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Lowland Rivers (lowland + river)
Selected AbstractsMovements of Murray cod (Maccullochella peelii peelii) in a large Australian lowland riverECOLOGY OF FRESHWATER FISH, Issue 4 2009J. D. Koehn Abstract,,, This study of Murray cod (Maccullochella peelii peelii) movements in a large lowland river in south-eastern Australia indicated that the species was not sedentary, but undertook complex movements that followed a seasonal pattern. While there were sedentary periods with limited home ranges and high site fidelity, Murray cod also under took larger movements for considerable portions of the year coinciding with its spawning schedule. This generally comprised movements (up to 130 km) from a home location in late winter and early spring to a new upstream position, followed by a rapid downstream migration typically back to the same river reach. Timing of movements was not synchronous amongst individuals and variation in the scale of movements was observed between individuals, fish size, original location and years. [source] Lateral movement of common carp (Cyprinus carpio L.) in a large lowland river and floodplainECOLOGY OF FRESHWATER FISH, Issue 1 2009M. J. Jones Abstract,,, Common carp (Cyprinus carpio L.) are a major freshwater invader and knowledge of their movements is important for planning control efforts. To investigate the movement patterns of common carp, radio-tags were implanted into 46 adult fish; 37 near a large floodplain wetland, the Barmah-Millewa forest, and 9 in the Murray River approximately 175 km upstream. Tagged fish were located every second week between August 1999 and March 2001. Common carp occupied total linear ranges (TLR) between 0.4 and 238 km (mean 30 ± 61 km), with 25 fish (62.5%) occupying a TLR < 10 km. Two fish made large distance movements approximately 650 km downstream. Fish sex, the number of locations, time at large, or tagging location explained little variability (P > 0.05) in TLR. Monthly distance from release varied from 0.04 to 238 km (mean 15 ± 44 km), and was not significantly related to river discharge and water temperature, but 29 of 31 (93.5%) fish tagged at Barmah moved from the Murray River into adjacent floodplain habitats upon flooding. Five fish (12.5%) moved large distances (>127 km) upstream of the Barmah-Millewa forest. Fourteen fish (35%) showed site fidelity to within 20 m and usually occupied one or two home sites. Twenty-six fish (65%) showed site fidelity to within 100 m occupying up to five sites during the study period. Movement patterns of common carp were complex, and individuals exhibited different strategies, which is typical of invasive species. Efforts to control and potentially reduce common carp populations in regulated river-floodplain environments should target key floodplain access points and over-wintering habitats to reduce adult biomass, spawning and recruitment levels. [source] Annual movement of adult pike (Esox lucius L.) in a lowland riverECOLOGY OF FRESHWATER FISH, Issue 2 2006A. Koed Abstract,,, The movement of ten radio-tagged adult pikes (57,113 cm) in the River Gudenå, Denmark, was investigated from September 1998 to September 1999. The movements of pike were characterised by long resident periods in the submergent vegetation, interrupted by short excursions to nearby areas. Two periods with more intense movement were observed; one period during early winter; and one period during spring from mid-March to mid-May. The increased movement during early winter may have been initiated by a slight temperature increase at this time, whereas the increased movement during spring coincided with the spawning of pike. Despite suitable spawning areas nearby the areas where pike resided most of the year, several pike, mainly females, migrated to distant localities during spring. [source] Is water temperature an adequate predictor of recruitment success in cyprinid fish populations in lowland rivers?FRESHWATER BIOLOGY, Issue 4 2003A. D. Nunn SUMMARY 1. Higher than average ambient water temperature in the first year of life may be responsible for strong cohorts of adult cyprinid fish. Whilst temperature explains much of the variation in year-class strength (YCS), however, it is not the only influential factor as high temperature does not inevitably yield strong year-classes. Furthermore, years in which a strong year-class is prevalent in one species do not necessarily result in strong year-classes in other coexisting species, suggesting other biotic and abiotic factors are important in regulating recruitment success. 2. The relationships between water temperature, river discharge, the position of the Gulf Stream, 0-group fish growth and recruitment success (YCS) were examined in three cyprinid fish species in an English lowland river, using a 15-year data set. 3. Mean length of 0-group fish at the end of the summer was positively correlated with water temperature (cumulative degree-days >12 °C) and negatively correlated with river discharge (cumulative discharge-days above basal discharge rate). Water temperature was negatively correlated with river discharge. 4. YCS was positively correlated with mean 0-group fish length at the end of the summer and with the position of the North Wall of the Gulf Stream. 5. 'Critical periods' (i.e. periods in the first summer of life when fish may be more susceptible to increases in river discharge) were difficult to discern because of interannual variations in river discharge relative to the timing of fish hatching. YCS of roach and chub was most strongly correlated with discharge in the period from June to September inclusive, while YCS of dace was most significantly correlated with discharge in August. 6. River discharge (rather than water temperature) may be the key factor in determining YCS, either directly (through discharge-induced mortality) or indirectly (via reduced growth at lower water temperatures, discharge-associated increases in energy expenditure or reduced food availability). It could be that, in effect, water temperature determines potential YCS while discharge determines realised YCS. [source] Efficacy of a nature-like bypass channel in a Portuguese lowland riverJOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2005J. M. Santos Summary Throughout Europe in the last decade there has been a steady shift away from more technical fish pass designs to more nature-like passes, such as nature-like bypass channels. Upstream fish passage in a nature-like bypass channel was investigated in a lowland river, the Lima River, for 117 days from March 2000 to May 2002. Fish passage was recorded using an automatic video recording system. Electrofishing samples within the bypass and below the weir were compared with species abundance found on the tape recordings. More than 7500 individuals of eight species passed through the bypass channel. Species composition was dominated by striped mullet (65.3%) and potamodromous species (34.3%), which used the bypass mainly at night. Of the environmental variables considered, bypass discharge explained most of the variation in the number of cyprinids, whereas water temperature was more important for diadromous species. Comparing species composition below the weir using passage recordings provided a useful tool to assess species efficacy of the bypass, although biological requirements should also be taken into account. This study proved the efficacy of the bypass for passage of almost all occurring species and life stages and also for providing suitable habitat for fish fauna, highlighting the use of these facilities for river restoration schemes. [source] Patternizing of impoundment impact (1985,2002) on fish assemblages in a lowland river using the Kohonen algorithmJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2005T. Penczak Summary Impoundment impact on fish assemblage structure was investigated in the dammed middle course of the Warta River. A backwater site (AB) was located 2 km upstream of the Jeziorsko Reservoir, and a tailwater site (CD) 1.5 km downstream of the dam. Both sites were studied for 3 years in the pre-impoundment period (1985,1987) and 15 years after damming (1988,2002). Quantitative electrofishing in spring and autumn assured obtaining yearly average biomass for each population. Most of the data analysis aimed to assess the dam impact on the fish assemblage structure but other accompanying impacts such as discharge manipulations, revetment, different forms of engineering, and water quality improvement in the tailwater and backwater reaches were also discussed. The Kohonen algorithm (self-organizing map, SOM) was used for the analysis, and perfectly separated AB and CD samples into two clusters. Samples from the backwater (AB) proved that this reach of the Warta River had maintained its almost natural character and that fish assemblages had changed moderately, now occupying only five neighbouring hexagons out of a total of 16. In the tailwater (CD), however, because of considerable fluctuations in fish assemblages the SOM produced three subclusters, which engaged nine hexagons: (i) the pre-impoundment period (1985,1987, two hexagons); (ii) 7 years after the definite closure of dam sluices (1988,1994, five hexagons); and (iii) the past 8 years of sampling (1995,2002, two hexagons), when stabilization in the assemblage was observed. The SOM also definitely proved profound changes in fish assemblage composition: most lithophilous species declined and many phytolithophilous and phytophilous species became dominants, particularly in the tailwater site where downstream migration of 0+ of successfully spawned species from the reservoir took place. [source] Hydroacoustic target strength validation using angling creel census dataFISHERIES MANAGEMENT & ECOLOGY, Issue 6 2002P. A. FREAR Validation of hydroacoustic in-situ target strength is problematic in large, deep lowland rivers, which cannot be sampled easily by conventional methods such as netting or electric fishing. A sampling programme involving three different techniques (split beam sonar, angling census and post-angling competition data collection) was conducted to examine methodologies suitable for target strength validation. This combination of techniques also assessed the relative merits of each method for best describing fish populations and the stocks exploited in a recreational coarse fishery. The sonar estimated the greatest number of fish of the three techniques, with a strong positive size correlation with the other two methods. The angling census and post-competition census accounted for more larger fish, >26 cm, than were detected acoustically, indicating a stratification of species that were exploited by angling but not detected by horizontal sonar. The combined techniques demonstrated a suitable, cost-effective, hydroacoustic validation method for large UK rivers, which supports recreational coarse fisheries management, with the added advantage of species identification. [source] Constraints on recovery: using molecular methods to study connectivity of aquatic biota in rivers and streamsFRESHWATER BIOLOGY, Issue 4 2007JANE M. HUGHESArticle first published online: 2 MAR 200 Summary 1. The ,Field of Dreams Hypothesis' states ,if we build it, they will come', referring to the assumption that if habitats are restored, species will recolonise them. However, the ability of a species to recolonise a restored site will depend not only on the appropriate habitat being present, but also on the ability to get there. This is likely to depend on both the species' dispersal behaviour and the position of a site in the landscape. 2. Animals with good potential for dispersal are more likely to be able to disperse to newly restored sites. Similarly, sites in lowland streams with limited altitudinal differences between sites may be easier to reach than upstream sites. This is because upstream sites are connected to one another via lowland streams that have different characteristics and therefore may be difficult for animals to traverse. 3. In this paper, genetic data from a range of freshwater species that have been analysed in my laboratory are used to assess the importance of life cycle and position in the landscape (i.e. upland versus lowland streams) on connectivity patterns (and thus recolonisation potential) among populations. 4. In general, contemporary dispersal across catchment boundaries is negligible, except for aquatic insects with an adult flight stage. Dispersal among streams within catchments appears to be more limited than was predicted from knowledge on life histories, except for fish in lowland rivers and streams. 5. As predicted, dispersal of fish, crustaceans and molluscs among streams within catchments is significantly greater in lowland rivers than in upland streams. 6. Overall, these analyses suggest that, with the exception of most insects, and fishes in lowland rivers, natural recolonisation of restored sites is only likely from sites within the same stream. If a species has disappeared from the whole stream, then restoration of habitat alone may not be sufficient for its re-establishment. [source] Distribution of aquatic vascular plants in lowland rivers: separating the effects of local environmental conditions, longitudinal connectivity and river basin isolationFRESHWATER BIOLOGY, Issue 3 2005BENOÎT O. L. DEMARS Summary 1. Changes in species distributions along rivers have rarely been observed independently of changes in environmental conditions and meaningful comparison between different catchments is made difficult by the limited geographical distribution of species. This study presents a new approach to quantify the effect of the spatial structure of lowland river networks on aquatic plant distribution and to explore the potential underlying processes using species life-history characteristics. 2. Twenty-five species of aquatic vascular plants recorded in 62 sites across five calcareous river basins were used to investigate (i) the temporal turnover of plant species, (ii) the habitat utilisation of species, (iii) the trade-offs between different plant life-history characteristics and (iv) the relationship between species life-history characteristics and habitat utilisation. 3. The annual plant turnover within a 3-year period was, although significant, extremely low. It suggests that results from spatial surveys conducted over 3 years should not be undermined by temporal changes. 4. Spatial connectivity along and between rivers was more important than in-channel physical characteristics in shaping species assemblages. Neither chemical factors (ammonium, phosphate) nor extrinsic biotic competitors (filamentous green algae) significantly influenced plant distribution. 5. The most common combinations of life-history characteristics were neither related to environmental conditions nor to spatial isolation. Instead, they could reflect natural selection processes associated with larger scales than those considered in this study. 6. Plant distribution was most strongly related to the dispersal and regeneration abilities of the plants, supporting the hypotheses relating to longitudinal connectivity. The hypothesis that different growth forms would be associated with different in-channel physical features was not verified. As expected, there were no substantial differences in plant life-history characteristics between river basins. [source] Seasonal and interannual variation of bacterial production in lowland rivers of the Orinoco basinFRESHWATER BIOLOGY, Issue 11 2004María M. Castillo Summary 1. We examined the influence of hydrologic seasonality on temporal variation of planktonic bacterial production (BP) in relatively undisturbed lowland rivers of the middle Orinoco basin, Venezuela. We sampled two clearwater and two blackwater rivers over 2 years for dissolved organic carbon (DOC), chlorophyll, phosphorus and bacterial abundance to determine their relationship to temporal variation in BP. 2. Dissolved organic carbon concentration was greater in blackwater (543,664 ,m) than in clearwater rivers (184,240 ,m), and was generally higher during periods of rising and high water compared with low water. Chlorophyll concentration peaked (3 ,g L,1) during the first year of study when discharge was lowest, particularly in blackwater rivers. Soluble reactive phosphorus (SRP) was very low in the study rivers (<3.8 ,g L,1) and concentration increased during low water. 3. Average BP was higher in clearwater (0.20,0.26 ,g C L,1 h,1) than in blackwater rivers (0.14,0.17 ,g C L,1 h,1), although mean bacterial abundance was similar among rivers (0.6,0.8 × 106 cells mL,1). 4. Periods of higher chlorophyll a concentration (low water) or flushing of terrestrial organic material (rising water) were accompanied by higher BP, while low BP was observed during the period of high water. 5. Interannual variation in BP was influenced by variations in discharge related to El Niño Southern Oscillation events. 6. Seasonal variation in BP in the study rivers and other tropical systems was relatively small compared with seasonal variation in temperate rivers and lakes. In addition to the low seasonal variation of temperature in the tropics, low overall human disturbance could result in less variation in the inputs of nutrients and carbon to the study rivers compared with more disturbed temperate systems. [source] Is water temperature an adequate predictor of recruitment success in cyprinid fish populations in lowland rivers?FRESHWATER BIOLOGY, Issue 4 2003A. D. Nunn SUMMARY 1. Higher than average ambient water temperature in the first year of life may be responsible for strong cohorts of adult cyprinid fish. Whilst temperature explains much of the variation in year-class strength (YCS), however, it is not the only influential factor as high temperature does not inevitably yield strong year-classes. Furthermore, years in which a strong year-class is prevalent in one species do not necessarily result in strong year-classes in other coexisting species, suggesting other biotic and abiotic factors are important in regulating recruitment success. 2. The relationships between water temperature, river discharge, the position of the Gulf Stream, 0-group fish growth and recruitment success (YCS) were examined in three cyprinid fish species in an English lowland river, using a 15-year data set. 3. Mean length of 0-group fish at the end of the summer was positively correlated with water temperature (cumulative degree-days >12 °C) and negatively correlated with river discharge (cumulative discharge-days above basal discharge rate). Water temperature was negatively correlated with river discharge. 4. YCS was positively correlated with mean 0-group fish length at the end of the summer and with the position of the North Wall of the Gulf Stream. 5. 'Critical periods' (i.e. periods in the first summer of life when fish may be more susceptible to increases in river discharge) were difficult to discern because of interannual variations in river discharge relative to the timing of fish hatching. YCS of roach and chub was most strongly correlated with discharge in the period from June to September inclusive, while YCS of dace was most significantly correlated with discharge in August. 6. River discharge (rather than water temperature) may be the key factor in determining YCS, either directly (through discharge-induced mortality) or indirectly (via reduced growth at lower water temperatures, discharge-associated increases in energy expenditure or reduced food availability). It could be that, in effect, water temperature determines potential YCS while discharge determines realised YCS. [source] Geomorphologic control on pollutant retardation at the groundwater,surface water interfaceHYDROLOGICAL PROCESSES, Issue 24 2008J.W.N. Smith Abstract The results of research on the pollutant retardation potential of permeable riverbed sediments in catchments with significant groundwater,surface water (GW-SW) interaction are presented. The fraction of organic carbon and cation exchange capacity of fluvial sediments in various geomorphologic environments have been quantified. Sediments in selected reaches of the rivers Tern and Leith (UK), from the underlying Permian sandstone aquifers, and from along the length of the rivers Severn and Eden into which the Tern and Leith discharge have been investigated. Statistical analyses show significant variation in the geochemistry and pollutant retardation potential of sediments from different geomorphologic features, and between upland and lowland rivers. The sorption potential of fine-grained sediments deposited in pools was greater than sand in runs and coarser deposits in riffles. Similarly, sediments in lowland rivers were found to have a greater retardation potential than those in upland rivers. There was generally greater retardation potential in fluvial sediments of all types than in the underlying aquifers, and in lowland rivers the fluvial sediment retardation potential greatly dominated that of the aquifer. The findings demonstrate the potential for pollutant retardation processes in riverbed sediments of sandstone catchments, and suggest that consideration of retardation processes at the groundwater,surface water interface should be included into environmental risk-assessment studies, in order to better assess and manage the effects of contaminated groundwater discharges to rivers, particularly in lowland catchments. Copyright © 2008 John Wiley & Sons, Ltd. [source] A comparative analysis of restoration measures and their effects on hydromorphology and benthic invertebrates in 26 central and southern European riversJOURNAL OF APPLIED ECOLOGY, Issue 3 2010Sonja C. Jähnig Summary 1.,Hydromorphological river restoration usually leads to habitat diversification, but the effects on benthic invertebrates, which are frequently used to assess river ecological status, are minor. We compared the effects of river restoration on morphology and benthic invertebrates by investigating 26 pairs of non-restored and restored sections of rivers in Austria, Czech Republic, Germany, Italy and the Netherlands. 2.,Sites were grouped according to (1) region: central Europe vs. southern Europe; (2) river type: mountain vs. lowland rivers; (3) restoration approach: active vs. passive restoration and (4) a combination of these parameters. All sites were sampled according to the same field protocol comprising hydromorphological surveys of river and floodplain mesohabitats, microhabitats at the river bottom and habitat-specific sampling of benthic invertebrates. Restoration effects were compared using Shannon,Wiener Indices (SWIs) of mesohabitats, microhabitats and invertebrate communities. Differences in metric values between non-restored and restored sites were compared for 16 metrics that evaluated hydromorphology and the benthic invertebrate community. 3.,Mean SWIs differed for both mesohabitats (1·1 non-restored, 1·7 restored) and microhabitats (1·0 non-restored, 1·3 restored), while SWIs for invertebrate communities were not significantly different (2·4 non-restored, 2·3 restored). Meso- and microhabitat metrics in the restored sections were usually higher compared with the non-restored sections, but the effects on invertebrate metrics were negligible. 4.,Measures in southern Europe and mountainous regions yielded larger differences between non-restored and restored sections of rivers. Differences in the meso- and microhabitat metrics were largest for actively restored sections of central European mountain rivers and rivers from southern Europe, followed by passively restored mountain rivers in central Europe. The smallest differences were observed for lowland sites. There was no significant restoration effect on invertebrate metrics in any categories. 5.,Synthesis and applications. Restoration measures addressing relatively short river sections (several hundred metres) are successful in terms of improving habitat diversity of the river and its floodplain. Active restoration measures are suitable if short-term changes in hydromorphology are desired. To realize changes in benthic invertebrate community composition, habitat restoration within a small stretch is generally not sufficient. We conclude that restoring habitat on a larger scale, using more comprehensive measures and tackling catchment-wide problems (e.g. water quality, source populations) are required for a recovery of the invertebrate community. [source] Nutrient limitation along eutrophic rivers?APPLIED VEGETATION SCIENCE, Issue 3 2009K input in a species-rich floodplain hay meadow, Roles of N Abstract Question: Is the growth of biodiverse floodplain plant communities along nutrient-rich lowland rivers still limited by nutrients? Location: Floodplains of the river Overijsselse Vecht, the Netherlands. Methods: Soil characteristics and potential nutrient limitation of the vegetation types were studied in two hay meadows, both belonging to the Fritillario-Alopecuretum, in the floodplain of the eutrophic river Overijsselse Vecht (the Netherlands). The meadows had different fertilization histories: one was a species-rich hay meadow managed as a nature reserve, the other a newly created nature reserve that had been used as an agricultural pasture before. Sods collected from both locations were transferred to a glasshouse, fertilized weekly with NP, NK, PK, NPK or control solutions and harvested three times a year during two successive growing seasons. Results: Biomass production of sods from both locations of this floodplain still appeared to be limited by N. Interestingly, the sods from the existing nature reserve were also limited by K, but only in the second year. Fertilization caused a shift in the relative abundance of the different plant families. Tissue nutrient concentrations were increased by fertilization with the nutrient in question, but decreased if biomass production was stimulated. Conclusions: Even in eutrophic river areas, the nutrient concentrations of the surface water may still determine the development of potentially biodiverse floodplain vegetation. Nomenclature: Van der Meijden (2005) [source] Freshwater mussel abundance predicts biodiversity in UK lowland riversAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2007David C. Aldridge Abstract 1.Indicator taxa are widely used as a valuable tool in the assessment of freshwater biodiversity. However, this approach to identifying sites of conservation priority requires surveyors to possess expert taxonomic knowledge. Furthermore, sorting and microscopic examination of material can present logistical and financial constraints. 2.Comparisons were made between the taxon richness and the density of freshwater mussels (Bivalvia: Unionidae) from 30 sites in seven UK lowland rivers, ranging from ca 3 m to 50 m width and ca 0.5 m to 4 m depth. Where mussels occurred, taxon richness of other invertebrates was strongly correlated with both mussel density and mussel biomass. Overall mussel density was a better predictor of taxon richness than the density of any individual mussel species. 3.It is suggested that this association arises from the ,keystone' role that mussels play in many freshwater ecosystems. Local biota can benefit from the mussels' filtration, excretion, biodeposition and physical presence. 4.Using mussel abundance as a surrogate provides a rapid and straightforward alternative to conventional methods of assessing freshwater biodiversity. No expert knowledge is required and any standardized sampling technique can be used. Freshwater mussels are found throughout the world's lentic and lotic fresh waters and this approach therefore has the potential for widespread utility, especially where rapid comparisons of biodiversity are required between biogeographically similar regions. In addition, the results highlight the ecosystem-level consequences of allowing the global decline of freshwater mussels to remain unchecked. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||