Library

Notes: The Moor House Nature Reserve, Westmorland, is situated in typical north Pennine moorland and experiences a rigorous climate. Three of the streams arise between 700 and 750 m O.D. and the fourth at 590 m O.D. The sampling sites lie between 570 and 540 m O.D. and conditions in the streams range from slow-flowing peaty-bottomed reaches to typical fast-flowing stony streams. Samples were taken in riffles and pools in May, August and October using the kick method. 111 taxa were recorded from the four streams, 90 of which were identified to the species level. The most abundant and widespread taxa were Leuctra inermis, L. fusca, Rhithrogena semicolorata, Elmis aenea and Chironomidae. Seasonal and annual variation in abundance of several species was marked with L. inermis most numerous in May, E. aenea and Chironomidae in August and R. semicolorata most abundant in October. The total number of animals caught was generally higher in riffles than in pools and the mean number per 60-sec kick for riffles and pools, based on May, August and October samples between 1967 and 1970, ranged from 110 to 128 in the four streams. Capnia bifrons, Paraleptophlebia submarginata, P. cincta, Leptophlebia marginata, Centroptilum pennulatum, Plectrocnemia geniculata, Cyrnus trimaculatus, Lepidostoma hirtum, Hydropsychidae (larvae indet.) and Philopotamidae (larvae indet.), are all additions to the lists of previously studied groups on the Reserve. All the species of Tricladida, Annelida, Coleoptera, Hydrachnellae and Pisidium are here recorded for the first time for the Reserve.Great Dodgen Pot Sike supported the largest number of species and species groups (88) and was characterized by having water with the lowest pH (6.75) of all the streams and by having the most gentle gradient and a relatively stable bottom. The fauna is discussed and compared with that of the adjacent Cow Green area. Some of the differences between these areas may be attributable to the slightly greater variation in flow-conditions and water chemistry in the Cow Green basin. Comparison with other areas in the British Isles are made briefly and it is suggested that habitat diversity may account for the species richness of the Moor House streams.

Notes: In 1967 a programme was initiated by the Freshwater Biological Association to study fish populations within the proposed Cow Green reservoir basin and in the Tees downstream of the dam, before and after impoundment. This paper describes the result of a supporting study on aquatic invertebrates covering the pre-impoundment period 1967–70.The benthic faunas of six streams in the reservoir basin, the Tees below Cauldron Snout and Maize Beck, a tributary ofthe Tees below the dam, were studied. Species list are presented for each habitat and changes in seasonal and annual abundance are discussed.All areas sampled lie at altitudes between 440 and 550 m O.D. and are situated amongst moorland and limestone grassland. Conditions in the streams ranged from slow-flowing peaty reaches to small streams with moss-covered bottoms and larger stony rivers and streams with relatively unstable bottoms.Samples were taken in riffles and pools using the ‘kick’ method wherever possible. An attempt was made to quantify kick-sample catches by comparing them with shovel-sample catches which cover a known area of stream bottom. It was found that 10 5 kicks gave a catch equivalent to the populations of 1 m2, giving a population density of about 1200 animals/m for the reservoir-basin riffles.Over 120 taxa were recorded, 100 of which were at the species level. In the reservoir-basin streams, 116 taxa were found with seventy-one in Maize Beck and fifty-six in the Tees below Cauldron Snout. Ephemeroptera were the most abundant group in the reservoir basin and Maize Beck faunas with Rhithrogena semicohrata, Heptagenia lateralis and Baetidae being the most abundant forms, although Ecdyonurus spp. especially E. dispar were much more common in Maize Beck. In other groups Leuctra spp. and Gammarus pulex were very common. In the Tees below Cauldron Snout Limnaea peregra, Chironomidae and Baetidae formed the bulk of the fauna and Plecoptera were uncommon. Amongst the reservoir basin streams Weelhead Sike supported the largest number of species and species groups (eighty-one), and all the streams had forty-nine or more taxa represented.Information on seasonal changes in the numbers of those species or species groups composing 90% or more of the total fauna is presented. Faunal density was high in May with Ephemeroptera, particularly Ecdyonuridae, and the plecopteran Leuctra inermis being the most abundant forms. In August, the numbers of animals appeared t o fall and common members of the community were Baetidae, Diptera, Leuctra fusca and Ecdyonuridae. In October, Ecdyonuridae particularly R. semicolorata, were most abundant.A comparison ofthe bottom fauna of riffles and pools was made and more animals were found in riffles than in pools.The effect of gravel extraction on the bottom fauna of the Tees was examined. A severe drop in the numbers of animals was observed after extraction. Diptera were the first group to return to their pre-disturbance density. Elminthidae and Annelida were worst affected and slowest to recover.The fauna of the area is discussed and possible reasons for its relative species richness are put forward. Habitat diversity and chemical richness appear to be the most likely reasons for the relatively large number of species found.

Notes: Patterns of habitat use by fish assemblages in two chalk streams in southern England were examined to identify species preferences with respect to major habitat gradients. Both study sites, although differing in some physical habitat characteristics, mainly channel width, water temperature and instream cover, could be arranged similarly along a continuum extending from erosional to depositional habitats. Twelve fish species were collected from stream surveys conducted during July 1993. The habitat was partitioned into six fish species associations that could be assigned to three habitat guilds: depositional (Barbatula barbatula, Gasterosteus aculeatus and Anguilla anguilla), riffle (Leuciscus leuciscus, Thymallus thymallus and Salmo salar) and generalist (Salmo trutta, Phoxinus phoxinus, Gobio gobio, Cottus gobio, Lampetra planeri and Pleuronectes flesus). At low to moderate densities the different species associations were collected in the same habitat patch, but at higher densities there was a clear tendency to mutual avoidance. In particular, large trout appeared as strong interactors that tended to exclude other species from their territories. It is hypothesized that the fish assemblage of the Mill Stream and Bere Stream have partitioned the habitat in such a way as to minimize potential Competition.

Notes: SUMMARY. 1. Macro-invertebrate species lists were obtained for 268 sites on forty-one river systems throughout Great Britain by qualitative sampling in spring, summer and autumn. Information on twenty-eight environmental variables was also collated for each site. The sites were ordinated on the basis of their species content using detrended correspondence analysis (DCA) and classified by two-way indicator species analysis (TWINSPAN). Correlation coefficients between ordination scores and single environmental variables indicated that Axis 1 distinguished between types of rivers and Axis 2 reflected variation along the length of rivers. A preliminary classification of sites into sixteen groups has been proposed, together with a key which allows new sites to be classified. Information on the species and environmental features which characterize each group is also presented.2. Multiple discriminant analysis (MDA) was employed to predict the group membership of the 268 sites using the twenty-eight environmental variables. 76.1% of sites were classified correctly. An independent assessment of predictive ability using forty test sites yielded a 50% success rate. Predictive ability was higher for the classification presented in this paper than in fifteen additional classifications produced using data from single seasons and/or different taxonomic treatments.3. TWINSPAN and MDA were found to be useful approaches to the classification of running-water sites by their macro-invertebrate fauna and the prediction of community type (as indicated by the occurrence of species in the sites comprising the group) using environmental variables. Extension of the scope of the classification, coupled with the use of additional environmental variables to increase predictive ability, is now in progress.

Notes: SUMMARY. 1. Macro-invertebrate samples were collected from 268 running-water sites in Great Britain in each of three seasons (spring, summer and autumn). A combined seasons’treatment was generated by amalgamating the individual seasons’data. These four seasonal options were each subjected to four distinct taxonomic analyses differing in level of identification and whether the data were quantitative or qualitative. Thus sixteen data-sets were available for analysis. Environmental data on physical and chemical variables, macrophyte cover and date of sampling were also recorded for each site.2. All sixteen data-sets were ordinated by detrended correspondence analysis and classified by two-way indicator species analysis. There were strong correlations between the sixteen ordinations and significant concordance between classifications.3. The relationships between ordination scores and single environmental variables were investigated. Muhiple discriminant analysis was used to fit environmental data to eight selected classifications covering the full range of seasonal and taxonomic treatments. The environmental variables most useful in distinguishing between rivers were substratum characteristics, alkalinity and total oxidized nitrogen. Within-river differences were often highly correlated with discharge, distance from source, width and depth. Slope and altitude contributed strongly to both between-river and within-river distinctions.4. Between-site variation (beta diversity), eigenvalues of ordination, the reliability of classifications, the proportion of sites correctly assigned to their biological group using environmental data and the standardized similarity between observed and predicted fauna were all higher when identifications were taken to species level, rather than one of three family treatments. Qualitative data on a reduced list of families gave comparable or better results than more detailed family treatments.5. Combined seasons’data enabled better categorization and prediction than single season's.6. The values of the Czekanowski Index of Similarity between the observed and predicted fauna of test sites were close to realistic maximum values.7. Recommendations are made concerning potential usages of the various classifications. The species level classification has uses in the field of conservation and in the prediction of biological response to environmental change. The family level classifications have value in developing local site inventories and in the interpretation of pollution surveillance programmes.

Notes: SUMMARY. 1. A procedure has been developed which uses environmental data to predict the probabilities of macro-invertebrate taxa occurring at running-water sites in Great Britain.2. Biological, physical and chemical data were collected from twenty- one sites on three river systems in order to evaluate the procedure.3. For most sites the number and type of taxa recorded, using a standard sampling programme, were very close to those predicted using twenty-eight environmental variables.4. Comparison with other studies at the same sites showed that most taxa whose probability of occurrence was ≥0.5 could be found with more intensive sampling.5. Reducing the number of variables used in making the predictions from twenty-eight to five resulted in only a slight loss of predictive accuracy.6. Combinations of chemical and physical variables gave better predictions than equivalent numbers of physical variables only but the latter may be more appropriate where chemical pollution is known, or suspected to occur.7. The procedure is of practical value in the detection and assessment of pollution.8. It may also be used to explore patterns in the structure and functioning of stream communities.

Notes: Abstract There are increasing concerns about the ecological effects of water abstraction and in the UK, these concerns have been hightened by the 1976, 1984 and 1988-92 droughts. This paper assesses macroinvertebrate and environmental changes induced by surface and groundwater abstractions on 22 streams throughout the UK. The approach involved comparative research to assess differences between reference and impacted sites. Using a database comprising 204 sets of biological and environmental data (89 taxa and 16 environmental variables) a preliminary ordination using principle components analysis clearly differentiated three types of sites: upland, lowland and an intermediate type. At this scale, any effects of abstractions on invertebrate communities are shown to be insignificant relative to regional controls. A simultaneous ordination of the environmental and faunal differences between pairs of sites was undertaken separately for each of the three regional groups. Differences are considered as vectors having both direction and amplitude and the analysis elucidates common patterns in the faunal and environmental data. Important changes were observed in two situations: upland streams affected by major diversions as part of hydro-power schemes in Scotland and lowland rivers impacted by groundwater abstractions. No strong patterns of change (either in amplitude or orientation) were demonstrated within any of the taxonomic groups. However, within the upland type some rheophilous taxa were shown typically to be reduced in abundance at impacted sites. Within the lowland type, a consistent pattern in the dataset is demonstrated by a group of taxa that are reduced in abundance at the impacted sites.

Notes: Abstract A new easily retrieved folding artificial substratum sampler is described and its performance compared with that of trays in Cow Green Reservoir at a depth of 15–18 m.

Notes: Abstract A technique, which uses environmental data to predict the macroinvertebrate fauna of running water sites, was used to investigate the response of faunal communities to flow regulation below a set of upland reservoirs in Great Britain. Five variables (total oxidised nitrogen, alkalinity, chloride, substratum type and site distance from stream source) were used to predict family presence and abundance at 30 regulated sites. The predictions were compared with the observed fauna recorded in samples taking in spring, summer and autumn. Of the 37 commonly occurring families 22 showed statistically significant trends. Twelve of these occurred at lower abundances than predicted and the effect was greatest in Heptageniidae, Simuliidae, Elminthidae, Perlodidae and Rhyacophilidae. Ten families were more more abundant than predicted and these included Polycentropodidae, Sphaeriidae, Sialidae and some groups of chironomids and oligochaetes. Fifteen families showed no significant trends. Most families showed little difference in the observed and expected frequency of occurrence in the 30 sites but Taeniopterygidae and Perlidae amongst others occurred at less than the expected number of sites and Hydridae, Prodiamesinae and Muscidae occurred more commonly than expected. These faunal responses are discussed in relation to environmental changes arising from flow regulation. The possible uses of the predictive technique in simulating and assessing the effects of regulation on downstream fauna are outlined.

Notes: A four-stream computer-controlled reinforced reaction injection molding (RRIM) machine has been developed that attains high accuracy in dispense ratios throughout the injection period. This machine has been used for novel processing of polyurethanes, offering a route to varying product properties either throughout a shot or on a shotto-shot basis. It also has been used for what appears to be the first production on commercial scale RRIM equipment of a polyurethane-acrylic interpenetrating polymer network (IPN) in commercial cycle times of around 2 min.