bluuebunny/crossref_metadata_2025_split huggingface dataset:
Riparian vegetated buffer strips in water‐quality restoration and stream management
Authors: OSBORNE LEWIS L. , KOVACIC DAVID A. 
Published: May 2006

SUMMARY A review is presented of the literature on riparian vegetated buffer strips (VBS) for use in stream‐water‐quality restoration and limitations associated with their use are discussed. The results are also presented of recent investigations on the effectiveness of a forested and a grass vegetated buffer strip for reducing shallow subsurface inputs of nutrients from agriculture to a stream in central Illinois, U.S.A. Because riparian zones link the stream with its terrestrial catchment, they can modify, incorporate, dilute, or concentrate substances before they enter a lotic system. In small to mid‐size streams forested riparian zones can moderate temperatures, reduce sediment inputs, provide important sources of organic matter, and stabilize stream banks. Several questions on the utility and efficiency of vegetated buffer strips for stream restoration still remain unanswered, including: what types (grassvforest) are most efficient; do they become nutrient saturated; are they only temporary sinks; how does species composition influence effectiveness; and, what is the optimal width of buffer to facilitate nutrient reduction under different conditions? Water samples were collected (1989–90) from lysimeters located at three depths (60, 120, and > 120cm) in an upland area planted in conventional row crops (corn and soybean) and in three adjacent riparian buffer treatments, a 39m wide grass buffer. a 16 m wide mature forested buffer, and a buffer planted in row‐crops to the stream bank. Concentrations of dissolved and total phosphorus and nitrate‐N in each sample were determined following major precipitation events over a seventeen month period. Both the forested and grass VBS reduced nitrate‐N concentrations in shallow groundwater (up to 90% reduction). On an annual basis the forested VBS was more effective at reducing concentrations of nitrate‐N than was the grass VBS, but was less efficient at retaining total and dissolved P. During the dormant season, both grass and forested buffer strips released dissolved and total P to the groundwater. The VBS apparently acted as a nutrient sink for much of the year, but also released accumulated nutrients during the remaining portion of the year. Periodic harvesting of plant biomass may reduce the amount of P released during the dormant season. VBSs are not as effective in agriculture areas with tile drained fields. Alternative restoration practices such as discharging drain tiles into wetlands constructed parallel to the stream channel may prove to be a more effective means of controlling non‐point‐source agricultural inputs of nutrients in such areas.
Identification of predominant environmental factors structuring stream macroinvertebrate communities within a large agricultural catchment
Authors: RICHARDS CARL , HOST GEORGE E. , ARTHUR JOHN W. 
Published: May 2006

SUMMARY

Patterns of macroinvertebrate community composition were examined in streams within a 40000‐km2 catchment in central Michigan, U.S.A., to identify the major environmental gradients influencing community variation. Agriculture and associated clay and sandy soils predominated in much of the region.
Eighty macroinvertebrate taxa were collected from stream surveys conducted during May and August 1990. Community composition varied primarily by the proportions of Plecoptera and Ephemeroptera. Benthic communities from the heaviest agricultural zones were most different from those at other sites.
Chemical composition among the sites varied most in relation to nutrients (NH3, NO3, PO4). Other parameters were relatively similar. Physical characteristics of the sites were scored in six habitat categories: (i) substrate characteristics, (ii) instream cover, (iii) channel morphology, (iv) riparian zone and stream‐bank conditions, (v) riffle/run quality, (vi) pool quality. Most physical habitat scores were lowest in the intense agriculture zones.
The relative importance of physical and chemical variables in explaining variation in macroinvertebrate communities was quantified using canonical correspondence analysis. Substrate characteristics were most important in both surveys. Significant correlations (P<0.05 and P<0.10) were observed between substrate quality and total numbers of Ephemeropteran, Plecopteran, and Trichopteran taxa. These relationships reflected correlations from sites in the clay soil‐type region (P<0.01 and P<0.10) which contrasted with non‐significant results from the less impacted, sandy soil‐type region.
Effective stream restoration efforts in this region will require the alteration of local land‐use activities that influence the physical habitat. Further development of empirical relationships between catchment activities and substrate and channel characteristics within natural geomorphic regions is essential for the evaluation of restoration projects.
Reproduction in two submersed macrophytes declines progressively at low pH
Authors: TITUS JOHN E. , HOOVER DAVID T. 
Published: May 2006

SUMMARY

Greenhouse experiments tested the effect of pH 5 v pH 7.5 on reproductive success for the freshwater macrophytes Najas flexilis, an annual, and Vallisneria americana, which perennates as a tuber.
Seed production by the small Najas plants grown at pH 5 averaged 0.25 seeds/plant, in contrast to 95.5 seeds/plant at pH 7.5. At low pH, Vallisneria grown from seeds produced no flowers and too few tubers to replace themselves, so that sexual reproduction failed nearly completely for both species.
Vallisneria grown from tubers produced 97% less total tuber mass at pH 5 (0.4 v 14.9 g), the compounded result of producing, on average, 89% fewer and 82% smaller tubers. The smaller tubers developed at pH 5 were less likely to overwinter in the field, and those surviving tubers subsequently grew into smaller plants.
These findings generated the hypothesis of a closing spiral: growth at low pH (and relatively low CO2 concentrations) results in small plants that produce a smaller number of progressively smaller tubers each autumn, which in turn develop into progressively smaller plants each summer. This hypothesis was supported by field transplant experiments in two acidic Adirondack Mountain (NY) lakes.
Spatial variation in the distribution of stream invertebrates: implications of patchiness for models of community organization
Authors: DOWNES BARBARA J. , LAKE P.S. , SCHREIBER E.S.G. 
Published: May 2006

SUMMARY

Variation in abundances of stream fauna across a range of spatial scales has been neglected, yet such variation can have important implications for experimental and descriptive work. We tested the hypothesis that the abundances of stream animals living on stones vary between sites within the same stream order, riffles within the same site and groups of stones within the same riffle. We also examined how epilithon and water depth and velocity varied over these spatial scales.
Thirty stones were sampled from each of three sites in a fourth‐order section of the Taggerty and Steavenson Rivers, south‐eastern Australia. At each site, fifteen stones were taken from each of two riffles; within each riffle, the fifteen stones were collected as five groups of three stones within 0.5m of each other. For each stone, we measured water depth and velocity, took samples of epilithon to estimate chlorophyll a concentrations, organic biomass and bacterial and algal cell densities, and collected all macroinvertebrates.
Hierarchical analyses of variance revealed that species richness did not vary over any of the spatial scales, but densities of individuals varied substantially between riffles and groups of stones. Of the thirty‐five most abundant taxa, three‐quarters (twenty‐seven) varied over one or more of the spatial scales, with variation between riffles being particularly common. DECORANA analyses confirmed that two of the three sites had riffle faunas that were dissimilar to each other, whereas the third site had riffle faunas that were very similar. Significant spatial variation was observed also in water velocities and depths and chlorophyll a and organic biomass concentrations.
Overall, we have demonstrated that significant variation in faunal densities may occur over small spatial scales, such as those represented by groups of stones. Moreover, such variation was not consistent between taxonomically or functionally related species within the assemblage.
The results emphasize the need for stream ecologists to be aware of the ramifications of such variation. Neglect of small‐scale variation has produced spatially confounded designs in both surveys and experimental studies. Additionally, the assumption that variation over small scales does not occur or is trivial seems to have been responsible for the virtual enshrinement of certain large‐scale models of community organization.
Macroinvertebrate communities in streams in the Himalaya, Nepal
Authors: RUNDLE SIMON D. , JENKINS ALAN , ORMEROD S.J. 
Published: May 2006

SUMMARY

Macroinvertebrates were sampled in the riffles of fifty‐eight streams from three regions of the Himalaya (Anapurna, Langtang and Everest) in Nepal. A semi‐quantitative method with identification to family level was used to describe communities on‐site.
Stream physicochemistry was assessed and the community structure of macroinvertebrates was related to chemistry, physiography (substratum composition, altitude and size), geographical location and the dominant land use in each catchment (terraced agriculture, forest or scrub). Community data were analysed by ordination (DECORANA) and classification (TWINSPAN).
The concentration of cations in stream water decreased significantly with altitude. Chemistry also differed between regions; sites from Anapurna had a higher pH and conductivity than those in the other two areas.
Communities were dominated by aquatic insect larvae, with Ephemeroptera, in particular the Baetidae, most numerous across sites.
There were, nevertheless, differences in community structure between sites, which were related closely to stream physicochemistry. Ordination scores were strongly correlated with altitude, magnesium concentration and substratum composition. Classification was also linked to altitude and chemistry, differentiating high‐altitude sites with low silica concentrations from others. Sites from the Anapurna and Everest regions, with their contrasting chemistry, were also separated.
Community structure was also related to land use: streams draining catchments dominated by terraced agriculture had different communities from those in scrub or forest. This result was confounded, however, by the strong relationship between land use, altitude and chemistry; sites in terracing were at lower altitude, had higher concentrations of silica and a higher proportion of fine sediments than those in the other land‐use types.
Overall, our data indicate that natural features of the relief and geology in the Himalaya create strong gradients in their invertebrate faunas, but that activities of man may have an effect on stream structure and ecology through catchment management.
The effect of temperature on morphology, life history and growth rate of Filinia terminalis (Plate) and Filinia cf. pejleri Hutchinson in culture
Authors: SANOAMUANG LA‐ORSRI 
Published: May 2006

SUMMARY

Experiments on the influence of temperature (5–25°C) on morphology, life history and growth rate of Filinia terminalis and F. cf. pejleri were performed in replicated individual cultures with Oocystis sp. as food.
Some morphological characteristics previously used for the identification of both species were found to be affected by temperature and also by life cycle stage. However, numbers of unci teeth were not affected.
Body and setal lengths, life spans, all stages of development, and growth rates of both species decreased with increasing temperature.
Offspring number per female of both rotifers was highest at 20°C. Maximum growth rate of F. terminalis was at 25°C, whereas that of F. cf. pejleri was at 20°C.
Impact of larval Dorosoma predation on Daphnia parvula dynamics
Authors: SHAHADY THOMAS D. 
Published: May 2006

SUMMARY

In reservoirs of the south‐eastern United States, Daphnia typically decline in abundance during the summer months. Current understanding suggests that adult shad (Dorosoma spp.), the dominant planktivore in these reservoirs, plays a limited role in Daphnia midsummer declines. The impact of shad larvae is beginning to be documented.
To examine the impact of larval shad on Daphnia seasonal dynamics, larval dynamics were studied over two seasons and stomach contents were analysed during one season.
Initial Daphnia panwla declines correlated with abundance of shad larvae. During the decline, shad stomach contents consisted of 97—100%D. parvula. After D. parvula declined, Bosmina and Diaphanosoma accounted for up to 97% of larval diets. When shad diets included other cladocerans, D. parvula abundance increased in the reservoir.
When this predation pattern was incorporated into a predictive model, larval shad predation accounted for an initial, temporary decline in D. parvula abundance. However, when other crustaceans were incorporated into the shad diet, D. parvula populations increased.
These results suggest that larval shad have a temporary, strong influence on the structure and abundance of D. parvula populations in south‐eastern reservoirs of the United States.
Predation on ciliates by freshwater calanoid copepods: rates of predation and relative vulnerabilities of prey
Authors: BURNS CAROLYN W. , GILBERT JOHN J. 
Published: May 2006

SUMMARY

The susceptibility of ciliates in a mesotrophic lake to predation by Epischura lacustris, Diaptomus minutus and D. pygmaeus was assessed during summer. Oligotrichs, particularly Strobilidium velox (c. 43 μm), were removed efficiently by adult copepods and contributed substantially to the diet of female D. minutus. The presence of approximately 1,6 adult Epischura 1‐−1, or sixteen adult female Diaptomus 1‐−1, could halt the growth of S. vechx populations in summer.
Factors affecting the rate at which copepods prey on ciliates were examined in experiments with D. pygmaeus and cultured ciliates. Rate of predation on S. velox, the preferred species, became saturated at 5 S. velox ml−1 (45ngCml−1) and did not change with a 10‐fold increase in alternative algal food.
Behavioural differences among ciliates, and the presence of other ciliates, contributed to differences in ciliate susceptibility to predation and suggest reasons why rates of removal of ciliates are not related to ciliate size.
By feeding selectively, at high rates, calanoids may suppress populations of some ciliates and thereby influence microzooplankton community structure.
Seasonal variation in pH and alkalinity and recruitment of sunfish populations
Authors: JARRETT J.N. , CUTLER M.B. , EBERSOLE J.P. , HAGAR W.G. 
Published: May 2006

SUMMARY

In a study of five ponds sensitive to acid precipitation, we document seasonal acidification profiles and assess the impact of short‐term acid pulses on the reproductive success of resident sunfish (Lepomis spp.).
Three years of water sampling at 2–3 week intervals showed substantial seasonal variation in pH and alkalinity consistent with a carbonate buffering system. Though all ponds shared a common seasonal pattern in pH, ponds with relatively low pH and alkalinity showed the greatest variation in these parameters. Spring minima may dispose some of the ponds towards episodes of extreme acidity during heavy spring rains.
Otolith analysis of young‐of‐the‐year sunfish revealed recruitment failures for eggs laid early in spring in ponds with relatively low alkalinity and pH, and, in the most extreme case, missing day classes at subsequent irregular intervals even though average pH and alkalinity were well above those demonstrated to affect centrarchid fishes.
Age‐class distributions of sunfishes revealed gaps in adult age distributions which could be traced through 3 years of the study, but there was no clear‐cut relationship between pond acidification and the age structure of adult fish.
Seasonal profiles of acidity may enable researchers to predict the time during which a pond or lake may be highly sensitive to acid inputs. Comparative otolith analysis of young‐of‐the‐year fishes and short‐term continuous monitoring of water chemistry may provide an early warning of biological effects of acidification in sensitive bodies of water.
Trophic coupling within the microbial food web: a study with fine temporal resolution in a eutrophic freshwater ecosystem
Authors: BERNINGER ULRIKE‐G. , WICKHAM STEPHEN A. , FINLAY BLAND J. 
Published: May 2006

SUMMARY

The major components of the microbial food web (dissolved organic carbon, bacteria, protozoa, rotifers and algae) of Priest Pot, a small freshwater pond, were investigated over a period of 5 months. Water samples were collected from the epilimnion every 1–3 days.
Time series analysis helped identify the trophic relationships within the planktonic community. There were strong predator—prey relationships between both ciliates and large rotifers and the total nanoplankton, between rotifers and small ciliates and between the total microzooplankton community and phytoplankton. Small rotifers and small ciliates probably share the same food resources. The major bacterivores in the system could not be identified with our methods. However, our previous results point to a dominating role of nanoplanktonic (2–20 μm) heterotrophic protists as the main grazers of bacteria.
Rotifers are the major type of metazoan zooplankton in Priest Pot; crustacean zooplankton are absent from the community. Bacterial production probably reaches rotifers via a variety of pathways: there may be a three‐step link from bacteria to bacterivorous nanoplankton, to ciliates and then to rotifers. Furthermore, a strong correlation between the nanoplankton and rotifers suggests a direct link between these components, implying a much shorter pathway. Some of the rotifers in the pond can graze directly on bacteria, and many of the larger planktonic organisms (large ciliates and rotifers) are algivores. The latter two predator—prey relationships suggest an efficient transfer of bacterial and primary production to higher trophic levels.
The limnology of Lac ďIfni (High Atlas Mountains, Morocco), an unusually productive mountain lake
Authors: GEE JOHN H.R. , DUIGAN CATHERINE A. 
Published: May 2006

SUMMARY

Lac ďIfni (surface area 30 ha, zmax 60 m, altitude 2300 m) lies in a catchment comprised of Precambrian igneous rocks in the High Atlas Mountains of Morocco. Previously described as a typical ohgotrophic lake, it was also reported to have a warm layer at the base of the hypolimnion which was ascribed to phreatic water supply and drainage.
Visits to the lake made in May/June and September 1990 showed strong thermal stratification but no hypolimnial warm layer. Drainage from the lake is subterranean, through a natural rubble dam, and the water level dropped by at least 7m through the summer. The flushing rate is about 0.6 year−1.
The upper part of the metalimnion and the lower epilimnion were strongly supersaturated with oxygen in June, and there was a pH gradient from 7 to 10.5 between the hypolimnion and the epilimnion. These features were less marked in September when planktonic gross primary productivity was estimated to be about 145mgCm−2 h−1. In September the hypolimnion was 38% saturated with oxygen; the areal hypolimnetic oxygen deficit between June and September was 0.073mg O2 cm−2 day−1. Total dissolved phosphate concentrations were 7–14 μgl−1.
The open water faunal assemblage consisted of Brachionus calyciflorus and Filinia lotigiseta (Rotifera), Cyclops abyssorum (Copepoda), and stunted Salmo trutta (Pisces). Trout diets were comprised principally of adult copepods and copepodites, which showed diurnal vertical migration, and of algal material apparently scraped from rock surfaces. The dry biomass density of Cyclops was at least 2gm−2 in June and at least 4.1 gm −2 in September.
Tubifex tubifex (Oligochaeta) dominated the benthos below depths of 40m. Mean dry biomass density was 2.8gm−2, but ranged from 0.6–8.1 gm−2 between samples. About 50% of the lake bottom is below 40m depth.
The persistent oxygen supersaruration of the euphoric zone, the field estimate of primary productivity, the hypolimnetic oxygen deficit, the biomass of zooplankton and the benthic biomass together indicate that Lac ďIfni is an unusually productive mountain lake. This high level of productivity may be sustained by nutrient addition through contamination by dust originating outside the catchment, aided by efficient nutrient recycling in the euphoric zone.
Response to Frutiger & Schib (1993) ‘Limitations of FST hemispheres in lotic benthos research’
Authors: STATZNER B. 
Published: May 2006

SUMMARY

This response to the paper of Frutiger & Schib (1993) focuses on substantial errors that are relevant to the interpretation of results and deficiencies in their study design. I include some reanalysis of the original data of Schib (1991), which formed the basis of Frutiger & Schib's paper.
The paper of Frutiger & Schib (1993) is flawed because of their sampling strategy (sequence of measurements, depth stratification, and the long duration of the study in relation to temporal changes in the insect populations), the selection of study sites (one lake outlet, one river disturbed by bathers), the mixing of single‐species and multiple‐species units in the analysis, the pooling of data and its analysis, the omission of essential information given by Schib (1991), and the generation of doubtful arguments. Their approach and interpretation places FST hemispheres at an unreasonable disadvantage in a debate about the relative utility of hemispheres and propeller‐type current meters and consistently discriminates against the general role hydraulics play in the micro‐distribution of the eight insect taxa that were studied.
Despite the deficiencies of their study, my reanalysis of the original data of Schib (1991) provides significant models of insect abundance in relation to hemisphere density for six of the eight insect taxa, with r2 values between 0.62 and 0.86 for five of them.
Influence of nymphal size, sex and morphotype on microdistribution of Deleatidium (Ephemeroptera: Leptophlebiidae) in a New Zealand river
Authors: COLLIER KEVIN 
Published: May 2006

SUMMARY

The interaction of water depth and velocity with size, sex and morphotype of nymphs belonging to the leptophlebiid mayfly genus Deleatidium was investigated in a New Zealand river.
Velocity had a significant effect on distribution such that larger nymphs tended to be found more commonly in faster water. Depth also influenced size distribution, but in different ways at different sites.
Water velocity or depth alone did not significantly influence the distribution of sexes (1.0 mm head width), but the combined effect of these two factors was significant. Final instar males appeared to be relatively more abundant in slower water than final instar females.
Nymphs (1.0 mm head width) belonging to the informal lillii group (apically pointed gills) were present over a wide range of depth and velocity conditions, but those belonging to the myzobranchia group (round‐tipped gills) were largely restricted to fast water (>0.9ms−1).
Several mechanisms thought to cause variations in microdistribution are discussed. These include differential effects of oxygen availability, food requirements and drag forces, nymphal behaviour, and selection of oviposition sites by adults.