Floodplain Habitats Research Articles

Short-term Home Range and Habitat Selection by Feral Hogs in Northern Texas

Texas is estimated to harbor more than 2 million feral hogs, Sus scrofa. The increasing abundance of feral hogs throughout the United States is a testament to their ability to adapt to nearly any environment. We GPS-collared and tracked 16 feral hogs in the spring of 2015 and 2016 in the Texas Panhandle, United States. We determined home range and core area size using kernel density (KDE) and minimum convex polygon (MCP) estimators and selection of habitats by feral hogs in two field sites. Mean (±se) KDE home range and core area sizes were 9.73 ± 1.74 km2 and 1.31 ± 0.23 km2, respectively. Mean (±se) MCP home range and core area sizes were 15.13 ± 3.49 km2 and 3.14 ± 0.69 km2, respectively. Home range sizes were slightly larger but comparable to other home range sizes in Texas, and with home range and core area sizes larger for males than female. Feral hogs did not exhibit second-and-third order habitat selection at random (P < 0.005) in both field sites. Hogs selected for woodland and floodplain habitats over human developed areas. Feral hogs spent more time in agricultural habitats during crepuscular and nighttime periods and more time in natural habitats throughout the day. These results suggest management techniques in northern Texas need to be executed for the removal or deterrence of feral hogs in areas of cultivated crops, ideally before the planting period through the harvesting season.

Пойменные крупнотравные леса острова Сахалин (класс Salicetea sachalinensis Ohba 1973)

Пойменные крупнотравные леса острова Сахалин (класс Salicetea sachalinensis Ohba 1973)

Reproduction of two loricariid species in a confined river and implications for environmental impacts of dams

ABSTRACT Fish reproduction in floodplain rivers is often linked to flow regime and with the inundation of floodplain habitats. However, in confined rivers, where floodplains are absent, the relation between reproduction and flow can in comparison be expected to be distinct. In this study, we describe the reproductive life-history of Hemiancistrus fuliginosus and Hypostomus isbrueckeri in a confined river and discuss its differences relative to floodplain loricariids and also the implications for effects of dam construction and flow regulation. We found the reproductive peak of both species occurred during lowering waters, just after maximum river flow, in contrast to floodplain species that tend to spawn during rising waters. The studied species presented attributes of equilibrium life-history strategy, which are related to predictable river flow variation. Because both species spawned during low river flow, which is historically predictable in summer, we suggest that their reproduction may be severely disrupted, depending on how flow regime is affected by dam operation. These results have implications for assessing and mitigating the impacts of river damming on fish populations in confined rivers, and we point to ecologically driven flow management and conservation of free-flowing rivers as mitigation and conservation alternatives.

Serial discontinuity in naturally alternating forest and floodplain habitats of a Michigan (USA) stream based on physicochemistry, benthic metabolism, and organismal assemblages

ABSTRACTWe tested the response of several different water quality metrics at 6 sites along a 4-km alternating forest (canopied) and floodplain (non-canopied) reach of the East Branch of the Black River, an undisturbed northern Lower Michigan trout stream, during summer 2015. Physicochemical parameters were unchanged between sites and reflected an undisturbed continuum. In-stream woody debris was higher at the forest sites, whereas relative canopy cover and sunlight intensity were higher at the floodplain sites. Both benthic macroinvertebrates and adult caddisflies exhibited greater species richness and a higher abundance of shredders at the forest sites, and a higher abundance of scrapers at the floodplain sites. Fish specimen abundance, species richness, and percentage of trout were not different between sites, and instead all increased throughout the summer. Community respiration was unchanged between the single tested floodplain site and the forest sites upstream and downstream of it. Gross primary production and net daily metabolism were higher at the floodplain site, leading to stream autotrophy. This result was also obtained when tested in summer 2017. Our results support the idea that terrestrial habitat changes can singularly affect the fundamental ecological functioning of an undisturbed stream, primarily due to deviations in sunlight penetration and allochthonous input. Moreover, the short distances between sites with alternating results indicate the dynamic and serially discontinuous state of natural rivers.

Sibling mice species of the genus Sylvaemus Ognev, 1924 (Mammalia, Rodentia) in the Ukrainian Carpathians

Three species of the genus Sylvaemus occur in the region of the Ukrainian Carpathians: the yellow-necked field mouse (S. tauricus), the long-tailed field mouse (S. sylvaticus) and the pygmy field mouse (S. uralensis). Issues of the genus’s taxonomy and identification of species have remained controversial in some parts of the geographic range, while in the Ukrainian Carpathians they have been studied scarcely at all. We studied about 250 mice specimens from the Ukrainian Carpathians belonging to the genus Sylvaemus, among which 216 were analysed morphometrically based on 4 external and 11 cranial characters. Results indicate that by linear body dimension only S. uralensis can be differentiated with high probability. For the pair of species tauricus–sylvaticus, the hind foot length is the least variable among linear body characters, which might be considered diagnostic, although values of this character also tend to overlap. To identify species correctly, it is necessary to use craniometrical characters. For the pair of tauricus–sylvaticus, the least variable among the 11 studied characters are the upper molars length (M13), braincase width (CRB), and braincase height (CRH). Mixed samples of adult specimens of the three species can be differentiated with minimal or practically no overlap by using the relation of the upper molars length to braincase width, condylobasal length, and auditory bulla length. Analysis of characters’ uniformity in adult specimens showed that S. tauricus and S. sylvaticus differ from one another the most by the upper molars length (M13), braincase width (CRB), braincase height (CRH), condylobasal length (CBL), and auditory bulla length (BUL). A similar tendency was revealed for the pair of S. sylvaticus and S. uralensis. A regional identification key was developed for differentiation of adult mice, which allows identifying reliably 93.5% of specimens. Results of the revision of samples suggest that S. tauricus has the widest altitudinal and habitat preferences, S. sylvaticus occurs mainly in humid floodplain biotopes (shrubs, woods) entering far into the mountains along river valleys, while S. uralensis is represented only by few records from lowland floodplain habitats.

Copepod assemblage structure (Crustacea: Copepoda) along a longitudinal environmental gradient in a tropical river-floodplain system, Brazil

Abstract Aim: In this study, we analyzed the structure of the copepod community along a longitudinal axis of the last undammed stretch of the Upper Paraná River floodplain, downstream of Porto Primavera reservoir. We hypothesized that (i) copepod assemblage would show an increase in the abundance of organisms, species richness and specific diversity with the distance from the Porto Primavera reservoir, due to the arrival of species from adjacent lakes and tributaries; (ii) copepod abundance and species richness would be higher in tributaries and adjacent lakes located at the floodplain, which show higher environmental heterogeneity and function as a species source; and (iii) spatial patterns of copepod assemblage structure are related to the environmental gradient, since copepods show a rapid response to the variation of environmental conditions. Method Sampling was performed quarterly from August 2013 to July 2014, at the subsurface of the pelagic region. Sampling sites were located along the Paraná River, in seven of its tributaries, and in eight lakes located in its floodplain. Results We identified 29 species belonging to two families: Cyclopidae (21 species) and Diaptomidae (eight species). On contrary of our first hypothesis, ANOVA results showed a significant decrease in copepod abundance in the downstream direction. Similarly, the tributaries showed higher values of ecological attributes in the upstream stretch. RDA results showed that in axis 1, the Paraná River and the lakes were positively correlated with conductivity, pH, temperature and suspended organic matter, characterized by the most abundant copepod species. The tributaries, on the other hand, were negatively correlated with turbidity, total nitrogen, total phosphorus and depth. Axis 2 showed a positive correlation of the Paraná River with conductivity and suspended organic matter, and a higher abundance of Argyrodiaptomus azevedoi, Notodiaptomus iheringi, N. henseni, N. cearensis and N. cf. spinuliferus. On the other hand, the lakes were positively correlated with temperature and pH and also with a higher abundance of Thermocyclops minutus and T. decipiens. Conclusion We highlight the importance of the maintenance of the ecological integrity of the Upper Paraná River floodplain, especially of its tributaries, in order to support the high biodiversity registered in the last undammed stretch. Furthermore, we highlight the importance of manipulation of water levels in reservoirs located upstream of this stretch, a necessary condition to maintain the hydrological connectivity between floodplain habitats and the main river.

Habitat diversity and connectivity govern the conservation value of restored aquatic floodplain habitats

Floodplains have been strongly altered by human activities such as channelization and other river regulations. Globally, there is a growing interest in their restoration because of an increasing understanding of the ecological importance of these habitats for feeding, spawning, nursery or overwintering of aquatic species. In this study, a large floodplain restoration project of the upper Danube River was used to investigate colonization and succession patterns of fish, macroinvertebrates, macrophytes and periphyton in relation to abiotic habitat variables that can be restored through ecosystem management. Highest species diversity was detected near the contact zones of the floodplain channel to the main stem of the Danube, and in the transition zones of river sections (RS) and oxbow lakes (OS). The highest proportions of all taxa (82%) and of distinctive species (22%) were detected in RS, followed by OS (66% of all taxa, 8% distinctive species) and floodplain ponds (FP, 47% of all taxa, 5% distinctive species). The habitat types RS, OS and FP significantly differed in overall community composition and their colonization processes comprising fast colonization of current-adapted specialists in RS, and mostly generalist species in OS and FP. Our results indicate that restoration of floodplain habitats should not only consider the re-establishment of maximum connectivity, but also provide a mosaic of distinct habitat types with different degrees of connectivity and disturbance. Each habitat type in the floodplain supported a unique assemblage of species, which suggests that such habitat mosaics can facilitate exceptionally diverse ecosystems.

Phosphorus nutrition of Populus × canescens reflects adaptation to high P-availability in the soil.

Phosphorus (P) constitutes one of five macronutrients essential for plant growth and development due to the central function of phosphate in energy metabolism, inheritance and metabolic control. In many ecosystems, plant available soil-P gets limited by soil aging. Hence, plants have developed adaptation strategies to cope with such limitation by an efficient plant and ecosystem internal P-cycling during annual growth. The natural floodplain habitat of fast-growing Populus × canescens is characterized by high soil-P availability. It was thus expected that the P-nutrition of P. × canescens had adapted to this conditions. Therefore, different P-fractions in different twig tissues were investigated during two annual growth cycles. The P-nutrition of P. × canescens markedly differs from that of European beech grown at low soil-P availability (Netzer F, Schmid C, Herschbach C, Rennenberg H (2017) Phosphorus-nutrition of European beech (Fagus sylvatica L.) during annual growth depends on tree age and P-availability in the soil. Environ Exp Bot 137:194-207). This was mainly due to a lack of tree internal P-cycling during annual growth indicated by the absence of P-storage and remobilization in twig bark and wood. Hence, strategies to economize P-nutrition and to prevent P-losses had not developed. This fits with the fast-growth strategy of P. × canescens at unrestricted P-availability. Hence, the P-nutrition strategy of P. × canescens can be seen as an evolutionary adaptation to its natural growth habitat.

The Application of Chironomid Pupal Exuvial Technique (CPET) for Ecological Analysis in a Neotropical Large River System.

This field ecological study, based on the chironomid pupal exuvial technique (CPET), is new for the Paraná River and proposes an efficient tool to be used in future ecological approaches and biomonitoring. Drifting of pupal exuviae in a river-floodplain system of the Middle Paraná River floodplain was represented by 34 Chironomidae taxa, being the characteristic association obtained from the CPET: Lopescladius, Onconeura, Paralauterborniella, Polypedilum, and Harnischia complex. Diversity, richness, dominance, total density, and density of dominant taxa were different between the longitudinal and lateral dimensions but not between hydrologic phases, with a greater diversity and richness in the main channel of the river and higher density and dominance in floodplain habitats. The species turnover is the dominant process in structuring studied assemblages in spatial and temporal analysis, increasing in the floodplain habitats and in low-water phase. The results obtained showed that drifting exuviae in the longitudinal axis were coming from different assemblages and environments of a wider area (regional), while exuviae recorded in the connections of the floodplain environments in the lateral dimension could reflect the local assemblages. We demonstrated the ecological value of CPET studies to interpret the attributes of Chironomidae assemblage in river-floodplain systems of large rivers in an integrated way.

Floodplain habitat is disproportionately important for bats in a large river basin

Floodplain ecosystems across the world have declined with river regulation and floodplain development, reducing flood frequency and extent and fragmenting flood-dependent vegetation. There is growing evidence that these changes to flooding disproportionately affect terrestrial taxa, such as bats. We compared bat activity and insect abundance across the floodplain mosaic (river, lake, vegetated wetland, floodplain forest, floodplain woodland) representing decreasing flooding histories, and two dry habitats (dry vegetation, agricultural). We replicated these habitats in each of six floodplain systems of the Murray-Darling Basin, a large semi-arid river basin (1,042,730km2) in south-eastern Australia. Our sites were spread across >400,000km2, traversing climatic and hydrological gradients. Rivers and lakes with open water and riparian trees had greater total activity (5 times), foraging activity (14 times) and bat richness (1.5 times) than dry vegetation. Activities of all mesic bat species, as well as some widespread and arid-adapted bat species, were positively associated with floodplain habitats when compared with dry vegetation. Lowest overall total activity, foraging activity and richness were observed in dry agricultural (cropping, grazing and fallow) habitats, with two of six threatened species in our study area never recorded in agricultural habitats. Prey abundance was not correlated with bat activity or habitat. The mosaic of floodplain habitats appears to be of disproportionate value for bat communities compared to dominant land covers of agricultural and dry vegetation. Loss of floodplain habitats through continued river regulation and floodplain development are likely reduce diversity and abundance of bats that rely on floodplains for foraging and roosting. Lags in bat roost formation and forest structure mean these changes could take over a century to reverse. To sustain bat communities, we recommend increasing environmental flows to floodplains during the bat lactating season, implementing stronger protection of floodplains from river regulation and floodplain development and where possible, restoring floodplains affected by agriculture into functioning wetlands.

Habitat use of the European mudminnow Umbra krameri and association with other fish species in a disconnected Danube side arm.

Fish assemblages along the longitudinal course of an old, disconnected and modified side arm of the Danube floodplain downstream of Vienna, Austria, as well as habitat structure, hydro-morphological and hydro-chemical factors, were investigated in order to analyse the key environmental determinants of the European mudminnow Umbra krameri. Generally, U. krameri was the most abundant species in the system. It occurred in disconnected ditches, ponds and pools with dense reed belts and comparatively low nutrient content, indicating its natural association with marsh habitats. At infrequently disturbed sites it was associated with a small group of stagnophilious and highly specialized species with adaptations to strong oxygen fluctuations. At frequently flooded sites, the species was absent or occurred in low abundances, indicating its adaptation to water bodies in older successional stages and its low competitive power in permanently connected floodplain habitats.

Relationships between forest cover and fish diversity in the Amazon River floodplain

AbstractHabitat degradation leads to biodiversity loss and concomitant changes in ecosystem processes. Tropical river floodplains are highly threatened by land cover changes and support high biodiversity and important ecosystem services, but the extent to which changes in floodplain land cover affect fish biodiversity remains unknown.We combined fish and environmental data collected in situ and satellite‐mapped landscape features to evaluate how fish species with different ecological strategies and assemblage structures respond to deforestation in floodplains of the Amazon River. We surveyed 462 floodplain habitats distributed along a gradient of land cover, from largely forested to severely deforested. Rather than analyse only taxonomic metrics, we employed an integrative approach that simultaneously considers different aspects of fish biodiversity (i.e. β diversity and taxonomic and functional assemblage structure) to facilitate mechanistic interpretations of the influence of land cover.Spatial patterns of fish biodiversity in the Amazon River floodplain were strongly associated with forest cover as well as local environmental conditions linked to landscape gradients. Several species and functional groups defined by life‐history, feeding, swimming/microhabitat‐use strategies were positively associated with forest cover. Other species, including some that would usually be considered habitat generalists and species directly dependent on autochthonous resources (e.g. planktivores), were most common in areas dominated by herbaceous vegetation or open water habitats associated with the opposite extreme of the forest cover gradient. β diversity and the degree of uniqueness of species combinations within habitats were also positively associated with forest cover.Synthesis and applications. Our results demonstrating that spatial patterns of fish biodiversity are associated with forest cover, indicate that deforestation of floodplains of the Amazon River results in spatial homogenization of fish assemblages and reduced functional diversity at both local and regional scales. Floodplains world‐wide have undergone major land cover changes, with forest loss projected to increase during the next decades. Conserving fish diversity in these ecosystems requires protecting mosaics of both aquatic habitats and floodplain vegetation, with sufficient forest cover being critically important.

Variability of species of Babesia Starcovici, 1893 in three sympatric ticks (Ixodes ricinus, Dermacentor reticulatus and Haemaphysalis concinna) at the edge of Pannonia in the Czech Republic and Slovakia.

The distribution, variability and host specificity of species of Babesia Starcovici, 1893 were studied in questing ticks collected on the northwestern edge of the Pannonian Basin in the south-easternmost part of the Czech Republic and in western Slovakia. The area is characterised by relatively natural floodplain habitats and the sympatric occurrence of three tick species possessing wide host spectra, namely Ixodes ricinus (Linnaeus), Dermacentor reticulatus (Fabricius) and Haemaphysalis concinna Koch. Analysis was carried out on 1,408 I. ricinus, 2,999 D. reticulatus and 150 H. concinna altogether, collected from 59 localities. We documented the presence of Babesia spp. not only in I. ricinus but also in H. concinna in the Czech Republic. Two isolates from I. ricinus were classified as B. venatorum Herwaldt, Cacciò, Gherlinzoni, Aspöck, Slemenda, Piccaluga, Martinelli, Edelhofer, Hollenstein, Poletti, Pampiglione, Löschenberger, Tura et Pieniazek, 2003 (formerly determined as Babesia sp. EU1), which is a zoonotic parasite and can cause human babesiosis. The rest of our amplicons were very similar to B. canis (Piana et Galli-Valerio, 1895), which is usually transmitted by D. reticulatus. Despite the huge amount of examined samples, all D. reticulatus ticks were Babesia-free. Due to this finding, we did not consider our obtained isolates to be B. canis, but other closely related species possessing a similar sequence of the studied portion of 18S rDNA. Although this genetic marker is most frequently used in PCR-based diagnostic methods of babesias, its low variability compromises its reliability in studies based only on this marker.

Impacts of river regulation and other anthropogenic activities on floodplain vegetation: A case study from Sri Lanka

Since the initiation of large-scale development in late 1970s, the Mahaweli River basin in Sri Lanka has experienced significant changes. However, no comprehensive study has been undertaken so far to evaluate the impacts of river regulation on associated ecosystems including floodplains in the downstream. The present study was aimed at identifying the impacts due to both river regulation and other anthropogenic activities on inland floodplain habitats (locally known as villus) located along the final stretch of the River Mahaweli before reaching the Indian Ocean. Four villus, Handapana (HAN), Bendiya (BEN), Karapola (KAR) and Gengala (GEN), were selected for the study. HAN and BEN can be considered as highly influenced (HI) by river regulation while KAR and GEN as less influenced (LI) due to their respective locations. Due to the absence of pre- regulation vegetation data, HI villus were compared with LI villus in order to explore any potential impacts of river regulation. Vegetation was enumerated using belt transect method. To find out other on-going anthropogenic impacts on these villu ecosystems, a survey was conducted using 100 individuals living in two villages located nearby. The results revealed some significant modification in the composition and the diversity of the vegetation, most possibly due to river regulation and other on-going anthropogenic activities. However, the most notable changes were recorded in the herbaceous layer. Some native aquatic herbaceous species have been completely absent over the period of two decades since the developmental activities begun, while some exotic invasive aquatic species (Eichhornia crassipes) dominated the herbaceous layer in HI villus threatening the survival of the remaining native species. Density and richness of lianas too diminished significantly in HI villus perhaps due to changes of micro-habitat conditions as a result of river regulation and also due to over-harvesting for commercial purposes. The results suggest that these ecosystems have been altered over the years due to culmination of factors including altered flow regimes following river regulation and some on-going human influences. The present study highlights the importance of regulating such human influences on villus including fishing and extracting cane and reed in order to protect these vulnerable ecosystems for future generations. The potential of these ecosystems to develop ecotourism has also been emphasized.

Linking ecological science with management outcomes on New Zealand's longest river

AbstractNew Zealand's Waikato River has had a short but intense history of development, primarily through land‐use change and flow regulation in the upper river, and in the lower river through flood control works, non‐native species invasion, and land‐use intensification. The river undergoes sharp transitions across montane‐flood plain‐coastal environments over a short distance and under similar climate. Together with specialized life‐history requirements of many native fish, these features provide valuable insights into large river ecology and management. Testing approaches to determine outcomes of water quality changes have highlighted the value of functional indicators over traditional biotic measures for monitoring anthropogenic impacts. Initiatives to enhance native fish populations in the lower river have included remediation of migration barriers to improve access to tributary habitat, enhancement of tidal spawning habitat, and traps and gates to limit movement of large pest fish into flood plain lakes for spawning. This example of a southern temperate large river system highlights the importance of recruitment habitat and connectivity for native fish communities dominated by migratory species. Their slender bodies provide opportunities to create semipermeable barriers that enable access to flood plain habitats while restricting larger invasive fish. Recent initiatives have increased momentum to restore the ecological health of this river, but the underpinning science to guide priority actions is often lacking, and there is limited monitoring over the scales and time frames required to evaluate effectiveness.

Rearing and migration of juvenile Chinook salmon (Oncorhynchus tshawytscha) in a large river floodplain

Off-channel habitat has become increasingly recognized as key for migratory fishes such as juvenile Chinook salmon (Oncorhynchus tshawytscha). Hence, floodplain habitat has been identified as critical for the continued persistence of California’s Central Valley salmon, particularly the Yolo Bypass, the primary floodplain of the Sacramento River. To provide insight into factors supporting juvenile salmon use of this 240 km2, partially leveed floodplain, we examined inter- and intra-annual relationships between environmental correlates and residency time, apparent growth, emigration, migratory phenotype, and survival over more than a decade for natural-origin (“wild”) fish and experimentally-released hatchery fish. Flood duration was positively associated with hatchery juveniles residing longer and achieving larger size. Wild juveniles grew larger and emigrated later with cumulative temperature experience (accumulated thermal units) and warmer average annual temperatures during flood years. Within years, both wild and hatchery salmon departed the floodplain as flood waters receded. Parr-sized juveniles dominated outmigrant composition, though fry and smolt-sized juveniles were also consistently observed. Survival to the ocean fishery was not significantly different between hatchery fish that reared in the Yolo Bypass versus those that reared in the main stem Sacramento River. Our study indicates improved frequency and duration of connectivity between the Sacramento River and the Yolo Bypass could increase off-channel rearing opportunities that expand the life history diversity portfolio for Central Valley Chinook salmon.

Application of key ecological attributes to assess early restoration of river floodplain habitats: a case study

The Nature Conservancy acquired the Emiquon Preserve along the Illinois River, Illinois, with the primary objective of restoring ecological floodplain processes and habitats that promote and sustain native species and communities. The Conservancy convened an Emiquon Science Advisory Council prior to restoration implementation that identified key ecological attributes (KEAs) for riverine and backwater targets, KEA indicators, and acceptable ranges for those indicators. We assessed the application of this methodology to evaluate status of conservation targets and to inform future science and management at Emiquon. The KEA framework provided an important function of directing a systematic monitoring program that provided fundamental data on changing environmental conditions that were incorporated into annual target evaluations. Data show that 46–55% of all indicators were within acceptable ranges prior to reconnection of the preserve with the Illinois River. Recent completion of a water control structure represents a critical intervention that provides potential to improve conservation status of those floodplain and riverine targets that depend on water management and river connectivity. Continued review and modification of the KEA model in conjunction with a strategic monitoring program will provide critical information to guide relevant management decisions and testable hypotheses to reduce potential threats and achieve future restoration goals.

Land Cover Changes (1963–2010) and Their Environmental Factors in the Upper Danube Floodplain

To analyze the changes in the Upper Danube Floodplain, we used aerial photos to quantify the change of landscape pattern from 1963 to 2010. We focused on typical floodplain habitats, i.e., riparian forest and floodplain grassland. We used landscape metrics and transformation matrix to explore changes in land cover structure and composition. The active floodplain experienced increasing fragmentation from 1963 to 2010. Despite an increase of aggregation, riparian forest suffered a 2.3% area loss from 1995 to 2010. Arable land in the active floodplain declined by 28.5%, while its patch size significantly increased. Elevation, distance to river and soil quality were the most relevant environmental factors for the land cover change in the floodplain. Higher soil quality or longer distance to river led to an increase of conversion from grassland into arable land; grassland patches with poorer soil quality were likely to change into riparian forest; riparian forest closer to the river and with a lower height above mean water level tended to remain stable. This comprehensive understanding of historical land cover change and environmental factors is needed for the enhancement of landscape functions and sustainable development in the floodplain.

Spatiotemporal heterogeneity of actual and potential respiration in two contrasting floodplains

AbstractFloodplains are vital components of river ecosystems and play an important role in carbon cycling and storage at catchment and global scales. For efficient river management and conservation, it is critical to understand the functional role of spatiotemporally complex and dynamic habitat mosaics of river floodplains. Unfortunately, the fundamental understanding of mineralization and carbon flux patterns across complex floodplains is still fragmentary. In this study, respiratory potential (i.e., electron transport system activity [ETSA]) was quantified seasonally across different aquatic and terrestrial habitats (wetted channels, gravel bars, islands, riparian forests, and grasslands) of 2 Alpine floodplains differing in climate, altitude, discharge, flow alteration intensity, and land use (Soča [natural flow regime, 12% grassland area] and Urbach [mean annual discharge reduction by 30% due to water abstraction, 69% grassland area]). In situ respiration (R) was measured, and ETSA–R ratios were calculated to examine differences in exploitation intensity of the overall respiratory capacity among floodplain habitats and seasons. ETSA and R provided potential and actual estimates, respectively, of organic matter mineralization in the different floodplain habitats. Hierarchical linear regression across habitat types showed that organic matter, grain sizes &lt;0.063 mm, and water content were the most important predictors of ETSA in both floodplains, and grain sizes 2–0.063 and &gt;8 mm were also highly important for the Soča floodplain. The combination of ETSA and R measurements conducted in contrasting floodplains increased our understanding of the relationships between floodplain habitat heterogeneity, organic matter mineralization and human impacts, that is, structural–functional linkages in floodplains. These data are integral towards predicting changes in floodplain function in response to environmental alterations from increasing human pressures and environmental change.

Comparison of nine different methods to assess fish communities in lentic flood-plain habitats.

This study compares the effectiveness and representativeness of electrofishing, snorkelling, seining, baited lift netting, multi-mesh gillnetting, baited fish traps, fyke netting, angling and longline fishing, considering three typical lentic flood-plain habitats at different times of day. Electrofishing was by far the most effective method yielding highest species richness, species trait representation and catch per unit of effort (CPUE), followed by seining. For single species like dace Leuciscus leuciscus, European ruffe Gymnocephalus cernua, common bream Abramis brama and silver bream Blicca bjoerkna, seining was more effective than electrofishing. With both methods, some species were more consistently caught during night, dusk or dawn than during daylight. All other methods tested cannot be generally recommended for fish community assessments in shallow backwaters due to their low representativeness of species inventory and generally low CPUE. Based on these results, electrofishing of 30 m transect replicates at different times of day for monitoring the fish community in shallow backwaters, can be recommended, enabling the maximum possible comparability to adjacent river habitats. Seining should be considered as an alternative if accessibility of habitats is restricted or electrofishing is prohibited. The 25 species detected in the backwaters also suggest that these habitats contribute a large proportion of fish diversity and should be included in standard assessments of river ecological status.