Km Of Stream Research Articles

Assessing stream bank condition using airborne LiDAR and high spatial resolution image data in temperate semirural areas in Victoria, Australia

Stream bank condition is an important physical form indicator for streams related to the environmental condition of riparian corridors. This research developed and applied an approach for mapping bank condition from airborne light detection and ranging (LiDAR) and high-spatial resolution optical image data in a temperate forest/woodland/urban environment. Field observations of bank condition were related to LiDAR and optical image-derived variables, including bank slope, plant projective cover, bank-full width, valley confinement, bank height, bank top crenulation, and ground vegetation cover. Image-based variables, showing correlation with the field measurements of stream bank condition, were used as input to a cumulative logistic regression model to estimate and map bank condition. The highest correlation was achieved between field-assessed bank condition and image-derived average bank slope (R2 1/4 0.60, n 1/4 41), ground vegetation cover (R2 1/4 0.43, n 1/4 41), bank width/height ratio (R2 1/4 0.41, n 1/4 41), and valley confinement (producer's accuracy 1/4 100%, n 1/4 9). Crossvalidation showed an average misclassification error of 0.95 from an ordinal scale from 0 to 4 using the developed model. This approach was developed to support the remotely sensed mapping of stream bank condition for 26,000 km of streams in Victoria, Australia, from 2010 to 2012.

A watershed-scale goals approach to assessing and funding wastewater infrastructure

Capital needs during the next twenty years for public wastewater treatment, piping, combined sewer overflow correction, and storm-water management are estimated to be approximately $300 billion for the USA. Financing these needs is a significant challenge, as Federal funding for the Clean Water Act has been reduced by 70% during the last twenty years. There is an urgent need for new approaches to assist states and other decision makers to prioritize wastewater maintenance and improvements. We present a methodology for performing an integrated quantitative watershed-scale goals assessment for sustaining wastewater infrastructure. We applied this methodology to ten watersheds of the Hudson-Mohawk basin in New York State, USA that together are home to more than 2.7 million people, cover 3.5 million hectares, and contain more than 36,000 km of streams. We assembled data on 183 POTWs treating approximately 1.5 million m3 of wastewater per day. For each watershed, we analyzed eight metrics: Growth Capacity, Capacity Density, Soil Suitability, Violations, Tributary Length Impacted, Tributary Capital Cost, Volume Capital Cost, and Population Capital Cost. These metrics were integrated into three goals for watershed-scale management: Tributary Protection, Urban Development, and Urban-Rural Integration. Our results demonstrate that the methodology can be implemented using widely available data, although some verification of data is required. Furthermore, we demonstrate substantial differences in character, need, and the appropriateness of different management strategies among the ten watersheds. These results suggest that it is feasible to perform watershed-scale goals assessment to augment existing approaches to wastewater infrastructure analysis and planning.

A Two‐Decade Watershed Approach to Stream Restoration Log Jam Design and Stream Recovery Monitoring: Finney Creek, Washington

AbstractA federal, state, and private partnership leveraged resources and employed a long‐term, systematic approach to improve aquatic habitat degraded by decades of intensive forest management in Finney Creek, a tributary to the Skagit River of Northwest Washington State. After more than a decade of work to reduce sediment sources and the risk of landslides within the watershed, log jam installation commenced in 1999 and progressed downstream through 2010. Log jam design was adapted as experience was gained. A total of 181 log jams, including 60 floating log ballasted jams, were constructed along 12 km of channel. The goal was to alter hydraulic processes that affect aquatic habitat formation along 39 km of stream with emphasis on 18.5 km of lower Finney Creek. Aquatic habitat surveys over a five‐year period show an increase in the area of large pools and an accompanying increase in residual and maximum pool depth in the lower river reach. Channel cross sections show a generally deeper channel at the log jams, better channel definition in the gravel deposits at the head of the log jams, and improved riffle and thalweg development below the log jams. Stream temperature in the upper river decreased by 1.0°F in the first three years, and 1.1°F in the lowest treated reach over nine years. There is a trend of less stream heating over the restoration time period. Photo points show that riparian vegetation is recolonizing gravel bars.

Eradication of Nonnative Brook Trout with Electrofishing and Antimycin‐A and the Response of a Remnant Bull Trout Population

AbstractA remnant population of native Bull Trout Salvelinus confluentus was threatened with extirpation by competition and hybridization with introduced Brook Trout S. fontinalis in Sun Creek, a second‐order headwater stream in Crater Lake National Park, Oregon. Between 1992 and 2005, artificial barriers were installed to exclude nonnative fish, and multiple applications of electrofishing and the piscicide antimycin‐A were used to remove Brook Trout from 14.6 km of stream. Several novel methods were employed, including diver‐directed and trap‐net electrofishing and the use of a portable raceway to hold Bull Trout during piscicide treatments. Electrofishing likely eradicated Brook Trout from a small headwater section of the stream but required more effort (54 person‐days/km) than antimycin treatments (17 person‐days/km) in the same reach to ensure eradication. For eradication of Brook Trout from larger downstream reaches, antimycin treatments applied in consecutive years were more successful than multiple treatments applied within a single year. Brook Trout have not been detected by annual surveys in the project area since 2005. The total effort expended to eradicate Brook Trout from 14.6 km of stream was approximately 138 person‐days/km. Between 1989 and 2010, Bull Trout abundance increased approximately tenfold, and distribution increased from approximately 1.9 km to 11.2 km. These results exemplify the response of an imperiled Bull Trout population after removal of Brook Trout. The large investment of time and resources required to restore small populations like this one may be warranted only for critical population segments with special status or local management importance.Received November 10, 2011; accepted October 31, 2012

Selection, implementation and cost of restorations in lowland streams: A basis for identifying restoration priorities

Abstract Restorations have been conducted in Danish lowland streams for almost 30 years to combat the poor physical conditions resulting from decades of channelisation, flood plain drainage and other impacts. Despite this effort, the recently drafted River Basin Management Plans show that physical improvements are still required in more than 7000 km of stream in order to comply with the Water Framework Directive. In this study we used published studies and expert knowledge to describe the restoration approaches most likely to achieve the environmental goals. In addition, we collected information about the economic costs of the different restoration approaches based on Danish experiences. For heavily impacted lowland streams (channelised and deeply incised streams) we described only two different restoration methods, both of which are relatively expensive. For lesser impacted streams (channelised but not deeply incised streams) we described six different options for improving ecological quality, varying significantly in cost. Our analysis showed that the cost may increase dramatically if several remedial actions are required or if land owners are entitled to large monetary compensations. Consequently, stream managers face an important challenge in the future prioritisation of restoration efforts aimed to obtain ecological improvements within tight budgets. The information presented in this paper can help the decision-making of managers.

Restoring native fish assemblages to a regulated California stream using the natural flow regime concept

We examined the response of fishes to establishment of a new flow regime in lower Putah Creek, a regulated stream in California, U.S.A. The new flow regime was designed to mimic the seasonal timing of natural increases and decreases in stream flow. We monitored fish assemblages annually at six sample sites distributed over approximately 30 km of stream for eight years before and nine years after the new flow regime was implemented. Our purpose was to determine whether more natural stream flow patterns would reestablish native fishes and reduce the abundances of alien (nonnative) fishes. At the onset of our study, native fishes were constrained to habitat immediately (<1 km) below the diversion dam, and alien species were numerically dominant at all downstream sample sites. Following implementation of the new flow regime, native fishes regained dominance across more than 20 km of lower Putah Creek. We propose that the expansion of native fishes was facilitated by creation of favorable spawning and rearing conditions (e.g., elevated springtime flows), cooler water temperatures, maintenance of lotic (flowing) conditions over the length of the creek, and displacement of alien species by naturally occurring high-discharge events. Importantly, restoration of native fishes was achieved by manipulating stream flows at biologically important times of the year and only required a small increase in the total volume of water delivered downstream (i.e., water that was not diverted for other uses) during most water years. Our results validate that natural flow regimes can be used to effectively manipulate and manage fish assemblages in regulated rivers.

Introduced alien ringed crayfish (Orconectes neglectus neglectus [Faxon, 1885]) threaten imperiled coldwater crayfish (Orconectes eupunctus Williams, 1952) in the Eleven Point River drainage, Missouri, USA

The Eleven Point River drainage in the Ozarks ecoregion of North America contains the largest known populations of and critical habitat for the globally imperiled coldwater crayfish (Orconectes eupunctus). We present here the discovery of an introduced population of alien ringed crayfish (Orconectes neglectus neglectus) in Jolliff Spring Branch in the upper reaches of the drainage. Sampling was conducted at eight sites throughout the tributary to determine the extent of the alien species’ range in the stream. Orconectes n. neglectus were found at four sites extending along 3.4 km of stream, with reproducing populations confirmed at two upstream sites, and few individuals found at two others. This invasion represents a threat to O. eupunctus, which occurs a few kilometers further downstream in the drainage and has been recorded from only the lower reaches of Barren Fork and throughout the mainstem Eleven Point River. Introduced O. neglectus were previously associated with localized extirpation of O. eupunctus in another drainage. Study results warrant monitoring of the invasion and possible reassessment of the conservation status for O. eupunctus.

Recent invasion and status of the raccoon (Procyon lotor) in Spain

In this study we present the results of a baseline study designed to assess the status of the raccoon (Procyon lotor) throughout Spain. The species was reported in 28 localities, mostly consisting of sporadic observations of single individuals. In central Spain an apparently thriving population of raccoons has been recently discovered. Our data confirmed the spread of feral raccoons throughout this region, where the species has already colonized about 100 km of streams and rivers. Predation on local fauna was also proved, and the first approximation for spatial movement and habitat use analyses in Spain is presented. Our results suggest that deliberate releases of raccoons by pet owners are an important cause for the existence of feral raccoons in Spain. Further research should focus on monitoring established individuals to collect detailed data on their population and reproductive parameters. Meanwhile, urgent actions should be taken to stop releases into the wild and to control and eradicate this unwelcome invasive species.

Counting Australia’s protected rivers

Summary Australia is committed to protecting its important and representative ecosystems. Foremost among protection measures is the network of terrestrial and marine protected areas that comprise the National Reserve System (NRS). However, these reserves were often established with little regard for the conservation needs of riverine ecosystems. There has been no conservation status assessment to determine whether riverine ecosystems are adequately protected within terrestrial reserves. This study begins this task by determining the extent of riverine protection through the NRS. Three classes of protection are defined based on the proportion of the catchment of each stream segment (the link between tributary confluences) that is contained within a protected area, and the presence of major in-stream barriers. The analysis reveals cause for concern. While nearly 225 000 km (7.6%) of the 2.9 million kilometres of streams assessed fall within a protected area of IUCN class I to IV where the principal objective is nature conservation, just 12 334 km of stream, less than half of one per cent of the total stream length, receives Class A protection, the strongest level of protection against threat. Class A is achieved where an entire drainage basin is contained within a protected area. Most of the protected stream length of the larger, named streams is potentially threatened by land-use activities occurring in unprotected headwaters or is fragmented by major dams and thus receives the lowest class of protection. Owing to a variety of pervasive threats, a more comprehensive conservation status assessment of these ecosystems would undoubtedly yield an even more pessimistic result. Such an assessment is recommended.

Assessing ecosystem vulnerability to invasive rusty crayfish (Orconectes rusticus)

Despite the widespread introduction of nonnative species and the heterogeneity of ecosystems in their sensitivity to ecological impacts, few studies have assessed ecosystem vulnerability to the entire invasion process, from arrival to establishment and impacts. Our study addresses this challenge by presenting a probabilistic, spatially explicit approach to predicting ecosystem vulnerability to species invasions. Using the freshwater-rich landscapes of Wisconsin, USA, we model invasive rusty crayfish (Orconectes rusticus) as a function of exposure risk (i.e., likelihood of introduction and establishment of O. rusticus based on a species distribution model) and the sensitivity of the recipient community (i.e., likelihood of impacts on native O. virilis and O. propinquus based on a retrospective analysis of population changes). Artificial neural networks predicted that approximately 10% of 4200 surveyed lakes (n = 388) and approximately 25% of mapped streams (23 523 km total length) are suitable for O. rusticus introduction and establishment. A comparison of repeated surveys before vs. post-1985 revealed that O. virilis was six times as likely and O. propinquus was twice as likely to be extirpated in streams invaded by O. rusticus, compared to streams that were not invaded. Similarly, O. virilis was extirpated in over three-quarters of lakes invaded by O. rusticus compared to half of the uninvaded lakes, whereas no difference was observed for O. propinquus. We identified 115 lakes (approximately 3% of lakes) and approximately 5000 km of streams (approximately 6% of streams) with a 25% chance of introduction, establishment, and extirpation by O. rusticus of either native congener. By identifying highly vulnerable ecosystems, our study offers an effective strategy for prioritizing on-the-ground management action and informing decisions about the most efficient allocation of resources. Moreover, our results provide the flexibility for stakeholders to identify priority sites for prevention efforts given a maximum level of acceptable risk or based on budgetary or time restrictions. To this end, we incorporate the model predictions into a new online mapping tool with the intention of closing the communication gap between academic research and stakeholders that requires information on the prospects of future invasions.

English

Abandoned underground mines in the Pittsburgh coalbed continue to be a source of pollution to over 48 km of streams in the Raccoon Creek watershed. Raccoon Creek watershed is located in Western Pennsylvania and drains 176,890 ha into the Ohio River. In 2006, an evaluation of selected discharges with conceptual treatment approaches was developed that included the ELF project, which had the potential to substantially eliminate AMD impacts to Burgetts Fork for 5.3 km to the confluence with Raccoon Creek. For simplicity, the acronym, ELF, is used to identify the discharge that would be created by consolidation of discharges from Erie Mine, Langeloth Mine, and Francis- Patterson Mine. This project addresses the initial physical feasibility of the ELF System by identifying if the opportunity exists to combine and relocate AMD from various locations in the Burgetts Fork sub-watershed by inter-mine pool transfer to a single discharge point for future reuse or treatment. To evaluate the degree of hydrologic interconnectedness of the mine workings, two tests were conducted. The tests indicate that there is no apparent impediment to flow within the Erie Mine and that the Erie Mine discharge can be successfully relocated by implementation of the ELF system. The tests also indicate that withdrawal from the Langeloth Mine Shaft with injection into the Erie Mine may substantially decrease the discharge from the Francis mine that flows through and out of the Patterson Mine. The physical feasibility of the ELF system to decrease or eliminate the flow from the Patterson Mine requires additional confirmation prior to implementation.

Effects on aquatic and human health due to large scale bioenergy crop expansion

In this study, the environmental impacts of large scale bioenergy crops were evaluated using the Soil and Water Assessment Tool (SWAT). Daily pesticide concentration data for a study area consisting of four large watersheds located in Michigan (totaling 53,358 km 2) was estimated over a six year period (2000–2005). Model outputs for atrazine, bromoxynil, glyphosate, metolachlor, pendimethalin, sethoxydim, triflualin, and 2,4-D model output were used to predict the possible long-term implications that large-scale bioenergy crop expansion may have on the bluegill ( Lepomis macrochirus) and humans. Threshold toxicity levels were obtained for the bluegill and for human consumption for all pesticides being evaluated through an extensive literature review. Model output was compared to each toxicity level for the suggested exposure time (96-hour for bluegill and 24-hour for humans). The results suggest that traditional intensive row crops such as canola, corn and sorghum may negatively impact aquatic life, and in most cases affect the safe drinking water availability. The continuous corn rotation, the most representative rotation for current agricultural practices for a starch-based ethanol economy, delivers the highest concentrations of glyphosate to the stream. In addition, continuous canola contributed to a concentration of 1.11 ppm of trifluralin, a highly toxic herbicide, which is 8.7 times the 96-hour ecotoxicity of bluegills and 21 times the safe drinking water level. Also during the period of study, continuous corn resulted in the impairment of 541,152 km of stream. However, there is promise with second-generation lignocellulosic bioenergy crops such as switchgrass, which resulted in a 171,667 km reduction in total stream length that exceeds the human threshold criteria, as compared to the base scenario. Results of this study may be useful in determining the suitability of bioenergy crop rotations and aid in decision making regarding the adaption of large-scale bioenergy cropping systems.

Long‐term population dynamics in a Mediterranean aquatic snake

AbstractA review of several long‐term studies has recently suggested that snakes might be declining in large parts of the world. Additional data from other long‐term studies are therefore urgently needed in order to assess the generalities of such suggested declines. Based on a 20‐year study, we analyzed demographic data on adult dice snakes (Natrix tessellata) studied in central Italy between 1985 and 2004. Both male and female dice snakes were relatively long‐lived, with no significant differences in longevity between the sexes. Individual males and females were observed over a maximum of 10 and 14 years, respectively. However, the among‐year recapture rates between the year the snakes were initially captured and the subsequent year (i.e., year 1 to year 2) was significantly lower (45%) than the among‐year recapture rates during subsequent years (74%; i.e., year 2 to year 3), suggesting that a large proportion of the snakes at first capture were in fact not resident within our study area, and hence many snakes were migrating in and out of our 2‐km stream study site, with no inter‐sexual difference in dispersal rates. Sex ratio was virtually equal if we consider the study period as a whole. Significant annual fluctuations were, however, observed through the study. In 1985–1990, 1993–1995, 1998 and 1999 the sex ratio was male‐biased, whereas in 2000–2004 female‐biased. In terms of both survival and recapture probabilities, model selection showed that Akaike's information criterion favored the model incorporating body size, with the model incorporating year having an intermediate likelihood, and the model with sex included being the most disfavored. Total population number estimates suggest an average 86 adult individuals along the 2 km of stream with only minor annual variations. However, a significant decrease in the number of males occurred during the last 6 years of our study. Thus, further monitoring of this population is warranted in light of the decline of snake populations reported recently.

Predicted effects of climate warming on the distribution of 50 stream fishes in Wisconsin, U.S.A.

Summer air and stream water temperatures are expected to rise in the state of Wisconsin, U.S.A., over the next 50 years. To assess potential climate warming effects on stream fishes, predictive models were developed for 50 common fish species using classification-tree analysis of 69 environmental variables in a geographic information system. Model accuracy was 56·0-93·5% in validation tests. Models were applied to all 86 898 km of stream in the state under four different climate scenarios: current conditions, limited climate warming (summer air temperatures increase 1° C and water 0·8° C), moderate warming (air 3° C and water 2·4° C) and major warming (air 5° C and water 4° C). With climate warming, 23 fishes were predicted to decline in distribution (three to extirpation under the major warming scenario), 23 to increase and four to have no change. Overall, declining species lost substantially more stream length than increasing species gained. All three cold-water and 16 cool-water fishes and four of 31 warm-water fishes were predicted to decline, four warm-water fishes to remain the same and 23 warm-water fishes to increase in distribution. Species changes were predicted to be most dramatic in small streams in northern Wisconsin that currently have cold to cool summer water temperatures and are dominated by cold-water and cool-water fishes, and least in larger and warmer streams and rivers in southern Wisconsin that are currently dominated by warm-water fishes. Results of this study suggest that even small increases in summer air and water temperatures owing to climate warming will have major effects on the distribution of stream fishes in Wisconsin.

Mapping of riparian zone attributes using discrete return LiDAR, QuickBird and SPOT-5 imagery: Assessing accuracy and costs

Riparian zones in Australia are exposed to increasing pressures because of disturbance from agricultural and urban expansion, weed invasion, and overgrazing. Accurate and cost-effective mapping of riparian environments is important for assessing riparian zone functions associated with water quality, biodiversity, and wildlife habitats. The objective of this research was to compare the accuracy and costs of mapping riparian zone attributes from image data acquired by three different sensor types, i.e. Light Detection and Ranging (LiDAR) (0.5–2.4 m pixels), and multi-spectral QuickBird (2.4 m pixels) and SPOT-5 (10 m pixels). These attributes included streambed width, riparian zone width, plant projective cover, longitudinal continuity, vegetation overhang, and bank stability. The riparian zone attributes were mapped for a study area along Mimosa Creek in the Fitzroy Catchment, Central Queensland, Australia. Object-based image and regression analyses were used for mapping the riparian zone attributes. The validation of the LiDAR, QuickBird, and SPOT-5 derived maps of streambed width ( R = 0.99, 0.71, and 0.44 respectively) and riparian zone width ( R = 0.91, 0.87, and 0.74 respectively) against field derived measurements produced the highest accuracies for the LiDAR data and the lowest using the SPOT-5 image data. Cross-validation estimates of misclassification produced a root mean square error of 1.06, 1.35 and 1.51 from an ordinal scale from 0 to 4 of the bank stability score for the LiDAR, QuickBird and SPOT-5 image data, respectively. The validation and empirical modelling showed high correlations for all datasets for mapping plant projective cover ( R > 0.93). The SPOT-5 image data were unsuitable for assessment of riparian zone attributes at the spatial scale of Mimosa Creek and associated riparian zones. Cost estimates of image and field data acquisition and processing of the LiDAR, QuickBird, and SPOT-5 image data showed that discrete return LiDAR can be used for costs lower than those for QuickBird image data over large spatial extents (e.g. 26,000 km of streams). With the higher level of vegetation structural and landform information, mapping accuracies, geometric precision, and lower overall costs at large spatial extents, LiDAR data are a feasible means for assessment of riparian zone attributes.

Winter Longitudinal Thermal Regime in Four Mountain Streams

We measured winter thermal characteristics longitudinally in four third-order streams, two each in the Idaho Batholith and Blue Mountain ecoregions. From November to April we measured temperature along 3.7 km to 11.9 km of stream at six to eight sites. Streams were snow covered for most of the winter. There was a seasonal pattern of stream-wide cooling in November and warming in April at all streams. In the mid-winter months (December, January, and February), the sites in the Blue Mountain streams had mean monthly maxima ranging from 0.2 to 3.0 °C and minima -0.1 to 1.5 °C stream-wide, whereas both Idaho Batholith streams were near 0.0 °C throughout their length and had monthly ranges of 0.2 °C or less. Winter temperature differences between streams of the two ecoregions create substantial differences in cumulative degree-days which could be a factor in the structure of instream biotic communities.

Forecasting the distribution of the invasive round goby (Neogobius melanostomus) in Wisconsin tributaries to Lake Michigan

The Laurentian Great Lakes host more than 180 non-native species, including several that have resulted in major economic and ecological effects. This list includes the round goby ( Neogobius melanostomus ), an aggressive, benthic Ponto-Caspian fish that has established large populations in coastal Great Lakes habitats. Here, we document the inland dispersal of round gobies into Wisconsin tributaries of Lake Michigan. Round gobies were detected in 26 of 73 streams (36%) and found &gt;10 km upstream of Lake Michigan in nine watersheds. Round goby presence–absence was modeled using landscape-scale data from these invaded streams. We forecasted the future spread of round goby within Wisconsin’s Lake Michigan basin using our best model (80% accuracy), which included watershed area, stream gradient, and watershed slope as predictors. Round gobies were predicted to invade 1369 km of stream habitat up to the first stream barrier, and 8878 km of stream was identified as suitable looking beyond barriers at the broader Lake Michigan watershed (Wisconsin only). Our results depict the Great Lakes as a springboard for invasive species to disperse into inland ecosystems and, because round gobies are not usually reported in small streams in their native range, emphasize the utility of data from invaded regions when forecasting invasive species distributions.

Threatened fishes of the world: Moapa coriacea Hubbs and Miller, 1948 (Cyprinidae)

Common name: Moapa dace. Conservation status: Endangered (U.S. Department of the Interior 1967), Critically Endangered, IUCN (Gimenez 1996). Identification: Small embedded scales, narrow caudal peduncle and a bright black spot at the base of deeply forked tail. Pharyngeal teeth (0,5–4,0) hooked but with a grinding surface. Adults 50 to 120 mm total length. Drawing adapted from La Rivers (1962). Distribution: Endemic to the upper Muddy River system, Clark County, Nevada where the river originates from over 20 thermal springs. Prior to 1995 Moapa dace occupied 9.5 stream km including the upper Muddy River and spring-fed tributaries (U.S. Fish and Wildlife Service 1995). Distribution has contracted to 2 km (unpublished data) since the 1995 invasion of blue tilapia, Oreochromis aurea. Abundance: In 1994 the population was about 3,800, but after tilapia invasion dropped below 1,600 (Scoppettone et al. 1998) where it has remained (unpublished data). Habitat and ecology: Omnivorous but tends toward carnivory. Feed primarily on drift in areas adjacent to fast water 26–32°C. Reproduction: Occurs year round in spring-fed tributaries to the Muddy River in water temperature of 30–32°C (Scoppettone et al. 1992). Threats: Nonnative species (Scoppettone 1993; Scoppettone et al. 1998) and ground-water pumping (Mayer and Congdon 2008). Conservation actions: Moapa Valley National Wildlife Refuge was established in the upper Muddy River for the protection and perpetuation of Moapa dace. Barrier installation and chemical removal of blue tilapia downstream of refuge habitat provides 2 km of stream without tilapia. Conservation recommendations: Eliminate tilapia from the Muddy River system and control or eliminate other nonnative species. Protect spring discharge from excessive water withdrawal. Remarks: Given a high priority for recovery by the U.S. Government. Environ Biol Fish (2009) 86:339–340 DOI 10.1007/s10641-009-9524-1

Metabolism and ecology of the water mould, Leptomitus lacteus (Oomycota), blooming in winter in a Nova Scotia stream

The water mould Leptomitus lacteus bloomed in a small stream in northern Nova Scotia, Canada, for at least four months from December through March when water temperatures were near 0 °C and the stream was fre- quently ice-covered. The bloom occupied much of the substratum along 1.5 km of stream below the effl uent outfall from a composting facility. A true fungus, Saprochaete saccharophila, was a minor component of the bloom. L. lacteus colonies appeared robust against freezing and regrew quickly after scouring fl oods. L. lacteus preferred rif- fl es and fast-fl owing water, evidently because of a high oxygen requirement. In mid-winter, the standing crop of L. lacteus approached 2.5 kg m -2 fresh mass, or 2000 kg along the whole length of stream. The bloom ended abruptly in April when water temperatures rose above 5 °C. In the laboratory, clumps of L. lacteus demonstrated vigorous oxygen consumption near 0 °C. Oxidative metabolism was largely confi ned to the outer 6 mm of the colonies, interior to which (O2) declined precipitously. Evidence suggests that L. lacteus blooms in winter to take advantage of a rich food source and high (O2) while avoiding competition. Similar blooms of L. lacteus elsewhere may be overlooked because winter weather and ice cover discourage investigations.

Culvert Replacement and Stream Habitat Restoration: Implications from Brook Trout Management in an Appalachian Watershed, U.S.A.

Abstract Large‐scale culvert replacement programs could benefit migratory fish populations by reconnecting reproductive and foraging habitats in fragmented watersheds. The objectives of this study were to: (1) identify stream and culvert characteristics contributing to fish passage barriers within an Appalachian watershed, U.S.A.; (2) quantify the total amount of Brook trout (Salvelinus fontinalis) reproductive habitat isolated above culverts; and (3) use an ecological currency to identify culvert replacement priorities and stream mitigation credit opportunities. We surveyed 120 state‐owned culverts and used a fish passage assessment filter to determine the “passability” of each culvert. We then constructed a geographic information system stream network model to quantify the amount of trout reproductive habitat isolated by culverts. Ninety‐seven percent of surveyed culverts were classified as obstacles or complete barriers to trout dispersal. Culvert impassability was higher in small streams with slopes exceeding 3–5%, suggesting a direct relationship between slope and impassability. Thirty‐three percent of Brook trout reproductive habitat, representing over 200 km of stream, was isolated by culverts. This is a conservative estimate, because we did not survey privately or federally owned culverts. The top 20 prioritized culverts accounted for nearly half of the habitat loss. Our results indicate that standard culvert designs placed in streams with slopes exceeding 5% consistently produce trout dispersal barriers and should be avoided during new road construction. The process developed here provides an efficient method for identifying culvert replacement priorities and may be used to maximize watershed scale benefits of stream restoration.