Effects of Experimental Acidification on Phyto-, Bacterio-and Zooplankton in Enclosures of a Highly Humic Lake

In situ enclosure experiments were performed in a highly humic lake to examine the effects of acidification on phyto-, bacterio- and zooplankton. The acidity of three enclosures was adjusted with H₂SO₄ to pH 3.5, 4 and 5 and one enclosure and the lake served as controls. The diversity of plankton as well as the mean concentration of chlorophyll α, primary production and respiration of plankton decreased with increasing acidity. Bacterial density was slightly lower in the pH 3.5 enclosure than in the other enclosures and in the lake, but there were no differences in the morphological type or mean volume of the cells between different treatments. In the acidified enclosures Cryptomonas ovata and Chlamydomonas spp. were the dominant phytoplankters, while Dinobryon and Mallomonas species seemed to be most sensitive to acidity. Keratella cochlearis, Kellicottia longispina and Bosmina longispina were the most tolerant zooplankton to acidity.     

A review of studies on Pichavaram mangrove, southeast India

We studied a tropical mangrove ecosystem, situated at Pichavaram, southeast India. We found 13 species of mangrove trees, with Avicennia marinaand Rhizophora species predominant, besides 73 spp. of other plants, 52 spp. of bacteria, 23 spp. of fungi, 82 spp. of phytoplankton, 22 spp. of seaweeds, 3 spp. of seagrass, 95 spp. of zooplankton, 40 spp. of meiobenthos, 52 spp. of macrobenthos, 177 spp. of fish and 200 spp. of birds. The bacteria performed activities like photosynthesis, methanogenesis, magnetic behaviour, human pathogens and production of antibiotics and enzymes (arysulphatase, L-glutaminase, chitinase, L-asparaginase, cellulase, protease, phosphatase). The microzooplankton included tintinnids, rotifers, nauplius stages of copepods and veliger larvae of molluscs, with a predominance of tintinnids. Tintinopsis spp. alone accounted for 90% of abundance. The macrozooplankton consisted of 95% of copepods and coelenterates. The meiofauna was rich with nematodes (50–70% of the component), followed by foramifera. The macrofauna included polychaetes, bivalves, gastropods, tanaids, isopods, amphipods, cirripedes, crabs, hermit crabs and shrimps. The mangrove harboured a large number of juvenile fishes, especially during summer and post-monsoon. The water was fertile and productive in having several fold-higher levels of nutrients, microbes, plankton and other biological resources, than the adjoining estuarine, backwater and neritic environments. The gross primary production was 8 g cm^-3 d^-1; about 21% of which was contributed by phytoplankton of 5–10 m size. Unfortunately, 90% of the mangrove cover in the study area was degraded. Possible factors that cause degradation of the ecosystem are detailed and remedial measures suggested. Techniques for regeneration of the degraded areas are proposed.     

Bartonellosis,an increasingly recognized zoonosis

Cat scratch disease is the most common zoonotic infection caused by Bartonella bacteria. Among the many mammals infected with Bartonella spp., cats represent a large reservoir for human infection, as they are the main reservoir for Bartonella henselae, Bartonella clarridgeiae and Bartonella koehlerae. Bartonella spp. are vector‐borne bacteria, and transmission of B. henselae by cat fleas occurs mainly through infected flea faeces, although new potential vectors (ticks and biting flies) have been identified. Dogs are also infected with various Bartonella species and share with humans many of the clinical signs induced by these infections. Although the role of dogs as source of human infection is not yet clearly established, they represent epidemiological sentinels for human exposure. Present knowledge on the aetiology, clinical features and epidemiological characteristics of bartonellosis is presented.     

Some Dinophycean Red Tide Plankton Species Generate a Superoxide Scavenging Substance

Recent studies indicate that some raphidophycean red tide flagellates produce substances able to scavenge superoxide, whereas there have been no reports on superoxide scavenger production by dinophycean red tide flagellates. In this study, we examined the superoxide-scavenging activity of aqueous extracts from dinophycean red tide flagellates, Gymnodinium spp., Scrippsiella trochoidea, and Karenia sp., by a luminol analog L-012-dependent chemiluminescence (CL) method and an electron spin resonance (ESR)-spin trapping method, and compared the activity to that of raphidophycean red tide flagellates, Chattonella spp., Heterosigma akashiwo, and Fibrocapsa japonica. In the experiment applying the L-012-dependent CL method, only the aqueous extracts from raphidophycean red tide flagellates showed superoxide-scavenging activity. On the other hand, applying the ESR-spin trapping method, we found that the aqueous extracts from dinophycean red tide flagellates also showed superoxide-scavenging activity. This is the first report on the production of a superoxide-scavenger by dinophycean red tide flagellates.     

Pigment and lipid compositions of algal and bacterial communities in Ace Lake,Vestfold Hills,Antarctica

The compositions of carotenoids, chlorophylls and lipids at four depths in Ace Lake have been determined as a means of studying the vertical zonation of species in the lake and for comparison with the lipids found in the bottom sediments. The four major species of phytoplankton found in the lake were identified by electron microscopy. The most abundant phytoplankter was Pyramimonas gelidicola McFadden (Chlorophyta, Prasinophyceae) which occurred in greatest numbers at 10 m, the base of the oxylimnion. The pigments and lipids at this depth were mainly derived from this alga. At 11 m (the top of the anoxylimnion) only traces of lipids and pigments attributable to P. gelidicola were found, indicating only limited settling of algal cells through to the anoxylimnion, at least in summer. The pigments at 11 m were dominated by bacteriochlorophylls c derived from green photosynthetic bacteria Chlorobium spp. These pigments were also abundant at 23 m suggesting the presence of intact bacterial cells which had settled out from higher in the water column. Major non-polar lipid classes in the sediments included sterols, alcohols, hydrocarbons and an unusual suite of very long-chain unsaturated ketones and esters which have not previously been reported from antarctic environments. Several novel compounds, not found previously in either sediments or organisms, are reported. These include tri- and tetra-unsaturated straight-chain C₃₉ methyl ketones and C₄₀ ethyl ketones and the methyl ester of a tetra-unsaturated straight-chain C₃₆ fatty acid. The distributions of lipids in the sediment were markedly different from those in the water column indicating extensive bacterial degradation and recycling of labile lipids.     

Impact of invasive Asian clams,Corbicula spp., on a large river ecosystem

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Comments on the antarctic Rotifera

The Southern and Western water of L. Kyoga is characterised by low mean alkalinities, 1.23±0.08 m eq 1^-1; conductivities, 106±5 µS cm^-1; pH, 7.2±0.2 and high transparencies, 1.7±0.3 m. In the east, comparatively high alkalinities, 1.96±0.34 m eq 1^-1; conductivities, 168±21 µS cm^-1; pH of 7.4±0.2 and low transparencies, 0.8±0.2 m are encountered. Hardness varies as closely as alkalinity from 0.6±0.1 m eq 1^-1 in the west to 1.0±0.2 m eq 1^-1 in the east. SiO₃·Si and SO₄·S decrease westwards from the eastern lake arms, while NO₃·N and PO₄·P vary seasonally in the lake, which is mostly saturated with oxygen (86–120%) from the surface to the bottom. Some evidence of polymixis was encountered.A rich plytoplankton flora occurred with the major groups well represented. Chlorophyceae (37%), Bacillariophyceae (36%) and Cyanophyceae (26%). Synedra spp. (20%). Anabeana spp. (16°10), Nitzschia spp. (10%) were the dominant species groups during July–August 1981. The macrophyte genera Vallisneria, Potamogeton, Nymphaea, Ceratophyllum, Hydrilla occur prominently in the clearer southern lake water. Rotifers and Crustacean Zooplankters found are also recorded. Meroplanktonic crustaceans, chironomids and insects often occur in large numbers.     

Larval Mirogrex terraesanctae (Cyprinidae) of Lake Kinneret (Israel): growth rate,plankton selectivities,consumption rates and interaction with rotifers

The rotifer Synchaeta pectinata dominated gut content of first feeding Mirogrex larvae (7 mm, 10 days age) and was a selected prey of neuston-caught larvae up to 15 mm TL. A negative L-value (linear index of selection) applied to predation on nauplii and copepodites by 7 and 8 mm larvae; nevertheless, caloric intake was dominated by copepods in 8–10 mm larvae. Neuston-caught larvae 13–20 mm TL fed selectively on Cladocera, especially Bosmina, and on the rotifer Asplanchna spp.Growth, estimated from otolith ring counts and from analysis of size distribution data, ranged from 3 to 7 mm mo^–1, with higher rates for early spawned larvae. When consumption as estimated from gut content, was compared to amounts of food required for growth, it appeared that the smallest larvae were underfed, while 13–16 mm fish obtained rations close to sufficiency.Rotifer standing stock biomass in Lake Kinneret has decreased in recent years, especially in winter, the spawning period of Mirogrex. Postulated causes are predation by an increasingly large population of Mirogrex larvae, and decrease of external supply. Larval distribution appeared to be linked to S. pectinata abundance; highest densities of both organisms occurred in the area of inflow from the Jordan and Golan streams. Larval food enrichment of inflow water by fish pond drainage might have caused observed increases in Mirogrex stock size since 1960.     

Euduboscquella costata n. sp. (Dinoflagellata,Syndinea), an Intracellular Parasite of the Ciliate Schmidingerella arcuata: Morphology,Molecular Phylogeny,Life Cycle,Prevalence, and Infection Intensity

The syndinean dinoflagellate Euduboscquella costata n. sp., an intracellular parasite of the tintinnid ciliate Schmidingerella arcuata, was discovered from Korean coastal water in November of 2013. Euduboscquella costata parasitized in about 62% of the host population, with infection intensity (= number of trophonts in a single host cell) ranging from 1 to 8. Based on morphology and nuclear 18S ribosomal RNA gene sequences, the parasite is new to science. Euduboscquella costata n. sp. had an infection cycle typical of the genus, but had morphological and developmental features that distinguished it from congeneric species. These features include: (1) episome of the trophont with 25–40 grooves converging toward the center of the shield; (2) a narrow, funnel‐shaped lamina pharyngea extending from the margin of the episomal shield to the nucleus; (3) persistence of grooves during extracellular development (sporogenesis); (4) a single food vacuole during sporogenesis; (5) separation of sporocytes early in sporogenesis, regardless of type of spore formed; and (6) dinospore size (ca. 14 μm in length) and shape (bulbous episome with narrower, tapering hyposome). After sporogenesis, E. costata produced four different types of spore that showed completely identical 18S rRNA gene sequences. The gene sequence was completely identical with a previously reported population, Euduboscquella sp. ex S. arcuata, from Assawoman Bay, USA, indicating that the two populations are likely conspecific. Favella ehrenbergii, a widely recorded tintinnid known to host Euduboscquella spp., co‐occurred with S. arcuata, but was not infected by E. costata in field samples or during short‐term, cross‐infection experiments.     

The ecology and phylogeny of oomycete infections in Asplanchna rotifers

1. Recently, the potential for parasites to influence the ecology and evolution of their zooplankton hosts has been the subject of increasing study. However, most research to date has focussed on Daphnia hosts, and the potential for parasites to influence other zooplankton taxa remains largely unstudied. 2. During routine sampling of zooplankton in a eutrophic lake, we observed that the rotifer Asplanchna girodi was often infected with a parasitic oomycete. Epidemics of this parasite occurred frequently, with three separate events in a single year. Prevalence at peak infection ranged from 29 to 41% and epidemics lasted from 17 to 56 days. Our data indicate that high densities of the host population are required for epidemics to occur. 3. Our morphological and molecular analyses suggest that this parasite is in the genus Pythium. Most Pythium spp. are plant pathogens, but our study supports recent work on Daphnia, suggesting that Pythium spp. are also important parasites of zooplankton. 4. As the parasite in this study was recalcitrant to cultivation, we developed an alternative method to verify its identity. Our approach used quantitative PCR to show that the ribosomal sequences identified increased with increasing density of infected hosts and, thus, were associated with the parasite. This approach should be generally applicable to other plankton parasites that are difficult to cultivate outside their hosts. 5. Infections significantly reduced host fecundity, lifespan and population growth rate. As a result of the virulence of this parasite, it is likely to influence the population ecology and evolution of its Asplanchna host, and may be a useful model system for studies on host–parasite coevolutionary dynamics.     

Tick tubes reduce blacklegged tick burdens on white-footed mice in Pennsylvania,USA

Lyme disease cases are increasing in the United States. The vector of the pathogen that causes Lyme disease is the blacklegged tick (Ixodes scapularis Say) (Acari:Ixodidae). While there are several tick control options, many are expensive or involve large-scale or ecological interventions such as landscape acaricide spraying or wildlife baiting. Tick control tubes, cardboard tubes with acaricide-treated cotton that can be used as nesting material by tick hosts, offer an alternative to more invasive tick control by treating tick hosts with an acaricide. In this study, tick tubes with cotton treated with two formulations of acaricide and water as a control were evaluated for wildlife use and for tick burden reductions on Peromyscus spp. an important reservoir host for the Lyme disease pathogen. Tick tubes were deployed for four weeks. Ticks parasitizing Peromyscus spp. and cotton use by wildlife were evaluated pre-deployment and post-deployment. Cotton from both treatments was used similarly, and permethrin-treated cotton was used more frequently than the control. In addition, I. scapularis were eliminated from hosts captured in treatment plots post-tick tube deployment. Tick tubes show promise as a tool for tick control on Peromyscus spp., especially as part of an integrated pest management plan.     

Airborne pollen grains in Yalova,Turkey, 2004

In this study, airborne pollen grains of Yalova province were investigated using VPSS 2000 from January to December 2004. During studying period, a total of 22409 pollen grains/m³ which belonged to 46 taxa and 74 unidentified pollen grains were recorded. From the identified taxa, 26 belong to arboreal and 20 to non-arboreal plants. Total pollen grains consist of 80.50% arboreal, 19.17% non-arboreal plants and 0.33% unidentified pollen grains. In the investigated region, from arboreal plant taxa Platanus spp. (29.08%), Cupressaceae/Taxaceae (21.22%), Pinus spp. (7.34%), Alnus spp. (4.75%), Castanea spp. (3.03%), Quercus spp. (3.07%), Olea spp. (2.50%), Acer spp. (2.21%), Corylus spp. (1.41%) and Fagus spp. (1.15%), and from non-arboreal plant taxa Poaceae (10.01%), Asteraceae (2.86%), Plantago spp. (1.47%) and Artemisia spp. (1.11%) were responsible for the greatest amounts of pollen.     

Serological survey of selected infectious diseases in mouflon (Ovis aries musimon) from south-central Spain

Serum samples from 101 mouflons (Ovis aries musimon) collected from July 2002 to January 2006 were tested for antibodies against Anaplasma spp., Brucella spp., bovine viral diarrhea virus, Chlamydophila abortus, Coxiella burnetii, Mycobacterium avium ssp. paratuberculosis, and Maedi-Visna virus. Mouflon came either from extensive farms or high ungulate density fenced hunting estates. Antibodies were detected against Anaplasma spp. (22.2%), C. burnetii (4.0%), M. avium ssp. paratuberculosis (1.0%) and C. abortus (1.0%). According to our results, mouflons could participate as a wild reservoir in the epidemiology of Anaplasma spp. infection and maybe Q fever, but they do not seem to contribute in the epidemiology of the rest of the studied infectious diseases in south-central Spain.     

Bloom forming cyanobacterial complexes co-occurring in a subtropical large reservoir: validation of dominant eco-strategies

In this study, we analyse the spatial distribution of cyanobacterial summer blooms in a large subtropical reservoir located in the Uruguay River, from 2007 to 2011; these extraordinary algal growth events are mainly represented by scum-forming and nitrogen-fixing eco-strategists of the Dolichospermum and Microcystis genera. The use of the eco-strategists approach, based on ecophysiological work and field observations, allowed us to explain the differences in the distribution pattern and temporal dynamics of both cyanobacterial complexes. Spatial differences were produced due to much higher and fluctuating cyanobacterial abundances at the right margin of the reservoir and at the littoral areas closer to the dam. Satellite imagery (LANDSAT 5 TM) clearly depicted the stronger algal development in the reservoir arms and in the section closer to the dam. The Microcystis spp. complex achieved higher density than the Dolichospermum spp. complex. We hypothesise that the hydrological cycle explains the inter-annual fluctuations of the intensity and frequency of cyanobacterial blooms, and that spatial differences in cyanobacterial presence between the reservoir arms, its margins and the main channel is mainly a response to morphometrical and hydrological characteristics.     

Molecular detection of Bartonella in fleas (Hexapoda,Siphonaptera) collected from wild rodents (Cricetidae,Sigmodontinae) from Argentina

Bartonella are facultative intracellular Gram‐negative bacteria, transmitted mainly by hematophagous arthropods, and the rodents act as a natural reservoir. Different species of Bartonella associated with rodents have been implicated as causing human disease. Studies from Argentina are scarce and no Bartonella from fleas have been reported previously. The present study investigated the presence of Bartonella spp. in fleas associated with sigmodontine rodents in four localities of the Santa Cruz Province, Argentina. In total, 51 fleas (four species) were analysed of which 41.2% were found to be positive for the gltA gene fragment via a nested polymerase chain reaction. All positive fleas were of the species Neotyphloceras crackensis from three different localities. Eight of the 21 amplified samples were sequenced, and the presence of three different genotypes was detected with an identity of 95.5–98.8% amongst themselves. Bartonella genotypes from American rodents and rodent fleas were recovered in a monophyletic group. Similarly, most of the Peruvian and all Argentinean variants constitute a natural group sister of the American remainder. The importance of the Bartonella spp. with respect to public health is unknown, although future studies could provide evidence of the possible involvement of N. crackensis in the Bartonella transmission cycles.     

Plankton composition,biomass, phylogeny and toxin genes in Lake Big Momela,Tanzania

Lake Big Momela, one of the East African soda lakes in Northern Tanzania characterised by highly saline-alkaline conditions, making them inhospitable to a range of organisms, although supporting massive growths of some adapted planktonic microorganisms that serve as food for birds, such as Lesser Flamingo. The temporal dynamics of plankton, with an emphasis on cyanobacteria, were examined in 2007 using morphological traits and ribosomal genetic markers (16S and 18S rRNA). Cyanobacterial genes encoding for hepatotoxins (mcyE and ndaF) were also screened. Rotifers and copepods dominated the zooplankton, whereas cyanobacteria, such as Anabaenopsis elenkinii and Arthrospira fusiformis dominated the phytoplankton community, and these being related to representatives in other East African soda lakes. The cyanobacteria community also showed distinct seasonal patterns influenced by environmental parameters, mainly salinity, pH and nitrate. Significant positive correlations were found between phytoplankton abundance and nitrate concentrations (r = 0.617, p = 0.033). No signals of the hepatotoxin synthetase genes mcyE and ndaF were retrieved from cyanobacteria during the whole year. In general, our data illustrate the presence of rich planktonic communities, including some unique and potentially endemic cyanobacteria.     

Impact of whitefish on an enclosure ecosystem in a shallow eutrophic lake: changes in nutrient concentrations,phytoplankton and zoobenthos

Large bag-type (75 m³) and tube-type (105 m³) enclosures were set up in the shallow eutrophic Lake Suwa and were each stocked with exotic planktivorous whitefish (Coregonus lavaretus maraena). The release of whitefish caused the increase in nutrient concentration in the tube-type enclosure whereas no such increase was observed in the bag-type enclosure. Bottom sediment seemed to be an important source of chironomid food for whitefish. The proportion of phytoplankton measuring<10μm and 20–40μm, which respectively corresponded toOchromonas spp. andCryptomonas sp., were lower in the fish enclosures than in the control, which might have been caused by high grazing pressure by rotifers. The predation by whitefish might have affected the species composition of phytoplankton through reducing copepod predation on rotifers, not through reducing the densities of cladocerans which directly feed on phytoplankton as many investigators have reported. The phytoplankton biomass was not affected much by the release of fish. Possible reasons are that the increase in density of rotifers reduced the biomass of available phytoplankton and also that inedible Cyanophyceae were in the decreasing phase of their seasonal succession and could not increase successfully in spite of elevated nutrient levels.     

Effects of silver carp (Hypophthalmichthys molitrix) and nutrients on the plankton community of a deep,tropical reservoir: an enclosure experiment

1. An in situ enclosure experiment was conducted in a deep reservoir of southern China to examine (i) the effects of a low biomass (4 g wet weight m^?3) of silver carp (Hypophthalmichthys molitrix) and nutrients on the plankton community and (ii) the response of Daphnia to eutrophication. 2. In the absence of fish, Daphnia galeata dominated the zooplankton community, whereas calanoids were dominant in the fish treatments, followed by D. galeata. Silver carp stocking significantly reduced total zooplankton biomass, and that of D. galeata and Leptodorarichardi, but markedly increased the biomass of smaller cladocerans, copepod nauplii and rotifers. In contrast, nutrient enrichment had no significant effect on the plankton community except for cyclopoids. 3. Chlorophyta, Cryptophyta and Bacillariophyta were dominant phytoplankton groups during the experiment. Chlorophyta with high growth rates (mainly Chlorella vulgaris in the fish enclosures and Ankyra sp. in the fishless enclosures) eventually dominated the phytoplankton community. Total phytoplankton biomass and the biomass of edible phytoplankton [greatest axial linear dimension (GALD) < 30 μm], Chlorophyta, Cryptophyta, Bacillariophyta and Cyanobacteria showed positive responses to fish stocking, while inedible phytoplankton (GALD ≥ 30 μm) was significantly reduced in the fish enclosures. However, there was no significant effect on the plankton community from the interaction of fish and nutrients. 4. Overall, the impact of fish on the plankton community was much greater than that of nutrients. High total phosphorus concentrations in the control treatment and relatively low temperatures may reduce the importance of nutrient enrichment. These results suggest it is not appropriate to use a low biomass of silver carp to control phytoplankton biomass in warmer, eutrophic fresh waters containing large herbivorous cladocerans.     

The prevalence of opportunistic pathogens associated with intraoral implants

Aims: The aim of this study was to determine the prevalence and proportions of opportunistic pathogens harboured on orthodontic retainers. Methods and Results: First, Staphylococcus spp. and Candida spp. were isolated from the retainer’s inner surface and from other mucosal surfaces of the subject’s mouth by routine bacterial culture. The prevalence and proportions of these micro‐organisms on retainers was compared in different areas of the mouth within a group of retainer wearers, and mucosal carriage was compared to a group of nonretainer wearers. Staphylococcus spp. were isolated from 50% of the retainers and comprised on average 8·4% of the viable microbiota. Candida spp. comprised 0·13% of the viable microbiota and were recovered from 66·7% of the retainers. Neither genus was isolated from nonretainer wearers. Second, the two most commonly worn retainers manufactured from different materials were sampled; again Staphylococcus spp. and Candida spp. were recovered; however, no statistical differences were observed between the devices. Conclusions: Opportunistic, nonoral, pathogenic micro‐organisms were recovered from orthodontic retainers. Significance and Impact of the Study: It is possible that an orthodontic retainer could be a reservoir for opportunistic pathogens and act as a source of cross‐, self‐ and re‐infection.