Uncertainty in Diatom Assessment: Sampling, Identification and Counting Variation

Despite the widespread application of periphytic diatoms to water quality assessment at a regional level, there is no standard European sampling protocol or associated assessment metrics. Furthermore, relatively little is known about the uncertainty in the results of such assessments. One of the objectives of the European project for the Standardisation of River Classifications (STAR) is to improve and standardise diatom assessment methods. An extensive diatom ring test, together with an audit of the project results, provided a better understanding and quantification of the uncertainty in quality assessment of running waters using diatoms. The variation in multimetric analysis shows that the choice of site and substrate for sampling, the inter-operator differences in diatom taxonomy and the counting techniques are the primary sources of uncertainty. To some extent, this variation also reveals the robustness of specific metrics in relation to the sources of uncertainty. Of the three most common substrate types tested (stone, macrophyte and sediment), macrophytes emerge as the most preferred substrate for diatom sampling when performing multimetric water quality assessment.     

Subfamily Dichomeridinae (Lepidoptera, Gelechiidae): Phylogeny, classification, and position in the system of gelechiid moths

On the basis of comparative morphological analysis, taking into account the male genital musculature, a cladogram of the tribes and subfamilies of gelechiid moths is proposed. In accordance with the main branches of the cladogram the new system of the family Gelechiidae consisting of 5 subfamilies (Physoptilinae, Anomologinae, Gelechiinae, Anacampsinae, and Dichomeridinae) is developed. The subfamily Physoptilinae is considered as a sister-group to other gelechiids, the monophyly of the latter is supported by a complex of synapomorphies (female retinaculum with anteriorly directed row of scales located on the base of radial stalk; muscles m ₃ running across the longitudinal body axis, connecting the lateral arms of vinculum with margins of juxta; protractors of aedeagus m ₅ divided into two bunches m _5a and m _5b). The subfamilies Anacampsinae and Dichomeridinae are regarded as sistergroups. The monophyly of the subfamily Dichomeridinae is based on the complex of synapomorphies (presence of parategminal sclerites, which are the apodemes for muscles m ₄; presence of distinct ventral wall in tegumen; intrategminal position of the muscles m ₂). The subfamily Dichomeridinae is considered to consist of three tribes, Anarsiini, Chelariini and Dichomeridini, with 34 genera in total. The cladogram for the genera of the subfamily Dichomeridinae is proposed.     

Biogeographic Patterns of Intertidal Macroinvertebrates and their Association with Macroalgae Distribution along the Portuguese Coast

Geographical patterns in the distribution of epifaunal crustaceans (Amphipoda, Isopoda and Tanaidacea) occurring with dominant macroalgal species were investigated along the Portuguese rocky coast. Three regions, each encompassing six shores, were studied. Algal species were selected according to their geographical distribution: Mastocarpusstellatus and Chondrus crispus (north); Bifurcariabifurcata (north-centre); Plocamiumcartilagineum and Cystoseiratamariscifolia (centre-south); Corallina spp. and Codiumtomentosum (entire coast). Multivariate techniques were used to test for differences in crustacean assemblage composition between sub-regions and host algal species. A clear gradient of species substitution was observed from north to south. Differences in abundance and diversity of epifaunal crustaceans were observed between southern locations and the remaining sites. Four species were recorded for the first time in the Portuguese coast. Among the 57 taxa identified, southern distribution limits were observed for three species and northern distribution limits were observed for four species. Interestingly, the observed geographical patterns in epifaunal abundance and diversity were not related with geographical changes in the indentity of the dominant algal species.     

A Feasibility Study to Monitor the Macroinvertebrate Diversity of the River Nile Using Three Sampling Methods

The River Nile is one of the world’s major rivers. Its’ catchment in Egypt has a population of 75,000,000. River flow is highly regulated and there are known discharges of pollutants. 1035 km of the river downstream of the Aswan high dam was studied to test the hypothesis that representative qualitative samples can be used to estimate macroinvertebrate biodiversity. Benthic macroinvertebrates are difficult to sample in large rivers and a reliable sampling strategy is required to evaluate their ecological status. Three methods for sampling have been investigated. Ekman Grab, macrophyte sweep netting and Artificial Substrate Samplers (ASS) were used to sample 15 sites from Aswan to Cairo between September 2001 and June 2002. Organisms were identified to species level where possible. Taxon accretion curves indicated that the all taxa present at a site should be collected using either 15 grab samples, 10 macrophyte samples or 5 ASS. The best time to sample was May–June. The biodiversity of macroinvertebrates in the Nile was recorded as 50 taxa with values of 7–31 at individual bank-side sites. Mid-stream biodiversity was much lower (0–19). Lowest biodiversity occurred at sites with known pollution inputs whilst highest occurred at sites with high levels of sedimentation. A regular programme for biomonitoring is recommended which will allow current status to be confirmed and future changes detected.     

A Review of the Genera Croconema Cobb, 1920 and Pseudochromadora Daday, 1899 (Nematoda, Desmodoroidea): New Species from the Coasts of Kenya and Australia

This article is a review of the subfamily Desmodorinae (Nematoda, Desmodoroidea) and two related genera within this subfamily, Croconema Cobb, 1920 and Pseudochromadora Daday, 1899 with keys to genus or species level, genus diagnoses and lists of valid species. An emended diagnosis of, and discussion on, Sibayinema Swart & Heyns, 1991, is presented. Three new species are described: Croconema floriani sp.n. from the coast of Kenya, Pseudochromadora galeata sp.n. and P. securis sp.n. from the coast of Australia.     

Recent histories of six productive lakes in the Irish Ecoregion based on multiproxy palaeolimnological evidence

Palaeolimnological data from six mesotrophic, eutrophic and hypertrophic lakes in the Irish Ecoregion, in the form of microfossil (cladocera, diatoms and pollen) and sediment chemistry data from radiometrically dated sediment cores, were used to reconstruct past variations in lake water quality and catchment conditions. Basal sediments from sediment cores from the six sites ranged in age from the late 18th century to the early 20th century. A weighted averaging partial least squares regression model was developed to reconstruct past epilimnetic total phosphorus concentrations. The results indicate that all but one of the study sites currently are in a far more productive state compared with the beginning of the sediment core record and that those same five lakes have experienced accelerated enrichment post c. 1980. Two of the sites demonstrated long-term enrichment, in one case beginning in the late 19th century, while both eutrophication and oligotrophication have occurred at three sites. The results highlight the difficulties in applying a general temporal end-point for reference conditions and demonstrate that productive lakes in the Irish Ecoregion have complex, locally specific and often long histories of enrichment. These may not be responsive to reduced external loadings of phosphorus and, as a result, restoration could prove particularly challenging. The results also provide evidence of the ways in which palaeolimnological techniques can assist implementation of the EU Water Framework Directive. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Use of Optical Density Detection Times To Assess the Effect of Acetic Acid on Single-Cell Kinetics

The growth of Listeria innocua at different acetic acid concentrations (0 to 2,000 ppm) was monitored by optical density measurements in a Bioscreen (Labsystems, Vantaa, Finland). The generated populations came from low inocula that were obtained by serial dilution. A new method to estimate both the growth rate and the lag time of single cells from the detection times (time to reach an optical density of 0.11) was developed. It assumes that the single-cell lag times follow a gamma distribution and takes into account the randomness of the inoculation level. (The initial cell number per well was assumed to follow a Poisson distribution.) In this way, relatively small numbers of replicates are sufficient to obtain a robust estimation of the distribution of single-cell lag times. The results were validated with plate count experiments. It was found that logarithms of both the growth rates and of population lag times increased linearly with the acetic acid concentration. The logarithm of the scale parameter of the gamma distribution of the single-cell lag times also increased linearly with the acetic acid concentration irrespective of the phase of the inoculum.     

Studies of the Extracellular Glycocalyx of the Anaerobic Cellulolytic Bacterium Ruminococcus albus 7

Anaerobic cellulolytic bacteria are thought to adhere to cellulose via several mechanisms, including production of a glycocalyx containing extracellular polymeric substances (EPS). As the compositions and structures of these glycocalyces have not been elucidated, variable-pressure scanning electron microscopy (VP-SEM) and chemical analysis were used to characterize the glycocalyx of the ruminal bacterium Ruminococcus albus strain 7. VP-SEM revealed that growth of this strain was accompanied by the formation of thin cellular extensions that allowed the bacterium to adhere to cellulose, followed by formation of a ramifying network that interconnected individual cells to one another and to the unraveling cellulose microfibrils. Extraction of 48-h-old whole-culture pellets (bacterial cells plus glycocalyx [G] plus residual cellulose [C]) with 0.1 N NaOH released carbohydrate and protein in a ratio of 1:5. Boiling of the cellulose fermentation residue in a neutral detergent solution removed almost all of the adherent cells and protein while retaining a residual network of adhering noncellular material. Trifluoroacetic acid hydrolysis of this residue (G plus C) released primarily glucose, along with substantial amounts of xylose and mannose, but only traces of galactose, the most abundant sugar in most characterized bacterial exopolysaccharides. Linkage analysis and characterization by nuclear magnetic resonance suggested that most of the glucosyl units were not present as partially degraded cellulose. Calculations suggested that the energy demand for synthesis of the nonprotein fraction of EPS by this organism represents only a small fraction (<4%) of the anabolic ATP expenditure of the bacterium.