Macroinvertebrate richness is lower in high-elevation lakes vs nearby streams: evidence from Grand Teton National Park,Wyoming

Mountain ecosystems will be strongly impacted by climate change, yet little is known of extant biodiversity in high-elevation lakes, particularly in North America. In this study, we sampled the littoral zone of six alpine and subalpine lakes in Grand Teton National Park (GRTE), Wyoming, to characterise invertebrate diversity and environmental variation in these climate change-threatened ecosystems. Overall, we collected 19 aquatic invertebrate taxa, and found that each lake harboured a unique assemblage of invertebrates despite close geographic proximity in some instances (e.g. less than 5 km). The results of this study complement previous efforts focused on macroinvertebrate diversity of streams in the Teton Range, highlighting much lower diversity in montane lakes vs nearby streams. Taken together, the two studies establish an important baseline understanding of mountain freshwater biodiversity in GRTE. With rapidly changing hydrologic inputs to mountain lakes driven primarily by the recession of alpine glaciers, these results may help target aquatic invertebrates to monitor as climate change affects the region. Moreover, these data clarify habitat factors, both biotic and abiotic, that influence high-elevation lake assemblages of the Teton Range.     

A comparison of riparian condition and aquatic invertebrate community indices in central Nevada

The importance of maintaining healthy riparian communities to sustain natural stream processes and function is well documented. Land management agencies in the West are currently developing methods to assess and monitor riparian community condition to adapt land use practices that would better protect rangeland ecosystems. To determine whether these methods also provide an indication of abiotic and biotic stream condition, we compared the classification system of riparian communities developed by the U.S. Forest Service (USFS) to physical parameters of stream condition and to aquatic invertebrate community assemblages. Thirty-three sites in 19 different streams of the Toiyabe Range in central Nevada were measured for water quality, substrate characteristics, and fish abundance and diversity. We sampled aquatic invertebrates and calculated community indices based on environmental tolerance levels, taxonomic diversity, and abundance of sensitive taxa. USFS personnel classified these sites by dominant riparian plant community type (meadow, willow, or aspen) and ecological status (low, moderate, or high) using plant abundance data, rooting depth, and soil infiltration to determine similarities to potential natural communities. Riparian condition indices as well as community diversity were significantly correlated to proportions of fine and small-diameter substrate in streambeds. Accumulation of silt was significantly related to plant community type, with meadow sites expressing highest proportions. Further examinations indicated that 2 of 6 invertebrate community indices were significantly related to ecological status, with highest diversity levels occurring mainly in willow- and aspen-dominated sites in moderate ecological condition. Nevertheless, we show that several other environmental variables, including substrate characteristics, dissolved oxygen, water temperature, and species richness of fish communities, were more strongly and consistently related to invertebrate assemblage patterns. Our results demonstrate that information on aquatic invertebrates and stream condition could augment the existing riparian classification system and provide useful monitoring tools to more thoroughly examine ecosystem health in rangelands.     

Freshwater macroinvertebrates of Lord Howe Island

Studies on freshwater invertebrate fauna on islands are rare but a few suggest species richness can be high. A survey of the freshwater invertebrates of Lord Howe Island (LHI) yielded 38 taxa, bringing the total recorded from LHI to 54. The majority of the taxa from the survey were from the Insecta, with 15 Diptera (true flies), five hemipterans (true bugs) and five trichopterans (caddisflies). Two species of gastropods, three mites and eight other arthropods were also found. The total number of taxa on LHI, although smaller than other islands, is the highest per unit area ever recorded (3.9 taxa per km²). High levels of endemism were recorded for most taxonomic groups and two previously undescribed chironomid species were found. However, further taxonomic and genetic work is necessary in order to assess true levels of endemism by investigating the genetic similarities and differences of these taxa with nearby islands.     

Exclusion experiments with backwater invertebrate communities of the Green River, Utah

The role of biotic interactions in structuring freshwater invertebrate communities has been extensively studied but with mixed results. For example, fish effects on invertebrates are most pronounced in pelagic and soft-sediment benthic habitats that lack structural complexity, yet appear insignificant in benthic rubble habitats. Backwaters of the Green River, Utah, are shallow, structurally simple, quiet-water embayments adjacent to the river. These habitats form in middle to late summer and are colonized by benthic and epibenthic invertebrates that produce standing crops significantly higher than the river. Backwaters are also utilized by a large number of fish species. We used cages to determine if selective exclusion of backwater organisms could significantly change invertebrate community structure. Results showed that backwater invertebrate community components changed significantly in response to exclusion treatments. Two taxa (both predators), the chironomid genus Tanypus (Diptera: Chironomidae) and the corixid genus Trichocorixa (Hemiptera: Corixidae), increased in density in exclusion cages while cladocerans, immature copepods, the cyclopoid copepod Eucyclops speratus , and the chironomid genus Procladius all decreased in density. Diversity of adult copepods was reduced by exclusion treatments, though density of only a single species changed significantly.     

Annotated inventory of invertebrate populations of an alpine lake and stream chain in Colorado

Benthic macroinvertebrates were collected during the ice-free season (1 July-20 October) over a five-year period from a chain of alpine lakes and intervening streams in the Green Lakes Valley (3,347-3,615 m) in Boulder County, Colorado. A list of taxa was developed for 1981 and 1982, with taxonomic additions for 1983- 1985 and comments on community structure, seasonal and elevational changes in species abundance, and noteworthy occurrences. A total of 111 taxa was collected, of which 84% occurred in streams, 58% being exclusively lotic. Dipterans composed 73-81% of total abundance in streams. The littoral benthic zone of lakes was predominantly trichopterans and dipterans, 44-60% and 24-39%, respectively. Numerically important organisms in various lakes and streams were chironomids, simuliids (particularly Metacnephia ), oligochaetes, and the bivalve Pisidium casertanum . An isolated lake and its outlet stream, with unique characteristics, were the sole locations of Gammarus lacustris (Amphipoda) and Glossiphonia complanata (Hirudinea). Manipulated lowering of a lake along the main drainage exposed abundant and luxuriant colonies of the bryozoan Fredericella sultana . This organism was found on 43% of all rocks sampled, a preponderance heretofore unknown for this, or any, ectoproct in alpine or arctic lakes.     

Trichoptera and other macroinvertebrates in springs of the Great Basin: species composition, richness, and distribution

Detailed surveys of aquatic invertebrates in 28 springs along the western border of the Great Basin were made using pan traps, emergence traps, black lights, and benthic sampling devices from 1994 to 1998. Although all macroinvertebrate groups were collected, caddisflies (Insecta: Trichoptera) were sampled most intensively. Fifty-eight species of caddisflies were collected from the 28 springs, with up to 18 species from a single spring. Although several springs had very similar physicochemical characteristics, none had identical trichopteran species composition. Using Wards minimum variance clustering technique, and with all macroinvertebrates identified to the lowest possible level, we found 3 taxa assemblages. These assemblages occurred in springs with the following physical conditions: (1) warm water (15.9° C), low elevation (1794 m); (2) cold water (8.5° C), mid-elevation (2334 m); and (3) cold water (6.6° C), high elevation (1794 m). Although the warm water group had a distinct assemblage of invertebrates (amphipods, gastropods, Trichoptera), distinct assemblages did not separate the 2 cold water groups. Discriminant analysis indicated that temperature, conductivity, alkalinity, and elevation were most responsible for discriminating group 1 from groups 2 and 3; temperature and elevation distinguished the latter 2 groups. Spring permanence, lack of disturbance, and cold water temperatures were the factors most responsible for explaining higher species richness of Trichoptera.     

Species composition and habitat associations of benthic algal assemblages in headwater streams of the Sierra Nevada, California

Despite their trophic importance and potential importance as bioindicators of stream condition, benthic algae have not been well studied in California. In particular there are few studies from small streams in the Sierra Nevada. The objective of this study was to determine the standing crop of chlorophyll- a and benthic algal species assemblages present in the small 1st- and 2nd-order streams of the Kings River Experimental Watersheds (KREW, watersheds of Bull, Providence, Duff, and Teakettle Creeks) and determine the associations of these measures with stream habitat. We collected samples of benthic algae from rock substrata in September 2002 (7 sites) and 2005 (the same 7 sites plus 5 additional sites). Habitat and water-quality data were collected concurrently. Chlorophyll- a values ranged from 0.2 to 3.2 mg ? m –2 . Chlorophyll- a in the Bull Creek watershed was generally lower than in the other watersheds. Benthic algal assemblages were dominated by diatoms and cyanobacteria. We collected 79 taxa of diatoms in 2002 and 126 taxa in 2005. Diatom taxa richness in individual samples ranged from 15 to 47. Nonmetric multidimensional scaling analysis of arcsine square-root transformed proportional abundances of diatoms identified 3 groups of sites. Bull Creek sites were generally different from other sites (group 1), and the sites from Bull Creek were different in 2002 (group 2) and 2005 (group 3). Five taxa appeared to be particularly important in distinguishing groups: Achnanthidium minutissimum , Cocconeis placentula , Eunotia incise , Eunotia pectinalis var. minor , and Planothidium lanceolatum . Elevation, water temperature, pH, specific conductance, and canopy were habitat variables correlated with the differences in diatom assemblages among sites. Our results provide a valuable baseline for future studies of benthic algae in Sierra Nevada headwater streams and will be particularly important in understanding the effects of different forest restoration management strategies being tested in the KREW project.     

Present effects of past wildfires on leaf litter breakdown in stream ecosystems

We investigated the present effects from a 10-year-old wildfire on leaf litter breakdown rates in 3 headwater streams in central Idaho. These systems experienced a massive debris flow one year after the fire. Based on soil instability and burn patterns, we identified 3 stream conditions: unburned, burned only, and burned/scoured. We placed leaf bags containing willow leaves ( Salix sp.) in each stream type and removed bags at various time intervals until all bags were collected 100 days after their introduction. Leaf material was dried and weighed, and decay rate coefficients were calculated. Macroinvertebrates colonizing the bags were enumerated and identified, and selected taxa were placed into trophic groups. We found that the unburned stream had the fastest leaf litter breakdown rate, the lowest level of incident light reaching the stream, and the largest amount of benthic organic matter. The burned/scoured stream was nearly opposite in all respects. Numbers of 2 detritivore invertebrate taxa, Serratella tibialis and Zapada oregonensis, were highest in the unburned stream but lowest in the burned/scoured stream. A third taxon, Baetis sp., showed the opposite relationship. Presence of predatory invertebrates did not affect detritivore abundance or leaf decay rate in the bags. Our research suggests that recovery response variables of some stream systems may not have returned to prefire levels even a decade after the initial wildfire. In this study, the recovery of our streams appears to be connected to the return of the riparian zone, though fire-induced debris flows may slow or alter final recovery of the stream system.     

Invertebrate fauna of wastewater ponds in southeastern Idaho

Water column invertebrates were sampled with 3.8-L activity traps in 15 sewage, industrial, and radioactive wastewater ponds at the Idaho National Engineering Laboratory in southeastern Idaho. One collection was made per pond, per month, during all months the ponds were ice-free from June 1990 through July 1991. Arsenic, barium, boron, lead, selenium, and mercury were detected in ponds. Sewage ponds generally had higher nitrogen and phosphorus levels than industrial and radioactive ponds. Of the 30 aquatic invertebrate taxa collected, the most ubiquitous were Rotifera, Daphnidea, Eucopepdoa, Ostracoda, Acari, Baetidae, Corixidae, Notonectidiae, Dytiscidae, and Chironomidae. Activity trap samples from sewage ponds contained more Rotifere, Daphnidae, and Notonectide, whereas industrial ponds yielded more Chydoridae, Acari, and Baetidae. Numbers of Oligochaeta, Eucopepoda, Ostracoda, Corixidae, Dytiscidae, and Chironomidae collected were not significantly different between sewage and industrial ponds. Compared with natural systems, these ponds had fewer taxa, but a greater number of individuals of most taxa. The high number of invertebrates collected is attributed to the lack of fish in wastewater ponds and the high levels of nitrogen and phosphorus, particularly in sewage ponds.     

Macroinvertebrate community structure and related environmental variables in two forks of the Virgin River, Utah

Using multivariate analysis techniques, we analyzed variation in the structure of the benthic macroinvertebrate community in the North Fork and East Fork of the Virgin River in and above Zion National Park in concert with a number of naturally occurring and anthropogenic environmental variables. Correspondence analysis revealed that the community structure in the 2 streams was markedly different despite occurring in areas similar in topography, elevation, and terrestrial vegetation cover. Subsequent analyses of the 2 streams separately using canonical correspondence analysis to test for strength of association of environmental variables with variations in benthic macroinvertebrate community structure revealed that communities in the East Fork of the Virgin River were more associated with nitrogen-related variables influenced by agricultural and urban activities along the river and that communities in the North Fork were most strongly associated with naturally occurring physical variables.     

Aquatic invertebrate fauna of a northern prairie stream: range extensions and water quality characteristics

The benthic macroinvertebrate fauna of southern Saskatchewan, Canada, has received little attention relative to other regions of western North America. Therefore, little is known of the related aquatic ecosystem health and biogeography of regional aquatic insects. Here we present the results of an aquatic macroinvertebrate survey for the Pipestone Creek watershed in southeastern Saskatchewan. We qualitatively sampled aquatic macroinvertebrates in 5 sites on 4 dates through spring, summer, and fall 2006. Sampling produced 294 taxa of macroinvertebrates including 25 provincial range extensions to the southeast corner of the province. Presence/absence data of taxa grouped the sites into lentic and lotic sites. However, the relative proportions of the taxa varied greatly among sites, with no 2 sites having a community similarity greater than 50%. Functional feeding group analyses separated the sites into collector-dominated and scraper/grazer-dominated sites. However, the taxonomic make-up of the feeding groups varied among sites and also among dates. A modified Hilsenhoff Biotic Index of the site communities indicated that all were influenced by organic pollution. Results of this study suggest that although the watershed is enormously diverse, its biological communities are likely influenced by organic pollution. Further, range expansions of species found here, such as the stonefly Perlesta placida , have implications for invasion pathways and post-glaciation species islands in a prairie landscape.     

Large, wetland-associated mayflies (Ephemeroptera) of Glacier National Park, Montana

We describe species richness and habitat associations of mayflies (Ephemeroptera) collected during amphibian surveys of 355 water bodies in Glacier National Park (NP), Montana, in 2006–2008. We collected 9 taxa (in 7 genera) of mayflies that were identifiable to species. Callibaetis ferrugineus hageni was collected most frequently, followed by Siphlonurus occidentalis, S. phyllis, Ameletus celer, A. similior, Parameletus columbiae, Ephemerella dorothea infrequens, Baetis bicaudatus, and Leptophlebia cupida. Siphlonurus phyllis had not been reported in the western United States prior to our surveys, and P. columbiae is a species of concern in the region. The identifications of 4 additional taxa were uncertain due to the poor condition of specimens found at only one site ( Centroptilum sp. and Paraleptophlebia sp.) or because nymphal specimens could not be confidently identified ( Cinygma sp. and Cinygmula sp.). Species richness of mayflies in wetlands seems low compared to that in streams and lakes in Glacier National Park. We found the most species of mayflies in beaver ponds, where we detected some species not commonly associated with lentic water bodies. Our survey was the first extensive survey of wetland invertebrates in Glacier NP and only the second that we are aware of in western Montana.     

Assessing high compositional differences of beetle assemblages across vertical woodland strata in the New Forest,Hampshire, England

Closed-canopy woodlands are complex ecosystems with strong vertical environmental stratification. The degree to which this vertical stratification has led to compartmentalisation in invertebrate assemblages in temperate woodlands has been researched to a limited extent, yet there are still gaps in our understanding. Here, we used five different sampling methods to sample beetles across vertical strata of nine woodland sites in the New Forest National Park, Hampshire, England. The sampling methods yielded 2412 individuals across 157 species, of which 46 were significant indicator species for one stratum or a combination of strata. Multivariate analysis of composition showed a strong separation at a subfamily level between strata, with many only found in a single stratum. This suggests a strongly compartmentalised vertical stratification of the beetle assemblages at both species and higher taxonomic levels. Our results display that multiple strata need to be sampled to obtain true estimates of overall beetle species richness in woodlands and forests. Limitations in using a single sampling method and biases using mixed sampling method protocols across a vertical transect are also discussed.     

Species-environment relationships among filter-feeding caddisflies (Trichoptera: Hydropsychidae) in Rocky Mountain streams

Species-environment relationships were determined for filter-feeding macroinvertebrates from 55 Rocky Mountain stream sites to establish species distribution patterns. Species abundance and 20 environmental variables were measured at each site with species-environment relationship determined using canonical correspondence analysis and stepwise multiple regression. Results suggest that the distribution of several taxa was strongly related to upstream-downstream environmental gradients. Arctopsyche grandis abundance increased with stream size (width and depth) and decreased with increasing turbulence (Reynolds number). Brachycentrus abundance also increased with stream size (depth). Hydropsyche abundance increased with increasing baseflow. Parapsyche elsis abundance also increased with stream size (depth). Hydropsyche abundance increased with increasing baseflow. Parapsyche elsis abundance demonstrated negative correlation with depth, Froude number, and conductivity. Taxa followed previously reported patterns, partitioning habitat according to stream size. Arctopsyche grandis , Brachycentrus , and Hydropsyche were found in larger (3rd- to 6th order) streams, while Parapsyche elsis was observed in small headwater (1st- and 2nd- order) streams. Other filter-feeding taxa such as Simulium, Pisidium and ostracods exhibited little or no apparent habitat partitioning among stream sites.     

Dynamics of ostracod populations from shallow lakes of Patagonia: life history insights

Wetlands are one of the most valuable natural resources, providing a number of ecosystem services and socio-economic values. Small ponds sustain a rich aquatic biodiversity and because of their short hydrological regimen and small size are excellent environments for population studies of microcrustaceans such as ostracods. This study describes the population dynamics of the Ostracoda fauna in three temporary shallow lakes during one hydroperiod in Argentine Patagonia. Three cosmopolitan species were determined: Cypris pubera, Tonnacypris lutaria and Eucypris virens. Among them, T. lutaria is here reported for the first time from the Neotropical region. Multivariate ordination techniques were used to examine the relationships among environmental variables and ostracod density on each sampling site. High values of conductivity, absorption at 320 nm (as a measure of dissolved organic matter), dissolved oxygen concentration, temperature and chlorophyll a concentration correlated positively with ostracod density. All the populations studied reproduced parthenogenetically, and the life cycles of E.virens and C. pubera were followed in detail by weekly sampling of their populations. The former displayed continuous reproduction, whereas the latter showed a multivoltine strategy. The life history of C. pubera was affected by the seasonality of the habitat. The development rate correlated positively with water temperature; conductivity and temperature had a positive effect on adult size in C. pubera, while conductivity had a negative effect on adult size in E. virens. In this study, we present the first data set on the development and life history of ostracods in Patagonian freshwater environments. However, several questions remain and encourage us to further investigate the relative importance of ostracods in food webs, as well as the importance of inter-specific interactions between ostracods and other taxa.     

Freshwater invertebrates of subantarctic South Georgia

Twenty‐one lakes, ten pools, seven coastal pools, three streams, two seal wallows, a penguin wallow, and three flooded moss carpets on South Georgia were sampled for aquatic invertebrates. More than 100 invertebrate species were found comprising 59 species of Rotifera, 29 Arthropoda (including five Anomopoda, three Calanoida, two Harpacticoida, three Ostracoda, 12 Acarina and four Insecta) and at least 22 other invertebrate species (including four Platyhelminthes, three Gastrotricha, six Tardigrada, six Nematoda, and two species of Annelida). The fauna of South Georgia, although similar to that of the other Scotia Arc Islands, particularly Signy Island, is much richer by virtue of its lower latitude and milder climate.     

Winter macroinvertebrate communities in two montane Wyoming streams

Macroinvertebrate communities were examined on 4 winter dates over a 4-yr period in 2 high-altitude Rocky Mountain streams to document overwintering assemblages potentially experiencing spring acid pulses. Taxa richness values were comparable to other published lists for alpine and montane stream systems despite the fact that most literature reflected summer collections. Mean benthic density ranged from 1406 to 19,734 organisms/m 2 , and drift rates ranged from 0 to 1740 organisms/100 m 3 . Benthic collections showed higher taxa richness than drift collections while the Ephemeroptera and Plecoptera occurred in greater proportions in drift than in benthos. The Nemouridae (Plecoptera), Ephemerellidae and Heptageniidae (Ephemeroptera), Chironomidae (Diptera), and Hydracarina were the numerically dominant taxa in benthic collections. Grazer/scrapers and shredder/detritivores were always the numerically dominant functional feeding groups at all sites, composing 60-90% of the benthos. Predators, constituting approximately 15% of the community, occurred in the same relative proportion at all sites on all dates. Winter macroinvertebrate communities in these low-order, montane streams exhibit high taxonomic richness and benthic densities as great as lower-elevation mountain streams in the West.     

The marine green and brown algae of Rodrigues (Mauritius,Indian Ocean)

The marine benthic green and brown macroalgae of Rodrigues, collected during an expedition in October 2001, are documented and 18 of the 60 taxa of Chlorophyta (53 species) and 18 species of Phaeophyceae are illustrated. Fifty taxa of green and 12 taxa of brown algae are added to the existing species list of the island. Turf algae and smaller epiphytic species are not or are only sporadically included in this study. All records are listed with bibliographic, biogeographic, taxonomic and nomenclatural comments. Infrageneric identification keys are included. The new combination Caulerpa mexicana var. exposita is proposed and the discovery of a new Udotea species is mentioned. The algal flora of Rodrigues is of a typical Indian Ocean composition but appears to be relatively poor when compared to the nearby island of Mauritius.     

Short-term effects of wildfire on montane stream ecosystems in the southern Rocky Mountains: one and two years post-burn

The frequency and intensity of wildfire in the western United States has increased over the last century, creating a heterogeneous mosaic of landscapes in various stages of recovery. The 2002 Hayman Fire was one of the largest wildfires in Colorado history and was unprecedented for its speed and intensity, with over 50%–70% of the burn area classified as moderate to high severity where much of the canopy crown was consumed. We evaluated the short-term impact of the Hayman Fire on ecological properties in montane stream ecosystems in the summers of 2003 and 2004, one and two years post-fire. Fire significantly altered surface temperature, dissolved oxygen concentration, and the chemical composition of stream water, including concentrations of nitrate, phosphate, and mineral salts. However, fire did not have significant impacts on stream conductivity, pH, or total concentrations of cations or anions during our study period. Streams in the burn area contained fewer benthic macroinvertebrate taxa compared to unburned streams during the year after fire and contained lower invertebrate densities and biomass compared to reference streams 2 years post-fire. Average C:N ratio of the benthic macroinvertebrate community was significantly and negatively related to stream nitrate concentration, possibly due to a shift in community composition or invertebrate nitrogen acquisition in fire-affected streams.     

Temporal dynamics of invertebrate and aquatic plant communities at three intermittent ponds in livestock grazed Patagonian wetlands

Ponds are recognized worldwide as biodiversity hotspots; nevertheless in Patagonia studies are still needed that reveal the composition and status of their communities. This paper analyses the temporal patterns of aquatic invertebrates and assesses the environmental factors that best predict the variation in community structure at three small intermittent ponds, subjected to ranching practices (summer stocking) in the Patagonian steppe. Variables identified as important in structuring community assemblages were related to environmental conditions (rainfall and water temperature), chemical features (conductivity and pH) and biotic factors (macrophyte coverage). During the connected phase only a small number of invertebrate species were present, in contrast to the 11 taxa that were frequent and abundant during the isolated period (Eucyclops chilensis, Hyalella curvispina and Rhionaeschna sp. were dominant). In this sequence the submersed Myriophyllum quitense and Lilaeopsis macloviana played a crucial role offering habitat and food resources. The present study provides valuable information that can contribute to minimizing the environmental damage and the development of strategies for the conservation of Patagonian wetlands.