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Озера и водохранилища.

Озера: местообитания.


Oikos

Volume 98 Issue 2 Page 177-189 - August 2002

Habitat coupling in lake ecosystems

Daniel E.Schindler and Mark D.Scheuerell

Lakes are complex ecosystems composed of distinct habitats coupled by biological, physical and chemical processes. While the ecological and evolutionary characteristics of aquatic organisms reflect habitat coupling in lakes, aquatic ecology has largely studied pelagic, benthic and riparian habitats in isolation from each other. Here, we summarize several ecological and evolutionary patterns that highlight the importance of habitat coupling and discuss their implications for understanding ecosystem processes in lakes. We pay special attention to fishes because they play particularly important roles as habitat couplers as a result of their high mobility and flexible foraging tactics that lead to inter-habitat omnivory. Habitat coupling has important consequences for nutrient cycling, predator-prey interactions, and food web structure and stability. For example, nutrient excretion by benthivorous consumers can account for a substantial fraction of inputs to pelagic nutrient cycles. Benthic resources also subsidize carnivore populations that have important predatory effects on plankton communities. These benthic subsidies stabilize population dynamics of pelagic carnivores and intensify the strength of their interactions with planktonic food webs. Furthermore, anthropogenic disturbances such as eutrophication, habitat modification, and exotic species introductions may severely alter habitat connections and, therefore, the fundamental flows of nutrients and energy in lake ecosystems.

Озера: литофильная фауна литорали.


Freshwater Biology

Volume 39 Issue 3 Page 577-592 - May 1998

The fauna in the upper stony littoral of Danish lakes: macroinvertebrates as trophic indicators

Klaus P. Brodersen, Peter C. Dall AND Claus Lindegaard

1. The macroinvertebrate fauna living on stones in the exposed stony littorals of

thirty-nine Danish lakes were examined by multivariate numerical methods. The data

were derived from 125 semi-quantitative samples and a species list of 126 taxa. The

mean number of individuals per sample was 960, and among the most common taxa

were Asellus aquaticus, Gammarus, Oulimnius, Tinodes, Cricotopus and

Dicrotendipes.

2. The total number of species and fourteen individual taxa were positively

correlated to mean depth of the lakes and eleven taxa were correlated to the total

phosphorus concentration. The Shannon diversity was negatively correlated to the

chlorophyll a concentration ([Chla]).

3. Community patterns were examined by detrended correspondence analysis

(DCA), and the relationship between species data and selected environmental

variables was analysed by canonical correspondence analysis (CCA). Mean lake

depth was found to be the strongest environmental variable in explaining the species

data. The [Chla] and Secchi depth also explained significant variation in the

distribution of the stony littoral invertebrates. Wind fetch and relative exposure did

not explain any variation in the faunal composition among sites.

4. The abilities of the macroinvertebrates to predict the lake trophic state, expressed

as log ([Chla]), were explored by means of weighted averaging (WA) regression

and calibration. Two tolerance-weighted WA models using inverse and classical

regression for deshrinking are presented. The models were assessed by the root

mean square error (RMSE) of prediction, using bootstrapping as cross validation,

and by the correlation between observed and inferred log ([Chla]). The model using

inverse deshrinking had a RMSEboot=0.41 and r2=0.63. By using classical

regression, the predictability in the ends of the gradient was improved but the

RMSE increased: RMSEboot=0.46.

5. Although the factors determining faunal distribution patterns in the Danish

lowland lakes were highly multivariate and difficult to disentangle, it seems

reasonable to use the WA estimated species optima and tolerances to [Chla] in a

bio-assessment model.



Бентос в целом.

Бентос: расселение.


Freshwater Biology

Volume 47 Issue 3 Page 483 - March 2002

Расселение водных организмов околоводными птицами:

обзор наработок и приоритетные направления дальнейших исследований.

Dispersal of aquatic organisms by waterbirds: a review of past research and

priorities for future studies

JORDI FIGUEROLA & ANDY J. GREEN

1.Inland wetlands constitute ecological islands of aquatic habitat often isolated by

huge areas of non-suitable terrestrial habitats. Although most aquatic organisms lack

the capacity to disperse by themselves to neighbouring catchments, many species

present widespread distributions consistent with frequent dispersal by migratory

waterbirds.

2.A literature review indicates that bird-mediated passive transport of propagules of

aquatic invertebrates and plants is a frequent process in the field, at least at a local

scale. Both endozoochory (internal transport) and ectozoochory (external transport)

are important processes.

3.The characteristics of the dispersed and the disperser species that facilitate such

transport remain largely uninvestigated, but a small propagule size tends to favour

dispersal by both internal and external transport.

4.We review the information currently available on the processes of waterbird-

mediated dispersal, establishing the limits of current knowledge and highlighting

problems with research methods used in previous studies. We also identify studies

required in the future to further our understanding of the role of such dispersal in

aquatic ecology.



Динамика бентоса: рассредоточение.


Authors: Palmer-MA Allan-JD Butman-CA

Рассредоточение как региональный регулятор локальной динамики

морского и речного макробентоса.

Dispersal as a Regional Process Affecting the Local Dynamics of Marine and Stream Benthic Invertebrates

TRENDS IN ECOLOGY & EVOLUTION 1996, Vol 11, Iss 8, pp 322-326

Abstract:

Recent work has shown that benthic invertebrate assemblages

may be influenced in an ongoing fashion by dispersal. Water-

column movements of meiofauna, juvenile insects and marine

postlarvae are common and can act to alter greatly local

dynamics such as predator-prey and competitive interactions in

marine and stream ecosystems, These findings are important

because past research on the role of dispersal in invertebrate

dynamics has focused almost exclusively on how planktonic larval

supply influences the establishment, and maintenance of local

assemblages, on the colonization of newly opened sites, or an

the settlement success of new recruits. The emerging framework

is that dispersal needs to he viewed as a regional process that

may routinely influence local benthic dynamics, because fauna

can move to and from water-column dispersal 'pools' and may do

so at frequent intervals.


Бентос: общие черты пресноводных беспов.


Freshwater Biology

Volume 43 Issue 2 Page 175-205 - March 2000

Биологические черты пресноводного зообентоса.

Biological and ecological traits of benthic freshwater macroinvertebrates:

relationships and definition of groups with similar traits

Philippe Usseglio-Polatera*, Michel Bournaud, Philippe Richoux and Henri Tachet


Summary


1. Relating species traits to habitat characteristics can provide important

insights into the structure and functioning of stream communities. However,

trade-offs among species traits make it difficult to predict accurately the

functional diversity of freshwater communities. Many authors have pointed

to the value of working with groups of organisms as similar as possible in

terms of relationships among traits and have called for definition of groups

of organisms with similar suites of attributes.

2. We used multivariate analyses to examine separately the relationships

among 11 biological traits and among 11 ecological traits of 472 benthic

macroinvertebrate taxa (mainly genera). The main objective was to

demonstrate (1) potential trade-offs among traits; (2) the importance of the

different traits to separate systematic units or functional groupings; and (3)

uniform functional groups of taxa that should allow a more effective use of

macroinvertebrate biological and ecological traits.

3. We defined eight groups and 15 subgroups according to a biological trait

ordination which highlighted size (large to small), reproductive traits (K to r

strategists), food (animal to plant material) and feeding habits (predator to

scraper and/or deposit feeder) as significant factors determining the

ordination of taxa. This ordination partly preserved phylogenetic

relationships among groups.

4. Seven ecological groups and 13 ecological subgroups included organisms

with combinations of traits which should be successively more adequate in

habitats from the main channel to temporary waters, and from the crenon to

the potamic sections of rivers, and to systems situated outside the river

floodplain. These gradients corresponded to a gradual shift from (1)

rheophilic organisms that lived in the main channel of cold oligotrophic

mountain streams to (2) animals that preferred eutrophic habitats of still or

temporary waters in lowlands. The groups with similar ecological traits had

a more diverse systematic structure than those with similar biological traits.

5. Monitoring and assessment tools for the management of water resources

are generally more effective if they are based on a clear understanding of the

mechanisms that lead to the presence or absence of species groups in the

environment. We believe that groups with similar relationships among their

species traits may be useful in developing tools that measure the functional

diversity of communities.

Бентос: классификация сообществ. Австралия.


Fresh Water Biology

Volume 41 Issue 2 Page 253-268 - March 1999



Classification of macroinvertebrate communities across drainage basins

in Victoria, Australia: consequences of sampling on a broad spatial scale

for predictive modelling

R. Marchant*, A. Hirst*, R. Norris and L. Metzeling

1. Spatial scale may influence the interpretation of environmental gradients that

underlie classification and ordination analyses of lotic macroinvertebrate

communities. This could have important consequences for the spatial scale over

which predictive models derived from these multivariate analyses can be applied.

2. Macroinvertebrate community data (identified to genus or species) from edge

and main-channel habitats were obtained for sites on rivers from 25 of the 29

drainage basins in Victoria. Trends in community similarity were analysed by

carrying out separate multivariate analyses on data from the edge habitats (199 sites)

and the main-channel habitats (163 sites).

3. Hierarchical classification (UPGMA) showed that the edge data could be placed

into 11 site groups and the main-channel data into 12 site groups.

4. Ordination analysis (hybrid multidimensional scaling) showed no sharp

disjunctions between site groups in either habitat; overlap was frequent. Correlation

of the ordination patterns with environmental variables showed that edge

communities varied longitudinally within a drainage basin and from the east to the

west of Victoria. These two trends were superimposed on one another to form a

single gradient on the ordination. The taxon richness of edge communities was also

related to the species richness of macrophytes at a site. Main-channel communities

also displayed a longitudinal and a geographic gradient, but these two gradients

were uncorrelated on the ordination.

5. Community similarity only weakly reflected geographic proximity in either habitat.

A preliminary subdivision of Victoria into a series of biogeographic regions did not

match the pattern of distribution of site groups for the edge habitat, illustrating the

difficulties of applying to lotic communities a priori regionalizations based on

terrestrial features of the landscape.

6. The longitudinal gradients in the two data sets were commonly observed in data

gathered at smaller spatial scales in Victoria. The other gradients (geographic,

macrophyte), however, were either not consistently repeated or not evident at

smaller spatial scales. At small spatial scales (i.e. within a single drainage basin)

gradients were related to variables that varied over restricted ranges, e.g. mean

particle size of the substratum.

7. Species richness was very variable when plotted against river slope or distance of

site from source; both of these are measures of position on the longitudinal

gradients. In contrast to suggestions in the literature, species richness did not show

a unimodal trend on these gradients, or any other trend.

8. Environmental gradients (apart from longitudinal gradients) that underlie

predictive models of macroinvertebrate distribution are reflections of the spatial

scale on which the model has been constructed and cannot be extrapolated to

different scales. Models must be suited to the spatial scale over which predictions

are required.


Сообщества бентоса: влияние биот.факторов


Kolar-CS Rahel-FJ

Interaction of a Biotic Factor (Predator Presence) and an Abiotic Factor (Low-Oxygen) as an Influence on Benthic Invertebrate Communities

OECOLOGIA 1993, Vol 95, Iss 2, pp 210-219

UNIV-WYOMING, DEPT ZOOL & PHYSIOL, LARAMIE, WY 82071, USA
We examined the response of benthic invertebrates to hypoxia and predation risk in bioassay and behavioral experiments. In the bioassay, four invertebrate species differed widely in their tolerance of hypoxia. The mayfly, Callibaetis montanus, and the beetle larva, Hydaticus modestus, exhibited a low tolerance of hypoxia, the amphipod, Gammarus lacustris, was intermediate in its response and the caddisfly, Hesperophylax occidentalis, showed high tolerance of hypoxia. In the

behavioral experiments, we observed the response of these benthic invertebrates, which differ in locomotor abilities, to vertical oxygen and temperature gradients similar to those in an ice-covered pond. With adequate oxygen, invertebrates typically remained on the bottom substrate. As benthic oxygen declined in the absence of fish, all taxa moved above the benthic refuge to areas with higher oxygen concentrations. In the presence of fish mayflies increased activity whereas all other taxa decreased activity in response to hypoxia. Mayflies and amphipods remained in the benthic refuge longer and endured lower oxygen concentrations whereas the vertical distribution of caddisflies and beetle larvae was not influenced by the presence of fish. As benthic oxygen declined in the presence of fish, all but the beetle larva reduced activity over all oxygen concentrations compared to when fish were absent. As benthic oxygen continued to decline, mayflies and amphipods moved above the benthic refuge and were preyed upon by fish. Thus, highly mobile taxa unable to tolerate hypoxia (mayflies and amphipods) responded behaviorally to declining oxygen concentrations by migrating upward in the water column. Taxa that were less mobile (beetle larvae) or hypoxia-tolerant (caddisflies) showed less of a response. Taxa most vulnerable to fish predation (mayflies and amphipods) showed a stronger behavioral response to predator presence than those less vulnerable (caddisflies and beetle larvae). Because invertebrates differ in their ability to withstand hypoxia, episodes of winter hypoxia could have long-lasting effects on benthic invertebrate communities either by direct mortality or selective predation on less tolerant taxa.



Структура сообществ речного бентоса.


Authors: Palmer-MA Arensburger-P Botts-PS Hakenkamp-CC Reid-JW

Нарушения и структура сообществ речного бентоса - значение пятнистости и убежищ.

Disturbance and the Community Structure of Stream Invertebrates - Patch-Specific Effects and the Role of Refugia

FRESHWATER BIOLOGY 1995, Vol 34, Iss 2, pp 343-356

Abstract:

1. We have previously shown that the impact of spates on

stream invertebrates may differ among patches separated by

distances of metres or less. Here we analyse the species-

specific flood responses of larval chironomids and adult and

near mature copepods living in different patch types. Four patch

types (with eight replicates of each) were compared: the sandy

mid-channel, fine sediments around darns, coarse sediments

around dams, and dam debris. Additionally, since some fine

sediment patches had been shown previously to act as flow

refugia while others did not, we also examined species specific

responses in refugium vs. non-refugium fine sediment patches.

Detrended correspondence analysis was used to test for changes

in assemblage structure (species composition and relative

abundance).

2. Species richness was not altered in a predictable manner

by floods; the least stable patch types (mid-channel and coarse

patches) did not necessarily show reduced species richness

during the spate.

3. As indicated by the spread of DCA ordination scores,

there was generally a high degree of overlap in the species

composition among the four patch types. Nevertheless, copepod

species composition and relative abundance were more similar

among patch types during the spate than pre-spate. Spates may

induce a re-distribution of copepod species among the patch

types. Chironomid species composition and relative abundance

were no more similar among patch types during the spate than pre-

or post-spate.

4. For both chironomids and copepods, species composition

and relative abundance (as assessed by DCA ordination scores) in

refugium patches changed more in response to the spate than in

the non-refugium patches. An influx of individuals from just a

few species for each group was responsible for the change in

assemblage structure. Thus, despite the fact that our past work

has shown that refugia may confer enhanced resistance and

resilience of copepod and chironomid assemblages in terms of

total faunal abundances, the present work suggests that

resistance and resilience of the species composition of the

community apparently are no greater in refugium patches than in

non-refugium patches.





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