Biotic Habitat Research Articles

Constructed treatment wetlands provide habitat for zooplankton communities in agricultural peat lake catchments

Zooplankton are an essential component of healthy functioning lake and wetland ecosystems. Despite this, zooplankton communities within constructed treatment wetlands (CTWs) in agricultural landscapes remain unstudied. Taxa richness, total abundances and community composition were evaluated for zooplankton assemblages from three habitat types (lakes, CTWs and drainage ditches) within five intensive agricultural peat lake catchments in New Zealand. Relationships to water quality, physicochemical and biotic habitat variables were examined. Zooplankton were dominated by cladocerans, copepods, ostracods and rotifer taxa, representing a range of communities typical of lake and pond habitats. CTWs supported species otherwise absent from lake and drain habitats, increasing the overall biodiversity of the highly-modified peat lake catchments. Taxa richness of CTWs was higher than that of drains, and a few CTWs had greater diversity than several lakes. The morphological variables area and depth contributed to the greatest differences between habitats, followed by pH, inorganic nitrogen, conductivity and temperature. Correspondingly, zooplankton communities were significantly influenced by habitat area, depth and pH, as well as ammonium, phosphate, water temperature, dissolved oxygen, and macrophyte cover. Opportunities were explored for refining CTW designs to enhance zooplankton biodiversity and potentially improve treatment efficiency through increasing the complexity and diversity of CTW habitat niches.

Different Factors Drive Emergence and Persistence in an Invasive Grass

Premise of research. Hypotheses to explain nonnative plant invasions often suggest that propagule pressure promotes invasion success. However, interactions between propagule pressure and abiotic or biotic habitat characteristics also may regulate establishment and persistence of invaders, but they are not often tested. Additionally, results from the few published studies considering interactions among factors are conflicting, with some studies finding that propagule pressure overwhelms abiotic and biotic conditions and others suggesting that environmental factors play a key role in determining invasion success independent of propagule pressure.Methodology. We conducted a field study to evaluate the roles played by propagule pressure (1-, 4-, or 16-rhizome segments), disturbance (disturbed or undisturbed, to manipulate environmental resistance), and their interaction in the emergence (initial ramet production) and persistence (presence at the beginning of the second growing season) of highly invasive cogongrass (Imperata cylindrica). To determine whether elevated propagule pressure or disturbance aids in overcoming environmental resistance in shaded habitats, we conducted the experiment in both open field (full sun) and forest understory (deep shade) habitats.Pivotal results. Cogongrass emergence was driven by both propagule pressure and disturbance, which enhanced emergence probability by threefold and more than twofold, respectively. However, persistence occurred only in open, full sun habitats, with no tillers surviving in the deeply shaded forest plots (average photosynthetically active radiation was 93% lower in forest than in open field plots) in the second growing season.Conclusions. Our results demonstrate that the emergence, persistence, and spread of plant invaders can be driven by different abiotic and biotic factors in the recipient habitat. Furthermore, these results were generated by monitoring an experimental invasion process for longer than a single season, providing a realistic and robust evaluation of the drivers of invasive plant success and suggesting a general need for longer-term establishment studies in invasive plant ecology.

Abiotic and biotic factors influence the habitat use of four species of Gymnogobius (Gobiidae) in riverine estuaries in the Seto Inland Sea

Gobies that are phylogenetically related or coexist in the same marine and estuarine systems often exhibit abiotic and/or biotic habitat segregation. Thus, it is possible that species of Gymnogobius inhabiting the same riverine estuaries also exhibit abiotic and/or biotic habitat segregation. The goal of this study was to determine the differences in abiotic and biotic habitat use between these species by sampling goby and host shrimps, and by examining the physical environments of the rivers where these species are found. The surveys of goby and host shrimps were conducted in the estuaries of the Saba and Ibo rivers, which drain into the Seto Inland Sea, a body of water that separates three of the four main islands of Japan. We used hand nets and shovels to collect goby and host shrimps, and measured median sediment particle size, elevation, and salinity at each site. Generalized linear models (GLMs) were used to assess the preferences in abiotic and biotic habitat use by the goby species. Median particle size, salinity, and elevation were used as the abiotic environmental predictors, whereas the presence/absence of host shrimps were re-organized into four categories consisting of “Upogebia major” only, “Nihonotrypaea japonica” only, “Upogebia major & Nihonotrypaea japonica,” and “Upogebia yokoyai,” which were used as the biotic environmental predictors. The GLMs demonstrated that median particle size had the largest influence of the abiotic variables, with goby species segregating according to differences in sediments; moreover, there was some evidence suggesting that the host and symbiont do not always correlate at the species level. Our results indicated that although there is some overlap in abiotic and biotic habitat use among the four species of Gymnogobius, the differences were broad enough to provide an explanatory mechanism as to how these species can coexist in the same river systems.

River Bank Erosion and the Influence of Environmental Flow Management.

Environmental flows aim to influence river hydrology to provide appropriate physical conditions for ecological functioning within the restrictions of flow regulation. The hydrologic characteristics of flow events, however, may also lead to unintended morphologic effects in rivers, such as increases in riverbank erosion beyond natural rates. This may negatively impact habitat for biota, riparian infrastructure, and land use. Strategic environmental flow delivery linked to monitoring and adaptive management can help mitigate risks. We monitor riverbank condition (erosion and deposition) relative to environmental flows on the Goulburn River, Victoria, Australia. We describe the process of adaptive management aimed at reducing potential impacts of flow management on bank condition. Field measurements (erosion pins) quantify the hydrogeomorphic response of banks to the delivery of planned and natural flow events. Managed flows provide opportunities for monitoring riverbank response to flows, which in turn informs planning. The results demonstrate that environmental flows have little influence on bank erosion and visual perceptions in the absence of monitoring are an unreliable guide. This monitoring project represents a mutually beneficial, science-practice partnership demonstrating that a traditional 'know then do' approach can be foreshortened by close collaboration between researchers and managers. To do so requires transparent, often informal lines of communication. The benefits for researchers-a more strategic and targeted approach to monitoring activities; and benefits for the practitioners-reduced time between actions and understanding response; mean that a learn by doing approach is likely to have better outcomes for researchers, stakeholders, the public, and the environment.

Comparative Morphometric Analysis of the Smallscaled Scorpionfish, Scorpaena Porcus (Scorpaenidae, Scorpaeniformes), from the Southern Coast of the Crimea and Eastern Part of the Adriatic Sea

Abstract Comparative analysis of morphometric characters of small-scaled scorpionfish from the Black Sea (near the southern coast of the Crimea) and from the eastern part of the Adriatic Sea showed significant differences in males and females on thirteen plastic and three meristic characters. These differences may be due to unequal abiotic and biotic habitat conditions, and refer about the geographical variability of the species, indicating the presence of two different populations in the study area.

The ecology of anaerobic degraders of BTEX hydrocarbons in aquifers.

The degradation of benzene, toluene, ethylbenzene and xylene (BTEX) contaminants in groundwater relies largely on anaerobic processes. While the physiology and biochemistry of selected relevant microbes have been intensively studied, research has now started to take the generated knowledge back to the field, in order to trace the populations truly responsible for the anaerobic degradation of BTEX hydrocarbons in situ and to unravel their ecology in contaminated aquifers. Here, recent advances in our knowledge of the identity, diversity and ecology of microbes involved in these important ecosystem services are discussed. At several sites, distinct lineages within the Desulfobulbaceae, the Rhodocyclaceae and the Gram-positive Peptococcaceae have been shown to dominate the degradation of different BTEX hydrocarbons. Especially for the functional guild of anaerobic toluene degraders, specific molecular detection systems have been developed, allowing researchers to trace their diversity and distribution in contaminated aquifers. Their populations appear enriched in hot spots of biodegradation in situ. 13C-labelling experiments have revealed unexpected pathways of carbon sharing and obligate syntrophic interactions to be relevant in degradation. Together with feedback mechanisms between abiotic and biotic habitat components, this promotes an enhanced ecological perspective of the anaerobic degradation of BTEX hydrocarbons, as well as its incorporation into updated concepts for site monitoring and bioremediation.

Relationships between air pollution, population density, and lichen biodiversity in the Niagara Escarpment World Biosphere Reserve

AbstractThe fragmented ecosystems along the Niagara Escarpment World Biosphere Reserve provide important habitats for biota including lichens. Nonetheless, the Reserve is disturbed by dense human populations and associated air pollution. Here we investigated patterns of lichen diversity within urban and rural sites at three different locations (Niagara, Hamilton, and Owen Sound) along the Niagara Escarpment in Ontario, Canada. Our results indicate that both lichen species richness and community composition are negatively correlated with increasing human population density and air pollution. However, our quantitative analysis of community composition using canonical correspondence analysis (CCA) indicates that human population density and air pollution is more independent than might be assumed. The CCA analysis suggests that the strongest environmental gradient (CCA1) associated with lichen community composition includes regional pollution load and climatic variables; the second gradient (CCA2) is associated with local pollution load and human population density factors. These results increase the knowledge of lichen biodiversity for the Niagara Escarpment and urban and rural fragmented ecosystems as well as along gradients of human population density and air pollution; they suggest a differential influence of regional and local pollution loads and population density factors. This study provides baseline knowledge for further research and conservation initiatives along the Niagara Escarpment World Biosphere Reserve.

Glaciations, deciduous forests, water availability and current geographical patterns in the diversity of European Carabus species

AbstractAimCurrent climate, biotic habitat provision and historical events are known drivers of diversity patterns. However, these three factors are seldom evaluated together. Here, we study the influence of climate, the distribution of deciduous forests and Pleistocene climate changes on the species diversity of Carabus ground beetles in Europe.LocationContinental Europe.MethodsWe used geographically weighted regressions (GWR) to explore geographical variation in the relationship between species richness and current climate in a spatially explicit context. Further, we analysed simultaneously the network of relationships among current temperature, climatic variability since the Last Glacial Maximum (LGM) and the distribution of deciduous forests through structural equation models (SEM). Also, we assessed dissimilarity in the composition of European faunas by means of beta diversity metrics related with true spatial replacement and nestedness.ResultsWe find that Carabus richness patterns are, at least in part, influenced by water–energy dynamics. However, the effects of current climate are also shaped by Pleistocene glaciations, as water and energy variables change in importance at the southern limits of the ice sheet during the LGM. Accordingly, this border results in abrupt shifts in the relative importance of both (1) current and past climate correlates on Carabus richness, and (2) nestedness and true turnover on the compositional changes among their assemblages. Moreover, we also detect a direct effect of the geographical distribution of deciduous forests on Carabus species richness in both northern and southern regions.Main conclusionsOur results confirm that the processes shaping diversity patterns may depend on the history of particular regions. While Carabus richness seems to be largely driven by current climate in southern Europe, in the north it appears to be more affected by the imprint of past climates. Our findings also suggest that the areas of influence of Pleistocene glaciations may depend on the idiosyncratic characteristics of particular taxa.

Diversity surrogates for estuarine fish assemblages in a temperate estuary in New South Wales, Australia

The efficacy of fish diversity surrogates is central to their utility in conservation planning and management. Here we examine the linkages among a range of biotic and abiotic surrogates for estuarine fish diversity within the Port Stephens estuary in NSW, Australia. We examine the effectiveness of using biotic habitats as surrogates for diversity, and examine whether this surrogacy persists through time. The study was conducted using fish assemblage data gathered across eight a priori identified biotic habitat types. Significant differences in fish assemblages, species richness, and functional richness were detected among 26 out of 28 biotic habitats pairs, and these differences persisted for over 1 year within key Dendronephthya australis (soft coral) and filter feeder habitats, demonstrating the potential for biotic habitats to be used as surrogates for estuarine fish diversity. Significant correlations between abiotic variables (i.e. depth, location, substrate type, and substrate complexity) and fish assemblages were also established. Overall, the results demonstrate that both abiotic variables and biotic habitats can be used as surrogates for fish diversity in the study estuary, and combining both these types of predictor variables can provide a high level of discrimination among estuarine fish assemblages. The use of both abiotic variables and biotic habitats in conservation planning can, therefore, improve representation of estuarine fishes within marine protected areas.

Restoration rocks: integrating abiotic and biotic habitat restoration to conserve threatened species and reduce fire fuel load

With rapid urban expansion, biodiversity conservation and human asset protection often require different regimes for managing wildfire risk. We conducted a controlled, replicated experiment to optimise habitat restoration for the threatened Australian pink-tailed worm-lizard, Aprasia parapulchella while reducing fire fuel load in a rapidly developing urban area. We used dense addition of natural rock (30 % cover) and native grass revegetation (Themeda triandra and Poa sieberiana) to restore critical habitat elements. Combinations of fire and herbicide (Glyphosate) were used to reduce fuel load and invasive exotic species. Rock restoration combined with herbicide application met the widest range of restoration goals: it reduced fire fuel load, increased ant occurrence (the primary prey of A. parapulchella) in the short-term and increased the growth and survival of native grasses. Lizards colonised the restored habitat within a year of treatment. Our study documents an innovative way by which conflicts between biodiversity conservation and human asset protection can be overcome.

The vulnerability of Arctic shelf sediments to climate change

The sediments of the pan-Arctic shelves contribute an important component to the Arctic Ocean ecosystem by providing a habitat for biota (benthos), a repository for organic and inorganic non-conservative substances entering or produced within the ocean, a reactor and source of transformed substances back to the water column, and a mechanism of burial. Sediments interact with ice, ocean, and the surrounding land over a wide range of space and time scales. We discuss the vulnerability of shelf sediment to changes in (i) organic carbon sources, (ii) pathways of sediment and organic carbon supply, and (iii) physical and biogeochemical alteration (diagenesis). Sedimentary environments of the shelves and basins are likely to exhibit a wide variance in their response to global change because of their wide variation in sediment sources, processes, and metabolic conditions. In particular, the Chukchi and Barents shelves are dominated by inflowing waters from oceans to the south, whereas the interior shelves are more closely tied to terrigenous sources due to river inflow and coastal erosion.

Macroinvertebrate responses to regime shifts caused by eutrophication in subtropical shallow lakes

The ecological status of subtropical floodplain lakes is threatened by eutrophication, which can shift lakes from a clear, macrophyte-dominated equilibrium state to a turbid, phytoplankton-dominated state. Such a shift is reflected in their macroinvertebrate assemblages, which may serve as good indicators of long-term changes in such lake ecosystems. We conducted a survey of benthic macroinvertebrates in 20 lakes in the Yangtze floodplain that were disconnected from the river channel to identify invertebrate response patterns along a gradient of eutrophication. Macroinvertebrate assemblages changed in parallel to the observed regime shift of a subgroup of those lakes. The most abundant groups were epiphytic invertebrates (e.g., Bithyniidae) in the macrophyte-dominated lakes and pollution-tolerant invertebrates (e.g., Tubificidae, Tanypus) in the phytoplankton-dominated lakes. Planktonic chlorophyll a concentration and wet biomass of submersed macrophytes were the key factors structuring macroinvertebrate assemblages. Macroinvertebrate taxon richness decreased along the eutrophication gradient, but density reached a minimum at a moderate eutrophication level and then increased. Scraper density (e.g., Bithyniidae) dropped abruptly at the moderate eutrophication level and did not increase again, whereas collector–gatherers (mainly Tubificidae and Chironomidae) and predators (e.g., Tanypus) increased continuously along the eutrophication gradient. We conclude that the abrupt disappearance of macrophytes during the regime shift means the loss of key habitat for biota associated with aquatic plants. Therefore, ecological restoration projects should be designed to reduce the nutrient concentration of floodplain lakes enough to allow re-establishment of a clear-water lake equilibrium dominated by aquatic macrophytes.

Contemporary connectivity is sustained by wind- and current-driven seed dispersal among seagrass meadows.

BackgroundSeagrasses are clonal marine plants that form important biotic habitats in many tropical and temperate coastal ecosystems. While there is a reasonable understanding of the dynamics of asexual (vegetative) growth in seagrasses, sexual reproduction and the dispersal pathways of the seeds remain poorly studied. Here we address the potential for a predominantly clonal seagrass, P. australis, to disperse over long distances by movement of floating fruit via wind and surface currents within the coastal waters of Perth, Western Australia. We first simulated the dominant atmospheric and ocean forcing conditions that are known to disperse these seagrass seeds using a three-dimensional numerical ocean circulation model. Field observations obtained at 8 sites across the study area were used to validate the model performance over ~2 months in summer when buoyant P. australis fruit are released into the water column. P. australis fruit dispersal trajectories were then quantified throughout the region by incorporating key physical properties of the fruit within the transport model. The time taken for the floating fruit to release their seed (dehiscence) was incorporated into the model based on laboratory measurements, and was used to predict the settlement probability distributions across the model domain.ResultsThe results revealed that high rates of local and regional demographic connectivity among P. australis meadows are achieved via contemporary seed dispersal. Dispersal of seeds via floating fruit has the potential to regularly connect meadows at distances of 10s of kilometres (50% of seeds produced) and infrequently for meadows at distances 100 s km (3% of seeds produced).ConclusionsThe spatial patterns of seed dispersal were heavily influenced by atmospheric and oceanographic conditions, which generally drove a northward pattern of connectivity on a regional scale, but with geographical barriers influencing finer-scale connectivity pathways at some locations. Such levels of seed dispersal infer greater levels of ecological and genetic connectivity and suggest that seagrasses are not just strongly clonal.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-015-0034-9) contains supplementary material, which is available to authorized users.

Ecological impacts of invasive alien species along temperature gradients: testing the role of environmental matching.

Invasive alien species (IAS) can cause substantive ecological impacts, and the role of temperature in mediating these impacts may become increasingly significant in a changing climate. Habitat conditions and physiological optima offer predictive information for IAS impacts in novel environments. Here, using meta-analysis and laboratory experiments, we tested the hypothesis that the impacts of IAS in the field are inversely correlated with the difference in their ambient and optimal temperatures. A meta-analysis of 29 studies of consumptive impacts of IAS in inland waters revealed that the impacts of fishes and crustaceans are higher at temperatures that more closely match their thermal growth optima. In particular, the maximum impact potential was constrained by increased differences between ambient and optimal temperatures, as indicated by the steeper slope of a quantile regression on the upper 25th percentile of impact data compared to that of a weighted linear regression on all data with measured variances. We complemented this study with an experimental analysis of the functional response (the relationship between predation rate and prey supply) of two invasive predators (freshwater mysid shrimp, Hemimysis anomala and Mysis diluviana) across. relevant temperature gradients; both of these species have previously been found to exert strong community-level impacts that are corroborated by their functional responses to different prey items. The functional response experiments showed that maximum feeding rates of H. anomala and M. diluviana have distinct peaks near their respective thermal optima. Although variation in impacts may be caused by numerous abiotic or biotic habitat characteristics, both our analyses point to temperature as a key mediator of IAS impact levels in inland waters and suggest that IAS management should prioritize habitats in the invaded range that more closely match the thermal optima of targeted invaders.

Habitat associations and behavioural patterns of Symphodus spp. (Pisces: Labridae)

The complexity and diversity of physical and biotic habitats are important features influencing the composition of shallow water reef fish assemblages, especially in temperate regions where abundant and diverse algal cover may have an important habitat-forming role. Coastal fish have adapted to these diverse habitats and to the temporal and spatial variations of algal assemblages in different ways. Wrasses are an important group of coastal rocky reef fish which present particular associations to algae in temperate systems. In this study, habitat associations were analysed in three species of wrasses: Symphodus bailloni, Symphodus melops and Symphodus roissali, and their behaviour was recorded. Eight main behavioural categories (comprising a total of 42 different behaviours) were identified: exploring, foraging, resting, agonistic interactions, cleaning, courtship, reproduction and nesting. S. melops occurred on shallower depths and was frequently involved in both intra- and interspecific agonistic interactions with the other wrasse species, although rarely with S. bailloni. S. roissali was associated with microhabitats of smaller size where it frequently hides. Feeding occurred mostly on bedrock habitat when compared to other microhabitats. Foraging and resting showed a marked seasonality in the three wrasses, related to shifts in biotic habitat structure and to changes in the behavioural repertoire during the breeding season.

The effects of topographic variation and the fire regime on coarse woody debris: Insights from a large wildfire

Coarse woody debris (CWD) is a common structural component of terrestrial ecosystems, and provides important habitat for biota. Fires modify the distribution of CWD, both spatially and temporally. Changes in fire regimes, such as those arising from prescribed burning and changing climatic conditions, make it critical to understand the response of this resource to fire. We created a conceptual model of the effects of fire on logs and dead trees in topographically diverse forests in which trees often survive severe fire. We then surveyed paired sites, in a damp gully and adjacent drier slope, ∼3.5years after a large wildfire in south-eastern Australia. Sites were stratified by fire severity (unburnt, understorey burnt and severely burnt), and fire history (burnt ⩽3years or ⩾20years prior to the wildfire). Both components of the fire regime influenced CWD availability in gullies. Severe wildfire and fire history ⩽3years reduced the volume of small logs (10–30cm diameter) in gullies, while severe wildfire increased the number of large dead trees in gullies. CWD on slopes was not affected by fire severity or history at ∼3.5years post-fire. Log volumes on slopes may recover more quickly after wildfire through rapid collapse of branches and trees. Gullies generally supported more logs than slopes, but longer inter-fire intervals in gullies may allow fuel loads to accumulate and lead to comparatively larger fire impacts. Given that fire severity and fire interval are predicted to change in many fire-prone ecosystems in coming decades, this study highlights the importance of understanding the interacting effects of multiple components of the fire regime with landscape structure. In particular, variation in fire interval and fire severity in relation to topographic position will influence the pattern of accumulation of coarse woody debris across the landscape, and therefore the structure and quality of habitats for biota.

Linking the land and the lake: a fish habitat classification for the nearshore zone of Lake Ontario

AbstractThe nearshore zones of the Great Lakes provide essential habitat for biota and are perhaps the region of the lakes most susceptible to human impacts. The objective of our study was to develop a fish habitat classification for the nearshore zone of Lake Ontario based on physical characteristics of that zone, land cover in the surrounding watershed, and fish community patterns. Nearly 80% of the spatial variation in fish community data was described by 2 physical variables (average fetch and bathymetric slope of the nearshore zone) and 2 land-cover variables (urban/industrial development and mixed forest cover) in adjacent watersheds. These variables are likely to be surrogates for other conditions in the nearshore, such as wave action, circulation, vegetation, and water quality. A 12-group fish habitat classification was developed from those variables. Validation and significance tests identified similarities and differences among the fish communities in the classes and indicated that the number of...

Evidence for two subspecies of Gunnison’s prairie dogs (Cynomys gunnisoni), and the general importance of the subspecies concept

Accurate taxonomy is essential for conservation, but subspecies-level systematics can be hampered both by a lack of consensus on what constitutes a subspecies and by discordance among data types (e.g., genetics vs. morphology). Here we provide a framework for evaluating subspecies using multidimensional criteria, and suggest that taxa must satisfy multiple criteria to qualify as subspecies. As a case study, we use the Gunnison’s prairie dog (Cynomys gunnisoni), a species for which there has been disagreement regarding the existence of subspecies due to inconsistent application of criteria for defining subspecies. To explicitly test the hypothesis that two subspecies exist, we generated five predictions that could be evaluated with genetic data, while also using morphological and ecological criteria. We sampled 838 Gunnison’s prairie dogs from across the species range and performed a series of genetic analyses using 16 microsatellite and two mitochondrial loci (cytochrome b and the control region). We compared subspecies morphology and quantitatively evaluated whether abiotic and biotic habitat characteristics encountered by each subspecies differed. Genetic results from all five predictions supported the existence of two distinct subspecies within the confines of a proposed revision in the boundary between subspecies. The subspecies differed marginally in morphology and significantly in their habitats, suggesting ecological differentiation. Our results, which are in line with historical descriptions of morphologically distinct subspecies, suggest the subspecies should be recognized. This work provides support for the utility of integrating multiple data and analysis types to inform systematics and conservation.

Typification of vessel-induced waves and their interaction with different bank types, including management implications for river restoration projects

Restoration projects often aim to initiate side erosion processes in order to improve the ecological situation, leading to banks of gentle slopes which positively affect biotic habitats. However, within navigable reaches such measures have to be planned under consideration of the impact of vessel-generated waves on YOY-fish. Hence an extensive study was conducted at different bank types to analyze and describe waves, induced by passing vessels. A high resolution wave gauge was exposed, to obtain wave data of different vessel types over a broad discharge range. Simultaneously vessel passage was recorded using an automatic identification system. Attributed to the ships, different wave types could be distinguished and their specific parameters (e.g., wave height) were described. Additionally we analyzed by which of these parameters wave height is primarily affected. For passenger ships a speed reduction of 5 km h−1 results in a reduction of wave height of 14 cm at the Danube. A morphological analysis was accomplished to identify habitat loss and shift of the water’s edge based on ship induced maximum drawdown. Habitat loss, expressed as retrogression of the water’s edge, ranged between 0.88 and 35 m for the highest drawdown recorded.

Floodplain connectivity facilitates significant export of zooplankton to the main River Murray channel during a flood event

This study assessed the role that floods play in providing lateral connectivity between riverine habitats and floodplains, stimulating productivity and contributing zooplankton from the floodplain to the river channel. The study took place on the Chowilla Floodplain of the River Murray, Australia, and the adjacent River Murray Channel throughout the 2010–2011 floods. We found that a considerable transfer of zooplankton from the floodplain into the river channel occurred. Average zooplankton abundance was higher on the floodplain than the main river channel and increased the zooplankton abundance in the river channel downstream. At the peak of the flood, flows reached ~93 000 megalitres per day (ML d−1), inundating ~67 km2 of floodplain. At the time of this study, up to 6.3 ± 1.6 (SD) tonnes per day of zooplankton (dryweight) was being exported from the Chowilla floodplain. Differences in species assemblages were also observed within the River Murray, which seemed to be caused by the influence of the Chowilla Floodplain. This study demonstrated that floodplains provide significant zooplankton biomass, which constitutes a resource input into the riverine food web. These results provide some evidence for the Flood Pulse Concept, which highlights the importance of lateral hydrological connectivity between riverine habitats and floodplains in stimulating productivity and providing a linkage between habitats for biota. Management of regulated lowland rivers should consider not only the provision of water to the floodplain, but also the return of the floodplain waters to the river to sustain riverine food webs .