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Факторы среды в водотоках
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- Бұл бет үшін навигация:
- Влияние древесного субстрата и паводков.
- Влияние бурности и течения.
- Влияние пищи и течения, трофика.
- Влияние течения, глубины, субстрата на бентос водотоков.
- Влияние древесного субстрата.
- Ледниковые водотоки, бентос: влияние факторов
- Влияние субстрата в водотоках.
- Горный поток: влияние древесных субстратов.
- Влияние стабильности местообитания.
- Водотоки: влияние локальных нарушений.
- Влияние стабильности биотопа
- Бентос в истоках реки: влияние загрязнений и гидрологии.
- Водотоки: влияние факторов среды.
- Водотоки: влияние факторов среды
- Водотоки: влияние факторов среды. Снег.
- Водотоки: влияние факторов среды. Загрязнение.
- Водотоки: предсказание фауны по факторам среды
- Водотоки: измерение скорости течения.
- Водотоки: влияние факторов среды. Течение.
- Водотоки: влияние неоднородности среды.
- Влияние железа на бентос.
- Влияние температуры и пищи: рученйики, мошки.
- Влияние детрита в горном потоке.
- Водотоки: разложение листового опада.
- Ординация бентоса по факторам среды
- Влияние света и выедания на перифитон
Факторы среды в водотоках.Влияние местообитания.Authors: Townsend-CR Hildrew-AG Связь особенностей видов и местообитания в речных системах. Species Traits in Relation to a Habitat Templet for River Systems FRESHWATER BIOLOGY 1994, Vol 31, Iss 3, pp 265-275 Работа проверяет идею, что местообитание играет роль шаблона, по которому эволюция подгоняет характеристики отдельных видов. Альтернативная гипотеза - что исторические и филогенетические причины определяют местообитание видов. Мы описывали параметры среды в реках: временную неоднородность (частоту нарушений) и пространственную пятнистость физико-хим. среды. Вторая, через создание убежищ для животных, отчасти компенсирует влияние первой. У животных описывали размер тела, форму, время генерации, тактику размножения, репродуктивный потенциал. Кроме того, оценивали видовое богатство сообществ - и соответствие всего этого параметрам местообитания. Оценивали широкий круг растений, животных и микроорганизмов, для каждой группы в подходящем для нее масштабе. Оказалось, действительно, требования видов предсказываются параметрами среды (степенью пространственной и временной неоднородности). Если наши методы адекватны, то habitat templet approach (подход, основанный на детерминанте местообитанием экологии видов) может стать основой для других построений и одним из постулатов в экологии водотоков. Abstract: 1. This paper focuses on the premise that the habitat provides the templet upon which evolution forges characteristic species traits. Alternative hypotheses are that there are historic and phylogenetic constraints on the match between organism and environment. 2. In our analysis of river systems, as one dimension of the templet we choose temporal heterogeneity and assume some relationship between this and the frequency of disturbance. The second dimension is spatial heterogeneity in the physicochemical environment and we pay particular attention to the way such variation can ameliorate the influence of disturbances through the provision of refugia. 3. We derive predictions about the traits of species, including size, generation time, reproductive tactics, body form, mobility and potential for regeneration, that are likely to occur in particular regions of the two-dimensional templet. We also present predictions about community-level characteristics such as number of species per resource category and total species richness. The general predictions are intended to apply to a wide range of plants, micro-organisms and animals, provided the measurements have been made at a scale appropriate to them. 4. Hypotheses can be tested by comparing traits predicted for particular habitats, whose spatial and temporal heterogeneity have been quantified, with those actually observed. If the fit turns out to be good, we will be able to conclude that the habitat templet approach offers a sound framework within which to pose questions in river ecology. Влияние факторов среды.Freshwater Biology Volume 47 Issue 8 Page 1333 - August 2002 Влияние гидрологических нарушений на плотность беспозвоночных хищников и жертв в береговом водотоке. The effects of hydrological disturbance on the densities of macroinvertebrate predators and their prey in a coastal stream JAMES R. THOMSON 1.Environmental Stress Models (ESMs) predict that abiotic disturbance or harshness will differentially affect predators and prey. Consumer Stress Models (CSMs) predict that consumers will be relatively more inhibited by disturbance than prey, and therefore predator impacts will be reduced. Conversely, Prey Stress Models (PSMs) predict that prey will be more adversely affected and consequently predator impacts will increase in disturbed habitats. This study compared the relative tolerances of lotic invertebrate predators and their prey to hydrological disturbance in an Australian coastal stream to test the initial predictions of ESMs. 2.Macroinvertebrates were sampled with a suction sampler at monthly intervals and immediately following four high flow events at five sites on the Cumberland River, in south-west Victoria, Australia. Various statistical procedures were used to compare the relative resistance and resilience of predatory and prey taxa to each high flow event. 3.The relative resistances of seven predator and nine prey taxa to four floods over a 12-month period were highly variable between floods and between runs within the same flood. Prey taxa appeared to be more resilient than predators to the largest flood event, but there were no differences in the resilience of predators and prey following smaller floods. If disturbance tolerance is determined by resistance and resilience, then there was no consistent pattern of differential tolerance to floods among invertebrate predators and prey in this system. 4.The variability in the relative tolerances of taxa to different disturbance events makes general predictions about the effects of disturbance on the community-wide impact of predation extremely difficult.
OECOLOGIA 1996, Vol 105, Iss 2, pp 247-257 Abstract: Disturbance may play an important role in generating patterns of abundance and distribution of biotic assemblages, particularly if its impact differs among habitat patches. Despite much speculation concerning the probable importance of spatial variation in the response of stream fauna to flooding, empirical work on patch-specific responses to spates is largely lacking. Floods typically reduce the abundance of lotic invertebrates dramatically in open-channel areas. We conducted a set of experiments to determine if faunal abundances are less affected in patches more sheltered due to the presence of woody debris dams. Specifically, we tested two hypotheses using chironomids and copepods living in a warmwater, 4th order stream: (1) the effect of flooding on the fauna varies between patches associated with debris dams versus the open channel, and (2) the absence of woody debris in a stream impedes faunal recovery throughout the channel following hoods. We tested the first hypothesis by quantifying faunal abundances prior to, during, and following two floods in four patch types: mid-channel sandy patches distant from dams, coarse sediments associated with dams, fine sediments associated with dams, and leafy debris in dams. The second hypothesis was tested by removing all of the woody debris from two stretches of the stream and comparing the impact of a flood on fauna in debris-removed versus control stretches. Across all of the eight study dams, there were patch-specific faunal responses to two floods. Removal of woody debris from the stream did not prevent faunal recovery throughout the channel; however, the presence of woody debris darns did confer greater resistance of fauna to floods (as measured by no decrease in abundance during flooding) in two patch types. Abundances of chironomids and, to a lesser extent, copepods in the leafy debris of darns and in fine sediment patches associated with some darns either did not change or increased during floods, despite the fact that abundances in the dominant patch type of the stream (the sandy mid-channel) were reduced by 75-95%. All instances of faunal increase were limited to fine sediment patches associated with dams, thus entire dams cannot be labeled as flow refugia per se. Statistically, we distinguished fine patches which accumulated animals during floods from the other fine patches based on two physical attributes. Patches accumulating animals were all characterized by low water flux and nearbed flow, which likely contributed to the retention and/or passive deposition of animals. Whole dam attributes (e.g. dam size or complexity) were not useful in predicting which of the dams would accumulate animals in their fine sediments during flooding. Although structural complexity - here in the form of wood and leafy debris - is clearly important in generating biotic pattern in many ecosystems, our work underscores the need to understand what processes are responsible for the link between physical structure and biotic pattern. Влияние бурности и течения.Authors: Quinn-JM Hickey-CW Linklater-W Гидравлическое воздействия на беспозвоночных перифитона и бентоса - симуляция эффекта бурности. Hydraulic Influences on Periphyton and Benthic Macroinvertebrates - Simulating the Effects of Upstream Bed Roughness FRESHWATER BIOLOGY 1996, Vol 35, Iss 2, pp 301-309 Abstract: 1. Hydraulic conditions, periphyton biomass and invertebrate communities were compared on artificial substrates exposed to a range of upstream roughness conditions across an area of uniform current velocity and depth in a gravel-bedded river. The effect of river bed roughness was simulated by installing roughness elements upstream of artificial substrates. 2. Increasing upstream roughness reduced the average near- bed velocity above the substrates and increased short-term variability in velocity (i.e. turbulence). 3. Periphyton chlorophyll n density showed a general decline with near-bed velocity and was significantly lower on the substrates exposed to the river bed reference and 0 mm roughness treatments than the 110 mm roughness elements. Chlorophyll a was also negatively correlated with the abundance of larger collector-browsing invertebrates. This indicates that effects of the changes in hydraulic conditions on invertebrates may have contributed to the observed treatment effects on periphyton. 4. Invertebrate abundance and diversity declined with increasing upstream roughness. Filter-feeders, collector- browsers and predatory invertebrates all declined in abundance with increasing upstream roughness, but the effect was strongest for filter-feeders. Eight of the nine most common taxa showed significant treatment effects. The orthoclad chironomid, Eukiefferiella sp., was not influenced strongly by upstream roughness, but its abundance was correlated significantly with periphyton biomass.
INTERNATIONALE REVUE DER GESAMTEN HYDROBIOLOGIE 1996, Vol 81, Iss 1, pp 79-91 Abstract: Macroinvertebrate communities were studied in relation to food (particulate organic matter and periphyton) availability and hydrologic regime in two reaches (autotrophic and heterotrophic) of the Aguera stream (Northern Spain). The structure of macroinvertebrate community reflected the trophic characteristics (main food sources) at each site. From a temporal point of view both food availability and hydrologic regime seem to be the main factors that determine the dynamics and structure of the community. In the autotrophic reach, shredder density showed significant relationship with CPOM, and scrapers with periphyton both in terms of density and biomass. Влияние течения, глубины, субстрата на бентос водотоков.Authors: Quinn-JM Hickey-CW Гидрологические параметры и распределение макробентоса в двух реках с гравийным дном в Новой Зеландии. Hydraulic Parameters and Benthic Invertebrate Distributions in 2 Gravel-Bed New-Zealand Rivers FRESHWATER BIOLOGY 1994, Vol 32, Iss 3, pp 489-500 Abstract: 1. Benthic invertebrates were sampled over a matrix of about eighty combinations of mean velocity (10-150 cm s-1) and depth (10-150 cm) in two rivers that differed in substrate size variability. Vertical velocity profiles were measured at each sample site and substratum roughness was measured and estimated from percentage cover by stone size classes. The influence of depth on periphyton biomass was also measured. 2. The hydraulic and substrate data were used to investigate the correlations between conventional (mean velocity, depth, substrate size) and complex hydraulic variables (Froude number, shear velocity, and water column and boundary Reynolds number) that were either calculated from direct measurements or inferred from mean velocity, depth, kinematic viscosity and substrate roughness. The ecological relevance of these hydraulic variables was investigated by comparing their degree of correlation with invertebrate densities and community metrics.
3. The invertebrate variables had similar correlations with mean velocity and the complex near-bed hydraulic variables in the river with uniform cobble substrates. In the river with diverse substrates, however, average correlations with Froude number, and inferred shear velocity and boundary Reynolds number were 25-45% higher than with velocity. Of all the individual hydraulic parameters, the boundary Reynolds number, calculated from simple measures, was most strongly correlated with benthic invertebrate distributions and taxa richness. However, invertebrate distributions were more strongly correlated with predictions of multiple regression models, incorporating substrate size, depth and mean velocity, than with any single hydraulic variable. 4. Hydraulic influences on food availability and oxygen concentration in the benthos are likely mechanisms affecting the hydraulic preferences of several taxa. Lower periphyton biomass with depth, partly attributable to light attenuation, appeared to have a non-hydraulic influence on a collector-browser species. Влияние древесного субстрата.Authors: Wallace-JB Webster-JR Meyer-JL Влияние добавления коряг на физические и биологические характеристики горного потока. Influence of Log Additions on Physical and Biotic Characteristics of a Mountain Stream CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES 1995, Vol 52, Iss 10, pp 2120-2137 Abstract: Three pairs of cobble riffle study sites were established in a second-order stream in North Carolina and logs added to the downstream riffle at each site. At log addition transects, stream depth increased, current velocity decreased, cobble substratum was covered by sand and silt, and both coarse and fine particulate organic matter increased dramatically. Log additions had less dramatic effects on uptake lengths of ammonium, nitrate, and phosphate, but they had immediate and significant impacts on invertebrate community structure: abundances and biomass of scrapers and filterers decreased; collectors and predators increased; overall shredder biomass did not change, but biomass of trichopteran and dipteran shredders increased, while that of most plecopteran shredders decreased; and plecopteran predators also decreased despite greater abundances of potential prey. These observations suggest that physiological and morpho-behavioral constraints preclude many animals from tracking resources among patches when patches display very different abiotic conditions. Secondary production of scrapers and filterers decreased, whereas that of collectors and predators increased. The shifts in functional group abundances, biomass, and production between reference and debris- dam transects, which differed considerably from those previously reported for low-gradient, sandy-bottom streams, accentuate the importance of localized abiotic factors in structuring invertebrate communities within patches. Ледниковые водотоки, бентос: влияние факторов03.01-04А2.75. Особенности структуры сообществ макробеспозвоночных в реках с ледниковым питанием в зависимости от факторов среды; синтез. Trends of macroinvertebrate community structure in glacier-fed rivers in relation to environmenta conditions: A synthesis / Milner Alexander M., Brittain John E., Castella Emmanuel, Petts Geoffrey E. // Freshwater Biol. - 2001. - 46, N 12. - С. 1833-1847. - Англ. Для прогнозирования таксономического богатства и таксономического разнообразия макробеспозвоночных в 7 европейских реках с ледниковым питанием использованы модели, содержащие 11 переменных факторов среды. Показано, что основную роль играют макс. т-ры воды и стабильность русла реки. На основе этих и ряда других данных представлена модифицированная концептуальная модель, предсказывающая встречаемость семейств и подсемейств разных макробеспозвоночных по данным о летнем периоде снеготаяния. При макс. т-ра воды <2°C единственными обитателями являются Diamesinae, при т-ре >2°, но ниже 4°C Orthocladiinae, а при этих т-рах и более стабильном русле также отмечены типулиды и олигохеты. При т-рах выше 4°C можно ожидать развития Periodidae, Taeniopterygidae, Baetidae, Simuliidae, Empididae. В другое время года при благоприятных внешних условиях реки с ледниковым питанием поддерживают более разнообразное и многочисленное сообщество макробеспозвоночных с рядом видов, не встречающихся в период летнего снеготаяния. Обсуждаются условия расселения макробеспозвоночных в реках с ледниковым питанием на островах и в некоторых альпийских зонах. Великобритания, School of Geography, Univ. of Birmingham, Edgbaston, Birmingham B45 8LY, UK. E-mail: a.m.milner@bham.ac.uk. Ил. 9. Библ. 60. Влияние субстрата в водотоках.Gayraud-S Philippe-M Does Subsurface Interstitial Space Influence General Features and Morphological Traits of the Benthic Macroinvertebrate Community in Streams Source: ARCHIV FUR HYDROBIOLOGIE 2001, Vol 151, Iss 4, pp 667-686 The benthic macroinvertebrate community and substratum characteristics were assessed at 17 study sites differing in the amount of interstitial space in the subsurface interstitial zone (0-15 cm deep). The invertebrate community was described in terms of density, taxonomic richness, Shannon diversity and morphological traits (size, flexibility and body shape of the invertebrates). The amount of interstitial space in the subsurface zone that is described by porosity was significantly and negatively related to percentage of fine sediment, but not to stream slope, particle heterogeneity and particle size. Invertebrate density was significantly and positively related to the amount of interstitial space whereas taxonomic richness was slightly and negatively related to fine particulate organic matter content. Relative abundance of intermediate body size (5- 10mm), intermediate body flexibility (10-300 degrees), and flattened or streamlined shape were significantly and positively related to the amount of interstitial space, contrasting with relative abundance of small body size (<5 mm), and cylindrical or spherical shape that were significantly and negatively related to this variable. These results highlight the importance of interstitial space, both as a factor partly controlling community structure and as an evolutionary factor acting on macroinvertebrate ability to penetrate the substratum. In addition to flow, the substratum selects the invertebrates through their different abilities to use the interstitial habitat.
Influence of log additions on physical and biotic characteristics of a mountain stream. Canadian Journal of Fisheries & Aquatic Sciences 52(10). 1995. 2120-2137. Three pairs of cobble riffle study sites were established in a second-order stream in North Carolina and logs added to the downstream riffle at each site. At log addition transects, stream depth increased, current velocity decreased, cobble substratum was covered by sand and silt, and both coarse and fine particulate organic matter increased dramatically. Log additions had less dramatic effects on uptake lengths of ammonium, nitrate, and phosphate, but they had immediate and significant impacts on invertebrate community structure: abundances and biomass of scrapers and filterers decreased; collectors and predators increased; overall shredder biomass did not change, but biomass of trichopteran and dipteran shredders increased, while that of most plecopteran shredders decreased; and plecopteran predators also decreased despite greater abundances of potential prey. These observations suggest that physiological and morphobehavioral constraints preclude many animals from tracking resources among patches when patches display very different abiotic conditions. Secondary production of scrapers and filterers decreased, whereas that of collectors and predators increased. The shifts in functional group abundances, biomass, and production between reference and debris-dam transects, which differed considerably from those previously reported for low-gradient, sandy-bottom streams, accentuate the importance of localized abiotic factors in structuring invertebrate communities within patches. Влияние стабильности местообитания.Authors: Death-RG Влияние стабильности местообитания на сообщество макробентоса - использование распределения видового обилия. The Effect of Habitat Stability on Benthic Invertebrate Communities - The Utility of Species Abundance Distributions HYDROBIOLOGIA 1996, Vol 317, Iss 2, pp 97-107 Abstract: Spatial and temporal patterns in the species abundance distribution of benthic invertebrate communities of 11 freshwater habitats (10 streams and a wind-swept lake shore) were examined with respect to habitat stability. Abundance patterns varied markedly between seasons at most sites. However, mean abundance distributions at 4 of the 5 unstable sites and the 2 most stable sites were dominated by one or two taxa with a large number of rare species, whereas sites of intermediate stability had more equitable distributions. Both the log series and log normal distributions were statistically indistinguishable, at the 5% level, from all the observed mean abundance patterns. In contrast, graphical comparisons of the observed and fitted distributions suggested the log series may be the better fit at most of the unstable sites and the two most stable sites, whereas the more equitable distribution at sites of intermediate stability suggested the log normal distribution was the better fit. If conditions at a site favoured one or two species, either through severe physical conditions, or through competitive superiority in the absence of disturbance then the log series distribution may result. However, if no species in the community was strongly advantaged over others, a log normal distribution should result. Given the discriminating power of the appropriate statistical test it may not, however, be possible to pick up these differences without graphical comparisons as well. Водотоки: влияние локальных нарушений.Moser D C. Minshall G W. Effects of localized disturbance on macroinvertebrate community structure in relation to mode of colonization and season. American Midland Naturalist 135(1). 1996. 92-101. Relative importance of different dispersal modes (drift and crawling) on macroinvertebrate colonization within seasons under differing disturbance regimes was tested by field experiment. Forty individual substrata (tiles) were placed in a series of riffles in Mink Creek, Idaho, a third-order, Rocky Mountain stream. Twenty tiles were mounted on steel bars to elevate them above the streambed and 20 were placed directly on the streambed to distinguish invertebrates colonizing by drift from those colonizing by crawling. After an initial colonization period of 32 days, all invertebrates were removed from tiles every 2, 4 or 8 days or left undisturbed during the 16 day experimental period. Experiments were conducted in the spring, summer and autumn of 1992. In the spring experiment, invertebrate abundance was greater (524%) but diversity (D) was lower (-42%) on elevated tiles as compared to unelevated tiles. No significant differences were found between elevated and unelevated tiles or disturbance frequencies in terms of abundance and diversity in summer. Abundance decreased with increasing levels of disturbance in autumn (-58%) (2-day disturbance to 8-day disturbance treatments). No significant differences in diversity were found between disturbance treatments or between tile elevations in the autumn. Relative importance of drift and crawling as modes of colonization varied with season. Colonization through drift was important in spring, when water temperature was low, discharge was high, and algal resources were low. In summer and autumn, when water temperature was high, discharge was low, and algal resources were abundant, drifting and crawling taxa colonized equally rapidly. Влияние стабильности биотопаAuthors: Death-RG Winterbourn-MJ Структура разнообразия сообществ речного макробентоса – влияние стабильности местообитания. Diversity Patterns in Stream Benthic Invertebrate Communities - The Influence of Habitat Stability ECOLOGY 1995, Vol 76, Iss 5, pp 1446-1460 Abstract: Invertebrate diversity patterns were examined in 11 freshwater habitats (10 streams and a windswept lake shore) of similar physicochemical nature but different thermal and hydrologic stability in the Cass-Craigieburn region, New Zealand. Species richness and density were markedly higher at the more stable sites, but species evenness peaked at sites of intermediate stability. Of the 20 environmental variables examined, a multivariate instability index incorporating temporal variation in depth, temporal variation in current speed, substrate stability, the Pfankuch channel stability index, temperature range, and stream reach tractive force was the single best predictor of the number of species, whereas epilithic pigment concentration was the single best predictor of invertebrate density. The pattern in species richness did not support any of three diversity hypotheses considered. In contrast, the pattern in species evenness suggested competitive exclusion may be occurring patchily and that Huston's dynamic equilibrium model may have some validity, at least at the level of the patch. However, the strong link between productivity and stability apparent in these habitats, and a lack of information on the effects of increased productivity on competition in stream benthic communities makes any firm assessment of the latter model difficult. The observed diversity patterns are, however, consistent with the idea that high diversity is maintained in these habitats by an interaction between low levels of disturbance and habitat patchiness.
Macroinvertebrate production in a headwater stream during recovery from anthropogenic disturbance and hydrologic extremes. Canadian Journal of Fisheries & Aquatic Sciences 52(11). 1995. 2402-2422. Recovery of the macroinvertebrate community inhabiting a headwater stream (catchment 54; C54) that received 3 years of seasonal insecticide treatment was investigated. Estimates of abundance, biomass, and production in C54 during 1989 and 1990 were compared with those of a nearby undisturbed reference stream (catchment 55; C55), and those of C54 during a pretreatment year (1985). Total macroinvertebrate abundance was similar throughout pretreatment, treatment, and recovery periods of C54. In contrast, biomass and production, which decreased during treatment, increased to levels similar to those of C54 in the pretreatment year and those of the reference stream during recovery. By 1990, the functional structure of C54 was similar to that of C55 and that of C54 before the treatment. However, taxonomic and developmental stage differences within some functional groups, particularly shredders, persisted. Despite poor recovery of some larger shredder taxa, rapid recovery of a relatively small trichopteran shredder, Lepidostoma spp., contributed significantly to recovery of ecosystem processes associated with shredders. Relationships between shredder biomass and coarse particulate organic matter differed during treatment and recovery periods. Invertebrate taxa with shorter life cycles recolonized rapidly, while those with life cycles gt 1 year generally displayed limited recovery. Hydrologic extremes during treatment (drought) and recovery (wet) periods affected organic matter and macroinvertebrate community dynamics in both streams, and may have influenced observed recovery patterns.
Volume 46 Issue 12 Page 1641 - December 2001 Macroinvertebrate community structure in relation to environmental variables in a Swiss glacial stream Brigitte Lods-Crozet, Emmanuel Castella, Diana Cambin, Christiane Ilg, Sandra Knispel & Helene Mayor-Simeant 1.Benthic macroinvertebrate distribution was examined in relation to channel characteristics (including stability), substratum, hydraulic variables, primary production (chlorophyll a) and coarse particular organic matter (CPOM) in an alpine glacial stream, the Mutt (Upper Rhone valley, Switzerland). Co-inertia analysis and canonical correspondence analysis were used to identify the major environmental gradients influencing community variations. 2.The Mutt (length: 3.6km, altitudinal range: 1800-3099m a.s.l.) exhibited typical characteristics of a kryal stream. Average summer temperature remained below 2°C immediately downstream from the snout but was on average 5°C higher 1700m downstream. Seasonal variations in water sources were evidenced by the high late- summer (September) contribution of groundwater with increased conductivity. 3.Sixty-six taxa were recorded from the five reaches sampled at three periods (snowmelt, ice melt and low water in late summer) in 1996 and 1997, of which 29 were Chironomidae. Three taxa of Diamesinae were the first colonizers of the stream below the glacier, but 16 taxa, including Ephemeroptera, Plecoptera and Trichoptera, were already recorded 200m downstream. Water depth, channel slope and Pfankuchs Index of channel stability were strongly correlated with the longitudinal faunal gradient. Maximum temperature, current velocity and water conductivity were also correlated, but to a lesser extent. 4.The rapid incorporation of non-chironomid taxa into the stream community represented a departure from Milner & Pettss (1994) conceptual model of invertebrate succession downstream of glacial margins. The results confirmed that glacial stream communities are primarily driven by physical determinants.
Водотоки: влияние факторов средыFreshwater Biology Volume 46 Issue 12 Page 1673 - December 2001 Physico-chemistry and aquatic insects of a glacier-fed and a spring-fed alpine stream Leopold Fureder, Cornelia Schutz, Manfred Wallinger & Rainer Burger 1.Physico-chemical conditions and benthic macroinvertebrates were studied in two adjacent alpine streams in the Tyrolean Alps, Austria, for 2years, and aquatic insect emergence was recorded for 1year. 2.In the spring-fed system, maximum discharge and increased concentrations of suspended solids, nitrate and particulate phosphorus occurred during snowmelt in June. In the glacier-fed stream, high discharge and strong diel fluctuations in flow and concentrations of suspended solids created a harsh and unstable environment during summer. Glacial ablation, variation in groundwater inflow, and water inputs from tributaries draining calcareous rocks caused water chemistry to vary both seasonally and longitudinally in glacier-fed Rotmoosache. 3.A total of 126 aquatic or semi-aquatic invertebrate taxa were collected, 94 of which were found in the glacier-fed stream and 120 in the spring-fed stream. Chironomid abundance was 2-8 times and taxa richness 2-3 times lower in the glacier-fed stream than in the spring-fed stream, as was the number of chironomid taxa (72 versus 93 total). 4.These results broadly support the conceptual model by Milner & Petts (1994) concerning glacier-fed stream systems. However, single samples and seasonal means showed relatively high invertebrate abundance and richness, especially during winter, indicating a considerable degree of spatial and temporal variability. 5.We suggest that the seasonal shifts from harsh environmental conditions in summer to less severe conditions in autumn and a rather constant environment in winter are an important factor affecting larval development, life-history patterns and the maintenance of relatively high levels of diversity and productivity in glacier-fed streams.
Водотоки: влияние факторов среды. Снег.Freshwater Biology Volume 46 Issue 12 Page 1691 - December 2001 Effects of snow cover on the benthic fauna in a glacier-fed stream Cornelia Schutz, Manfred Wallinger, Rainer Burger & Leopold Fureder 1.Alpine streams above the tree line are covered by snow for 6-9months a year. However, winter dynamics in these streams are poorly known. The annual patterns of macroinvertebrate assemblages were studied in a glacial stream in the Austrian Alps, providing information on conditions under the snow. 2.Snow cover influenced water temperature, the content of benthic organic matter and insect development. Taxa richness and abundance of macroinvertebrates did not show a pronounced seasonal pattern. The duration of the autumn period with stable stream beds was important in determining the abundance and composition of the winter fauna. 3.There were significant differences in species composition between summer and winter. Two potential strategies in larval survival were evident: adaptation to the extreme abiotic conditions in summer (e.g. Diamesa spp.) or avoidance of these conditions and development during winter (e.g. Ephemeroptera and Plecoptera). 4.A comparison of a stream reach with continuous snow cover and a stream reach that remained open throughout winter showed that conditions under snow are suboptimal. At the open stream site, with higher water temperatures and greater food supply (benthic organic matter content), abundance and taxa richness was higher and larval growth was faster. Several taxa were found exclusively at this site. 5.Winter conditions did not provide an entirely homogeneous environment, abiotic conditions changed rapidly, especially at the onset of snowfall and at snowmelt. Continuous monitoring is necessary to recognize spatial and temporal heterogeneity in winter environments and the fauna of alpine streams.
Водотоки: влияние факторов средыFreshwater Biology Volume 46 Issue 12 Page 1753 - December 2001 Macroinvertebrate stream communities along regional and physico-chemical gradients in Western Greenland Nikolai Friberg, Alexander M. Milner, Lars M. Svendsen, Claus Lindegaard & Soren Erik Larsen 1.Macroinvertebrates were collected and physico-chemical variables measured at 16 stream sites in Western Greenland during July 1999. Eight sites were located on Disko Island in an arctic oceanic climate and eight sites in the Kangerlussuaq area close to the icecap where the climate is arctic continental. The streams had different water sources (glacial, groundwater, snowmelt and lake water). 2.The streams showed pronounced differences in water temperature (2.2-17.3°C), concentrations of suspended solids (0-2400mgL1), and conductivity (10-109Scm1). Principal component analysis (PCA) analysis of the physico-chemical variables separated the Disko Island sites into a distinct group, whereas the sites in the Kangerlussuaq area were more dispersed. 3.A total of 56 macroinvertebrate species were found, including 31 species of Chironomidae, the most abundant of which was Orthocladius thienemanni. Diamesa sp. was only the sixth most abundant chironomid taxon. Species composition varied between sites, and abundance varied from about 20 individuals m2 in a glacier fed stream to more than 16000m2 in a lake outlet. 4.The macroinvertebrate communities of the 16 streams were separated into five TWINSPAN groups reflecting water source, irrespective of region. Lake outlets and ground-water-fed streams had the highest species richness and abundance, temperature and bed stability, while glacier-fed streams were characterized by low species richness, abundance, temperature, bed stability and high concentrations of suspended solids. Macroinvertebrate species richness was positively correlated with water temperature and negatively with bed stability. Conductivity was positively correlated with invertebrate abundance. 5.The results of this study suggest that the source of stream water can be used to predict invertebrate community composition in Greenlandic streams and thus the effects of changes in water balance and flow regime, and to identify sites of special conservation interest. Водотоки: влияние факторов среды. Загрязнение.Freshwater Biology Volume 46 Issue 10 Page 1409-1424 - October 2001 Relationships between land use, spatial scale and stream macroinvertebrate communities R. A. Sponseller, E. F. Benfield & H. M. Valett 1.The structure of lotic macroinvertebrate communities may be strongly influenced by land-use practices within catchments. However, the relative magnitude of influence on the benthos may depend upon the spatial arrangement of different land uses in the catchment. 2.We examined the influence of land-cover patterns on in-stream physico-chemical features and macroinvertebrate assemblages in nine southern Appalachian headwater basins characterized by a mixture of land-use practices. Using a geographical information system (GIS)/remote sensing approach, we quantified land-cover at five spatial scales; the entire catchment, the riparian corridor, and three riparian sub-corridors extending 200, 1000 and 2000m upstream of sampling reaches. 3.Stream water chemistry was generally related to features at the catchment scale. Conversely, stream temperature and substratum characteristics were strongly influenced by land-cover patterns at the riparian corridor and sub-corridor scales. 4.Macroinvertebrate assemblage structure was quantified using the slope of rank- abundance plots, and further described using diversity and evenness indices. Taxon richness ranged from 24 to 54 among sites, and the analysis of rank-abundance curves defined three distinct groups with high, medium and low diversity. In general, other macroinvertebrate indices were in accord with rank-abundance groups, with richness and evenness decreasing among sites with maximum stream temperature. 5.Macroinvertebrate indices were most closely related to land-cover patterns evaluated at the 200m sub-corridor scale, suggesting that local, streamside development effectively alters assemblage structure. 6.Results suggest that differences in macroinvertebrate assemblage structure can be explained by land-cover patterns when appropriate spatial scales are employed. In addition, the influence of riparian forest patches on in-stream habitat features (e.g. the thermal regime) may be critical to the distribution of many taxa in headwater streams draining catchments with mixed land-use practices.
Volume 41 Issue 4 Page 747 - June 1999 Predicting the macroinvertebrate faunas of rivers by multiple regression of biological and environmental differences 1. The prediction of macroinvertebrate community composition in flowing waters from environmental data has enabled pollution assessments that take account of natural variability. Polluted sites are identified by discrepancies between the observed fauna and the fauna expected at an unpolluted site on the same type of river. 2. The usual method of prediction involves a sequence of (a) classification of unpolluted reference sites by cluster analysis of macroinvertebrate community data (b) multiple discriminant analysis to relate site clusters to environmental variables, and (c) use of site clusters, discriminant functions and environmental data to estimate the probability of collection of each macroinvertebrate taxon at sites that are to be assessed (test sites). 3. This paper describes an alternative method that does not require classification and predicts abundance rather than probability of occurrence. The main steps are (a) multiple regression of biological differences between pairs of reference sites on differences in physical variables (b) use of the multiple regression relationship to predict the biological similarity of a test site to each reference site, and (c) estimation of the expected fauna at the test site as a weighted mean of the faunas at the reference sites. The predicted similarities of the test site to each reference site are used to derive the weightings. 4. The method is illustrated using macroinvertebrate and environmental data collected in the upper Murrumbidgee River catchment as part of Australias Monitoring River Health Initiative. In comparison with a classification-based analysis of these data, macroinvertebrate indices generated by the new method showed a greater distinction between human-disturbed and undisturbed test sites, and a similar or higher degree of correlation with physical and chemical indicators of human disturbance. Водотоки: измерение скорости течения.Freshwater Biology Volume 39 Issue 2 Page 301 - March 1998 An application of the plaster dissolution method for quantifying water velocity in the shallow hyporheic zone of an Appalachian stream system Ted Angradi* AND & Robert Hood 1. A method for quantifying interstitial water velocity based on the dissolution rate of plaster of Paris standards was developed as part of a study of vertical, longitudinal (1-4 order sites) and seasonal variation in the biotic and physical characteristics of the shallow hyporheic zone (0-30 cm) of a headwater stream system in West Virginia, U.S.A. 2. A calibration model was developed using a water velocity simulation tank to relate mass loss of plaster standards to water velocity and temperature. The model was then used to calculate water velocity through artificial substrata embedded in the shallow hyporheic zone of four stream reaches based on in situ mass loss of plaster standards. 3. Water velocity in the hyporheic zone increased with stream order, was highest in early spring and winter during high stream base flows, and decreased with depth into the substratum. There was a strong interaction between depth and season: during periods of high stream discharge, water velocity through the upper level of the shallow hyporheic zone (0-10 cm into the substrate) increased disproportionately more than velocity at greater depths. Mean interstitial velocity in March ranged from 0 cm s1 in the lowest level (20-30 cm) to 3.5 cm s1 at the upper level (0-10 cm) at the firstorder site, and from 2.5 cm s1 (20-30 cm) to 9.5 cm s1 (0- 10 cm s1) at the fourthorder site. Gradients in stream discharge and sediment permeability accounted for treatment effects. 4. Use of calibrated data improved the ability to resolve amongseason differences in interstitial water movement over the use of uncalibrated mass loss data. For some applications of the plaster standard method, empirical calibration may not be necessary.
Водотоки: влияние факторов среды.Freshwater Biology Volume 40 Issue 1 Page 175 - August 1998 Сообщества беспозвоночных в водотоках хвойных лесов Ирландии: взаимоотношение физико-химических и биотических факторов. Stream macroinvertebrate communities in a coniferafforested catchment in Ireland: relationships to physicochemical and biotic factors Clenaghan, , Giller,*, Ohalloran AND & Hernan 1. The influence of land use and physicochemical factors on stream macroinvertebrates was analysed at fifteen sites over a 2year period in a single coniferafforested catchment in Ireland, in an area subject to very low levels of atmospheric pollution. 2. Macroinvertebrate assemblages were classified using twoway indicator species analysis into five major groupings that were related to distance from headwaters and land use. Trends in macroinvertebrate community composition were related to changes in physicochemical and biotic characteristics of the river and its tributaries using canonical correspondence analysis. 3. Local ecological factors (e.g. acid water, moss, shading or agricultural runoff), longitudinal trends in stream physicochemistry (related to distance from headwaters, geology and land use) and season (related to life history patterns of the invertebrates) were the explanatory variables of spatiotemporal patterns in macroinvertebrate community composition in the catchment. 4. Spatial variation in macroinvertebrate density, taxon richness, diversity and evenness was investigated in relation to environmental characteristics of the study sites using Spearmans rank correlation, principal components analysis and stepwise multiple regression. Invertebrate density and richness increased with distance from the headwater and associated increases in pH, water hardness and nutrients. Macroinvertebrate density and richness also increased with increasing moss weight. Invertebrate diversity and evenness increased with shading of the channel. 5. The increase in macroinvertebrate density and richness and changes in community composition were particularly marked over a relatively short (1.2 km) distance in one tributary, and were concurrent with a rapid increase in stream pH of 1.7 units. 6. Although macroinvertebrate communities at coniferafforested sites were not impoverished in the same way as those in some other parts of Europe, they differed from the communities found above and below the plantation. This appeared to be owing to the primary importance of local ecological factors and the effect that the longitudinal position of these forest sites within the river system had on their physicochemical and biotic nature. Водотоки: влияние факторов среды. Течение.Freshwater Biology Volume 41 Issue 3 Page 605 - May 1999 Small-scale movements of lotic macroinvertebrates with variations in flow Jill Lancaster Summary 1.The small-scale movements and distribution patterns of invertebrates were observed in an attempt to identify the various mechanisms by which organisms may use flow refugia during flow disturbances. The microdistribution of lotic macroinvertebrates was examined in two replicate, non-circulating laboratory flumes with variations in flow among microhabitat patches (0.015-0.035m2). The discharge in one experimental flume was manipulated to mimic spates and alter near-bed flow patterns; the other flume acted as a control. After an initial settling period, the position and behaviour of animals within the flumes was recorded before, during and after a simulated spate. Three species with contrasting flow microhabitat preferences and movement behaviour were examined. 2.At low discharge, the microdistribution of all three study species in flumes was broadly consistent with field observations. In the field, the optimum current speed was lowest for adults of the dytiscid beetle, Oreodytes sanmarkii, and highest for mayfly nymphs, Ephemerella ignita, with nymphs of the stonefly, Leuctra inermis, most abundant at intermediate velocities. In the flumes, O.sanmarkii occurred only in very low velocity areas, L.inermis occurred widely throughout the flumes with highest density in low velocity areas and E.ignita also occurred throughout the flumes, but maximum density was in moderately high velocity areas. 3.Increased discharge did not reduce the total number of individuals in experimental versus control flumes for any of the three species studied, although total numbers did decrease over the observation period in both treatments. Simulated spates resulted in a change in the microdistribution of O.sanmarkii and E.ignita, but not L.inermis, such that numbers were reduced in very high velocity microhabitats and animals accumulated in lower flow areas, analogous to flow refugia. These distributional shifts were attributed to movements of individuals among microhabitats. 4.Both active and passive modes of movement contributed to the accumulation of E.ignita and O.sanmarkii in low flow microhabitats (i.e. flow refugia). Some nymphs of E.ignita actively crawled from high to low flow microhabitats. Both species drifted between microhabitats. Drift entry could be active or passive, whereas regaining the substratum was active: O.sanmarkii swam down and E. ignita altered its body posture to promote sinking.
Водотоки: влияние факторов среды. Течение.Freshwater Biology Volume 45 Issue 1 Page 57 - September 2000 Macroinvertebrate community structure along gradients of hydraulic and sedimentary conditions in a large gravel-bed river Laura L. Rempel* John S. Richardson Michael C. Healey 1.The spatial distribution of macroinvertebrate species was examined in relation to hydraulic and sedimentary conditions in a large gravel-bed river, the Fraser River, Canada. Mean annual discharge in the Fraser River is 2900m3s1 and annual flood discharge, due to snowmelt in May and June, averages 8760m3s1. 2.Invertebrates were sampled from four water depths (0.2, 0.5, 1.5, 3.0m) at various levels of discharge that together captured the spatial and temporal variability of the physical habitat. Several hydraulic (near-bed shear velocity, Boundary Reynolds number, turbulence intensity, depth-averaged velocity, Froude number, Reynolds number) and substratum variables (mean grain size, Trask's sorting coefficient, Nikuradse's roughness, percentage of fine sediment, and Shields entrainment function) were measured for each sample of macroinvertebrates. Concentrations of fine and coarse particulate organic matter were also assessed. 3.The physical habitat was characterized by a major gradient of hydraulic conditions that corresponded positively with increasing water depth and accounted for 52% of the total variation in the habitat data. Substratum conditions and the concentration of organic matter explained 24% of the total variation in the habitat data.
4.The distribution of invertebrates was correlated significantly with hydraulic variables and suggests that hydraulic conditions represent a major physical gradient along which the benthic community is organized. The distribution of organic matter and substratum texture were also important for some species. The spatial distribution of most species reflected morphological and trophic suitability to particular habitat conditions. 5.Hydraulic stress associated with foraging and maintaining position, as well as organic matter retention in coarse substrata, are probable mechanisms affecting the spatial distribution of macroinvertebrates.
FRESHWATER BIOLOGY 1995, Vol 33, Iss 3, pp 557-565 Abstract: 1. Increases in spatial heterogeneity may provide more food, create new resources or interfere with the foraging activities of a herbivore. 2. Three colonization experiments were performed in an upland stream to investigate the effects of one type of spatial heterogeneity (grooves on the substratum) on the relationship between an abundant herbivore, Agapetus monticolus (Banks, Trichoptera), and the epilithon on which it feeds. 3. The results indicate that grooves do not provide any different resources or interfere with the foraging activities of A. monticolus, but may increase food abundance, although the effect of grooves on food abundance appears to vary temporally. 4. Temporal variation in the effects of microspatial complexity raises the possibility that its importance to the community may be over- or underestimated unless experiments are designed to incorporate this temporal variation.
HYDROBIOLOGIA 1994, Vol 281, Iss 1, pp 1-17 Изучали в поле и в экспериментах влияние на макробентос высокого содержания железа и скоплений железобактерии Leptothrix ochracea. Бентос в 5 из 6 речек был угнетнен (depauerate) внутри скоплений железобактрий (inside blooms). Причины угнетения макробентоса железом и железобактериями: во-первых, прямой токсический эффект; во-вторых, поведенческое избегание бентосов субстратов, покрытых бактериями; в-третьих, невозможность использовать бактерий в пищу. У трех видов поденок повысилась смертность, у 5 видов ручейников и 1 вида веснянок - нет. 5 видов беспозвоночных избегают субстрата с железобактериями, 3 вида - нет. Stenonema fuscum не может есть Leptothrix, и Neophylax nacatus хуже растет на нем, а Heptagenia umbratica растет одинаково на питании Leptothrix или диатомеями. Работа показывает важную роль организмов эпилитона в модификации субстратов, и как они могут изменять обилие и распределение бентоса. Abstract: In field measurements and laboratory experiments we assessed the influence of high levels of iron, manganese, and concurrent blooms of iron-depositing bacteria, Leptothrix ochracea, on macroinvertebrates. Macroinvertebrate communities in five of six streams were depauerate inside blooms. Reasons for the decreased abundance vary among taxa, with our experiments demonstrating the importance, for one or more species, of (1) direct toxic effects, and,/or smothering, (2) behavioral avoidance of bacterial-coated substrates, and (3) an inability to use bacteria as food. Three mayfly species showed increased mortality when caged inside the blooms, but five trichopterans and one plecopteran did not. Five invertebrates avoided Leptothrix-coated substrate in choice trials, while three did not. Stenonema fuscum could not ingest Leptothrix, and Neophylax nacatus had reduced growth feeding on it, but Heptagenia umbratica grew equally well on diets of Leptothrix or diatoms. This study demonstrates the important role epilithic organisms play in modifying substrates, and how these changes may act to influence benthic abundance and distribution in streams.
Title: The Influence of Temperature and Food Quality on the Growth of Hydropsyche-Betteni (Trichoptera) and Simulium- Vittatum (Diptera) Source: JOURNAL OF FRESHWATER ECOLOGY 1991, Vol 6, Iss 1, pp 75-86 Language: English Document type: Article Addresses: COLGATE-UNIV, DEPT BIOL, HAMILTON, NY 13346, USA Keywords Plus: SOUTHERN ONTARIO; AQUATIC INSECTS; FEEDING ECOLOGY; STREAM; DIET; PLECOPTERA; EPHEMEROPTERA; BACTERIA; PATTERNS; ALGAE Abstract: Growth responses of Simulium vittatum and Hydropsyche betteni were observed at 5 C, 14 C and 20 C while on diets restricted to sterile or conditioned fine particulate leaf detritus (FPOM), cultured bacteria (Escherichia coli), a filamentous cyanobacterium (Oscillatoria lutea), two eukaryotic algae (Ulothrix confervicola and diatoms), and Daphnia magna (H. betteni only). Simulium showed little growth at 5 C regardless of food type; however, at 14 C growth of Simulium on conditioned leaf FPOM and O. lutea was greater than on sterile leaf FPOM or U. confervicola all of which resulted in lower growth rates than E. coli and diatoms. Growth was highest at 20 C, with all foods producing similar growth responses except sterile leaf FPOM, which produced a lower growth rate. Hydropsyche betteni also grew little or not at all at 5 C but showed positive growth on all foods at 14 C; furthermore, at 14 C, growth on algae and Daphnia was higher than for detrital/bacterial or cyanobacterial foods. At 20 C growth was negative on detrital FPOM, E. coli and O. lutea but positive on diatoms and Daphnia. These data suggest that colder temperatures restricted growth of both test animals regardless of food quality. Also, H. betteni could not use detrital/bacterial foods as a sole source of energy (especially at temperatures greater-than-or-equal-to 20 C) whereas Simulium grew equally well on algae, cyanobacteria and bacteria either alone or associated with detritus. Differences in growth responses to temperature and food type may help explain observed differences in distribution and abundance of these two species below lake outlets with epilimnial versus hypolimnial releases. Влияние детрита в горном потоке.Authors: Richardson-JS Neill-WE Title: Indirect Effects of Detritus Manipulations in a Montane Stream Source: CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES 1991, Vol 48, Iss 5, pp 776-783 Language: English Document type: Article Addresses: UNIV-BRITISH-COLUMBIA, DEPT ZOOL, ECOL GRP, VANCOUVER V6T-2A9, BC, CANADA Keywords Plus: PARALEPTOPHLEBIA-TEMPORALIS EPHEMEROPTERA; PARTICULATE ORGANIC-MATTER; COMMUNITY-WIDE PATTERNS; AQUATIC INSECTS; FOOD QUALITY; PERTURBATION EXPERIMENTS; ECOSYSTEMS; DYNAMICS; LEPTOPHLEBIIDAE; INTERFERENCE Abstract: To evaluate the common assumption in stream ecosystem theory that fine-particle feeders can indirectly benefit from coarse-particle detritus consumed by detritivores, we manipulated whole-leaf detritus in replicated experimental stream channels. Elevated input rates of detritus resulted in significantly higher densities of collectors and moderate but nonsignificantly higher densities of predators. When collectors were analyzed as filterers and gatherers separately, there were significantly higher densities of both groups at a high loading rate of leaves. The net rates of colonization for each trophic group did not differ significantly with respect to treatment, which suggests that the increased densities of collectors observed under high leaf input rates were due to increased survival of larvae. Density of no single taxon increased significantly in response to coarse particulate organic matter inputs; rather, most species showed moderate increases. Species richness showed no treatment effect. Increases in collector density may result indirectly from increased fine particulate organic matter production due to feeding by shredders. Predaceous species which responded were small taxa and were probably predators on collectors. These effects were observed over a period of less than 5 mo and demonstrate the potential strength of the interactions. Водотоки: разложение листового опада.Authors: Boulton-AJ Boon-PI Title: A Review of Methodology Used to Measure Leaf Litter Decomposition in Lotic Environments - Time to Turn over an Old Leaf Source: AUSTRALIAN JOURNAL OF MARINE AND FRESHWATER RESEARCH 1991, Vol 42, Iss 1, pp 1-43 Addresses: UNIV-ADELAIDE, DEPT ZOOL, GPO BOX 498, ADELAIDE, SA 5001, AUSTRALIA MURRAY-DARLING-FRESHWATER-RES-CTR, ALBURY, NSW 2640, AUSTRALIA Abstract: Despite the recognition of the relationship between microbial conditioning and invertebrate feeding, there has been little communication between microbial ecologists and zoologists studying the processing of leaf litter in streams. An appraisal of suitable methods is timely, to encourage workers to critically examine their experimental approach: it is often forgotten that results are determined largely by the methods used. We review some recent studies, emphasizing the application of microbiological and biochemical methods, and discuss some important decisions that must be made in experimental design and implementation. It is recommended that newly fallen, naturally abscissed leaves, bound in leaf packs and tethered to natural substrata, be used in studies attempting to simulate natural leaf decomposition. Drying and leaching leaves under extreme conditions should be avoided. Mass loss should not simply be equated with decomposition; instead, losses of the main types of chemical constituents of plant litter should be quantified. If the aim is to study decomposition rather than merely leaf breakdown, the metabolism of dissolved matter and fine particulate material lost from the decaying leaf must be addressed as well. Appropriate techniques should be used to study microbial assemblages: lipid biomarkers or nucleic-acid methods for assemblage composition, microscopy or biochemical analysis for microbial biomass, [H-3]-thymidine or [H-3]-leucine methods to determine growth rates. Exponential decay curves and processing coefficients should be used cautiously, especially if sample sizes are small and equal throughout the study. Ординация бентоса по факторам средыAuthors: Tate-CM Heiny-JS Ординация сообществ макробентоса бассейна South Platte River по факторам внешней среды. The Ordination of Benthic Invertebrate Communities in the South Platte River Basin in Relation to Environmental-Factors FRESHWATER BIOLOGY 1995, Vol 33, Iss 3, pp 439-454 Abstract: 1. Spatial patterns of benthic-invertebrate communities were examined in the 62 900 km(2) South Platte River Basin in Colorado, Nebraska and Wyoming, U.S.A., to determine major environmental factors associated with invertebrate distribution. Stable substrates were sampled semiquantitatively for invertebrates from 27 July to 7 August 1992, at twenty-one sites. Data on physical and chemical variables were collected concurrently at each site. 2. Four site groups were identified using detrended correspondence analysis (DCA), one in the mountains and three in the plains (braided channels, tributaries near the confluence with the main stem, and sites affected by effluent from wastewater-treatment plants). DCA axis 1 separated sites into the two major ecoregions (Southern Rocky Mountains and Western High Plains), and regression of DCA axis 1 with environmental variables indicated significant relationships primarily with slope, water temperature, specific conductance, and concentrations of organic nitrogen + ammonia and total phosphorus in surface water. Regression of DCA axis 2 with environmental variables indicated significant relationships with channel width and concentrations of nitrate + nitrite in surface water. 3. Invertebrate community composition and structure varied between ecoregions with greater number of taxa and number of insect families in mountain streams than in plains streams. Within an ecoregion, land use affected the invertebrate community. 4. Factors affecting invertebrate community distribution in stream ecosystems are scale dependent. Влияние света и выедания на перифитон02.02-04А2.75. Фитофагия и освещение определяют архитектуру перифитона в альпийской реке Швейцарии. Herbivory and irradiance shape periphytic architecture in a Swiss alpine stream / Wellnitz Todd A., Ward J.V. // Limnol. and Oceanogr. - 2000. - 45, № 1. - С. 64_ѕ75. - Англ. Изучали влияние света разной интенсивности и фитофагов, потребляющих разные виды водорослей перифитона, на его состав и обилие. Полный солнечный свет оказывал ингибирующее действие на развитие перифитона. Из двух изученных фитофагов, Ecdyonurus sp. и Drusus lateralis, первый оказывал большее влияние на биомассу перифитона. США, Dep. of Biology, Colorado State Univ., Colorado 80523. Ил. 4. Табл. 5. Библ. 64. жүктеу/скачать 1.21 Mb. Достарыңызбен бөлісу:
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