The diversity of life in headwater streams (intermittent, first and second order) contributes to the biodiversity of a river system and its riparian network. Small streams differ widely in physical, chemical, and biotic attributes, thus providing habitats for a range of unique species. Headwater species include permanent residents as well as migrants that travel to headwaters at particular seasons or life stages. Movement by migrants links headwaters with downstream and terrestrial ecosystems, as do exports such as emerging and drifting insects.

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The contribution of headwater streams to biodiversity in river networks

Great Plains streams are highly endangered and can serve as model systems for studying disturbance ecology and related issues of resistance and resilience in temperate freshwaters. These streams exist in a precarious balance between flood and drying. In general, microbial activity recovers in days to weeks after drying or flooding, and invertebrate and fish species are quick to follow. In lower forested reaches, floods may be more intense but drying less common. Upstream reaches of prairie streams are characterized by frequent drying, little canopy cover, and limited leaf input. Life history and adaptations alter the ways in which stream organisms respond to these linear patterns. Human modification has altered these patterns, leading to large-scale loss of native grassland streams. The future for Great Plains streams is bleak, given the land-use changes and water-use patterns in the region and the large areas required to preserve intact, ecologically functional watersheds.

https://www.k-state.edu/doddslab/journalarts/dodds%20et%20al%20bioscience%202004.pdf

Life on the Edge: The Ecology of Great Plains Prairie Streams

The American Fisheries Society Endangered Species Committee herein provides a list of all crayfishes (families Astacidae and Cambaridae) in the United States and Canada that includes common names; state and provincial distributions; a comprehensive review of the conservation status of all taxa; and references on biology, conservation, and distribution. The list includes 363 native crayfishes, of which 2 (⟨ 1%) taxa are listed as Endangered, Possibly Extinct, 66 (18.2%) are Endangered, 52 (14.3%) are Threatened, 54 (14–9%) are Vulnerable, and 189 (52.1%) are Currently Stable. Limited natural range continues to be the primary factor responsible for the noted imperilment of crayfishes; other threats include the introduction of nonindigenous crayfishes and habitat alteration. While progress has been made in recognizing the plight of crayfishes, much work is still needed.

A Reassessment of the Conservation Status of Crayfishes of the United States and Canada after 10+ Years of Increased Awareness

A passive method for remote sensing of the nuisance green algae Cladophora glomerata in rivers is presented using an unmanned aerial vehicle (UAV). Included are methods for UAV operation, lens distortion correction, image georeferencing, and spectral analysis to support algal cover mapping. Eighteen aerial photography missions were conducted over the summer of 2013 using an off-the-shelf UAV and three-band, wide-angle, red, green, and blue (RGB) digital camera sensor. Images were post-processed, mosaicked, and georeferenced so automated classification and mapping could be completed. An adaptive cosine estimator (ACE) and spectral angle mapper (SAM) algorithm were used to complete the algal identification. Digital analysis of optical imagery correctly identified filamentous algae and background coverage 90% and 92% of the time, and tau coefficients were 0.82 and 0.84 for ACE and SAM, respectively. Thereafter, algal cover was characterized for a one-kilometer channel segment during each of the 18 UAV flights. Percent cover ranged from 50%, and increased immediately after vernal freshet, peaked in midsummer, and declined in the fall. Results indicate that optical remote sensing with UAV holds promise for completing spatially precise, and multi-temporal measurements of algae or submerged aquatic vegetation in shallow rivers with low turbidity and good optical transmission.

Remote Sensing of Submerged Aquatic Vegetation in a Shallow Non-Turbid River Using an Unmanned Aerial Vehicle

We evaluated the sampling efficacy of 1-m2 throw traps (active sampler) and baited minnow traps (passive sampler) across an experimental density gradient (1, 2, 4, 6, 8, 10, and 15/m2) of the slough crayfish (Procambarus fallax) in 2 trials with different crayfish populations. In both trials, throw-trap density estimates were highly correlated with actual crayfish density (r2 = 0.96). The form of the relationships between density estimates and stocked densities was consistent between trials, and indicated that throw traps captured a similar proportion of the stocked crayfish regardless of the stocked density. When we adjusted the relationships to account for clearing efficiency (proportion of captured animals actually recovered from the trap), the slopes of the regressions were not significantly different from 1 in either trial. Size distributions and sex ratios of crayfish collected by the throw traps accurately reflected those of the stocked populations. Baited minnow traps performed inconsisten...

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Evaluating active and passive sampling methods to quantify crayfish density in a freshwater wetland

Little is known regarding the impact of stream drying on community structure and habitat selection of lotic crayfish. Crayfish community structure was measured through quantitative sampling of riffle, run and pool habitats in 15 intermittent and 21 permanent streams in the Spring River watershed in the Ozark Plateau region of northern Arkansas and southern Missouri. MANOVA was used to determine whether stream permanence, habitat and crayfish size affect crayfish density and ANOVA was used to determine the effect of stream permanence and habitat type on species richness. Canonical Correspondence Analysis was used to determine the relationship between environmental variables and crayfish relative densities. Four crayfish species were collected: Orconectes marchandi, O. punctimanus, O. ozarkae and Cambarus hubbsi. Overall, crayfish densities were significantly greater in intermittent streams than in permanent streams with density of O. marchandi and O. punctimanus significantly greater in intermittent streams than in permanent streams. Densities of O. ozarkae and C. hubbsi did not differ significantly between the two stream types. Large individuals of O. punctimanus and O. ozarkae were found in significantly greater densities than small individuals. There was a significant relationship between crayfish relative density and abiotic environmental variables for permanent streams, but not for intermittent streams. In permanent streams, percent gravel, substrate diversity and mean current velocity were among the most important factors in determining crayfish density. Taxa mobility and predation risk are likely explanations for observed patterns of crayfish density.

Effects of Stream Permanence on Crayfish Community Structure

The Mammoth Spring crayfish (Orconectes marchandi) is listed as endangered by the American Fisheries Society's Endangered Species Committee and globally impaired by the Missouri Natural Heritage Database. Recorded at only three locations in the Spring River watershed (southern Missouri and northern Arkansas), little information exists on its range, associations with other crayfish and habitat selection. We sampled stream-dwelling crayfish with kicknets and quadrat samplers during spring-summer over 2 y in the Spring River drainage to determine distribution, relative density, habitat use, species associations, and life history characteristics of O. marchandi and other associated crayfish species. Nine crayfish species were collected in the Spring River watershed including a previously unrecorded invasive species, O. neglectus chaenodactylus, that appears to have replaced the native O. eupunctus from a portion of the watershed where it was previously abundant. The known distribution of O. marchandi...

Distribution, Habitat Use and Life History of Stream-dwelling Crayfish in the Spring River Drainage of Arkansas and Missouri with a Focus on the Imperiled Mammoth Spring Crayfish (Orconectes marchandi)

Rivers regulated by dams are typically characterized by altered biotic communities and habitat structure in downstream reaches. In the Jackson River (Alleghany Co., VA), a relatively constant flow regime below Gathright Dam and anthropogenic nutrient loading have apparently contributed to nuisance levels of periphyton (>300 mg chlorophyll a m−2). These nuisance growths cause low dissolved oxygen concentrations in the water column and altered benthic habitats in the Jackson River. The use of periodic pulsed flows has been suggested as a restoration practice that could potentially reduce periphyton biomass. We investigated the effects of increased flow on periphyton chlorophyll a (chl a), ash-free dry mass (AFDM), % organic matter (%OM) using streamside channels in which periphyton-colonized tiles were subjected to near-bed velocities ranging from 20 (control) to 240 cm s−1. Analysis of variance (ANOVA) and regression were used to examine periphyton responses to velocity treatments. There was a significant decrease in chl a and AFDM, and significant increase in %OM in velocity treatments of 150, 180 and 240 cm s−1 (p  100 cm s−1. Further study is needed to establish specific flow targets and evaluate the direct and indirect effects of pulsed flows on ecological conditions in the Jackson River. Copyright © 2009 John Wiley & Sons, Ltd.

Effects of pulsed flows on nuisance periphyton growths in rivers: a mesocosm study

Habitat selection by small (≤ 15.0 mm carapace length (CL)) and large (> 15.0 mm CL) individuals of the crayfish, Orconectes marchandi, O. ozarkae, O. punctimanus, and Cambarus hubbsi was examined at 4 sites in 2 streams in the Spring River watershed. Replicate quadrat samples were collected from riffle, run, pool, emergent vegetation, stream margin, and backwater habitats during the summers of 1998 and 1999. A 3-factor ANOVA was used to determine effects of habitat, species, and year on crayfish density for each site and stream. Habitat selection by crayfish was determined by comparing habitat used to habitat available for each species and size class. There were significant temporal differences in habitat used by some species-size classes of crayfish, but significant species by habitat interactions were detected at all sites for both crayfish size classes. Small O. ozarkae and O. punctimanus used mainly vegetated habitat, whereas both size classes of C. hubbsi used mainly riffles and runs. Large...

Habitat use and selection within ozark lotic crayfish assemblages: spatial and temporal variation

We conducted field surveys and experiments to determine whether observed distributions of crayfish among habitats were influenced by differential resource availability, foraging profitability, and predation rates and whether these factors differed with crayfish size and habitat depth. We sampled available food resources (detritus and invertebrates) and shelter as rock substrate in deep (>50 cm) and shallow (<30 cm) habitats. We used an enclosure–exclosure experiment to examine the effects of water depth and crayfish size on crayfish biomass and survival, and to determine whether these factors affected silt accrual, algal abundance (chlorophyll a [chl a]), and detritus and invertebrate biomass (g ash-free dry mass) differently from enclosures without crayfish. We conducted tethering experiments to assess predation on small (13–17 mm carapace length [CL]) and large (23–30 mm CL) Orconectes marchandi and to determine whether predation rates differed with water depth. Invertebrate biomass was signific...

https://www.jstor.org/stable/10.1899/06-103.1

C. A. Flinders

Papers

Effects of Stream Permanence on Crayfish Community Structure

Distribution, Habitat Use and Life History of Stream-dwelling Crayfish in the Spring River Drainage of Arkansas and Missouri with a Focus on the Imperiled Mammoth Spring Crayfish (Orconectes marchandi)

Effects of pulsed flows on nuisance periphyton growths in rivers: a mesocosm study

Habitat use and selection within ozark lotic crayfish assemblages: spatial and temporal variation

Effects of depth and crayfish size on predation risk and foraging profitability of a lotic crayfish