База резюме и ссылок по экологии бентоса
Бентос водотоков: обобщения
жүктеу/скачать 1.21 Mb.
|
- Бұл бет үшін навигация:
- Размерные спектры ручьевого бентоса
- Классификация сообществ рек, Финляндия
- Водотоки: биоразнообразие.
- Предпочтение речных биотопов бентосом, Техас
- Горный ручей, метаболизм сообщества, Германия.
- Лесные водотоки: разнообразие беспозвоночных.
- Бентос водотоков: размерная структура.
- Бентос тропических водотоков: асезонность.
- Экология весенних ручьев.
- Бентос рек: размерные спектры.
- Структура ручьевого бентоса, Аппалачи.
- Речной бентос: убежища и структура сообществ.
- Речной бентос: экосистемы с доминированем детритофагов.
- Бентос и листовой опад, водоток тропиков.
- Влияние бентоса на субстрат.
- Водотоки: методика сбора проб
- Водотоки: фауна листового опада.
- Водотоки: особенности экосистем в тропич.лесу
- Речки: классификация биотопов.
- Водотоки: методика сбора бентоса.
Бентос водотоков: обобщения.Литореофилы ручьев и озерSPATIAL SCALE AND ECOLOGICAL RELATIONSHIPS BETWEEN THE MACROINVERTEBRATE COMMUNITIES OF STONY HABITATS OF STREAMS AND LAKES Авторы Richard K. Johnson, Willem Goedkoop, Leonard Sandin Журнал Freshwater Biology Год выпуска 2004 Том 49 Номер 9 Страницы 1179-1194 Статус Summary 1. Comparative studies of distinct, but not ecologically isolated, systems such as lakes and streams may improve our understanding of the importance of ecological linkages in aquatic ecosystems. 2. In this study we compared the macroinvertebrate benthos of stony habitats in Swedish lakes and streams. Community composition was used to evaluate zoogeographic patterns and functional feeding guilds were used to identify mechanisms potentially affecting such patterns. 3. Stream communities were generally more diverse and species-rich and had a higher proportion of grazers, shredders and passive-filter feeders than lakes. Lake communities had a higher proportion of predators and collector-gatherers. Of the 10 most common taxa, only Leptophlebia mayflies, clams (Sphaeriidae) and the isopod Asellus aquaticus were recorded in both lakes and streams. 4. Among-site variance in macroinvertebrate communities accounted for by regional-scale variables was low (6.4% for lakes and 10.1% for streams), compared with that by local-scale variables (21% for lakes and 37.6% for streams). For lakes, the among-site variance in macroinvertebrate communities was best explained by habitat-scale characteristics followed by ecosystem, riparian, catchment, geographic position and ecoregion. For streams, the variance in macroinvertebrate communities was best explained by ecosystem characteristics followed by habitat, catchment, riparian, ecoregion and geographic position. 5. Conspicuous differences in spatial pattern were revealed between lakes and streams. For lakes, the most unequivocal differences in community composition and function occurred at the transition zone between the mixed forests in the south and the boreal coniferous forests in the north. Surprisingly, streams did not respond as strongly to profound landscape-level differences in climate and vegetation cover. 6. The spatial differences noted between macroinvertebrate communities of lakes and streams may be because of differences in retention of detrital matter. Our findings imply that detrital inputs are qualitatively similar, but that the retention and processing of coarse particulate organic matter was presumably higher in lake littoral regions than in stream riffle habitats. 7. Although our findings support the conjecture that species distribution is determined fundamentally by conditions prevailing at the local-scale, regional factors such as land use/type and the role of history were important and seemingly act as strong determinants of large-scale patterns in biodiversity. 1. Сравнительные исследования отличных, но не экологически изолированный, системы типа озер и потоков могут улучшить наше понимание важности экологических редактирований в водных экосистемах. 2. В этом исследовании мы сравнили макробесхарактерный бентос каменных сред обитания в шведских озерах и потоках. Состав сообщества использовался, чтобы оценить образцы zoogeographic, и функциональные питательные гильдии использовались, чтобы идентифицировать механизмы, потенциально затрагивающие такие образцы. 3. Сообщества потока были вообще более разнообразны и богаты разновидностями и имели более высокую пропорцию grazers, шинковок и едоков пассивного фильтра чем озера. Сообщества озера имели более высокую пропорцию хищников и сборщика-собирателей. Из 10 самых общих таксонов, только подёнки Leptophlebia, моллюски (Sphaeriidae) и isopod Asellus aquaticus были зарегистрированы и в озерах и в потоках. 4. Среди-участка разница в макробесхарактерных сообществах, составляемых переменными регионального масштаба была низка (6.4 % для озер и 10.1 % для потоков), по сравнению с этим переменными местного масштаба (21 % для озер и 37.6 % для потоков). Для озер, среди-участка разница в макробесхарактерных сообществах лучше всего объяснялась в соответствии с особенностями масштаба среды обитания, которые сопровождает экосистема, прибрежная, дренаж, географическое положение и ecoregion. Для потоков, разница в макробесхарактерных сообществах лучше всего объяснялась в соответствии с особенностями экосистемы, которые сопровождает среда обитания, дренаж, прибрежный, ecoregion и географическое положение. 5. Заметные различия в пространственном образце были показаны между озерами и потоками. Для озер, наиболее определенные различия в составе сообщества и функции произошли в зоне перехода между смешанными лесами на юге и арктических хвойных лесах на севере. Удивительно, потоки как настоятельно не отвечали на глубокие различия уровня пейзажа в покрытии растительности и климате. 6. Пространственные различия, отмеченные между макробесхарактерными сообществами озер и потоков могут быть из-за различий в retenti ... [Source text was truncated]
Авторы Tracey K. Stead, Jenny M. Schmid-Araya, Alan G. Hildrew Журнал Freshwater Biology Год выпуска 2003 Дата март Том 48 Номер 3 Страницы 532-547 Статус SUMMARY 1. The whole metazoan community (i.e. including the meiofauna) of an acidic, fishless stream in south-east England was surveyed over 14 months between March 1999 and April 2000. Invertebrate density, biomass and taxonomic richness were assessed on each sampling occasion in relation to physico-chemical variables. 2. The meiofauna were more numerous and diverse than the macrofauna, while their total biomass occasionally equalled that of the macrofauna. 3. The meiofaunal and macrofaunal assemblages appeared to respond to different environmental factors. The meiofauna showed genuine species turnover through the year, while the macrofauna varied less in taxonomic composition though there were substantial variations in density. 4. These data suggest that the meiofauna and macrofauna exist at different temporal and spatial scales and perceive their environment with a different 'grain'. . Целое metazoan сообщество (то есть включая meiofauna) кислого, fishless поток в юго-восточной Англии было рассмотрено более чем 14 месяцев между мартом 1999 и апрелем 2000. Бесхарактерная плотность, биомасса и таксономическое богатство были оценены в каждом случае осуществления выборки относительно физико-химических переменных. 2. Meiofauna были более многочисленные и разнообразные чем макрофауна, в то время как их полная биомасса иногда равнялась биомассе макрофауны. 3. Meiofaunal и макрофауновый assemblages, казалось, отвечали на различные экологические факторы. Meiofauna показал подлинный товарооборот разновидностей в течение года, в то время как макрофауна изменилась меньше по таксономическому составу, хотя были существенные изменения в плотности. 4. Эти данные предлагают, чтобы meiofauna и макрофауна существовали в различных временных и пространственных масштабах и чувствуют их окружающую среду с различным 'зерном'.
На 32 реках бореального водосбора Финляндии изучали согласованность результатов классификации рек, полученных на рыбах, донных беспозвоночных и бриофитах. Наблюдаемое отсутствие согласованности результатов, полученных при использовании разных таксономических групп, связано с тем, что на них влияют разные факторы среды. Сообщество донных макробеспозвоночных коррелирует гл. обр. с размерами реки и pH, бриофиты _ѕ с цветностью воды, содержанием биогенов и вариабельностью речных биотопов; структура ихтиоценоза определяется глубиной реки, размерами частиц субстрата и содержанием в воде кислорода. Канада, Dep. of Zoology, Univ. of Toronto, Ontario, M5S 3G5, E-mail: rpaavola@cc.jyu.fi. Ил. 3. Табл. 3. Библ. 46. Водотоки: биоразнообразие.Freshwater Biology Volume 46 Issue 6 Page 807-819 - June 2001 Разработка концепции биоразнообразия в экологии рек. Biodiversity: towards a unifying theme for river ecology Ward & Tockner 1.A broadened concept of biodiversity, encompassing spatio-temporal heterogeneity, functional processes and species diversity, could provide a unifying theme for river ecology. 2.The theoretical foundations of stream ecology often do not reflect fully the crucial roles of spatial complexity and fluvial dynamics in natural river ecosystems, which has hindered conceptual advances and the effectiveness of efforts at conservation and restoration. 3.Inclusion of surface waters (lotic and lentic), subsurface waters (hyporheic and phreatic), riparian systems (in both constrained and floodplain reaches), and the ecotones between them (e.g. springs) as interacting components contributing to total biodiversity, is crucial for developing a holistic framework of rivers as ecosystems. 4.Measures of species diversity, including alpha, beta and gamma diversity, are a result of disturbance history, resource partitioning, habitat fragmentation and successional phenomena across the riverine landscape. A hierarchical approach to diversity in natural and altered river-floodplain ecosystems will enhance understanding of ecological phenomena operating at different scales along multidimensional environmental gradients. 5.Re-establishing functional diversity (e.g. hydrologic and successional processes) across the active corridor could serve as the focus of river conservation initiatives. Once functional processes have been reconstituted, habitat heterogeneity will increase, followed by corresponding increases in species diversity of aquatic and riparian biota. Предпочтение речных биотопов бентосом, Техас03.10-04А2.205. Предпочитаемые биотопы водных макробеспозвоночных в реке с песчаным дном в восточном Техасе. Habitat preference of aquatic macroinvertebrates in an east Texas sandy stream / Phillips Edward C. // J. Freshwater Ecol. - 2003. - 18, № 1. - С. 1_ѕ11. - Англ. В реке с песчаным дном макробеспозвоночные из всех предлагаемых субстратов предпочитали водные макрофиты (Hydrocotyle umbellata, Justica ovata, Alternantha philoxeroides), где их плотность достигала 815,8 экз./м{2}. Далее по предпочитаемости шли грубые древесные остатки (697,7 экз./м{2}), упаковки листового опада (516 экз./м{2}), погруженные в воду корни прибрежных деревьев (492,5 экз./м{2}), макрофиты Najas на скалах (218,6 экз./м{2}) и донный песок (216,3 экз./м{2}). Плотность макробеспозвоночных на древесных остатках сильно зависела от степени их разложения. Видовое богатство макробеспозвоночных было макс. в упаковках листвы, минимально _ѕ на Najas (соотв. 46 и 24 вида). США, Biology Dep. Gannon Univ. 109 Univ. Square Erie, PA 16541. E-mail: phillips010@gannon.edu. Табл. 3. Библ. 37. Горный ручей, метаболизм сообщества, Германия.Pusch M. Inst. Gewaesseroekol. und Binnenfischerei, Mueggelseedamm 260, D-12562 Berlin, Germany. The metabolism of organic matter in the hyporheic zone of a mountain stream, and its spatial distribution Hydrobiologia 323(2). 1996. 107-118. Community respiration in hyporheic sediments (HCR) was studied in a characteristic riffle-pool-sequence of a mountain stream. HCR activity at the riffle site strongly exceeded that at the corresponding pool site with a mean ratio of 5.3. The vertical distribution of HCR activity was homogeneous in the pool, while there was a distinct maximum in the uppermost layer in the riffle. Similarly, the spatial distribution of certain fractions of particulate organic matter (POM), and their turnover, was largely determined by stream morphology. Mean annual HCR per unit area of stream bed was estimated as 1.71 g O-2 m-2 d-1. Hence, HCR contributes significantly to total heterotrophic activity in streams, thus enhancing the relative importance of heterotrophic processes in running waters containing hyporheic zones. Лесные водотоки: разнообразие беспозвоночных.Oikos Volume 97 Issue 1 Page 18-30 - April 2002 Predicting invertebrate diversity from disturbance regimes in forest streams Russell G. Death The link between substrate disturbance and stream invertebrate species richness is often complicated by the fact that substrate disturbance removes both invertebrates and periphyton (a potential food source). It is never clear whether disturbance acts directly on species diversity by removing animals or indirectly by reducing one of their food sources. To examine this relationship invertebrate diversity patterns were examined in 25 forest streams in Urewera National Park, New Zealand, where light attenuation from the forest canopy was postulated to limit periphyton biomass and remove the confounding influence of periphyton on the link between substrate disturbance and invertebrate diversity. Invertebrate species richness declined linearly with increasing substrate disturbance. Although periphyton biomass was comparatively low, species richness was more strongly related to periphyton biomass than to any disturbance measure. The highly mobile nature and terrestrial reproductive stage of many lotic invertebrates suggest that colonisation dynamics may have a more important influence on diversity patterns than monopolisation of resources for population growth. Although both the intermediate disturbance hypothesis and the dynamic equilibrium model encompass colonisation as a critical determinant of diversity both models also require a trade-off between the colonising and competitive ability of individual species; a phenomenon which does not appear to occur widely in lotic communities. Rather, it is postulated that resource levels will set an upper limit to the species richness of a benthic community that can be achieved through colonisation of taxa in the absence of disturbance, while disturbance removes taxa and resets the colonisation process.
Source: JOURNAL OF THE NORTH AMERICAN BENTHOLOGICAL SOCIETY 2001, Vol 20, Iss 3, pp 421-431 We examined the temporal, longitudinal, and among-substrate variation of the size structure of the invertebrate assemblage in a Mediterranenan river (Aniene River, central Italy). Sampling was conducted with quantitative methods on different substrates every 2 mo at 2 sites for 1 y and at 9 additional sites in spring 1997. Water-quality variables, periphyton standing crop, and physical characteristics of sites were also recorded. The Aniene River showed large longitudinal changes in overall physical features, periphyton biomass, and water quality that were reflected in dramatic changes of the taxonomic composition of the invertebrate assemblage. Insects were numerically dominant in the upper reach and codominant with gastropods in the middle reach, whereas oligochaetes, crustaceans, and chironomids were predominant in the lower and polluted reach. Despite these changes, the shape of the size structure of the invertebrate assemblage was similar among sites, dates, and substrates, with limited departures from the average size spectrum. Body mass alone accounted for the largest part of the variance of the abundance per size class (48%) whereas date, site, and substrate accounted for an additional 13%. These data support early observations of size spectrum invariance from North American streams and rivers, reinforcing the view that size-dependent processes may structure lotic benthic assemblages.
Aseasonality of benthic invertebrates in a tropical stream on Bougainville Island, Papua New Guinea. Archiv Fuer Hydrobiologie 137(1). 1996. 95-117. The benthic invertebrate fauna of Konaiano Creek, a small, aseasonal, tropical, mountain rainforest stream on Bougainville Island, Papua New Guinea, was quantitatively studied over a period of 22 months. Konaiano Creek supported a diverse, mostly undescribed, fauna dominated by two closely related species of Simuliidae (55% of the total specimens collected), and two species of Hydropsychidae. Over 182 taxa were recorded, more than half of which were Diptera. The community exhibited no pattern of seasonal change in faunal abundance or species composition. The life cycles of 15 species were examined (8 Trichoptera: Hydropsychidae spp. 1 and 2, Chimaera sp., Philopotamidae sp., Nyctiophylax sp., Anisocentropus sp., nr Triaenodes sp., Apsilochorema sp.; 3 Ephemeroptera, Platybaetis sp., Barba sp., Prosopistoma sedlaceki; one Zygoptera, Lieftinckia kimminsi; one Blephariceridae, Apistomyia sp. and two Simuliidae, Simulium (Morops) spp. 1 and 2). They all exhibited asynchronous aseasonal life cycles with continuous hatching and growth. This strategy appeared to be in response to the lack of environmental cues to enable synchronization of hatching, growth and emergence, since the climate of Bougainville Island is remarkably equable throughout the year with regard to temperature, rainfall and humidity, and there is a yearly variation in photoperiod of only 36 min. It is further suggested that asynchrony of life histories would be promoted by the frequent intense but unpredictable spates in Konaiano Creek since the presence of all life stages at any one time (particularly flying adults) would enhance a species' survival. Экология весенних ручьев.Authors: Cushing-CE Экология холодных весенных бесплодных ручьев. The Ecology of Cold Desert Spring-Streams ARCHIV FUR HYDROBIOLOGIE 1996, Vol 135, Iss 4, pp 499-522 Abstract: Cold desert spring-streams exhibit several features which make their structure and function unusual as compared to more mesic systems. These include anomalies between autotrophy and export, low macroinvertebrate populations probably related to severe winter spates, and secondary production rates intermediate between mesic streams and hot desert streams.
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES 1993, Vol 50, Iss 12, pp 2659-2666 Размерные спектры бентоса в речках отличаются от известных для планктона, но могут отражать узкие таксономические рамки предварительных исследований. Когда водоросли, простейшие и беспозвоночные из трех каменистых речек в Квебеке были объединены в логарифмическом масштабе в единый спектр, распределение биомассы оказалось близким к равномерному во всех точках и временах съемки, несмотря на различия в таксономической структуре составляющих. В размерном спектре наблюдались пики и провалы, но биомасса во всех классах обычно лежала близко к средней. Наклон нормализованного спектра все время был меньше -1 (в среднем -0.91), показывая незначительное увеличение биомассы в больших размерных классах. Сильно изрезанный спектр, наблюдавшийся ранее для беспозвоночных, смазывается водорослями и протистами. Сравнение этого спектра с описанными для бентоса и планктона озер и морей показывает замечательное сходство. Таким образом, равномерное распределение биомассы в логарифмических размерных классах есть общее свойство структуры сообществ, не ограниченное спецификой планктона. Размерно-ориентерованный подход может быть полезен для упрощения описания сложных речных сообществ.Abstract: The size spectra of benthic invertebrates in streams appear to differ from those reported in planktonic systems, but could reflect the narrow taxonomic scope of previous studies. When algae, protozoans, and invertebrates growing on rocks in three Laurentian streams (Quebec) were grouped in logarithmically increasing size classes, patterns in the distribution of biomass were consistent over sites and dates, despite large differences in taxonomic composition. Peaks and troughs were observed in the size spectra, but the biomass of the various size classes usually lay within an order of magnitude of the mean of all classes. The slopes of the normalized size spectra were always shallower than -1 (median = -0.91) indicating a slight biomass increase in the larger size classes. Strongly peaked spectra previously observed for stream invertebrates were smoothed by the inclusion of algae and protozoans. Comparison with size spectra described for benthic and planktonic communities in lakes and oceans, showed remarkable similarities among habitats. These findings suggest that roughly similar biomass in logarithmic size classes is a general community pattern not restricted to the peculiarities of plankton communities. A size-based approach could be useful to simplify the description of complex stream communities. Структура ручьевого бентоса, Аппалачи.Angradi T R. Inter-habitat variation in benthic community structure, function, and organic matter storage in 3 Appalachian headwater streams. Journal of the North American Benthological Society 15(1). 1996. 42-63. Inter-habitat variation in benthic community structure and function was investigated in 3 headwater streams in West Virginia, USA. Abundance and biomass of benthic macroinvertebrates and salamanders together with standing crop of benthic organic matter were estimated for riffles, rock faces, plunge pools, debris-dam pools, and leaf packs. In 1 stream, installation of log dams for fish habitat (K-dams) created artificial plunge pools and debris-dam pools. Standing crop of benthic organic matter was lowest in riffles and rock faces ( apprxeq 50 g ash-free dry mass/m-2) and was dominated by coarse (1-10 mm) and fine (0.25-1 mm) particles. Mass of benthic organic matter was highest in debris-dam pools ( gt 2 kg ash-free dry mass/m-2), and was dominated by coarse particles and wood. Mean animal density (macroinvertebrates and salamander larvae) was highest in debris-dam pools and on rock faces ( gt 10,000/m-2) and lowest in riffles and plunge pools ( lt 5000/m-2). Standing biomass of animals was highest in pools (3-8 g dry mass/m-2) and lowest in riffles and on rock faces ( lt 2 g dry mass/m-2). Chironomids and the stonefly Leuctra were the most abundant taxa in most habitats; co-dominant taxa differed among habitats. Ordination of macroinvertebrate taxa showed that community structure was more similar among habitats than among streams. Functional organization differed among habitats. In riffles, all functional groups were well represented. Scrapers, filters, and gatherers predominated on rock faces. In pools, shredders and predators dominated biomass, although gatherers were the most abundant group. In plunge pools, crayfish (Cambarus) were relatively more abundant than in debris dam pools; the opposite was true for macroinvertebrate predators. Overall, inter-habitat variation in taxonomic structure, animal abundance, biomass, functional organization, and benthic organic matter exceeded among-stream variation. Comparison with published data for a North Carolina headwater stream revealed common patterns of inter-habitat variation in functional organization. Installation of K-dams in a headwater stream influenced the abundance, biomass, and functional organization of the benthos by providing habitat for taxa able to exploit debris-dam pools formed upstream of K-dams, which retain abundant organic matter.
Disturbance and the community structure of stream invertebrates: Patch-specific effects and the role of refugia. Freshwater Biology 34(2). 1995. 343-356. 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 dams, 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.
Institution Sect. Ecol. Syst., Corson Hall, Cornell Univ., Ithaca, NY 14853, USA. Title
Ecosystem engineering by a dominant detritivore in a diverse tropical stream.
Source Ecology 77(6). 1996. 1845-1854. Prochilodus mariae (Characiformes:Prochilodontidae) is a detritivorous fish distributed throughout the Orinoco river basin of South America. Spectacular migrations of these fishes occur at the end of the rainy season into the Andean foothills. Prochilodus ingest large quantities of sediments and may thereby modify habitats in neotropical streams. The major objectives of this study were (1) to explore experimentally the importance of Prochilodus in structuring a tropical stream in the Venezuelan Andean piedmont, and (2) to determine whether there was sufficient ecological redundancy in a diverse and abundant assemblage of epibenthic fishes to compensate for the removal of Prochilodus. Community structure was compared among three experimental treatments: (1) Prochilodus exclusion, (2) Prochilodus enclosure, and (3) the natural fish assemblage. Selective exclusion of Prochilodus resulted in striking changes in community structure as measured by patterns of sediment accrual and the composition of algal and invertebrate assemblages. Highly significant increases in total dry mass and in ash-free dry mass of sediments accruing on stream-bottom substrates were observed almost immediately following the exclusion of Prochilodus. Moreover, the composition of algal and invertebrate assemblages was significantly modified by Prochilodus. Taxa such as diatoms were reduced in number when Prochilodus was present; in contrast, Prochilodus appeared to facilitate nitrogen-fixing cyanobacteria. Total invertebrate densities were greatest in the Prochilodus removal treatment; however, a variety of responses to the experimental treatments was observed among different taxa analyzed individually, including density reductions, increases, and no measurable effects. This study suggests that the detritivore Prochilodus is a functionally dominant species in Andean foothill streams via sediment-processing activities. Moreover, it provides little evidence to support the notion that strongly interacting species are limited to simple systems with few food web components. Бентос и листовой опад, водоток тропиков.Benstead J P. Institution Inst. Ecol., Univ. Ga., Athens, GA 30602, USA. Title
Macroinvertebrates and the processing of leaf litter in a tropical stream. Source
Biotropica 29(3). 1996. 367-375. The processing of leaf litter in temperate streams has been the subject of numerous studies but equivalent tropical ecosystems have received little attention. The decomposition and macroinvertebrate colonisation of leaf litter was investigated using litter bags placed in a first-order rainforest stream over a 48 day period. Changes in leaf chemistry were also studied. Decay of the fresh, mixed-species litter was rapid (2.5% day-) in comparison to that typically observed in temperate streams. The high water temperatures (21 degree C) at the study site are considered an important factor in the decay rate observed. Initially, average nitrogen content was high (3.5%). Content decreased to 3.1 percent after six days immersion and, thereafter, remained relatively constant. The consequent lack of evidence for microbial conditioning was attributed to species-specific differences in decay rate, giving rise to an overlapping sequence of conditioning and mineralisation of each leaf species within individual litter bags. Soluble polyphenols were largely leached from litter during the initial period of immersion. Constancy in remaining polyphenol content may be due to complexing with proteins and/or lignin compounds. The invertebrate community which colonised litter bags was dominated by insect groups and species richness was lower than that typical of many temperate streams. Colonisation dynamics differed among functional feeding groups: collector abundance increased on a linear basis whereas shredder and predator groups increased logarithmically. Despite differences in decay rate and taxonomic composition of the invertebrate community, the pattern of leaf litter utilisation and decay in the tropical scream studied was similar to that typically observed in temperate streams.
Title: The Role of Invertebrates on Leaf-Litter Decomposition in Streams - A Review Source: INTERNATIONAL REVIEW OF HYDROBIOLOGY 2001, Vol 86, Iss 4-5, pp 383-393 Leaves entering low order streams are subject to physical abrasion, microbial degradation and invertebrate fragmentation. Aquatic invertebrates feeding on leaves are known as shredders and their densities tend to be correlated with the spatial and temporal accumulation of organic matter in streams. Shredders discriminate among the variety of leaves normally found in the stream; this discrimination may be related to differences in leaf toughness, plant nutrient content of leaves and the presence of secondary compounds. Shredders also consume leaves preferentially after the establishment of a well-developed microbial community. This preference may be the result of changes in leaf matrix carried out by the microbial community or the presence of fungal hyphae with a higher nutrition value than the leaves themselves. The immediate consequence of invertebrate feeding on leaves is the incorporation of plant material into secondary production and the fragmentation of leaves. The relative importance of fungi and invertebrates in the decomposition process depends upon the density of shredders, which, in turn, may depend on litter accumulation in streams. Therefore, the type of riparian vegetation has the potential to control the diversity and abundance of shredders and changes in riparian vegetation have the potential to affect the assemblages of aquatic invertebrates. Водотоки: методика сбора пробFreshwater Biology Volume 44 Issue 2 Page 355 - June 2000 The effect of fixed-count subsampling on macroinvertebrate biomonitoring in small streams Craig P. Doberstein*, James R. Karr and Loveday L. Conquest Summary
1. When rigorous standards of collecting and analysing data are maintained, biological monitoring adds valuable information to water resource assessments. Decisions, from study design and field methods to laboratory procedures and data analysis, affect assessment quality. Subsampling - a laboratory procedure in which researchers count and identify a random subset of field samples - is widespread yet controversial. What are the consequences of subsampling? 2. To explore this question, random subsamples were computer generated for subsample sizes ranging from 100 to 1000 individuals as compared with the results of counting whole samples. The study was done on benthic invertebrate samples collected from five Puget Sound lowland streams near Seattle, WA, USA. For each replicate subsample, values for 10 biological attributes (e.g. total number of taxa) and for the 10-metric benthic index of biological integrity (B-IBI) were computed. 3. Variance of each metric and B-IBI for each subsample size was compared with variance associated with fully counted samples generated using the bootstrap algorithm. From the measures of variance, we computed the maximum number of distinguishable classes of stream condition as a function of sample size for each metric and for B-IBI. 4. Subsampling significantly decreased the maximum number of distinguishable stream classes for B-IBI, from 8.2 for fully counted samples to 2.8 classes for 100-organism subsamples. For subsamples containing 100-300 individuals, discriminatory power was low enough to mislead water resource decision makers. Водотоки: мейобентосFreshwater Biology Volume 44 Issue 1 Page 1 - May 2000 An introduction to a special issue on lotic meiofauna A. L. Robertson*,S. D. Rundle and J. M. Schmid-Araya Summary 1. This special issue focuses on the meiofauna of lotic freshwater systems, providing a review of the biology and ecology of this relatively poorly studied constituent of the benthos in running waters. 2. Six papers review the biology and ecology of the major groups of lotic meiofauna: microturbellarians; rotifers and gastrotrichs; nematodes; water mites; microcrustaceans and tardigrades. 3 Current knowledge of the ecology of lotic meiofauna is presented further in six papers that also highlight important future directions for research.
Volume 40 Issue 2 Page 215-228 - September 1998 Leaf breakdown and associated macroinvertebrates in alpine glacial streams Christopher T. Robinson, Mark O. Gessner* AND J. V. Ward 1. The relationship between macroinvertebrate assemblages and the breakdown of alder [Alnus viridis (Chaix), Dc.] leaves was examined by exposing leaf packs in four streams in an alpine glacial floodplain over 8months. Although glacially fed, the four sites (pro-glacial, glacial lake outlet, main channel, and a side-channel with a mix of water sources) differed physically and contained different benthic communities. 2. Leaf breakdown and associated fungal properties differed widely among sites. Leaf decay rate varied by an order of magnitude (k ranged from 0.0029 to 0.0305 day1), and was fastest at the lake outlet (<20% leaf mass remaining by day 45) and slowest at the pro-glacial site (>75% remaining on day 45). Rapid processing at the lake outlet was because of the presence of Acrophylax zerberus Brauer, a shredding caddisfly. 3. There were few macroinvertebrate taxa at the pro-glacial site (two to four taxa present in packs) and leaf breakdown was attributed primarily to micro-organisms. Leuctra abundance in leaf packs was strongly correlated with fungal biomass but not with the sporulation activity of any specific aquatic hyphomycete. Other taxa, such as Baetis and chironomids, showed no relationship with any leaf characteristic, suggesting that leaf packs were used mainly as a habitat and not as a food resource. 4. The predatory stonefly Isoperla was significantly associated with the abundance of macroinvertebrate prey (Baetis, Chironomidae and Leuctra) in leaf packs at the main and side-channel sites. The results indicate that leaf breakdown can vary widely in alpine lotic environments, reflecting site-specific differences in habitat characteristics, and in macroinvertebrate and fungal composition. Водотоки: бентос опада.Freshwater Biology Volume 39 Issue 2 Page 325 - March 1998 Spatial scale and the aggregation of stream macroinvertebrates associated with leaf packs John F. Murphy, , Paul S. Giller* AND & Margaret A. Horan 1. An experimental field study examined the aggregation of stream macroinvertebrates associated with leaf packs over different spatial scales (several metres-km) (extent), at different patch sizes (grain) and temporal scales (2 and 4 weeks). 2. Standardized leaf packs were constructed and set in eighteen blocks of nine equally spaced packs in glide areas over a 2 km stretch of a wooded stream. The distribution of macroinvertebrates colonizing the artificial leaf packs was investigated to examine the extent of both intraspecific and interspecific aggregation across leaf packs. 3. All major colonizing taxa were intraspecifically aggregated across the leaf packs. Aggregation decreased with increasing patch size (grain) (from pack to block), and also decreased with decreasing spatial extent (from 2 km stretch to withinblock scale) with patch size held constant. Interspecific associations among all major taxa were not common on most occasions at the short temporal scale, although the proportion of significant associations tended to increase somewhat over time and with spatial scale, but did not exceed 42% of all possible associations. The vast majority of significant associations were positive rather than negative. 4. The influence of heterogeneity in a number of environmental variables measured for each leaf pack (accumulated detritus and sediment, leaf mass, flow and depth) on the distribution of invertebrates was considered, but this could only partially explain the variation in macroinvertebrate abundance across leaf packs. 5. The roles of intrinsic aggregation and stochastic processes were examined as alternative explanations for the distribution patterns observed. It is apparent from this study that intrinsic aggregation, in concert with resource partitioning, influences the community structure of stream macroinvertebrates associated with leaf packs. These findings may also have implications for the distribution of taxa in the benthos as a whole. Водотоки: особенности экосистем в тропич.лесуFreshwater Biology Volume 43 Issue 1 Page 31 - January 2000 Nutrient enhancement, food quality and community dynamics in a tropical rainforest stream R. G. Pearson and N. M. Connolly SUMMARY 1. A mixed nutrient supplement was added to stream-side experimental channels in a closed canopy rainforest in tropical Queensland over a 7- month period, raising nitrogen and phosphorus concentrations well above ambient. 2. Nutrient supplements enhanced decomposition of some leaf species, but levels of chlorophyll a and fine particulate organic matter did not differ between treatment and control channels. 3. Shredding by Anisocentropus kirramus (Trichoptera) had a significant effect on leaf litter breakdown, but nutrient supplements did not enable A.kirramus to shred more material; however, biochemical analysis of A. kirramus showed that nutrient supplements enhanced the nutritional quality of the litter for this species. 4. Treatment channels contained 75% more invertebrates than control channels, but significant differences in abundance (all positive) were detected in only five of the 109 invertebrate species present. There was no change in species richness or evenness between treatment and control channels. 5. The limited community response indicates that (a) variables other than nutrients (e.g. light) restricted primary productivity, (b) low nutrient concentrations limit invertebrate production, (c) invertebrate community composition in this closed canopy, forest stream is resistant to nutrient enhancement, and (d) there was no direct relationship between productivity and diversity in this tropical stream.
1.Stream reaches contain assortments of various habitat types that can be defined at different spatial scales, such as channel unit (e.g. pools, riffles) and subunit (patches within channel units). We described longitudinal (upstream- downstream) patterns of stream habitat structure by considering subunits as structural elements, and examined their effects on the abundance of masu salmon (Oncorhynchus masou) and rosyface dace (Leuciscus ezoe) in a third-order tributary of the Teshio River in northern Hokkaido, Japan. 2.Nine subunit types were determined on the basis of water depth, current velocity and substrate, using 0.50.5m grids. Although both masu salmon and rosyface dace used pools as a major habitat, the former preferred a subunit type occurring at pool heads (PH subunit) while the latter preferred a slow-current edge type (SE-2 subunit). 3.Along the course of the stream, slow-edge subunits (SE-1, 2 and 3) increased in frequency downstream while fast-edge subunits (FE-1 and 2) decreased, suggesting a downstream development of slow-current edges. Regression analyses indicated that longitudinal variation in masu salmon abundance was explained by the area of PH, rather than pools. Masu salmon density increased with the area of PH. Rosyface dace abundance was explained by a combination of water depth and the area of SE-2, both effects being positive. 4.Longitudinal variations in the abundance of both species were related to the abundance of their preferred habitat at the subunit scale, rather than channel-unit scale. The results emphasise the importance of fine-scale patchiness when examining stream fish habitats. Водотоки: методика сбора бентоса.Authors: Bretschko-G Title: The Effect of Escape Reactions on the Quantitative Sampling of Gravel Stream Fauna Source: ARCHIV FUR HYDROBIOLOGIE 1990, Vol 120, Iss 1, pp 41-49 This study deals with small-scale disturbances caused by the sampling procedure and their consequences for quantitative sampling of stream bed fauna. By N2 freeze coring, such artefacts can be avoided by in situ electro-positioning, but only for sediment-dwelling populations. Individuals staying on or near the sediment surface are able to escape sampling in spite of the precautions. Insect larvae are sensitive to perturbations according to their drift behaviour. This is not the case in crustacea. Cyclopoids are possibly an exception. In terms of abundance, sampling induced losses are 3.9 +/- 0.7% for insect dominated and 1.0 +/- 0.6% for crustacea/''worms'' (triclads, nematodes and oligochetes) dominated zoobenthic communities from the top 10 cm of the sediment. жүктеу/скачать 1.21 Mb. Достарыңызбен бөлісу:
|