Although the data on phosphate obtained in surveys are used to assess the distribution of river biota, the approach is flawed when the organisms use P fractions not included in routine analysis. This is especially important where aquatic phototrophs are partially or largely dependent on aqueous organic phosphate. This paper reports a study where the data are sufficient to assess the quantitative importance of organic phosphate in rivers in eastern UK. Filterable hydrolyzable phosphate-P (FHP) is used as a surrogate for organic phosphate, although FHP sometimes includes other P forms. Eighteen sites were sampled weekly for at least one, but mostly three years (2033 samples). The data are compared for mid- and lower-reach sites. FHP formed at least 20% TFP (total filterable phosphate-P) at 14 sites, with the percentage values higher at the more upstream and more northern sites. FHP exceeded 1000 μg.L−1 P in 32 mid- and 53 lower-reach records. The lower the TFP concentration, the higher the % FHP at both types of site. Five sites had over 25% of their records where FHP is likely to be especially important for growth of algae and bryophytes, based on FHP being >50 μg.L−1 P when TFP ≤200 μg.L−1 P. These include the upper site on River Swale, and other literature for this river indicates that FHP becomes increasingly important further upstream and even more so in tributary streams. FHP should be included in monitoring programmes for upland rivers, especially where the catchment includes peat-rich soils.

Escherichia coli is an indicator of fecal pollution used to mandate recreational and drinking water quality. Concentrations of culturable E. coli following contamination of surface water are determined by three factors: dilution; cell attachment to particulate material and settling or resuspension in the water column; and the net rate of change in viability. This study evaluated the variability in the latter parameter, and how predictive variation in death rate was of culturable population densities at the time of sampling. Water samples (N=232) with varying levels of E. coli contamination were collected from 46 discrete locations in four watersheds across Canada over a three-month period and enumerated for culturable E. coli by membrane filtration plate counting (T0EC). Water samples were again enumerated following a laboratory 24 h holding period at 30°C in the dark, and the difference considered the death rate (ΔEC). Relationships of T0EC and ΔEC with environmental and water chemistry factors were explored using step-wise multiple regression. The model predicting T0EC indicated that stream order, total rainfall seven days in advance of sampling day, total phosphorus, and ΔEC were the most significant contributors. The model predicting ΔEC indicated that turbidity and NH3+NH4 were the most important contributors. A model suggests that the persistence factor is less important than dilution (i.e. stream order) in describing E. coli densities, followed by factors that influence the loading of E. coli into watersheds.

In the present work, based on material from several localities in Brazil, the genus Aturbina is reviewed. Two new species, A. maculata, sp. nov. and A. nigra, sp. nov. are described based on nymphs and adults; the type-species, A. georgei, is redescribed based on nymphs and reared adults; the nymphs and adults of A. beatrixae are respectively described and redescribed, as well as recorded from Brazil for the first time. Based on these findings, an updated key to nymphs and adults of the genus is provided.

Taxonomical efforts in freshwater zooplankton are continuously needed for the delineation of species. Even today, confusion exists in correct identification of several European Cladocera because of poor original descriptions and subtle differences in morphology. In this context, we discuss three of the rarest Alona-like Chydoridae in the Palaearctic and their validity. 1) Alona moniezi, only reported once from Vichy area, France, has a male indistinguishable from that of A. elegans Kurz, 1875 while females show characters of A. elegans and of Coronatella rectangula. We provide a description of this taxon, with intermediate morphology and discuss the possibilities of hybridization. 2) Alona karelica is unusual as one of the few eurythermic species of a predominantly stenothermic A. pulchella-group. We discuss Neotropical A. cf. karelica from Mexico as its closest relative. Both show similarities with the semi-terrestrial A. bromelicola from Nicaragua, forming a small A. karelica-section within the A. pulchella-group. 3) A. weltneri is redescribed based on type material and we confirm it as a member of the A. costata-group. We discuss the three taxa and expand their diagnosis. A. weltneri and A. karelica are both found sporadically, and little is known about their ecology. Their scarcity in the Palaearctic may be linked with specialisation to a peculiar habitat and the possibility that these are true relicts.

Water microbiological and physicochemical characterizations at various depths of aquatic ecosystems are basic requirements in several fields of research. A chief difficulty in hydrobiology, limnology, biological oceanography and water environmental microbiology is that of taking accurate field collections that are representative of the natural environment and population at various depths of aquatic ecosystems. Gathering water/plankton samples in a level just below the surface of the water body upon rising in columns from various depths due to hydrostatic pressure variations provided a simple approach for water and plankton sampling. Based on this approach, several forms of simple devices for water and plankton sampling were developed for water microbiological and physicochemical characterizations at various depths of aquatic ecosystems. The described approach showed less sampling errors in comparison to Van Dorn bottle and was comparable to water pumping but requires no external source of power. The described samplers are inexpensive and can be self constructed.

The effects of the North Atlantic Oscillation (NAO) on water temperature (WT) in Lakes Jamno, Gardno, and Łebsko were studied between 1961 and 2000. Both sets of data (NAO and WT) consisted of monthly and seasonal values. Correlation and regression analyses were used and the relationships were tested for statistical significance (Fisher-Snedecor test, coefficients of correlation and determination). Positive and statistically significant (even at α=0.01) relationships were demonstrated for the winter months (December, January, February and March) and in October. The strongest relationships were demonstrated for winter (December–February) in lakes Jamno and Gardno (correlation coefficients of 0.73 and 0.74). Extreme winters, particularly the very mild ones, tended to diminish the strength of the relationships. Very mild winters were characterised by relatively favourable solar (sunshine) conditions as well as high air and water temperatures, while the NAO Index values were relatively low. Relationships for spring (March–May) and summer (June–August) were not significant. In those seasons, the effects of atmospheric circulation (NAO) on WT were thus low, while the influences of solar factors were strong. Asynchronous relationships bear some predictive value, particularly when the predictive variable is the January NAO Index (NAOJan). These relationships were significant at α=0.01, out to April (NAOJan vs. WTApr). Attention is also drawn to local factors (air temperature, geostrophic wind, solar conditions, and sea water intrusions into lakes) which affected the strength of the relationships investigated.

We investigated benthic macroinvertebrate communities in three contrasting habitats of a large shallow lake from February to November 2009. The three habitats differed markedly in their environmental characteristics (e.g., trophic status, substrate type, wind exposure). A total of 36 species were collected from the three habitats. The calculated descriptors (abundance, biomass and Pielou evenness index) differed significantly among the habitats. Generally, Tubificidae, Bivalvia and Gastropoda dominated the benthic community in abundance and biomass, but they varied greatly in abundance among the habitats. Analysis of similarities (ANOSIM) and non-metric multidimensional scaling (NMDS) analyses revealed significantly different macroinvertebrate assemblages among the habitats. North Bays had the lowest biodiversity and were exclusively dominated by pollution-tolerant species (e.g., Limnodrilus hoffmeisteri and Rhyacodrilus sinicus). Communities in the open lake contained intermediate biodiversity and were characterized by five species belonging to several taxonomic groups (e.g., Corbicula fluminea, L. hoffmeisteri and Gammarus sp.). Macrophyte-dominated habitats (East Bays) presented the highest diversity and evenness and were mainly characterized by gastropods. A canonical correspondence analysis (CCA) demonstrated that habitat-specific differences in trophic status, pollution level, wind-induced disturbance and macrophyte distributions were highly correlated with macroinvertebrate community structure.

A straightforward experimental approach was carried out to study the adaptation responses of a typical floating-leaved aquatic plant Nymphoides peltata to changes in water availability. N. peltata grown in terrestrial habitat was approximately 88.77% lower in total biomass, 62.75% higher in root biomass allocation, 80.9% higher in root-shoot ratio, and 54.5% longer in leaf longevity compared with N. peltata grown in aquatic habitats. Anatomical analyses suggest that aquatic-grown N. peltata exhibits a well-developed lacunal system in leaf, petiole, and coarse root. Moreover, aquatic-grown N. peltata had approximately a higher in lacunal system in leaf, petiole, and coarse root by 28.57%, 56.41% and 82.35%, respectively, than those of terrestrial-grown N. peltata. These results indicated that N. peltata was well adapted to the terrestrial habitat because of its biomass allocation, morphological, and anatomical strategies that depended on the increase in root biomass allocation and leaf longevity, as well as the decrease in the lacunal system volume in leaf, petiole, and coarse root. This indicates that N. peltata can develop multiple morphological and anatomical strategies, an integrated approach to enhance survival in dynamic and unpredictable environments.