The distribution of aquatic oligochaetes in brackish inland waters in the SW Netherlands (original) (raw)
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Typifying macrofaunal communities of larger disturbed waters in The Netherlands
Aquatic Conservation-marine and Freshwater Ecosystems, 1992
1. A survey was carried out in rivers, canals and large lakes in the province of Overijssel (The Netherlands) to describe the macrofauna assemblages and their environment. A total of 74 environmental variables was measured at each sampling site. The aim was to describe a typology of large-sized water bodies for this region.2. Different techniques of multivariate analysis were used in combination with ecological information on individual taxa to derive and describe site groups in terms of taxon composition and mean environmental conditions. The resulting site groups were termed cenotypes.3. Nine cenotypes were distinguished. They showed great similarity in their composition of ubiquitous taxa and in environmental conditions. This similarity is, in part, due to anthropogenic influences. The large-sized water bodies are mostly regulated or canalized and function as collectors of nutrients, organic material and toxicants. This results in cumulative chronic stresses which overrule the natural key factors of current and dimension.4. Despite the similarity, differences between taxon assemblages could be attributed to combinations of key environmental factors; some taxa characteristic of the reach of a river or the gradient in size of canals were still present.5. The typology offers a basis for practical use in regional water management and nature conservation. Some applications for water management are indicated.6. Typological studies are vital (especially in semi-natural landscapes) for an improvement in understanding, management and conservation of freshwater biota.
Springer eBooks, 2001
In most soft-bottomed, lowland streams in the Netherlands discharge regimes largely follow the precipitation pattern. Winter discharges are higher and much more dynamic then summer discharges, although rain storms throughout the year cause unexpected peak flows. Minimal precipitation, reduced stream flow and droughts can occur during the summer months. Lowland stream habitat, particularly in The Netherlands, is hydrologically dynamic, with substrates frequently moved or disturbed. Differences in discharge patterns in Dutch soft-bottomed lowland streams are expected to affect distribution patterns of macroinvertebrates and thus oligochaetes. Ten small to medium sized lowland streams, differing from one another in hydrological regime, were studied. Five major habitats in each stream were assessed on three occasions over a 15-month period. Each habitat sampled with a micro-macrofauna shovel; during each sampling period, several environmental parameters, especially hydrological and substrate parameters, were measured. Ordination (CANOCO) (Ter Braak, 1989) and statistical tests (chisquared test) (Lindgren & McElrath, 1970) were used to determine the major oligochaete distribution patterns between streams as well as between habitats within each stream. Each stream was characterized by its oligochaete assemblage; general distribution patterns and individual oligochaete-substratum relationships were documented. Hydro-morphological parameters together explained the differences in major distribution patterns. Preferences of oligochaetes for specific structural habitats are discussed.
Aquatic Oligochaetes, 1999
The benthic fauna of the Belgian part of the polluted Schelde estuary, called the Zeeschelde, was studied in September-October 1996 at 143 stations along 35 transects. This study is part of the OMES research program, funded by the Flemish Government, to build an ecosystem model of the Zeeschelde in order to help policy makers to decide upon the future of this unique estuarine system. Of all organisms retained on a 250 µm mesh-size, oligochaetes were co-dominant in the mesohaline part and the only dominant group in the tidal freshwater zone. The oligochaete fauna of the ß-mesohaline zone consisted of two brackish water tubificids, Heterochaeta costata and Tubificoides heterochaetus, and the euryhaline naidid Paranais litoralis. The freshwater species Limnodrilus hoffmeisteri penetrated as far as Boerenschans. Abundance in this zone is rather low with numbers increasing with exposure. The part of the oligohaline zone that coincides with the maximum turbidity zone is extremely poor in benthos, due to high physical, chemical and biological stress, with very low numbers of L. hoffmeisteri, Tubifex tubifex and P. litoralis. In the tidal freshwater section, mass populations of the tubificids L. hoffmeisteri and T. tubifex occur (peak densities of almost 3.10 6 ind m −2 , maximum biomass: 25.7 g ADW m −2 ) with lower numbers of Limnodrilus claparedeianus, Limnodrilus udekemianus and Limnodrilus profundicola mainly in the part of the Zeeschelde close to Gent where better oxygen conditions are found. Oligochaetes are more abundant in finer sediments, resulting in a clear vertical gradient with low mean values in the deeper subtidal coarse sediments and highest numbers in the upper intertidal where fluid muds consolidate. In comparison with L. hoffmeisteri, T. tubifex was more abundant in the finest sediments. Vorticellidae are more common on tails of oligochaetes in the oxygenenriched part (4-9%) than in the oxygen-deficient zone (< 0.5%). Regeneration rates, being considered as a suitable measure of predation pressure, increase with salinity and size of the worms and are highly specific. In comparison with other temperate estuarine systems, the Zeeschelde has impoverished communities with oligochaetes as the dominant taxa. Though a future improvement of the water quality will definitely result in a less productive but more varied benthic community in the freshwater tidal zone, oligochaetes will probably continue to play an important role due to sustained harsh conditions.
Micro-distribution of oligochaetes in a soft-bottomed lowland stream (Elsbeek; The Netherlands)
Aquatic Oligochaetes, 1999
This study focuses on a low-gradient, soft-bottomed stream which shows strong fluctuations in discharge, partly natural (i.e. due to rainfall) and partly due to agricultural land-use. This dynamic discharge pattern causes silt deposition between discharge peaks which in turn cause the silt to be washed out. This process occurs independently from the height of the peak. The main substrate in the stream is quite homogeneous fine sand. Twenty-three species of oligochaetes were found. Their distribution and abundance varied with season and substrate. Mature tubificids and Lumbriculus variegatus occurred throughout the year. Stylodrilus heringianus occurred in winter and spring. Different naidids occur in different seasons, though half of the species can be collected all year. The micro-habitat of three tubificids, one lumbriculid and eight naidids were be identified. A high number of oligochaete species coexisted in a small stretch of the stream due to a separation in micro-habitat in space and time. The temporal variation in distribution was due to season. Particle size, the mineral and organic component of the substrate, and position in the stream bed influenced the spatial distribution of species. Temporal and spatial distribution of oligochaetes can not be separated.
Hydrobiologia, 1996
Distribution patterns of aquatic oligochaete assemblages, inhabiting largely unpolluted watercourses, in the Northwestern Iberian Peninsula, and their relationships with chemical and physiographical characteristics were analyzed by means of multivariate analyses. Qualitative and quantitative samples from 47 stations were obtained seasonally during 1983/84 and 1988/90. The variables included in this study were altitude, order number, distance from the origin, mean width, mean depth, substrate, current velocity, oxygen content, pH, conductivity, alkalinity and concentration of different ions.
2007
Species richness and distribution of oligochaetes in six reservoirs on Middle and Low Tietê River (SP, Brazil). The objective of this study was to determine the structure of the Oligochaeta populations in six reservoirs located in the Middle and Low section of Tietê River. Sampling was carried out in November 2002, in the rainy season, and in August 2003, in the dry season. In each reservoir, three transects were established: upper, middle and lower (near dam). Duplicate samples were collected with a van Veen grab which sampled an area of 337.0 cm 2. Seventeen oligochaetes species were identified. A gradient was observed in the number of species per reservoir, which diminished steadily from Barra Bonita to Três Irmãos dam. Branchiura sowerbyi was the dominant specie in every reservoir from Bariri (58.57%) down to Nova Avanhandava (92.16%), being outnumbered only in Barra Bonita, where Limnodrilus hoffmeisteri was dominant, representing 59% of the oligochaetes recorded. The highest average total densities, 470 ± 205 ind.m-2 in November 2002 and 260 ± 123 ind.m-2 in August 2003, were recorded in the Bariri reservoir. The average density, as the species richness, of oligochaetes tended to diminish downstream towards Três Irmãos, where the densities varied between 18 ± 6 ind.m-2 (November 2002) and 30 ± 12 ind.m-2 (August 2003). The grouping of the reservoirs on the basis of oligochaetes density and on the climatic periods joined the reservoirs in accordance with its geographic sequence throughout the river and also reflected their trophic state. The abundance and diversity of oligochaetes reflect the trophic state of the reservoirs and can therefore be used as a biological indicator of trophic state conditions.
In order to determine the oligochaeta fauna of Lake Sapanca (Turkey) samples were collected from 5 stations monthly, between September 2000-August 2001. As a result of the study, 13 species, which belong to 9 genera, were determined. These species are Aulodrilus limnobius, Tubifex tubifex, Tubifex ignotus, Tubifex nerthus, Limnodrilus hoffmeisteri, Potamothrix hammoniensis, Potamothrix vejdovskyi, Nais communis, Spirosperma ferox, Psammoryctides barbatus, Ilyodrilus templetoni, Psammoryctides deserticola, Paranais frici. Also some physicochemical parameters of the water (temperature, dissolved oxygen, pH, turbidity and depth) were measured at the sampling site. The average density of total oligochaetes in the benthos of the lake was 1,887 ind m-2. According to Shannon-Wiener index, Lake Sapanca was found had 2.59 richness and, 5 th station were found to have highest diversity (3.87) while 3 rd station to have the lowest (1.59). There are almost no data on the Oligochaeta fauna of this lake so far. Hence, all the determined taxa from the localities are recorded for the first time.