The influence of habitat structure and flow permanence on invertebrate communities in karst spring systems

The macroinvertebrate fauna of five karst (limestone) springbrook systems with contrasting physical habitat and discharge patterns were investigated to examine the role of flow permanence and habitat structure on macroinvertebrate community composition. Clear physical differences were identified between perennial and intermittent springs and individual sampling stations. However, flow permanence, water temperature and the input of leaf litter exerted a greater influence on the aquatic invertebrate community than habitat structure. Perennial sites were characterised by a greater abundance of macroinvertebrates and greater Ephemeroptera, Plecoptera and Trichoptera (EPT) richness than intermittent sites. The fauna of all of the springbrook systems examined were dominated by relatively common and ubiquitous taxa (e.g. Gammarus pulex) although a number of taxa displaying life cycle adaptations to ephemeral aquatic habitats (e.g. Limnephilus auricula and Stenophylax permistus) were recorded at intermittent sites.     

Invertebrate fauna of ephemeral streams on Hauturu-o-Toi/Little Barrier Island in northern New Zealand

ABSTRACT

The invertebrate fauna of five ephemeral forest streams on Hauturu-o-Toi/Little Barrier Island in northern New Zealand was assessed in January 2014. Low summer flows restricted benthic sampling largely to pools that would, during periods of ‘normal’ flow, be main-channel riffle/run habitat. Additionally, adult stages of aquatic insects were sampled by light trapping. Fifty-three aquatic species/morphospecies were recorded during the study, including 25 new records, bringing total island species richness to 65. The fauna was dominated by Ephemeroptera and Trichoptera; species richness of Plecoptera and Diptera was low, and only single species of Mollusca and Crustacea were recorded. Species found were either common with broad New Zealand distributions, or species restricted to the North Island. No species was endemic to the island. Faunal comparisons with adjacent mainland streams indicated the island had similar assemblages of core taxa, but generally lower species richness, likely resulting from physiographic differences found there.     

How wide to cast the net? Cross‐taxon congruence of species richness,community similarity and indicator taxa in ponds

1. Broad‐scale assessments of biodiversity often rely on the use of surrogate taxa, whose reliability has rarely been tested, particularly in freshwater systems. Here we use data from 46 ponds in two regions of the U.K. to explore the performance of macroinvertebrate taxa as surrogates for the rapid assessment of pond biodiversity. For the four dominant taxonomic groups in these ponds (Chironomidae, Coleoptera, Gastropoda and Trichoptera) we explore cross‐taxon species richness relationships in each of the two regions, and also determine the degree of concordance between the different taxa in accurately representing the similarity relationships between pond assemblages. 2. Patterns of cross‐taxon congruence in species richness were highly variable among taxa and study sites, making the use of a single taxon as a predictor of overall macroinvertebrate species richness problematic. In contrast, all four taxa show >70% congruence with the pattern of community similarity between sites resulting from the entire macroinvertebrate dataset, this result being consistent within and between regions. Canonical correspondence analysis demonstrated that all taxa were related in a similar manner to measured environmental parameters, meaning that limited additional ecological information is gained by including a wider range of pond taxa in rapid site assessment. 3. Single taxonomic groups can, therefore, perform consistently as indicators of community similarity between ponds, and no one taxon dramatically outperforms any other in this respect. The relative merits of the four focal taxa as surrogates for pond invertebrate assemblage composition are discussed with reference to ease of survey, ease of identification and ecological range occupied. 4. It is suggested that Coleoptera have a number of advantages as a surrogate taxon, being diverse, easily sampled, readily identified, taxonomically stable, ecologically well understood and occurring across a wide spectrum of pond types. They are therefore recommended for use as a focal group in rapid pond biodiversity assessments, employing an approach such as ours, which examines patterns of assemblage similarity, rather than species richness alone.     

Macroinvertebrate–habitat relationships in the River Teifi catchment and the significance to conservation

SUMMARY. 1. A macroinvertebrale survey of various habitats (e.g. riffles, pools, tree roots) at sixteen sites in the Teifi catchment in September 1981 yielded 217 taxa excluding Hydracarina and Chironomidae.
2. Sites with the greatest number of habitats were generally rich in taxa and supported the highest number of 'rare' species, the latter generally being associated with vegetation. However, species were not generally restricted to particular habitats although ecdyonurid mayflies predominated in riffles and one leptocerid caddisfly was principally collected from tree roots.
3. Four groups of taxa which characterized three habitat groups were established using classification procedures and it was concluded that three habitat types (eroding, depositing and vegetation) should be sampled to describe adequately the macroinvertebrate fauna at each site.
4. Three attributes (species richness, species rarity and site uniqueness) were used to establish the conservational value of each site; in general, the main river and one lowland tributary were of highest conservational significance.
5. Multiple regression analyses were used to establish significant relationships between the three attributes and environmental features such as number of habitats, altitude, river width, pH and total hardness. Such relationships may facilitate a rapid assessment of resource value without expensive biological survey.     

Effects of fish predation and habitat type on stream benthic communities

The influence of habitat on interactions between a fish predator (brown trout Salmo trutta) and a benthic invertebrate community was studied in nine field enclosures (8 ×3 m) in a creek in southern Sweden. Three habitat treatments were tested, a shallow sandy habitat, a deep habitat containing a mixture of large and small cobbles and a moderately deep habitat with large cobbles. The one month-long experiment showed that there were no major differences in the abundance and biomass of the benthic macroinvertebrate fauna among these habitats as no functional groups of invertebrates and only a few taxa differed between treatments. Invertebrate drift rates decreased over time, which was probably related to seasonal changes in invertebrate life cycles or to effects of predation independent of habitat type, as there was no difference between treatments.     

Invertebrate community patterns in Mediterranean temporary wetlands along hydroperiod and salinity gradients

1. Temporary aquatic habitats often are inhabited by a unique fauna and flora and contribute significantly to regional diversity. Temporary wetlands around the world are disappearing rapidly. The individual and interacting impacts of factors influencing community structure and dynamics in temporary wetlands are not always well known.
2. Camargue wetlands are mainly characterized by variable salinity and hydroperiod. The individual and combined impacts of these local factors, together with regional variables, on invertebrate communities remain unknown. We therefore characterized and sampled invertebrates in 30 temporary wetlands along salinity and hydroperiod gradients in the Camargue (Southern France) 3, 5 and 7 months after inundation.
3. Over the three sampling occasions, a total of 17 cladoceran species and 49 macroinvertebrate taxa were identified. Hydroperiod and salinity were the most important variables explaining variation in taxonomic composition and can be considered key factors shaping the invertebrate communities in Camargue wetlands. The impact on taxon richness was significantly positive for hydroperiod but significantly negative for salinity. Regional factors had no significant effect on the structure of the studied invertebrate communities, suggesting that dispersal was not limiting and that species sorting was the most important structuring process.
4. The results of this study suggest that the combined and interacting effects of salinization and hydrological modification of Mediterranean temporary wetlands (due to water management, climate change, etc.) can result in reduced diversity in large numbers of Mediterranean wetlands and induce a considerable decline in regional diversity of aquatic invertebrates.     

Scale-specific correlations between habitat heterogeneity and soil fauna diversity along a landscape structure gradient

Habitat heterogeneity contributes to the maintenance of diversity, but the extent that landscape-scale rather than local-scale heterogeneity influences the diversity of soil invertebrates—species with small range sizes—is less clear. Using a Scottish habitat heterogeneity gradient we correlated Collembola and lumbricid worm species richness and abundance with different elements (forest cover, habitat richness and patchiness) and qualities (plant species richness, soil variables) of habitat heterogeneity, at landscape (1 km²) and local (up to 200 m²) scales. Soil fauna assemblages showed considerable turnover in species composition along this habitat heterogeneity gradient. Soil fauna species richness and turnover was greatest in landscapes that were a mosaic of habitats. Soil fauna diversity was hump-shaped along a gradient of forest cover, peaking where there was a mixture of forest and open habitats in the landscape. Landscape-scale habitat richness was positively correlated with lumbricid diversity, while Collembola and lumbricid abundances were negatively and positively related to landscape spatial patchiness. Furthermore, soil fauna diversity was positively correlated with plant diversity, which in turn peaked in the sites that were a mosaic of forest and open habitat patches. There was less evidence that local-scale habitat variables (habitat richness, tree cover, plant species richness, litter cover, soil pH, depth of organic horizon) affected soil fauna diversity: Collembola diversity was independent of all these measures, while lumbricid diversity positively and negatively correlated with vascular plant species richness and tree canopy density. Landscape-scale habitat heterogeneity affects soil diversity regardless of taxon, while the influence of habitat heterogeneity at local scales is dependent on taxon identity, and hence ecological traits, e.g. body size. Landscape-scale habitat heterogeneity by providing different niches and refuges, together with passive dispersal and population patch dynamics, positively contributes to soil faunal diversity. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Using macroinvertebrate species assemblages to identify river channel habitat units: an application of the functional habitats concept to a large,unpolluted Italian river (River Ticino,northern Italy)

The functional habitat concept was applied to a large Italian river for the first time. The characteristically wide range of hydraulic conditions present in this river (compared to previously-studied small, lowland, English rivers) were expected to be of central importance to biota and, therefore, to habitat definition. TWINSPAN analysis of the invertebrate assemblages sampled in the Ticino river identified five distinct habitats: two habitats in lotic areas (run-riffle and macrophytes in current), two along the river margins (with and without macrophytes) and one in backwater areas. These correspond to five of the functional habitats identified in U.K. lowland rivers. Each of these five functional habitats could be defined either in terms of hydraulics, substratum and/or presence/absence of macrophytes. Representative taxa are presented for each habitat and community structure discussed. Macrophyte and run-riffle habitats supported the most heterogeneous and abundant benthic fauna. No match was found between replicates grouped by invertebrate assemblage (the five functional habitats identified by TWINSPAN) and the grouping of the same replicates by PCA, carried out on the physical data matrix. While obvious velocity differences were found between the functional habitats, of particular note was the fact that the Froude number did not show any clear association with habitat type. In the future, improved river management will follow improved understanding of river habitats.     

Urban ponds as an aquatic biodiversity resource in modified landscapes

Urbanization is a global process contributing to the loss and fragmentation of natural habitats. Many studies have focused on the biological response of terrestrial taxa and habitats to urbanization. However, little is known regarding the consequences of urbanization on freshwater habitats, especially small lentic systems. In this study, we examined aquatic macro‐invertebrate diversity (family and species level) and variation in community composition between 240 urban and 782 nonurban ponds distributed across the United Kingdom. Contrary to predictions, urban ponds supported similar numbers of invertebrate species and families compared to nonurban ponds. Similar gamma diversity was found between the two groups at both family and species taxonomic levels. The biological communities of urban ponds were markedly different to those of nonurban ponds, and the variability in urban pond community composition was greater than that in nonurban ponds, contrary to previous work showing homogenization of communities in urban areas. Positive spatial autocorrelation was recorded for urban and nonurban ponds at 0–50 km (distance between pond study sites) and negative spatial autocorrelation was observed at 100–150 km and was stronger in urban ponds in both cases. Ponds do not follow the same ecological patterns as terrestrial and lotic habitats (reduced taxonomic richness) in urban environments; in contrast, they support high taxonomic richness and contribute significantly to regional faunal diversity. Individual cities are complex structural mosaics which evolve over long periods of time and are managed in diverse ways. This facilitates the development of a wide range of environmental conditions and habitat niches in urban ponds which can promote greater heterogeneity between pond communities at larger scales. Ponds provide an opportunity for managers and environmental regulators to conserve and enhance freshwater biodiversity in urbanized landscapes whilst also facilitating key ecosystem services including storm water storage and water treatment.     

The effect of habitat-specific sampling on biological assessment of water quality using a predictive model

1. Detection of impairment in macroinvertebrate communities using rapid biological assessment depends on the ability to compare sites, with confidence that differences obtained result from water quality. However, collections from more than one habitat type may introduce variation that can potentially mask water quality differences among sites. Data were collected from the riffle, edge, pool-rock and macrophyte habitats at reference (minimally disturbed) and test (disturbed) stream sites throughout the Australian Capital Territory. The effect of habitat-specific sampling on predictive models for detecting impairment in macroinvertebrate communities was determined. Four models were used: riffle only, edge only, each habitat as an individual object, and all habitats sampled at a site considered as a composite sample. 2. Macroinvertebrates from individual habitats generally clustered into separate groups because collections from the same habitat at different sites were more similar than collections from different habitats within a site. Thus, in the habitats as individual objects model, the taxa predicted to occur at a test site may be an indication of habitat type rather than water quality. The outputs of the composite habitats and riffle and edge models were similar. However, the variable number of habitats included at each site in the composite model may confound the detection of biological impairment because of unequal sampling effort. The riffle and edge models were the most robust because they were less confounded by inter-habitat variation and were based on comparisons made between equivalent environmental units. 3. Comparison of observed/expected taxa ratios for test sites showed that each model could detect biological impairment, indicating considerable data redundancy was introduced by sampling several habitats. In particular, the pool-rock and macrophyte habitats contributed no information with regard to macroinvertebrate taxon occurrence or detection of biological impairment that could not be obtained from either the riffle or edge habitats within the study area.     

Macroinvertebrate communities in Phragmites australis (Cav.) Trin. ex Steud. reed beds and open bank habitats in central victorian streams in Australia

Reed invasion is a common phenomenon of open streams with disturbed riparian vegetation in river catchments. Knowledge of the effects of such vegetation change on aquatic communities is fundamental to river management. Macroinvertebrate fauna in Phragmites australis (Cav.) Trin. ex Steud. and open bank habitats were examined in three rivers in central Victoria in order to understand the effect of such littoral habitat on macroinvertebrates. Data were analysed using Partially Nested Factorial ANOVA with season, river and habitats as main effects. Habitat structure had a significant effect (p<0.05) on macroinvertebrate species richness, however this was not seasonally consistent across the three rivers. There was a significant increase (p<0.05) in macroinvertebrate taxa richness in Phragmites habitats during winter and spring seasons. Total abundance of taxa showed no consistent significant differences in the two habitats. Results of Canonical Analysis of Principle Coordinates indicated significant differences (p<0.05) in macroinvertebrate assemblages between Phragmites and bare bank habitats in all seasons. Habitat selection by taxa could be related to the microphysical environment of the habitats. This study suggests that reed beds create important littoral habitat structures which support diverse macroinvertebrate assemblages.     

Invertebrate diversity on

Despite the global importance of New Zealands invertebrates, relatively little is known about them and their relationships with plants and plant communities in native habitats. Invertebrate diversity was examined by beating randomly chosen shrubs of the species Olearia bullata (Asteraceae) and Coprosma propinqua(Rubiaceae). Invertebrate taxon richness was assessed initially using morphospecies, which were identified subsequently by expert taxonomists. Though the taxon richness of invertebrates recorded from O. bullata was not significantly higher than that on C. propinqua (except for the orders Diptera and Hemiptera), there was a clear indication that O. bullata hosts a higher diversity of invertebrates. Mean number of taxa per shrub for O. bullata was higher in all cases (except Coleoptera), and so was the maximum number of taxa per shrub. Overall, O. bullata yielded 115 invertebrate taxa compared with 93 for C. propinqua. Moreover, 50 invertebrate taxa were restricted to O. bullata compared with 28 for C. propinqua. Since at least ten species of Oleariaare threatened or uncommon, this could be cause for concern with respect to the maintenance of invertebrate diversity. Therefore, sites where Oleariaspecies are still present are likely to be of significance for invertebrate conservation.     

The influence of habitat structure and flow permanence on macroinvertebrate assemblages in temporary rivers in northwestern Zimbabwe

Temporary rivers within the Nyaodza-Gachegache subcatchment in northwestern Zimbabwe were investigated to examine the role of flow permanence and habitat structure on macroinvertebrate community composition. Macroinvertebrate communities of intermittent and ephemeral rivers displayed significant differences in the number of taxa, macroinvertebrate abundance, Shannon and Simpson diversity indices and in size class structure. Intermittent sites were characterised by higher numbers of taxa, diversity and Ephemeroptera and Trichoptera richness compared to ephemeral sites. The fauna of ephemeral sites was dominated by a single taxon (Afrobaetodes) (Ephemeroptera, Baetidae) whilst larger sized taxa (e.g. Elassoneuria (Ephemeroptera, Oligoneuriidae), Dicentroptilum (Ephemeroptera, Baetidae), Aethaloptera (Trichoptera, Hydropsychidae), Pseudagrion (Odonata, Coenagrionidae) and Tholymis (Odonata, Libellulidae) were exclusively restricted to intermittent sites. Clear differences were observed between sand, gravel, cobble and vegetation habitats. Vegetation and cobbles supported distinct communities, with some taxa exclusively restricted either to vegetation (e.g. Pseudagrion, Leptocerina (Trichoptera, Leptoceridae), Cloeon (Ephemeroptera, Baetidae), Afronurus (Ephemeroptera, Heptageniidae) and Povilla (Ephemeroptera, Polymitarcidae) or cobble (e.g. Aethaloptera and Dicentroptilum) habitats. In terms of ensuring optimum diversity within the subcatchment, we consider conservation of critical habitats (cobbles and vegetation) and maintenance of natural flows as the appropriate management actions. Handling editor: D. Dudgeon     

Aquatic invertebrates in final void water bodies at an open-cut coal mine in central Queensland

Abstract  We describe the diversity of aquatic invertebrates colonising water-filled final voids produced by an open-cut coal mine near Moura, central Queensland. Ten disused pits that had been filled with water from <1 year to 22 years prior to the survey and three nearby 'natural' water bodies were sampled in December 1998 and again in March 1999. All invertebrates collected were identified to family with the exception of oligochaetes, cladocerans, ostracods and copepods, which were identified to these coarser taxonomic levels. Sixty-two taxa were recorded from >20 000 individuals. The greatest familial richness was displayed by the Insecta (33 families) followed by the mites (Acari) with 12 families. While natural water bodies held the greatest diversity, several mine pits were almost as rich in families. Classification analyses showed that natural sites tended to cluster together, but the groupings did not clearly exclude pit sites. Mining pits that supported higher diversity tended to be older and had lower salinity (<2000 µS/cm); however, salinity in all water bodies varied with rainfall conditions. We conclude that ponds formed in final voids at this mine have the potential to provide habitat for many invertebrate taxa typical of lentic inland water bodies in central Queensland.     

Responses of benthic invertebrates in an experimental channel to artificial flushes

A large experimental channel was used to examine the responses of benthic invertebrate communities to artificial flushes. Two artificial flushes were done at a 20-day interval with a 2-fold difference in peak discharge and duration between them. The effects of the flushes on macroinvertebrates were monitored by comparing the abundance of individual taxa, taxon richness, diversity measures, and similarity indices. Taxon richness and abundances of invertebrates were drastically reduced by every flush. However, the diversity of invertebrates was not significantly reduced by the flushes, and the composition was similar before and after each flush. The fast recruitment of some taxa, having short life cycles, reduced the diversity of invertebrates in the interval between the two flushes. The flushes caused significant reductions in the abundance of epiphytes and fauna living in the streambed. The fauna more resistant to flushes were invertebrates that fasten their cases or retreats by silk threads to substrata. Taxa living in sediment under stones and having a sucking apparatus were also resistant to flushes. Handling editor: R. Bailey     

Short-term colonisation by macroinvertebrates of cobbles in main channel and inundated stream bank habitats

In small, forested catchments, short rainfall events cause relatively rapid increases in river discharge that inundate previously dry streamside habitats and last for several days. We examined the colonisation and use of such newly inundated habitats by macroinvertebrates in the riffles of a cobble-dominated river over a 4-day period. First we simulated inundation by adding dry river rocks to the main channel of the stream. Second, we observed colonisation of streamside rocks that were inundated following rainfall and subsequent natural spate. Macroinvertebrates colonised rocks in both habitats within 24 h, yet overall macroinvertebrate abundance did not change significantly over the subsequent 3 days. The abundances of common taxa were similar on mid-channel and stream bank rocks but each habitat contained a unique suite of uncommon taxa. Taxon richness was significantly greater on the stream bank rocks, which we attribute to the non-selective colonisation of fauna to avoid high flows in the main channel during the spate. Our study shows that fauna use the stream bank habitat as a haven from high flows in the main river channel, but the fate of the animals colonising this habitat is uncertain. Handling editor: D. Dudgeon     

Niche breadth of invertebrate shredders in tropical forest streams: which taxa have restricted habitat preferences?

Despite the importance of shredders in organic matter processing in streams, information about the habitat specificities of different taxa is scarce. Herein, we evaluated the habitat preferences of invertebrate shredders in tropical forest streams. A total of 72 leaf patches were sampled in three Atlantic Forest streams (SE Brazil). For each sample, 20 environmental variables were measured, including water properties and characteristics of the leaf patch. We used an Outlying Mean Index analysis to evaluate the niche breadth and overlap of each taxon found as well as habitat preferences. In total, we found 14 shredder taxa in 68 leaf patches, and the gradient of environmental conditions influenced the distribution of most taxa. Considering taxa that occurred in atypical habitats in the study sites, Blaberidae (semiaquatic cockroaches) and Trichodactylus fluviatilis (Decapoda) showed niche segregation, while Macrobrachium potiuna (Decapoda), Tupiperla (Plecoptera), and Nectopsyche (Trichoptera) showed niche overlap. On the other hand, Heterelmis (Coleoptera), Stenochironomus (Diptera), Phylloicus major, and Triplectides gracilis (Trichoptera) occurred in typical habitats. These results showed that shredder taxa had different habitat preferences. The observed differences in niche breadths and habitat specificities among taxa probably result in different leaf processing rates across leaf patches in Atlantic Forest streams.

     

Patterns of invertebrate biodiversity across a natural edge

Abstract Most ecologists are comfortable with the notion of habitats as recognizable entities and also with situations where the junction between two adjacent habitats forms a discrete edge. Such edges form naturally because of sharp changes in important edaphic, geomorphological, climatic or chemical properties to which plants, in particular, respond. Less clear is the effect of such edges on assemblages of mobile organisms, especially invertebrates that operate at relatively small spatial scales. The objective of the present study was to sample invertebrate composition across a natural edge between a well‐developed riparian habitat on fluvial sands and a saltbush habitat developed on a stony gibber plain in a semi‐arid region of New South Wales, Australia. A total of 150 pitfall traps on five 1‐km‐long transects that straddled the edge produced more than 13 000 adult specimens from 21 ordinal invertebrate taxa. A total of 10 446 beetle, ant, wasp, fly and springtail specimens were further sorted into 426 morphospecies. Comparisons and estimates of trends in abundance and richness were made, along with computation of multivariate dissimilarity and permutation statistics, to determine if the land system edge was coincident with changes in invertebrate abundance and composition. These analyses were unable to detect disjunctions in diversity coincident with the edge. The data suggest that many taxa are either present consistently in both habitats or are mostly found in one habitat but ‘leak’ several hundred metres across into the other. Few taxa were unique to either habitat. The result is that assemblage composition for invertebrates changes gradually over distances of up to 400 m either side of the edge and that the distance to a recognizable change in composition is taxon dependent. Even sharp habitat edges, as defined by discrete changes in soils and plants, are not edges but broad transition zones for many invertebrate taxa. There are several implications of these results, especially for landscape ecology.     

Patchiness of River–Groundwater Interactions within Two Floodplain Landscapes and Diversity of Aquatic Invertebrate Communities

In fluvial systems, the interactions between rivers and groundwater significantly affect various ecological structures (for example, riparian vegetation) and functions. To examine the effects of hydrological exchange between groundwater and surface water on the distribution of aquatic invertebrates within a riverine landscape, we investigated the main stem, tributaries, and various surface and subsurface waters of two floodplains of a southern Alpine river (Brenno, Switzerland) in terms of their physicochemical, hydraulic, substratum, and faunal characteristics. The origins of the water were investigated by analyzing geomorphic settings and physicochemical variables. The two floodplains had different hydrological regimes. The middle floodplain was dominated by lateral inputs and exfiltration of hillslope groundwater from two different subcatchments. Bank filtration of river water sustained subsurface water only close to the channel. The aquatic habitats of the middle floodplain formed a rather homogeneous group with high taxon richness and intrahabitat diversities. These aquatic habitats resembled mountain springbrooks in their physicochemical characteristics and faunal compositions. In the lower floodplain, the exchange between river water and groundwater was more extensive. The aquatic floodplain habitats of the lower floodplain were fed mainly by deep and shallow alluvial groundwater, hyporheic exfiltration, and partly by surface water. In contrast to aquatic habitats of the middle floodplain, habitats of the lower floodplain showed a low intrahabitat and a high interhabitat diversity in terms of both substrate characteristics and faunal compositions. For both floodplains, ordination analyses showed a high concordance between the structure of the invertebrate community and the characteristics of the environmental habitat, including chemical, geomorphic, and hydraulic variables. Ordinations grouped aquatic habitats according to the origins of the waters. Taxon richness was related to local structural diversity, but species turnover was related to differential vertical and lateral connectivity. Exfiltration of groundwaters provided aquatic floodplain habitats for several specialized species. The results of this study show the significance of the river–groundwater connectivity for the creation of the habitat mosaic that sustains biodiversity in floodplains and thus have important implications for managing the ecological integrity of floodplains.     

When humans work like beavers: riparian restoration enhances invertebrate gamma diversity and habitat heterogeneity

Restoration has the potential to increase habitat heterogeneity through the creation of unique habitat patches that, in turn, increase regional species richness or gamma diversity. While biological diversity and habitat heterogeneity are important factors to consider under a shifting climate, restoration actions and outcomes rarely examine these components. In this study, we examined the effects of riparian beaver dam analog (BDA) restoration on aquatic invertebrate diversity and habitat heterogeneity. Although the effects of BDAs on hydrology, geomorphology, and salmonid habitat have been explored, we are unaware of any studies assessing their effects on aquatic invertebrate diversity and the food web that supports them. We sampled aquatic invertebrates, basal carbon resources, dissolved nutrients, turbidity, and water temperature in pre- and post-BDA pond, side channel, and mainstem habitat over a three-year period. The BDAs functioned similarly to natural beaver dams and created slow-water environments that accumulated fine particulate organic material and increased pelagic phytoplankton production. Nonmetric multidimensional scaling, permutation multivariate analysis of variance, and Mantel's tests demonstrated that these changes led to the formation of a unique invertebrate community populated by lentic macroinvertebrates and zooplankton, which increased beta-diversity and gamma diversity. Further, BDAs in our study maintained high densities of invertebrates and buffered water temperatures in comparison to adjacent lotic habitats. These results support our hypothesis that BDAs can enhance invertebrate beta and gamma diversity through the creation and colonization of unique pond habitat and improve habitat and resource heterogeneity for native fishes under variable climate conditions.