Two new aero-aquatic species of the hyphomycete genusHelicodendron from Austria

Two new aero-aquatic species of the genusHelicodendron are described and illustrated:H. coniferarum andH. longitubulosum spp. nov. Both belong to the ecological group of the aero-aquatic fungi which inhabit submerged litter in stagnant pools and ditches. The new species are compared with similar species (H. coniferarum withH. fuscum, H. cumbriense, H. multiseptatum andH. pinicola;H. longitubulosum withH. tubulosum andH. longisporum). In addition, ecology and substrates are recorded: WhereasH. coniferarum was isolated from pine litter submerged in oligotrophic peat bog ditches,H. longitubulosum grew on an oak leaf submerged in a eutrophic woodland pond. The presence of microconidia inH. longitubulosum is discussed.     

Neustonic versus epiphytic bacteria of eutrophic lake and their biodegradation ability on deltamethrin

This study evaluated biodegradation of the insecticide deltamethrin (1 μg l⁻¹) by pure cultures of neustonic (n = 25) and epiphytic (n = 25) bacteria and by mixed cultures (n = 1), which consisted of a mixture of 25 bacterial strains isolated from the surface microlayer (SM ≈ 250 μm) and epidermis of the Common Reed (Phragmites australis, (Cav.) Trin. ex Steud.) growing in the littoral zone of eutrophic lake Chełmżyńskie. Results indicate that neustonic and epiphytic bacteria are characterized by a similar average capacity to degrade deltamethrin. After a 15-day incubation, bacteria isolated from the surface microlayer reduced the initial concentration of deltamethrin by 60%, while the average effectiveness of the bacteria found on the Common Reed equaled 47%.     

Microturbellarian species richness and community similarity among temporary pools:relationships with habitat properties

Temporary water bodies exhibit a high level of biodiversity,much of which is unique tothese habitats.Studies of microturbellarian community ecology in temporary pools are scarce,eventhough turbellarians are potentially important in organizing community structure.Moreover,therehas been virtually no documentation of microturbellarians from Israel.We examined the re-lationships between several pool properties (surface area,water depth,permanence and sedimentdepth)and microturbellarian species richness among 52 temporary pools at a single site.A total of17 taxa of microturbellarians were identi ed,of which 14 were determined to genus or species level.Richness was positively related with surface area and with maximal sediment depth,togetherexplaining 54%of the variance.In more intensive sampling of a subset of 18 pools,surface areawas the only signi cant predictor,explaining 76%of the variance.Community dissimilarity waspositively related with di erences in both surface area and permanence.We identi ed three cate-gories of pool size,each characterized by di erent turbellarian species:large pools were dominatedbyCastrada viridis andGieysztoria cuspidata ,intermediate pools byDochmiotrema limicola ,and many of the small pools byGieysztoria ornata andOlisthanella obtusa .Large pools contributed themost to regional diversity,with 11 of the 17 observed taxa.However,some species were unique tosmall pools.Thus,in order to maintain maximal regional diversity of temporary water turbellar-ians,it is important to conserve habitats containing pools of various sizes.     

Rudd (Scardinius erythrophthalmus) introduced to the Iberian peninsula: feeding ecology in Lake Banyoles

The first data on the ecology of rudd (Scardinius erythrophthalmus) introduced to the Iberian peninsula are presented. The habitat and diet variation of rudd were studied in Lake Banyoles (Spain), an oligotrophic karstic lake dominated by exotic fish species. Rudd were strictly littoral and the diet was based on detritus and plant material. The most important animal prey were the cladocerans Daphnia longispinaand Scapholeberis rammneri, amphipods and several late stages of nematoceran dipterans. Rudd were more zooplanktivorous in spring and autumn and less in summer. There was also a size-dependent diet shift, from microcrustaceans to macroinvertebrates. The diet of rudd was also distinguished by the importance of plant material and various small neustonic invertebrates, particularly S. rammneriand late stages of nematocerans, showing a strong resource partitioning with other fish species. The degree of herbivory in Lake Banyoles was lower than usual.     

Field ecology of freshwater macroalgae in pools and ditches,with special attention to eutrophication

A review is presented on the occurrence of macroalgae in dune pools, ditches and moorland pools in The Netherlands, which were studied in the period 1980–1987. There are clear effects of eutrophication on biomass as well as on species composition. A general trend is that under mesotrophic or moderately eutrophic conditions, the filamentous macroalgae form a diversified component of the primary producers in shallow water bodies. Especially spore forming genera asSpirogyra andOedogonium can be represented with up to about 20 species per site. In hardwater ditches alsoVaucheria is an important component, especially the sediment dwellingVaucheria dichotoma. Under distinctly eutrophic conditions dense floating algal masses contain only one or a few species asCladophora glomerata, Enteromorpha intestinalis, Hydrodictyon reticulatum. Under hypertrophic conditions the water surface is covered by dense blanketing mats of duckweeds in summer and autumn. Besides trophic factors, other factors as alkalinity and chloride concentration play a role in species composition. The results are discussed in the framework of water quality assessment of polder waters and possible applications for water purification or use as manuring substance. The need for experimental ecophysiological studies is underlined.     

Isolation of viable cell mass from frozen <Emphasis Type="Italic">Microcystis viridis</Emphasis> bloom containing microcystin-RR

Cyanobacterial species commonly occur in the phytoplankton of freshwater lakes and sometimes develop as toxin-producing blooms. Microcystis is one of the most common genera of freshwater cyanobacteria and is often the dominating phytoplankton of eutrophic lakes all over the world. In eutrophic lakes, large amounts of Microcystis may overwinter in the sediment and re-inoculate the water column in spring. In most cases, the overwintering pelagic population—if it exists—is small, and its role in re-inoculation has not been clear yet. In December 2005, we found large amounts of Microcystis on the surface, frozen in the ice cover in a eutrophic pond (Pond Hármashegy, Hungary). We identified the Microcystis species and investigated the viability and the toxicity of the frozen cells. The dominant species in the bloom samples was Microcystis viridis. Viability tests showed that the colonies isolated from the ice cover were composed of living cells. The isolated strain was found toxic, we analyzed the microcystin composition in the frozen planktonic Microcystis mass; in the investigated samples microcystin-RR was the main cyanotoxin.     

Althenia filiformis Petit: contributo alla conoscenza della ecologia della germinazione

Abstract

New data on the ecology of germination of Althenia filiformis Petit. – The author investigated the natural environment where this species, halophyte and hydrophyte, germinates. The relationships between temperature, salt concentration of pools in which Althenia filiformis lives, and the dormancy of seeds were examined. In particular the author studied the behaviour of this species considering the natural conditions of pools of Orbetello (Tuscany) and Simbirizzi (Sardinia).     

The occurrence of two species of <Emphasis Type="Italic">Macroramphosus</Emphasis> (Gasterosteiformes: Macroramphosidae) in Japan: morphological and ecological observations on larvae,juveniles, and adults

Earlier opinions that Macroramphosus is monotypic are refuted, with two species apparently occurring in Japan (tentatively identified as M. gracilis and M. scolopax). In postsettlement young and adults, the former is characterized by a dark slender body (vs. red-orange and deep) and short second dorsal fin spine with a smooth posterior margin (vs. long spine with a serrated margin). Food habits also differ between the two species, which are either plankton or benthos feeders. Two types of Macroramphosus larvae and juveniles occurring at the surface were recognized, one having a straight ventral body profile of the body (identified here as M. gracilis) and the other having a notch in the anal region. The dark body of postsettlement M. gracilis is considered to be a retention of the character suited to the neustonic distribution of the larval and juvenile stages, the species remaining to ca. 40mm in standard length (SL) in that habitat (vs. to ca. 12mm SL in M. scolopax).     

Diversity,taxonomy and autecology of autochtonous epipelic cyanobacteria of the genus <Emphasis Type="Italic">Komvophoron</Emphasis> (Borziaceae,Oscillatoriales): a study on populations from the Czech Republic and British Isles

Epipelic cyanobacteria were studied in bottom sediments from ponds and lakes in the United Kingdom and the Czech Republic, covering a trophic gradient from deep, oligotrophic, glacial lakes to shallow, eutrophic, urban manmade ponds. Although many planktic species were observed, the most frequently occurring cyanobacteria were the motile filamentous genera Oscillatoria, Phormidium, Pseudanabaena and Komvophoron. These genera represent autochtonous epipelic assemblages, occurring in upper surface layers of the sediments throughout the year and exhibiting seasonal variation in their abundancy. The occurrence of individual Komvophoron species was influenced by sediment quality, particularly the proportions of fine mud and organic detritus. A new species Komvophoron hindakii sp. nov. is described. Morphological features, autecology and occurrence of all the Komvophoron-like morphospecies found are discussed.     

Trophic flexibility by roach Rutilus rutilus in novel habitats facilitates rapid growth and invasion success

Stable isotope and gut content analyses, in conjunction with backcalculated length‐at‐age estimates of growth, were employed to examine the relationship between trophic ecology and growth rate of a successful invader, Rutilus rutilus, in eight lakes in Ireland. The data revealed that R. rutilus was a trophic generalist in Irish lakes. It utilized a greater proportion of pelagic resources in mesotrophic lakes than in eutrophic lakes, potentially due to a greater density of benthic macroinvertebrates in eutrophic systems. The species was characterized by a large dietary and isotopic niche width and high temporal and spatial variations in diet. Growth rates were typical of those found in the native range of the species and were unrelated to either lake productivity or fish's diet. A generalist trophic ecology confers significant advantages on an invasive species, allowing it to exploit a variety of novel resources and fluctuations in prey availability.     

Ecological features affect patterns of plant communities in Mediterranean temporary rock pools

In this paper, the results of a study on the ecology, floristic composition and spatial assemblages of temporary limestone rock pool plant communities of a central Mediterranean area (S Sicily, the Maltese Islands and Lampedusa) are presented. A total of 76 temporary pools were studied, distributed between the infra-mediterranean and thermo-mediterranean bioclimatic belt. For each temporary rock pools, the floristic composition and cover of the species were determined using standard relevé methods. Moreover, for 50 of these pools, pH, conductivity, soil depth, water-level, altitude and floristic richness and diversity index were assessed. The plant communities were analysed using unweighted pair group method using arithmetic averages and Euclidean distance classification and ordination methods such as canonical correspondence analysis (CCA). A total of four plant communities with specific floristic composition were established, each one with a different dominant species: Callitriche truncata; Elatine gussonei; Tillaea vaillantii and Lythrum hyssopifolia. According to the CCA, the spatial patterns of plant communities follow an ecological gradient related to water level and depth/size of the rock pools: these are the main ecological features affecting the distribution of the plant communities of rock pools. In addition, floristic richness and diversity index showed a slight increase in trend from temporary pools submerged for long periods towards pools submerged for short periods.     

The mysterious ecosystem at the ocean’s surface

Life on the ocean’s surface connects worlds. From shallow waters to the deep sea, the open ocean to rivers and lakes, numerous terrestrial and marine species depend on the surface ecosystem and the organisms found therein. Organisms that live freely at the surface, termed “neuston,” include keystone organisms like the golden seaweed Sargassum that makes up the Sargasso Sea, floating barnacles, snails, nudibranchs, and cnidarians. Many ecologically and economically important fish species live as or rely upon neuston. Species at the surface are not distributed uniformly; the ocean’s surface harbors unique neustonic communities and ecoregions found at only certain latitudes and only in specific ocean basins. But the surface is also on the front line of climate change and pollution. Despite the diversity and importance of the ocean’s surface in connecting disparate habitats, and the risks it faces, we know very little about neustonic life. This Essay will introduce you to the neuston, their connections to diverse habitats, the threats they face, and new opportunities for research and discovery at the air-sea interface.

The mysterious ’neuston’ ecosystem at the ocean’s surface includes keystone organisms like the golden seaweed Sargassum that makes up the Sargasso Sea, floating barnacles, snails, nudibranchs, and cnidarians; this Essay explores threats to its wellbeing and the importance of further research.     

Lebensgemeinschaften koexistierender Arten der Wasserkäfergattung Hydroporus aus zwei norddeutschen Untersuchungsgebieten (Coleoptera; Dytiscidae)

The community structure of 15 species of the genus Hydroporus was investigated in various pools with the multivariate software DECORANA, TWINSPAN and CANOCO. Abiotic values measured at 22 bog pools were correlated to DECORANA-data. Typical communities in the Ohemoor (near Hamburg) are related to the factors shaddow, absorption, calcium, and sodium. Data of coexisting Hydroporus species (including other small Dytiscidae, Haliplidae, Noteridae) from 93 pools (near Seedorf/Schleswig-Holstein) could be devided into 4 typical communities (bog, wood, sand-pit, agricultural areas).     

<Emphasis Type="Italic">Coprinopsis austrophlyctidospora</Emphasis> sp. nov., an agaric ammonia fungus from Southern Hemisphere plantations and natural forests

A new ammonia fungus, Coprinopsis austrophlyctidospora, is described from Nothofagus and Pinus forests in New Zealand and from Eucalyptus forest in Australia. In ecology and macro-morphology, this species is similar to the Northern Hemisphere species C. phlyctidospora, but the new species differs in morphological characters of the basidiospore, i.e., in having a plage, more minute surface warts, and the smaller size of the basidiospore.     

Diel vertical migration of <Emphasis Type="Italic">Peridiniopsis niei</Emphasis>, Liu et al., a new species of dinoflagellates in an eutrophic bay of Three-Gorge Reservoir,China

In spring, a typical dinoflagellate (Peridiniopsis niei Liu et al.) constitutes most of the phytoplankton biomass in most of eutrophic bay of Three-Gorge Reservoir (TGR, China). There are few field observations on vertical migration of the members of the genus Peridiniopsis. We studied diel vertical migration of the new species (Peridiniopsis niei) at sampling stations A and B in an eutrophic bay (Xiangxi Bay) of TGR during both day and night in March 2007. The present study suggests that vertical migration by Peridiniopsis niei is similar in nature to the migration patterns observed for other dinoflagellates. Solar irradiance incident was an important factor regulating the ascent and descent of Peridiniopsis niei. The vertical descent of Peridiniopsis niei during nighttime was restricted when the thermocline (Temperature gradient >1°C m⁻¹) was present in the station B.     

The ecology of two species of primitive ciliated protozoa commonly found in standing freshwaters (Loxodes magnus stokes and L. striatus penard)

The distribution of Loxodes magnus and L. striatus (Karyorelictida) was investigated in two eutrophic waters (Esthwaite Water and Priest Pot, English Lake District). In the benthos, these species were most abundant at the sediment surface, at deeper sites, and when the bottom water was oxygenated. In the plankton, in Priest Pot, they were found only in the oxygen deficient summer hypolimnion. Experimental studies suggested that L. magnus and L. striatus required access to oxygen. Loxodes was apparently excluded from the oxygenated Priest Pot epilimnion by several adverse factors, one of which was bright light. It was concluded that the ecology of L. magnus and L. striatus resembles, in many ways, that of the advanced ciliates which were found associated with Loxodes.     

Seasonal variability of ichthyoneuston assemblage on the continental shelf and slope of the Southwest Atlantic Ocean,Brazil (20°–23°S)

Many marine organisms spend the early life history stages in neuston domain. Although the importance of ichthyoneuston, few studies were developed in the Southwest Atlantic Ocean. Therefore, this study aimed to improve the knowledge on ichthyoneuston of the Brazilian coast analyzing the vertical stratification and horizontal distribution of these organisms. Neuston samples were collected in daylight between 20°S and 23°S from February to April 2009 (late summer/early autumn; rainy season) and from August to September 2009 (late winter/early spring; dry season). Eggs of six taxa were identified: Anguilliformes, Engraulidae, Clupeidae, Synodontidae, Trichiuridae, and Maurolicus stehmanni (Sternoptychidae). The neustonic larval fish assemblage was composed by 40 families and 63 species. Mullidae and Myctophidae larvae were the most abundant in the rainy period while Mullidae and Mugilidae dominated in the dry season. Seasonal and spatial variation of larval fish assemblages in the neuston were structured by oceanographic features. The larval fish abundance on the outer slope stations may have been favored by the advection of an anticyclone that encompassed most of the study region during the cruise periods. In the rainy season, salinity and local depth structured the larval fish assemblage in a cross‐shelf gradient, while in the dry season the larval assemblage was structured around temperature and north‐south gradient. In the dry season, the cross‐shelf gradient was less pronounced mainly because of the low abundance and frequency of mesopelagic larvae. The low frequency and abundance of some species are probably related to the net avoidance of fish larvae during the day or dial vertical migration, as many species migrate to deeper layers during the day and ascend to neuston only at night. Nevertheless, the present study presented baseline information about the seasonal and spatial variation of the neustonic larval fish assemblage influenced by the oceanographic conditions in the Campos Basin. We recommend to additionally collect night samples to decrease larval escapement rates and to compare night versus day catches to further investigate the influence of daily migration in the neustonic larval fish in the area.