. More taxa and lower densities were generally observed at the upstream stations in the creeks than at the downstream stations resulting in greater species diversity values at the upstream stations. Species diversity was generally lower in the river than in the creeks, reflecting the lower numbers of taxa and the presence of several abundant species. Species diversity did not reflect extremes in physiochemical conditions. Although several different species were abundant in the streams during the present study, the most commonly occurring dominants were Gomphonema olivaceum and species belonging to the genera Navicula and Nitzschia. No consistent trend was observed in ash-free weight; however, the concentration of chlorophyll a was generally greater at the downstream stations in the creeks than at the upstream stations.     

Fish impingement at power stations situated along the rivers Rhine and Meuse in The Netherlands

Summary Substantial numbers of predominantly O⁺ fish were impinged on the cooling water screens of Harculo, Gelderland, Merwedehaven and Amer power stations. Low numbers were impinged at the two stations located on the river Meuse (Maas and Claus). Two possible reasons for this difference are suggested,viz. a low fish density in the river Meuse and the deep position of the cooling water intakes. In comparison with Bergum power station situated on a lake the impingement rate at the river stations was more than ten times as low.Most fish were impinged during the summer months when large numbers of juvenile fish are present in the rivers. Dominating species impinged were roach, pikeperch, bream and perch. The abundance of pikeperch in the screensamples, points to a recent increase in the population of pikeperch in the rivers. The growth pattern of O⁺ pikeperch and O⁺ roach during summer seemed very similar for power stations located at different rivers. Thirty fish species and four crustacean species were collected, among whichOrconectus limosus was quite abundant at Maas and Claus power stations.     

Biodiversity of epibenthic community in the inshore waters of southeast coast of India

The epifaunal assemblage was evaluated at three different depths (5, 15 and 25 m) in the inshore waters of Pazhayar, Parangipettai and Cuddalore apart from 5 m depth near SIPCOT covering totally 10 stations (11°21′ N to 11°42′ N; 79°46′49″ E to 79°52′34″ E) in the southeast coast of India, Bay of Bengal. The occurrence of as many as 112 species belonging to 6 groups was recorded. Among these, gastropods constituted the largest component (42.85%) with 48 species. Bivalves came next with the percentage contribution of 24.10% with 27 species. Crustaceans and polychaetes contributed with 16.96% (19 species) and 6.25% (7 species), respectively. Others contributed with 9.82% (11 species). The maximum number of species was recorded in Cuddalore transect (65 species) and the minimum in SIPCOT (20 species). The maximum abundance was recorded in SIPCOT (1363 ind./haul) but the diversity was found to be lower here than in the other stations. The bivalve, Scapharca inaequivalvis was abundant only in this station whereas the large sized polychaetes, Epidiopatra hupferiana monroi and Sternaspis scutata were found only in the Pazhayar transect during all the seasons. Multivariate analyses were done to define assemblages. The total number of species estimated by various extrapolators varied from 112 species to 169.73 species. The cluster analysis revealed the gradual change in species composition with increase in depth. In the principal coordinate analysis (PCO) the first two axes explained 49.8% of the total variability in the case of biota and 98.3% of the total variability in the case of environmental variables. The distance based linear model (DISTLM) was used to find out the relationship between the abundance of epifauna and environmental variables. Depth explained about 23.7% of the variability while temperature and pH explained 17.5 and 10.6%, respectively. The best solution suggested all the nine environmental variables to combinedly explain about 92.49% of the total variability     

Etude de la dynamique des populations de cilies d'un torrent experimental pendant deux annees

The sampling of Ciliates performed in a little experimental torrent through two years, showed a great similarity of the two annual cycles. This similarity concerns both the species composition as well as the dynamics of the Ciliates populations. The basic species which affect the community structure are as follows: Ctedoctema acanthocrypta, Mesodinium acarus, Cyclidium glaucoma, Cinetochilum margaritaceum, Pleuronema coronatum, Lacrymaria pupula, Aspidisca costata and Holosticha vernalis. The dynamics of the ciliated Protozoa living in this environment seem to be influenced by the speed of the current, the temperature and the amount of dissolved organic matter in the water.

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Etude de la dynamique des populations de cilies d'un torrent experimental pendant deux annees

     

Influence du substrat sur la répartition des Crustacés stygobies interstitiels du Haut-Atlas occidental

The interstitial stygobiont distributions of two rivers in the western High Atlas is analyzed in relation with sediment granulometry. Sixteen stations were sampled along the rivers N'Fis and Zat and their tributaries. Granulometry analyses were performed. Three grain size sediment types constitute the subterranean biotopes and reflect the local hydrodynamical conditions. The main rivers stations, which undergo frequent natural or human disturbances, are characterized by a high content of fine sediment; in contrast, tributaries stations show coarse and well-classified sediments due to more stable biotopes and more regular hydrological conditions. The 92 taxa group 28 stygobiontic species with 11 crustaceans species. PCA. based on 16 stations, three faunistic richness indexes and three granulometric factors display a high correlation between coarse grain-size content and the richness of stygobiontic taxa. A high silt content both limits the interstitial taxa and excludes crustaceans that occur only in coarse gravels. The granulometric preferenda in the species of the amphipod genus Metacrangonyx and isopods Microcerberus. Microcharon and Typhlocirolana are shown on Shepard triangular diagrams. Cohabitation of several species of the same genus could be explained by the occupancy of different ecological niches resulting from the grain-size proportion.     

Distribution and population dynamics of ostracodes (Crustacea,Ostracoda) in a karstic lake: Lake Banyoles (Catalonia,Spain)

Qualitative and quantitative benthic samples were collected monthly between December 1986 and December 1987 from several stations at various depths and basins in the karstic Lake Banyoles (Catalonia, Spain), to study the spatial distribution and seasonality of ostracodes. A total of eight ostracode species were found in the lake. Of these, Candona neglecta Sars, Isocypris beauchampi Paris and Cypria ophtalmica Jurine were the most common ostracodes at all depth stations. Darwinula stevensoni Brady & Robertson, Ilyocypris species (I. bradyi Sars and I. gibba (Ramdohr)), Cyprideis torosa (Jones) and Cyclocypris ovum Jurine, on the other hand, were confined to sublittoral and littoral areas of the lake.Substrate and organic matter content appeared to be relevant factors determining the distribution of ostracode species at the different stations. The highest abundance of ostracodes were in the sublittoral (Basin IV–7 m and Basin I-5 m) where the substrate was coarse and sediment had a high organic matter content (>35% LOI). Low oxygen levels in the hypolimnetic waters (i.e. < 1 mg l^–1) may explain the absence of ostracodes at deeper zones in stations where the anoxic period lasts more than four months. On the other hand, low temperatures seem to favour the development of C. neglecta and D. stevensoni, while with higher temperatures I. beauchampi, C. torosa and C. ovum increased their abundances. However, no clear pattern can be observed, so ostracode species in Lake Banyoles, apparently, have non-seasonal life histories.     

Species diversity and assemblages of macrobenthic Mollusca from the South Shetland Islands and Bransfield Strait (Antarctica)

During the research program BENTART 95, carried out from 16 January to 4 February 1995 on board RV Hesperides, a semi-quantitative Agassiz trawl and quantitative Van-Veen grabs were used at 31 subtidal stations between 40 and 850 m depth around Livingston Island, at Deception Island and in the Bransfield Strait. These data were used to search for and analyse the malacological assemblages. Among the molluscs sampled were 1,786 individuals belonging to 70 species of Solenogastres, Gastropoda Prosobranchia and Opisthobranchia, Scaphopoda and Bivalvia. The values of Shannon-Wiener diversity index ranged between 0.00 (one specimen) and 3.95, while Pielou's evenness index varied between 0.0 and 1.00. The bivalve Thyasira cf. dearborni was the most abundant species (227 specimens). Species richness varied from 1 to 19 species. Diversity showed great variations at different stations. The clustering analysis applying the Bray-Curtis coefficient allowed species classification according to constancy and fidelity, and distinguished four groups of stations: one that gathers clearly the stations of the inner bay of Deception Island, excepting station 1, and the other three fitting the remaining stations, located north and south of Livingston Island and in the Bransfield Strait, and correlated with environmental factors (granulometric composition, organic matter and carbonates). Accepted: 18 July 2000     

Distribution,biology and hybridization of Scaphirhynchus albus and S. platorynchus in the Missouri and Mississippi rivers

Synopsis Scaphirhynchus albus and S. platorynchus were studied in Missouri during 1978–1979 to assess their distribution and abundance, to obtain information on their life histories, and to identify existing or potential threats to their survival. S. platorynchus was collected in substantial numbers (4355 specimens) at all 12 sampling stations in the Missouri and Mississippi rivers, while only 11 S. albus were captured from 6 stations. Twelve specimens identified in the field as hybrids between the two species were captured from 4 stations. Morphometric and meristic comparisons of presumed hybrids with the parent species, using cluster and principal components analyses, demonstrated intermediacy of most specimens identified in the field as hybrids. Aquatic insects comprised most of the diet of S. platorynchus and S. albus, but S. albus and the hybrids had consumed considerable quantities of fish. S. albus grew more rapidly than S. platorynchus, while the growth of hybrids was intermediate. Hybridization appears to be a recent phenomenon, resulting from man-caused changes in the big-river environment. Hybridization may be a threat to survival of S. albus in the study streams.     

The biodiversity and biogeography of the free-living nematode genera Desmodora and Desmodorella (family Desmodoridae) at both sides of the Scotia Arc

Samples taken at two stations in the northern and southern parts of the Scotia Arc, at depths of 277 and 307 m, respectively, were analysed for metazoan meiofauna with special attention to the nematodes. Identification to species level was performed for two closely related subdominant nematode genera (Desmodora and Desmodorella) in samples from the two Scotia Arc stations and in other available samples from adjacent areas (Magellan Region, Drake Passage, Weddell Sea). Seven Desmodora species and three Desmodorella species were found, of which, respectively five and two species are new to science. The Scotia Arc stations show relatively high densities and average diversity on meiofauna and nematode level compared to adjacent areas. The distribution patterns of the various Desmodora and Desmodorella species suggest the Scotia Arc as a shallow bridge and a possible exchange route for meiofauna between the Antarctic and South America, especially since these species seem to be constrained by water depth.     

The ciliated protozoa of the monomictic Lake Kinneret (Israel): species composition and distribution during stratification

The ciliate taxa from epilimnion, hypolimnion, and littoral of Lake Kinneret were studied from November to December 1987 during stratification. Two collections of planktonic and benthic ciliates were taken at each of six sampling stations. Benthic ciliates from the littoral zone were collected at seven stations along the lake shore. Densities were determined for each ciliate species and for total protozoans at each station and sampling date. Thirty-six species of ciliates, representing 31 Genera, 18 Orders and 7 Classes, were identified. Planktonic protozoans characteristic of the epilimnion included Coleps hirtus and Vorticella mayeri. The more abundant taxa of benthic ciliates in the profundal of the lake included Saprodinium dentatum, Plagiopyla nasuta and Dexiotricha plagia. The predominant ciliate in the littoral was Pleuronema coronatum. Principal component analysis, performed on the correlation matrix of both sampling stations and species, revealed that epilimnion, hypolimnion, and littoral belt were colonized by different ciliate communities.     

Riunione Generale Straordinaria in Val D'aosta

Abstract

The present study focused on the bryoflora of watercourses of the Tiber River basin watercourses (Central Italy). A total of 20 bryophyte species, which included 14 mosses and 6 liverworts, were collected at 32 river stations. Most species were recorded at stations of the watercourses' upper sections, which have rocky substrate and where there is cool and well oxygenated running water, with low trophic load. Only few species, such as Leptodictyum riparium, Cinclidotus fontinaloides and Riccia fluitans, were also found at stations of the middle and lower sections, which are characterized by slow-flowing, turbid, warm and eutrophic waters. Some species are widely distributed, among which Fontinalis antipyretica ssp. antipyretica and Platyhypnidium riparioides, while others are very rare, such as Cinclidotus aquaticus, Dialytrichia mucronata and R. fluitans. Some of the collected species are new regional records (Hygroamblystegium fluviatile, D. mucronata), regional confirmations of rare taxa in Italy (C.aquaticus) or confirmations of old regional reports (Hygroamblystegium tenax, C. fontinaloides, Aneura pinguis).