The Influence of Environmental Factors and Microhabitat Availability on the Distribution of an Aquatic Oligochaete Assemblage in a Mediterranean River Basin (original) (raw)
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Ecology and distribution of ostracods in a polluted Mediterranean river
Palaeogeography, Palaeoclimatology, Palaeoecology, 1999
The present survey examines possible trends in the ecology of ostracod assemblages in a small Mediterranean river affected heavily by sewage and industrial effluents. Between January and July 1995, ten sampling stations situated along a 50 km stretch of the main channel of the River Magre (València, eastern Iberian Peninsula) were sampled monthly (physico-chemical variables being measured simultaneously). Although the entire site fauna was used to calculate diversity and biotic indexes, only Ostracoda were studied in depth, as little is known of the ecological preferences of this group. Ostracod assemblages encompassed 10 species, the most abundant genera being Herpetocypris and Heterocypris. Most species peaked in abundance towards the end of the study period (May-June) when water temperatures were rising. Ostracods were completely absent from the most disturbed sites, i.e. those with the lowest water quality index values. Different ostracod assemblages occurred along a gradient from high pollution towards the final 'recovery' zone. Combined classification (TWINSPAN, MDA) and ordination (DCA) techniques using species and site variable data showed that different groups of samples, related to the abundance of a particular ostracod assemblage, were linked to particular habitat features. Eucypris virens appeared in samples near to the source in winter, and in the early months of spring. During this period these sites were characterised by cool waters and relatively high alkalinity=Cl ratios. Furthermore two major groups of samples were related to the relative abundance of either Heterocypris incongruens and Herpetocypris intermedia, or Herpetocypris brevicaudata. Moderately polluted, clean waters are linked to these two groups, respectively. Additional division of both groups of samples was based on the total abundance of individual animals, and may be related to water temperature and season. These results may be used to assess possible changes in the trophic status of a palaeoenvironment when the species taken into account are recorded from a given sedimentary sequence.
Hydrobiologia, 1996
Many large and small lakes of varying depths are present in the Eastern Black Sea Range of Turkey, the nation's third most important glacial region following the Ağrı and Cilo-Sat mountain ranges. During the present study, 6 expeditions to collect aquatic oligochaetes from these lakes were conducted in July and August of 2005August of , 2006August of , and 2007; qualitative and quantitative samples were collected from 59 glacial lakes. We present and analyze the dominancy and distribution of aquatic oligochaete assemblages and their relation to environmental factors (temperature, dissolved oxygen, pH, electrical conductivity, salinity, turbidity, PO 4 -3 -P, HCO 3 -, organic carbon, hardness, Ca 2+ , Mg 2+ , Si, water depth, and altitude) using classifi cation and ordination techniques. Canonical correspondence analysis (CCA) was used to characterize the relationship between oligochaetes and the environmental variables. As a result, we determined the 4 most important environmental variables (elevation, water depth, dissolved oxygen, and temperature) aff ecting species distribution in general. Sampling localities were clustered into 8 groups with the unweighted pair-group method with arithmetic mean (UPGMA) based on physicochemical characteristics. Th e relationships between the total number of individuals and environmental measurements were determined by a simple analysis of variance (ANOVA) test. Th e results of our analyses suggest a signifi cant positive correlation between altitude (P < 0.05; F = 2.994) and the total number of individuals.
Man and River Systems, 1999
This study had a purpose to validate different tools based on the oligochaetes for the evaluation of the biological quality of sediments within a surveillance network. Biological data (IOBS index, percentage of Tubificidae with and without hair setae, worm densities), physical data (granulometrics) and chemical data (Cd, Cu, Cr, Hg, Ni, Pb, Zn, PCBs, PAHs) have been studied with co-inertia analysis. These analyses show an opposition between IOBS index and metals, a correlation between metals and percentage of Tubificidae without hair setae, and an association between PAHs, low index values, high densities and high percentage of Tubificidae with hair setae. For 24 sites, biological and chemical data gave similar information. In 11 cases on 36 they are conflicting. The use of metal speciations, according to the method of Teissier et al. (1979), show that the organic matter content seems to have an important role by sorbing metals leading to lower availability. Macrophyte cover could also explain some conflicting results. Granulometrics does not play a determinating role in the present case. As a conclusion, a table allowing the classification of river sediments is proposed for monitoring assessment. This table takes into account IOBS index values, the worm densities and the percentage of Tubificidae without hair setae.
Hydrobiologia, 1996
The oligochaete community of the Chioggia Lagoon (southern basin of the Venetian Lagoon) has been studied from May 1992 to May 1994, at ten fixed sampling stations, distributed across the lagoon. Numerous data regarding composition, abundance, biomass and the breeding periods of the species in the community have been obtained. Nine tubificid species, recently reported for the Mediterranean and Ponto-Caspian areas have been collected. Among them only three were abundant everywhere, except in the innermost part of the lagoon, and throughout the year: Tubificoides vestibulatus, T swirencowi and Limnodriloides maslinicensis. Only one enchytraeid genus, Grania, has been found restricted to an area near the connection with the sea. The values for the Shannon Diversity Index for the community never exceeded 0.8 and were mainly between 0.4 and 0.7. The most interesting result was the decrease of abundance and biomass, proceeding from the sea mouth (about 6000 ind m -2 ) towards the innermost part of the lagoon (less than 100 ind. m-2 ). Correlations are suggested with the different grain size of the sediment.
Using oligochaeta assemblages as an indicator of environmental changes
2012
We designed a field survey (the entire river length; not dammed: First and Second plateaus; dammed: Third Plateau) to test the hypothesis that the cascade of reservoirs promoted a reduction in species richness and changed the composition of Oligochaeta assemblage along the Iguaçu River. Changes in environmental variables and in richness and composition of Oligochaeta were summarized by Canonic Correspondence Analysis. Along the Iguaçu River, conductivity, and altitude decreased, whereas temperature increased. Oligochaeta composition showed a significant spatial variation, with higher abundances of the family Tubificidae and the genus Dero (Naididae) occurring in the First Plateau. In the Second and Third plateaus, few species were dominant, with increases in the presence of species of Naididae below dams. We found a clear decrease in species richness along the Iguaçu River. Moreover, we found that Oligochaeta assemblage was influenced by some environmental variables such as altitude, conductivity, substrate type and temperature, and by anthropogenic activities (human occupation and damming). The results supported the use of Oligochaeta as surrogate taxa to predict environmental changes along impacted (dammed and eutrophic) rivers. The validity of this was indicated by the strong and significant gradient registered, from the headwater to mouth of the Iguaçu River.
Journal of Limnology, 2015
We investigated the responses of the assemblage of Oligochaeta and Aeolosomatidae to organic pollution; comparing taxonomic richness, diversity, abundance, and diet of the individuals inhabiting two lowland streams with different degrees of anthropic impact (the Rodríguez and the Carnaval) belonging to the Río de la Plata basin, Argentina. The physicochemical parameters in the Rodríguez Stream indicated a strong deterioration of the water quality compared to that of the Carnaval. A canonical-correlation analysis indicated that the Tubificinae, Megadrili, Enchytraeidae, and Rhyacodrilinae were more closely associated with the Rodríguez Stream; whereas the Naidinae, Pristininae, and Opystocystidae were more highly represented in the Carnaval. The diversity and taxonomic richness in the Rodríguez Stream exhibited significant differences from those of the Carnaval (P<0.001), but the abundance was not different between the two sites. Schoener's index revealed the higher degree of dietary overlap of the two streams because all the species analysed consumed a high proportion of detritus, especially the organisms in the Rodríguez. In the Carnaval Stream a higher number of alimentary items were consumed, and mainly by the Naidinae. This difference, probably reflecting the greater availability of this resource at sites impacted by organic pollution, underscores the fundamental role of oligochaetes in the food webs of aquatic ecosystems. The combined use of structural and functional parameters enables a more comprehensive view of how these lotic systems function and as such provides information that will serve to design tools for the management of such temperate environments.
Surface and Hyporheic Oligochaete Assemblages in a French Suburban Stream
Hydrobiologia, 2006
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Journal of Crustacean Biology, 1999
The ostracod fauna of the three main rivers of the central Mediterranean slope of the Iberian Peninsula was studied, with special attention being paid to ecology and distribution. Forty-six stations were sampled in spring and autumn 1995 and thirty ostracod species were collected, two of these (Trujancypris serrata and Heterocypris reptans) new to the Iberian fauna. The most common species were Ilyocypris bradyi, Herpetocypris brevicaudata, Cypridopsis vidua, and Limnocythere inopinata. Cluster analysis showed that these species, together with Ilyocypris inermis and Sarscypridopsis spp. form the most widespread ostracod assemblage in the area, although its widespread distribution is not related to any of the environmental variables monitored. However, factors such as altitude, mean January air temperature, distance from source, flow discharge, water quality, and degree of organic pollution play an important role in explaining the occurrence of less common species. One species group was linked to high elevations and BMWP' biotic index values and low winter temperatures. Candona neglecta best characterizes this assemblage. In the opposite part of this environmental gradient, Ilyocypris gibba, associated with lower altitudes, epitomizes the third species group. Heterocypris salina and Heterocypris incongruens were the species that were most tolerant of organic pollution. Our results are compared with those reported in studies from different habitats (e.g., springs) and latitudes. The implications of our findings for paleoenvironmental reconstruction and water resources management are discussed.
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.