Large Lowland River Research Articles

Testing the coherence of several macroinvertebrate indices and environmental factors in a large lowland river system (Volga River, Russia)

Abstract In contrast to most large rivers in Europe, the biggest European river Volga including its tributaries has still remained uncontaminated in its headwaters. Therefore the upper Volga River system represents an appropriate system for investigation of relations of bioassessment indices with natural environmental factors. Moreover, it allows the definition of reference conditions for medium-size and large lowland rivers in Europe. The aim of this study was to analyse relations between Saprobic Index (SI), SPEAR indices, and other macroinvertebrate community indices and basic environmental factors in the upper Volga River system. Besides, preliminary ecological status classification (according to the EU Water Framework Directive) was proposed for SI and SPEAR pesticides indices for the system investigated. The analysed data set contained information on macroinvertebrates, basic habitat characteristics and water physico-chemical parameters from 53 sample sites. The results showed that SI and SPEAR indices were independent of channel width and related river longitudinal factors. Furthermore, the results indicated the index SPEAR pesticides to be potentially applicable across different types of watercourses as well as across different biogeographical regions in Europe showing similar boundaries of ecological status classes (at least between High, Good, and Moderate). A Multi-Habitat-Sampling method was recommended for SPEAR pesticides . Saprobic reference conditions of the lowland rivers were found to be beta-mesosaprobic. The relatively high boundary between High and Good classes resulted from naturally high organic matter concentrations. Due to indicating common pollution sources (i.e. organic, agricultural and industrial), the herein suggested methodologies have a potential to be applied in other large river systems in Europe. The reference condition characteristics described for the headwaters of the Volga River system can be used as a reference for medium-sized and large rivers in the regions where establishment of reference sites of these types is impossible (e.g., many regions in Europe).

Assessment of water quality in a large lowland river (Narva, Estonia/Russia) using a new Hungarian potamoplanktic method

Phytoplankton is one of the four biological elements used for the assessment of the water quality of surface water bodies. In rivers phytoplankton-based assessment of water quality has not been conducted in Estonia up to now. The aim of the present study was to test a new Hungarian potamoplanktic method for the assessment of the water quality of the Narva River, a large river on the Estonian-Russian border. For testing the method, algal species in the phytoplankton of the Narva River were classified into functional groups. Then the Ecological Quality Ratio (EQR) was calculated and its value was compared with the corresponding values for different water quality classes given in the literature. The mean value of the EQR for the Narva River revealed seasonal variation: in most cases it indicated 'good' or 'excellent' quality classes in spring and summer and 'very bad' quality class in autumn. The median value for the vegetation period of 2001-2008 indicated 'moderate' quality class. Variation in the functional groups of phytoplankton and in the EQR values reflected the seasonal dynamics of phytoplankton and the impact of Lake Peipsi. Comparison of the results of the assessments made by using the phytoplankton EQR and benthic diatom indices revealed agreement between the two metrics in the summer period: both were sensitive to the water quality and indicated at least 'good' quality class. The new Hungarian method appears to be suitable for the assessment of water quality in this Estonian large river. However, the numerical boundaries of the EQR for different water quality classes should be specified in the future on the basis of a larger Estonian phytoplankton database.

Phytoplankton dynamics in relation to connectivity, flow dynamics and resource availability—the case of a large, lowland river, the Hungarian Tisza

Large lowland rivers with sufficient hydrological storage capacity are capable of supporting primary production, but the dynamics of the advecting phytoplankton is poorly understood. Our study aimed at exploring how longitudinal versus lateral connectivity, flow dynamics versus resource availability and continuous versus discontinuous environmental gradients shaped the species composition of phytoplankton. Samples were taken from February to October 2000 along the Hungarian Tisza River (HTR) and in its main tributaries. Longitudinal and seasonal patterns were related to resources (light and nutrients) availability and flow dynamics derived from a 1D hydrodynamic model. The HTR was autotrophic during the study period, but tributary input considerably exceeded net autochtonous production. The Szamos River was the major source of both phytoplankton and nutrients in the HTR. Chryso- and euglenophytes were flushed into the main river from floodplain oxbows during high discharge. Imported algae experienced discontinuity in environmental gradients when entering the main river. The merged impact areas of two dams (IAD) that separate the two large meandering patches of the HTR disrupted the longitudinal profiles of both physico-chemical variables and attributes of algal assemblages (biomass, species composition, richness, similarity between adjacent sampling sites). Hydraulic storage along the IAD selectively favoured the recruitment of cryptophytes that, however, could not compensate for the enhanced sedimentation of diatoms in terms of biomass. Although the meandering patches presented several small-scale differences in major environmental gradients, both patches supported the growth of planktonic diatoms. Changes in algal biomass were decoupled from nutrient availability. We conclude that various measures must be applied in various lowland rivers within the same catchment to control their trophic status as a component of the ‘good ecological status’ defined in the Water Framework Directive.

Movements of Murray cod (Maccullochella peelii peelii) in a large Australian lowland river

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.

The influence of river functionality on habitat selection by Ephemeroptera in spatially and temporally diverse lowland rivers, with particular reference to the River Bug

Abstract The purpose of this work is the designation of changes in the environmental preferences of mayflies in the prevailing conditions in a large lowland river little changed by human activity. During the study, the occurrence of the following species were recorded: Cercobrachys minutus (54.2%); Procloeon nana (24.5%); Pseudocentroptiloides shadini (7.6%); Ametropus fragilis (2.9%), which were numerously represented and formed a permanent element of the fauna, and Baetopus wartensis (0.1%) and Oligoneurisca borysthenica which were noted very rarely and were accidental species. The differences and similarities in the functionality of the psammophilous and other mayfly assemblages were assessed. The data from the last fifteen years of study was investigated and compared with those from other rivers which were more managed. PCA was used to distinguish the main factors influencing habitat selection at particular stages of life history and the tendency for drifting.

Diversity of aquatic malacofauna within a floodplain of a large lowland river (lower Bug River, Eastern Poland)

This study analyses the composition and species richness of aquatic molluscan communities within a large sector (over 100 km) of the valley of the Bug, a large lowland river in eastern Poland. An attempt was also made to determine the number of samples sufficient to compile a representative mollusc list within the whole study area and in groups of water bodies representing different degree of permanence, as well as to test the completeness of sampling of the malacofauna. Within the study area, 54 mollusc species were found – 36 snails and 18 bivalves. Up to 27 species were recorded from individual sites with a mean of 8+ 5 species per site. Mean number of species was significantly higher in permanent water bodies than in the two other site groups. Dominance patterns in molluscan communities and frequencies of individual species showed distinct differences within three groups of habitats differing in permanence. Species composition was related to permanence, size, depth, hydrological connectivity and successional stage of water bodies, as well as to the type of bottom sediments and macrophyte abundance. The aquatic malacofauna found within the study area was rich, comprising almost 90% of potential composition based on regional species lists. Rarefaction curves for the total malacofauna confirmed the low probability of finding additional species, whereas temporary and permanent water bodies showed incomplete species lists. About 20 samples should be sufficient to collect representative data in the study area and more than 60 samples would be necessary to collect a nearly complete dataset.

Direct and indirect effects in flowhabitatbiota relationships in the littoral zone of a large lowland river

An overall lack of generality still exists in relationships between degree of fl ow modifi cation and eco- logical/geomorphological response, important for better understanding and management of freshwater resources. Here, we model direct and indirect effects in fl ow-habitat-biota relationships in the littoral zone of a 230 km stretch of the lower River Murray (Victoria, Australia), a large and highly-regulated lowland river. We rely on a novel (to lotic ecology) statistical method called the 'd-sep test'. A number of theory-laden (including PHABSIM-based) competitive models were assessed, and model reliability further evaluated against alternative models. The model of choice was one with fl ow directly affecting all abiotic (substratum composition) and biotic (aquatic vegetation, zooplankton abundance, fi sh abundance) components. The latter were in turn linked in a bottom-up series, with inclusion of a direct effect of aquatic vegetation on fi sh abundance. However, an alternative model with a direct ef- fect of substratum composition on fi sh abundance was also partly supported by the data. We discuss the ecological signifi cance of the proposed model(s), along with their value, relevance, and implications in (fi sh) habitat assess- ment studies.

Influence of prey variables, food supply, and river restoration on the foraging activity of Daubenton’s bat ( Myotis daubentonii) in the Shibetsu River, a large lowland river in Japan

To conserve the foraging habitat of Daubenton’s bat ( Myotis daubentonii) in a large lowland river, we investigated the influence on this bat of prey variables (number or biomass) and insect origin (aquatic or terrestrial). We tested the hypothesis that river restoration (re-meandering) conducted in the Shibetsu River, northern Japan, enhances foraging habitat quality by increasing the abundance of aquatic insects. From June to September 2004, flying insects were collected using Malaise traps in restored and channelised reaches in the Shibetsu River. Bat activity was recorded by bat detectors placed near the Malaise traps in each of the two reaches. Foraging activity of Daubenton’s bat was more strongly related to the number of insects than to biomass, and to adult aquatic insects than to terrestrial insects. The high dependence of Daubenton’s bat on aquatic prey was attributed to the fact that aquatic insect numbers were always higher than those of terrestrial insects. Contrary to the hypothesis, Daubenton’s bat was more active in the channelised reach than the restored reach in all months except June, and it synchronized its foraging activity with the seasonal distribution of adult aquatic insects. However, the study was undertaken just two years after restoration and the riparian vegetation had not yet established itself. Our results demonstrate the importance of aquatic insect abundance for Daubenton’s bat throughout the seasons in large lowland rivers. A further decrease in aquatic insects, associated with progressive anthropogenic alteration of river environments, undoubtedly exerts a harmful influence on the conservation of this species.

Lateral movement of common carp (Cyprinus carpio L.) in a large lowland river and floodplain

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.

Summer microhabitat partitioning by different size classes of masu salmon (Oncorhynchus masou) in habitats formed by installed large wood in a large lowland river

Different size classes of masu salmon ( Oncorhynchus masou ) were partitioned in three-dimensional space in habitats created by artificially installed large wood (LW) structures in a large river. Fish >300 mm in size (L-sized) returning from the ocean distinctly occurred in sheltered areas near the riverbed, which had a moderate current velocity and contained large root wads or tree trunks; 140–200 mm (M-sized) and 100–120 mm (S-sized) fish selected deep areas of high velocity current adjacent to LW structures; ≤80 mm fish (SS-sized) were most common in the lower depth layers throughout all LW habitats, including shallow areas with moderate currents where LW structures blocked the fast currents. Some SS-sized fish used cover areas provided by branches and leaves. Masu salmon abundance in all size classes combined was greater in habitats with LW structures than in habitats without them. Our study suggests that the natural recruitment of whole trees from the riparian zone or artificial placement of whole trees will have a profound effect on creating salmonid habitats in large rivers.

Does wood type influence the colonisation of this habitat by macroinvertebrates in large lowland rivers?

Submerged woody habitat provides the major structure around which ecological processes operate in many lowland rivers. Colonisation by macroinvertebrates was measured in a south-eastern Australian river over a 32-day period in an experiment testing the hypothesis that wood type influences the invertebrate assemblage structure. The wood types were green wood, dry wood, and dry but previously waterlogged wood. All wood used was river red gum (Eucalyptus camaldulensis). Macroinvertebrates colonised previously waterlogged wood more rapidly than green or dry wood. The assemblage structure varied significantly over the sampling period, with copepods and cladocerans numerically dominating the assemblage during the first few days after the introduction of the wood. The assemblage became more diverse through time and was numerically dominated by dipterans, ephemeropterans and trichopterans. The results indicate that there was little difference in the time taken for macroinvertebrate colonisation after wood introduction when using either green or dry wood. This has implications for large-scale restoration projects, where green wood is likely to be a more readily available option for reintroduction than dry wood.

Estimating species richness and catch per unit effort from boat electro‐fishing in a lowland river in temperate Australia

Abstract Biodiversity estimates are typically a function of sampling effort and in this regard it is important to develop an understanding of taxon‐specific sampling requirements. Northern hemisphere studies have shown that estimates of riverine fish diversity are related to sampling effort, but such studies are lacking in the southern hemisphere. We used a dataset obtained from boat electro‐fishing the fish community along an essentially continuous 13‐km reach of the Murrumbidgee River, Australia, to investigate sampling effort effects on fish diversity estimates. This represents the first attempt to investigate relationships between sampling effort and the detection of fish species in a large lowland river in Australia. Seven species were recorded. Species‐specific patterns in catch per unit effort were evident and are discussed in terms of solitary and gregarious species, recreational fishing and the monitoring of rare and threatened species. There was a requirement to sample substantial lengths of river to describe total species richness of the fish community in this river reach. To this end, randomly allocated sampling effort and use of species richness estimators produced accurate estimates of species richness without the requirement for excessive levels of effort. Twenty operations were required to estimate species richness at this site, highlighting the need for comparable studies of river fish communities in lowland rivers elsewhere in Australia and the southern hemisphere.

Migration of rheophilic fish in the large lowland rivers Meuse and Rhine, the Netherlands

Abstract Large‐scale migratory patterns of adult rheophilic fish [barbel, Barbus barbus (L.), chub, Leuciscus cephalus (L.), ide, Leuciscus idus (L.), nase, Chondrostoma nasus (L.)] were studied in relation to habitat quality and possible migration barriers in the lower rivers Meuse and Rhine, the Netherlands, using a telemetry system with transponders and detection stations based on inductive coupling. Most fish moved over short distances (<10 km), especially those residing in river stretches with high habitat diversity year‐round. About 16% of fish used river stretches over 50 km and two ide moved more than 200 km along free‐flowing river stretches. One‐third of barbel, chub and nase from a Weir‐regulated river stretch moved upstream during the spawning season to spawning habitats. Some fish resided in the areas immediately downstream of weirs and fishways during the spawning season, although it was unclear to what extent these observations reflected habitat choice or barriers to migration.

Environmental flow methodologies to protect fisheries resources in human‐modified large lowland rivers

AbstractThe flow regimes of temperate large lowland rivers are manipulated to provide various services for society. Most water policy decisions are based on economic considerations, with little or no consideration toward fish conservation and fisheries. The prerequisite for a stronger implementation of these interests in water policy decisions is the development of appropriate tools for assessing the adequate flow needed to protect fish diversity and fisheries resources.From the 1970s onwards, environmental flow methodologies (EFMs) have been developed primarily to protect endangered fish species and to maintain fisheries resources in human‐modified rivers. Until now, their application had mainly been restricted to small upland rivers and headwater streams. Here, we investigate the applicability of commonly used EFMs for predicting and quantifying the consequences of flow manipulation on fish and fisheries of regulated large lowland rivers.Among the range of environmental flow methods currently available, habitat simulation methods are promising tools to assess adequate flow and to quantify the consequences of flow manipulation on the temporal and spatial availability of littoral habitats important for fish. However, habitat simulation methods may be effective only with those fish species whose recruitment is influenced by the availability of those habitats. To increase prediction accuracy, habitat simulation methods have to be linked to population dynamic models. More research is needed to improve understanding of the mechanisms controlling the dynamics of populations and assemblages in regulated large lowland rivers. Copyright © 2008 John Wiley & Sons, Ltd.

Methods for and fish responses to channel remeandering and large wood structure placement in the Shibetsu River Restoration Project in northern Japan

The Shibetsu River Restoration Project intends to reestablish a historic meander pattern by connecting a 3.5-km channelized reach with a series of oxbow lakes that were previously isolated by channel straightening. Prior to full-scale construction, a remeandering experiment (pilot) was conducted upstream of the project segment to assess the methods for and ecological responses to channel remeandering. Large wood (LW) structures were also installed in the experimental remeandering reach. The channel remeandering project with LW placement in a large lowland river is the first undertaken in Asia, and it has rarely been undertaken elsewhere. In this report, we present an overview of the Shibetsu River Restoration Project and the methods for and fish responses to channel remeandering and LW placement in the experiment.

Spatial dynamics of rotifers in a large lowland river, the Elbe, Germany: How important are retentive shoreline habitats for the plankton community?

The longitudinal dynamics of Rotifers in the Potamal region of the River Elbe between Dresden, km 46, and Geesthacht, km 583, was investigated on a Lagrangian survey in 2000 which included transversal sampling (left bank, main channel, right bank) and sampling of five major tributaries and backwaters to evaluate lateral impacts on the zooplankton community. A simple model of longitudinal development for the dominant species Trichocerca pusilla was calculated, based on the results of an in situ incubation in Dresden and on literature data and compared with the dynamics observed on the Lagrangian survey. To characterize the influence of groyne fields on the main channel zooplankton community, an additional lateral sampling was conducted in August 2000 at Havelberg, km 423. Zooplankton community was clearly dominated by rotifers. A distinct downstream-directed increase of rotifers was observed. Longitudinal development of rotifers could be explained predominantly by reproduction during downstream transport.

Role of suspended particles for extracellular enzyme activity and biotic control of pelagic bacterial populations in the large lowland river Elbe

Large rivers are often highly loaded with suspended particles, but the microbial metabolism related to these particles has rarely been studied. Hence, we investigated activities of the extracellular enzymes leucine aminopeptidase (LAP), phosphatase, β-D-glucosidase and exo-1,4-β-glucanase as well as microbial communities associated with suspended particles from the 8 th order River Elbe, and their potential controls. Three fractions were investigated separately - rapidly sinking particles (largest particles), intermediately sinking particles (medium- sized particles), and bulk water including slowly sinking particles (smallest particles). Overall, bulk water had the highest abundances of bacteria, heterotrophic fl agellates and ciliates. Extracellular enzyme activities per dry mass were also highest in bulk water, as 83-95 % of total bacteria occurred in this fraction. Medium-sized and large particles had lower enzyme activity per dry mass because of their smaller relative surface area and lower propor- tions of particulate organic carbon (POC) and particulate nitrogen (PN). Bulk water, the medium-sized and the largest particle fractions contributed 40-85 %, 5-20 % and 10-40 % to total enzyme activity per volume of river water, respectively. Leucine aminopeptidase exhibited its highest relative activity in bulk water, which also had the highest chlorophyll-a content. Cell-specifi c enzyme activities were generally correlated with the availability of particulate organic matter (POM) per bacterial cell and were therefore highest on medium and large-sized particles. These results indicate that the abundance and activity of attached bacteria were bottom-up controlled by the size and biochemical composition of the particles. However, bacterivorous fl agellates and ciliates were abundant on the larger particles. Thus, number and feeding types of particle-attached protozoans suggest that top-down control may have occurred during an algal bloom. Our results show that free-living bacteria dominated the overall microbial metabolism of the water column in the River Elbe. However, bacteria attached to medium-sized and large particles were the most active ones, and contributed 15-58 % to total extracellular enzyme activity in the water column, depending on enzyme and season.

Movements and habitat use of common carp (Cyprinus carpio) and Murray cod (Maccullochella peelii peelii) juveniles in a large lowland Australian river

Movements and habitat use of common carp (Cyprinus carpio) and Murray cod (Maccullochella peelii peelii) juveniles in a large lowland Australian river

Movements and habitat use of common carp (Cyprinus carpio) and Murray cod (Maccullochella peelii peelii) juveniles in a large lowland Australian river

Abstract – Native Murray cod (Maccullochella peelii peelii) are listed as a nationally vulnerable species, whereas non‐native common carp (Cyprinus carpio) are widespread and abundant. Understanding key aspects of life history, such as movement patterns and habitat selection by juvenile Murray cod and common carp, might be useful for conserving Murray cod populations and controlling common carp numbers. We used radio‐telemetry to track eight juvenile Murray cod and seven juvenile common carp in the Murray River, Australia, between March and July 2001. Common carp occupied a significantly greater total linear range (mean ± SD: 1721 ± 1118 m) than Murray cod (mean ± SD: 318 ± 345 m) and the average daily movement was significantly greater for common carp (mean ± SD: 147 ± 238 m) than for Murray cod (mean ± SD: 15 ± 55 m). All Murray cod and five of the seven common carp displayed site fidelity or residency to one, two or three locations. Murray cod were found only in the mainstream Murray River among submerged woody habitats, whereas common carp occurred equally in mainstream and offstream areas, and among submerged wood and aquatic vegetation. Murray cod were found in deeper (mean ± SD: 2.3 ± 0.78 m) and faster waters (mean ± SD: 0.56 ± 0.25 m·s−1) compared with common carp (mean ± SD: 1 ± 0.54 m; 0.08 ± 0.09 m·s−1) respectively. The presence of juvenile Murray cod only amongst submerged wood is an indication that these habitats are important and should be preserved. Conversely, juvenile common carp were equally present among all habitats sampled, suggesting that habitat selection is less specific, possibly contributing to their widespread success.

Temperature influence on the fish assemblage structure in a large lowland river, the lower Oder River, Germany

Abstract – Water temperatures were expected to structure river fish assemblages by promoting: (i) offspring's growth and densities in warm years, (ii) spring spawning fish when temperatures increase early and (iii) improved growth and overwintering condition from elongated vegetation periods. Favourable temperature conditions in their first year should improve growth and survival in consecutive years. In the lower Oder River, Germany, fish have been sampled annually, 0+ in July since 1997, and older fish in November since 1998. This data set was analysed to test the hypotheses mentioned above. The water temperature ranged between −0.4 and 25.1 °C during the study period, resulting in substantial variations of the 29 temperature metrics derived from daily means. Cumulative degree‐days until catch, in spring and during March, as well as minimum and mean temperatures in March and spring explained 63% of the variability observed. The mean total length of the most frequent 0+ fish differed significantly between years related to temperature. Increased length growth at higher temperatures was a general tendency. Total length and density of 0+ fish were significantly inversely correlated, but the potential influence of temperature on species densities was not significant. The mean fish densities varied not significantly between years. No indication was found that higher total length in the first year of life resulted in an improved growth in subsequent years.For future research and management it has to be expected that temperature impacts become increasingly significant in regulated river systems. With decreasing hydrodynamics the significance of temperature effects will increase.