Широтное изменение сообществ

Бентос ледниковых рек: широтный градиент, Европа

В 7 европейских реках от Свальбарда на севере до Пиреней на юге изучали

сообщества донных макробеспозвоночных. Таксономическое богатство, измеряемое из насекомых для хирономид, а также других макробеспозвоночных, возрастало в направлении с севера на юг (3 и 29 таксонов). При помощи моделирования оценена роль отдельных факторов среды в таксономическом богатстве макробеспозвоночных. Показано, что на состав зообентоса в ледниковых реках в основном влияет т-ра воды и стабильность субстрата, меняющиеся вдоль течения реки. Генерализованная

аддитивная модель позволяет прогнозировать изменения зообентосных сообществ в реках с ледниковым питанием при изменении климата и гидрологии.

Швейцария, Lab. d'Ecologie et de Biologie Aquatique, Univ. of Geneva, 18 ch. Des Clochettes, CH-1206 Geneva.

E-mail: emmanuel.castella@leba.unige.ch. Ил. 8.

Табл. 4. Библ. 62; Прилож. 2.

Пространственное распределение бентоса в водотоках.

Пространственное распределение бентоса рек и озер

FRESHWATER BIOLOGY 1995, Vol 33, Iss 3, pp 455-467

Abstract:

1. The effects of habitat stability on benthic invertebrate community structure were examined at eleven sites (ten streams and a wind-swept lake shore) with similar physicochemical characteristics but differing stability.

2. Habitat characteristics were assessed to place the study sites within the framework of the disturbance-productivity-diversity model, the intermediate disturbance hypothesis and a variant of the habitat templet model to examine their

predictions with respect to community structure.

3. Many of the most common invertebrate species were present at all the study sites, although their relative abundance and density differed markedly between sites. Thus, while stability did not appear to affect colonization of the

study sites by these taxa, it did affect their relative success.

4. Communities at unstable sites were very similar and shared a number of taxa such as Deleatidium, Austrosimulium and several species of chironomid, presumably well-adapted to surviving and recolonizing after flood events.

5. Communities at the stable sites differed markedly, both from each other and the group of unstable sites. The characteristic fauna at each of the stable sites seemed to be a result of the site's intrinsic character and possibly biotic interactions.

6. Although stability was a pervading influence on community structure, acting as a bottleneck to the development of a site-specific suite of taxa, none of the above models could adequately explain the observed patterns.

Водотоки: распределение бентоса, модель пятнистости.

Downes-BJ Lake-PS Schreiber-ESG

Spatial Variation in the Distribution of Stream Invertebrates - Implications of Patchiness for Models of Community Organization

FRESHWATER BIOL 1993, Vol 30, Iss 1, pp 119-132

Addresses: MONASH-UNIV, DEPT ECOL & EVOLUT BIOL, CLAYTON, VIC 3168, AUSTRALIA

1. Variation in abundances of stream fauna across a range of spatial scales has been neglected, vet 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.

2. 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 0.5 m 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.

3. 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.

4. 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.

5. 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.

Водотоки: простр.распределение литофильных обрастаний.

Volume 40 Issue 4 Page 655 - December 1998

Temporal and spatial variation in the epilithic biofilm of an acid stream

Mark E. Ledger AND Alan G. Hildrew

Summary

1. The extent of spatial and temporal variation, and the taxonomic and biochemical

Ashdown Forest, southern England.

2. The biofilm had an autotrophic component consisting of acidobiontic diatoms,

small coccoid green algae, zygnematacean filamentous green algae, and a

heterotrophic component of bacteria. Fungi were absent.

3. Diatoms were the dominant algal group in spring. These were succeeded by

coccoid green algae in summer. Synchronous variation existed between algae and

bacteria, suggesting a strong link between the two groups.

4. Quantitative community descriptors (algal and bacterial densities, chlorophyll,

ash-free dry matter) and biochemical descriptors (protein, lipid and carbohydrate

content) of biofilm presented a consistent temporal pattern in which biofilm

biomass peaked in spring and early summer and decreased subsequently.

5. Stepwise multiple regression revealed that temporal variation in the quantity of

biofilm coating substrata was primarily associated with photosynthetically active

radiation. The quantity of biofilm coating the upper surfaces of substrata increased

with substratum particle size (small stones, large stones and bedrock). Smothering

of algae by fine particulate organic matter, proximal shading by bed sediments, and

physical disturbance are proposed as mechanisms that brought about the pattern.

Водотоки: структура местообитаний бентоса.

Freshwater Biology

Volume 39 Issue 2 Page 207-220 - March 1998

The effect of two scales of habitat architecture on benthic grazing in a river

Belinda J. Robson* AND & Leon A. Barmuta

1.This experiment studied the effects of differing levels of the complexity of

substratum architecture at two spatial scales on the distribution and abundance of

benthic algae and invertebrates, and the strength of the trophic interaction between

invertebrate grazers and algae. Some estimates of the effects on invertebrate

colonization rates were also made.

2.Four levels of microhabitat architectural complexity were created using artificial

substrata (clay tiles) and placed in Mountain River, Tasmania, in two riffle types

(bedrock and bouldercobble) of differing largescale substratum complexity. After a

colonization period, invertebrate grazers were removed from half the tiles to

measure the effects of grazing. Invertebrates on the tiles were also counted and

identified. At the end of the experiment, algae were removed from the tiles and

analysed for chlorophyll a.

3.Invertebrate grazers did not reduce algal biomass during the experiment, and

microhabitatscale architecture influenced algal biomass more strongly than riffle

scale architecture. Highly complex microhabitat architecture increased algal biomass

by providing more surface area, but once standardized for surface area, algal

biomass decreased as the complexity of microhabitat architecture increased.

4.Microhabitatscale architecture was also predominant in determining invertebrate

density and the identity of the dominant grazer species. In contrast to algal biomass,

invertebrate densities and species density increased with the complexity of

microhabitat architecture, suggesting that refuges from flow (and possibly

predation) were as important to river invertebrates as the distribution of their food

source.

5.Rifflescale architecture had some effect on the colonization of two slowmoving

grazer taxa, but, overall, the colonization processes of slowmoving grazers were

determined mostly by the complexity of microhabitatscale architecture.

Водотоки: пространственное распределение бентоса.

Freshwater Biology

Volume 46 Issue 12 Page 1663 - December 2001 Spatio-temporal variation in

macroinvertebrate assemblages of glacial streams in the Swiss Alps C. T.

Robinson, U. Uehlinger & M. Hieber

1.Changes in water chemistry, benthic organic matter (BOM), and macroinvertebrates were examined in four different glacial streams over an annual

cycle. The streams experienced strong seasonal changes in water chemistry that

reflected temporal changes in the influence from the source glacier, especially in

water turbidity, particulate phosphorus and conductivity.

2.Nitrogen concentrations were high (nitrate-N values were 130-274gL1), especially during spring snowmelt runoff. Benthic organic matter attained >600gm2 dry mass at certain times, peaks being associated with seasonal blooms of the alga Hydrurus foetidus.

3.Macroinvertebrate taxon richness was two to three times higher (also numbers

and biomass) in winter than summer suggesting winter may be a more favourable

period for these animals. Benthic densities averaged 1140-3820ind.m2, although

peaking as high as 9000ind.m2. Average annual biomass ranged from 102 to 721mg/ m2, and reached >2000mgm2 at one site in autumn.

4.Taxa common to all sites included the dipterans Diamesa spp. and

Rhypholophus sp., the plecopterans Leuctra spp. and Rhabdiopteryx alpina, and

the ephemeropterans Baetis alpinus and Rhithrogena spp. Principal components

analysis clearly separated winter assemblages from those found in summer.

Водотоки: простр.размещение. Методики оценки числа видов.

Freshwater Biology

Volume 46 Issue 6 Page 711-721 - June 2001

Evaluation of methods for estimating macroinvertebrate species richness using

individual stones in tropical streams

Adriano S. Melo & Claudio G. Froehlich
1.The most straightforward way to assess diversity in a site is the species count.

However, a relatively large sample is needed for a reliable result because of the

presence of many rare species in rich assemblages. The use of richness estimation

methods is suggested by many authors as a solution for this problem in many

cases.

2.We examined the performance of 13 methods for estimating richness of stream

macroinvertebrates inhabiting riffles both at local (stream) and regional (catchment)

scales. The evaluation was based on (1) the smallest sub-sample size needed to

estimate total richness in the sample, (2) constancy of this size, (3) lack of erratic

behaviour in curve shape and (4) similarity in curve shape through different data

sets. Samples were from three single stream sites (local) and three from several

streams within the same catchment basin (regional). All collections were made from protected forest areas in south-east Brazil.

3.All estimation methods were dependent on sub-sample size, producing higher

estimates when using larger sub-sample sizes. The Stout and Vandermeer method

estimated total richness in the samples with the smallest sub-sample size, but

showed some erratic behaviour at small sub-sample sizes, and the estimated curves

were not similar among the six samples. The Bootstrap method was the best

estimator in relation to constancy of sub-sample sizes, but needed an unacceptably

large sub-sample to estimate total richness in the samples. The second order

Jackknife method was the second best estimator both for minimum sub-sample size

and constancy of this size and we suggest its use in future studies of diversity in

tropical streams. Despite the inferior performance of several other methods, some

produced acceptable results. Comments are made on the utility of using these

estimators for predicting species richness in an area and for comparative purposes

in diversity studies.

Водотоки: сравнение регионов.

Freshwater Biology Volume 46 Issue 11 Page 1503 - November 2001

Межрегиональное сравнение факторов, определяющих метаболизм сообществ в водотоках.

Inter-biome comparison of factors controlling stream metabolism

P. J. Mulholland, C. S. Fellows, J. L. Tank, N. B. Grimm, J. R. Webster, S. K. Hamilton, E. Marti, L. Ashkenas, W. B. Bowden, W. K. Dodds, W. H. Mcdowell, M. J. Paul & B. J. Peterson

1.We studied whole-ecosystem metabolism in eight streams from several

biomes in North America to identify controls on the rate of stream metabolism over a large geographic range. The streams studied had climates ranging from tropical to cool-temperate and from humid to arid and were all relatively uninfluenced by human disturbances.

2.Rates of gross primary production (GPP), ecosystem respiration (R) and net

ecosystem production (NEP) were determined using the open-system, two-station

diurnal oxygen change method.

3.Three general patterns in metabolism were evident among streams: (1) relatively

high GPP with positive NEP (i.e. net oxygen production) in early afternoon, (2)

moderate primary production with a distinct peak in GPP during daylight but

negative NEP at all times and (3) little or no evidence of GPP during daylight and a

relatively constant and negative NEP over the entire day.

4.Gross primary production was most strongly correlated with photosynthetically

active radiation (PAR). A multiple regression model that included logPAR and

stream water soluble reactive phosphorus (SRP) concentration explained 90 of the

variation in logGPP.

5.Ecosystem respiration was significantly correlated with SRP concentration and

size of the transient storage zone and, together, these factors explained 73 of the

variation in R. The rate of R was poorly correlated with the rate of GPP.

6.Net ecosystem production was significantly correlated only with PAR, with 53 of

the variation in logNEP explained by logPAR. Only Sycamore Creek, a desert

stream in Arizona, had positive NEP (GPP: R>1), supporting the idea that streams

are generally net sinks rather than net sources of organic matter.

7.Our results suggest that light, phosphorus concentration and channel hydraulics

are important controls on the rate of ecosystem metabolism in streams over very

extensive geographic areas.

Водотоки: факторы микрораспределения мейобентоса.

Freshwater Biology

Volume 44 Issue 1 Page 109 - May 2000

What drives small-scale spatial patterns in lotic meiofauna communities?

Christopher M. Swanand Margaret A. Palmer

1. Lotic meiofaunal communities demonstrate extremely variable dynamics,

especially when viewed at small spatial scales ( metres). Given the limited

amount of research on lotic meiofauna, we chose to organise our

discussion of their small-scale spatial patterns around the dominant factors

we believe drive their spatial distributions in streams. We separate scale-

dependent effects that structure lotic meiofauna into biotic factors (e.g.

predation, food quantity/quality, dispersal) and abiotic factors (e.g. local

flow dynamics and substratum characteristics).

2. The impact of predation on the distribution of meiofauna varies with the

scale over which predators forage (e.g. fish predation influences meiofauna

in different ways and at broader spatial scales than do invertebrate

predators), the type of streambed substrata in which the predator-prey

interactions occur, and the dispersal ability of different meiofauna. The

latter is greatly influenced by predator and prey (meiofauna) interactions

with the flow environment.

3. Organic matter influences the small-scale distribution of meiofauna in

streams. Both its quality as food (as indicated by C:N content, ATP

content, or microbial biomass) and its spatial distribution on the streambed,

influence meiofauna patchiness, community structure and life history

characteristics. As a habitat, the structure that organic matter provides (e.g.

wood or leaves) can influence predator-prey interactions, offer materials for

case-building and offer refugia during disturbance events - all of which

influence the small-scale spatial distribution of meiofauna.

4. Stream flow influences the distribution of meiofauna at broad scales (10s-

100s of metres), primarily because of the high susceptibility of meiofauna to

passive drift; small-scale interactions between flow and substrata are also

important, however, particularly at more localised ( metre) scales. At both

scales, substratum particle size is important to interstitial-dwelling fauna,

influencing the probability of passive drift by meiofauna as well as local

microhabitat conditions (e.g. dissolved oxygen; upwelling/downwelling in

the hyporheic zone) and, thus, the small-scale distribution among

microhabitats.

5. In general, the processes governing the distribution of meiofauna at small

scales cannot be separated entirely from those processes working at larger

scales. A conceptual diagram is presented illustrating the relative importance

of various factors in influencing the spatial patterns of meiofauna and over

what scales these factors act.

Поденки Baetidae: распределение.

Authors: Wuillot-J

Микрораспределение личинкок поденок Baetidae

в межень на камнях в р.Ниандан (Гвинея).

Microdistribution of Larval Baetidae in the Dry Season

on the Rocky Substrates of River Niandan (Guinea)

ARCHIV FUR HYDROBIOLOGIE 1994, Vol 131, Iss 4, pp 465-476

Abstract:

The specific richness of Baetidae (Insecta: Ephemeroptera) was very high at a station on the River Niandan (Guinea): 22 species were collected, of which 11 were abundant in at least one microhabitat. The coexistence of numerous morphologically similar species within a limited area is discussed. Most species showed a difference in vulnerability according to the sampling method (benthometre or sampling the lower surface of stones). Biotope preferences were varied (according to the degree of silting and the velocity of the current) and overlapped strongly. On rocky substrates, larval densities were higher in the erect stems of Podostemaceae. During the sampling period (February to April), the larval densities of Afroptilum christinae and Dicentroptilum papillosum decreased while those of Pseudopannota bertrandi and Pseudopannota muganinani increased.

Структура сообществ речного бентоса.

Carter J L. Fend S V. Kennelly S S.

The relationships among three habitat scales and stream benthic

invertebrate community structure.

Freshwater Biology 35(1). 1996. 109-124.

1. The relationships between three habitat scales and lotic invertebrate

species composition were investigated for the 15 540 km-2 Yakima River

basin in south-central Washington, U.S.A.

2. The three spatial scales were

sample (the sampled riffle), reach (a length of ten-twenty stream widths)

and segment (a length of stream of nearly uniform slope and valley form

having no change in stream order).

3. Physical variables were highly correlated between scales and expressed a relationship between altitude, basin form and small-scale physical structure.

4. Multiple discriminant function analyses indicated that segment- and reach-scale variables discriminated among species-defined groups better than sample-scale

variables.

5. Species composition varied along a complex altitudinal gradient of changing basin form and resultant land use.

6. There was no clear relationship between species richness and altitude on a site basis. However, when viewed at the basin scale, maximum richness was observed at

the transition between montane and valley sites.

Пространственная и сезонная структура макробентоса

Authors: Giller-PS Twomey-H

Пространственная и сезонная структура макробентоса в двух различных по типу реках.

Benthic Macroinvertebrate Community Organization in 2

Contrasting Rivers - Between-Site Differences and Seasonal Patterns

BIOLOGY AND ENVIRONMENT-PROCEEDINGS OF THE ROYAL IRISH ACADEMY 1993, Vol 93B, Iss 3, pp 115-126

Изучались пространственная структура и сезонная динамика макробентоса двух контрастных по условиям речках. Пространственная изменчивость заключалась в видовом составе (обусловленном жесткостью, рН и порядком реки), суммарной плотностью макробентоса (зависит от жесткости и прибрежной растительности), разнообразием и функциональной организацией (связана с гидрохимией, но также с берег.растительностью, порядком реки и расстоянием от истока (distance from headwaters). Общая плотность, видовое богатство, число измельчителей (shredders), фильтраторов и детритофагов-собирателей (deposit collectors), и доля фильтраторов выше в реке Awbeg - высокого порядка, с жесткой водой. Разнообразие и доля соскребателей (grazers) и хищников больше в р. Glenfinnish - низкого порядка с мягкой водой.

В р.Glenfinnish общая плотность бентоса максимальна в конце лета - начале осени и минимальна в начале лета. В р. Awbeg сезонная динамика определяется мошками, с пиком в конце лета. Ранговое распределение обилия варьирует от log series до geometric patterns круглый год. Видовое богатство и обилие измельчителей-разгрызателей и фильтраторов возрастает к концу лета в соответствии с сезонной динамикой, предсказанной Концепцией Речного Континуума. По другим группам, например по соскребателям, сезонной динамики не найдено, что связано с локальными условиями биотопов (в частности, с затенением).

Abstract:

Between-site differences and within-site seasonal patterns were studied in benthic macroinvertebrate communities from two physically and chemically contrasting streams in the River Blackwater catchment (the River Awbeg and the Glenfinnish River). Between-site differences occurred in species composition (related to water hardness, pH and stream order), total macroinvertebrate densities (related to hardness and riparian vegetation), diversity and functional group organisation (partially related to water chemistry, but also to riparian vegetation and stream order and distance from headwaters). Total density, taxon richness, numbers of shredders, filterers and deposit collectors and relative abundance of filterers were greatest in the higher-order, hard-water Awbeg. Diversity and relative abundance of grazers and predators were greatest in the lower-order, softer-water Glenfinnish.

Seasonal changes in total invertebrate numbers, diversity, rank/abundance distributions and functional group organisation were also observed. Overall densities were greatest in late summer/early autumn and lowest in early summer in the Glenfinnish River. Seasonality patterns in invertebrate abundance in the Awbeg were dominated by Simuliidae. peaking in late summer. Rank abundance distributions varied from log series to geometric patterns over the year. Taxon richness and abundance of shredders and filterers increased in late summer in both rivers in accord with seasonal patterns predicted under the River Continuum Concept. Other seasonal patterns, e.g. in grazers, did not; this was related to the local habitat conditions (e.g. shading).

Водотоки: простр.изменчивость бентоса в разных масштабах.

Freshwater Biology

Volume 46 Issue 1 Page 87 - January 2001

Variability in stream macroinvertebrates at multiple spatial scales

Judith Li, Alan Herlihy, William Gerth, Philip Kaufmann, Stanley Gregory, Scott Urquhart and David P. Larsen

1.We intensively sampled 16 western Oregon streams to characterize: (1) the

variability in macroinvertebrate assemblages at seven spatial scales; and (2) the

change in taxon richness with increasing sampling effort. An analysis of variance

(ANOVA) model calculated spatial variance components for taxon richness, total

density, percent individuals of Ephemeroptera, Plecoptera and Trichoptera (EPT),

percent dominance and Shannon diversity.

2.At the landscape level, ecoregion and among-streams components dominated

variance for most metrics, accounting for 43-72% of total variance. However,

ecoregion accounted for very little variance in total density and 36% of the variance

was attributable to differences between streams. For other metrics, variance

components were more evenly divided between stream and ecoregion effects.

3.Within streams, approximately 70% of variance was associated with unstructured

local spatial variation and not associated with habitat type or transect position. The

remaining variance was typically split about evenly between habitat and transect.

Sample position within a transect (left, centre or right) accounted for virtually none

of the variance for any metric.

4.New taxa per stream increased rapidly with sampling effort with the first four to

eight Surber samples (500-1000 individuals counted), then increased more

gradually. After counting more than 50 samples, new taxa continued to be added in

stream reaches that were 80 times as long as their mean wetted width. Thus taxon

richness was highly dependent on sampling effort, and comparisons between sites

or streams must be normalized for sampling effort.

5.Characterization of spatial variance structure is fundamental to designing sampling

programmes where spatial comparisons range from local to regional scales.

Differences in metric responses across spatial scales demonstrate the importance of

designing sampling strategies and analyses capable of discerning differences at the

scale of interest.

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