Pectinase production by Bacillus subtilis and its potential application in biopreparation of cotton and micropoly fabric

An alkaline and thermostable pectinase production from Bacillus subtilis SS was optimized under submerged fermentation and its application was tested in textile industry for desizing and bioscouring of cotton and micropoly fabrics. Desizing of fabric was the best with 5 U/g pectinase treatment for 120 min at pH 9.5 and 65 °C. Under optimized conditions of bioscouring, desized cotton showed highest reducing sugar liberation and weight loss than desized micropoly. Along with enzyme, addition of chelating (EDTA) and wetting agent markedly enhanced the weight loss compared to single use of enzyme or EDTA alone. Agitation (50 ± 2) enhanced the weight loss values of cotton (1.9%) and micropoly fabric (1.7%) at pH 9.5 after treatment time of 2 h. Bioscouring of fabrics with pectinase resulted in enhancement of various physical properties of fabrics viz. whiteness (1.2%), tensile strength (1.6%) and tearness (3.0%) over conventionally alkaline scoured fabrics.     

Taxonomic and functional diversity of stream invertebrates along an environmental stress gradient

Anthropogenic stress has been identified as main driver of freshwater biodiversity loss. Adverse effects on the biodiversity of freshwater organisms, such as macroinvertebrates, may propagate to associated ecosystem functions, such as organic matter breakdown (OMB). In this context, the functional diversity (FD) of communities has been suggested to be a more suitable predictor of changes in ecosystem functions than taxonomic diversity (TD). We investigated the response of TD and FD of invertebrate communities to an environmental stress gradient and the relation of both metrics to the rate of organic matter breakdown. For this, we sampled macroinvertebrates and determined OMB using leaf bags along an environmental stress gradient (i.e. changes in physicochemical and hydromorphological conditions) in 29 low-order streams. Taxonomic richness decreased with increasing environmental stress (r = −0.55) but was not related to OMB. Conversely, the Simpson diversity of communities was not associated with the gradient but correlated moderately (r = 0.41) with OMB. Of three functional diversity indices (functional richness, evenness and divergence), only functional richness correlated moderately with the stress gradient (r = −0.41) and any of the indices correlated with OMB. Nevertheless, functional metrics such as specific trait modalities and the total abundance of the dominant shredders correlated higher (r = 0.46 and 0.48) with OMB than the TD indices. Given a relatively small species pool in our study and methodical constraints such as the limited resolution of autecological information, the FD might perform better in other contexts and if focusing on response and effect traits for the stressor and ecosystem function under scrutiny, respectively.     

Organic matter breakdown as a measure of stream health in New Zealand streams affected by acid mine drainage

Functional indicators of stream health have the potential to provide insights into stream condition that cannot be gained by traditional structural indices. We examined breakdown of leaves, wood, and cotton cloth strips at 18 sites along a gradient of effects of drainage from coal mines in New Zealand to determine the usefulness of these methods as functional indicators of stream health. The pH varied from 2.7 to neutral across the streams, and the more acidic streams typically had higher concentrations of aluminum, iron, zinc, and other metal ions. Precipitates of metal (mainly iron) hydroxides were present in most streams affected by mine drainage, especially in those with a pH of 4–5. Breakdown rates of all organic matter types were highest in several reference streams with neutral pH and lowest in sites with high rates of metal hydroxide deposition. Breakdown was relatively fast in the most acidic streams (pH < 3), in some cases as fast as at reference sites; these sites also had elevated nutrient concentrations. Shredding invertebrates were absent in litterbags from acidic streams and common at only 2 reference sites; their presence contributed to fast breakdown of leaves in the field and in lab microcosms. Microbial respiration was closely related to breakdown rates of leaves and wood; it was high at neutral and highly acidic streams, but lower at sites with pH 4–5, where metal hydroxides were precipitating onto solid surfaces. In these metal hydroxide-stressed streams, leaf and wood breakdown was slower, and associated biota, including microbes, were more affected than by water chemistry stressors (pH, dissolved metals) associated with mine drainage. Litter breakdown and microbial respiration provide insight into the functioning of streams, yielding different responses than traditional structural measures based on macroinvertebrates, which did not accurately distinguish impacts from acid mine drainage.     

An advanced Index of Biotic Integrity for use in tropical shallow lowland streams in Costa Rica: Fish assemblages as indicators of stream ecosystem health

This paper presents an advanced version of the Index of Biotic Integrity (IBI), a multimetric index to indicate ecosystem health. The multimetric index has been adapted in such a way that it not only indicates overall condition but also specific causes of environmental disturbance. The newly developed index (a) uses data of tolerant as well as intolerant species in a single metric to indicate environmental disturbance, (b) does not require knowledge about species from the literature, and (c) can be applied to artificial landscapes.The metrics proposed here consist of indicator species assemblages that are selected directly for their relationship with an environmental component or specific type of environmental degradation. Thus, each metric indicates a type of environmental concern, which enables conservation practices to be targeted more effectively. Species assemblages for each single metric consist of a combination of species that can be negatively and positively related to environmental disturbances, providing a better indication of stream ecosystem health.The area studied was assumed to be too diverse for one single index. Canonical Indirect-Gradient Principal Component Analysis indicated that the optimal division of subindices based on stream typology was for streams with drainage basin sizes <10 km² and >10 km². Pearson Product-Moment Correlations were used to identify relationships between anthropogenic disturbances and the composition and abundance of fish species at impacted as well as undisturbed sites. This index proved to be useful for indicating overall stream ecosystem health as well as local onsite environmental disturbances or the environmental components of greatest concern. This index does require extensive information about measured levels of anthropogenic disturbances with the accompanying composition and abundance of fish species.     

Scouring of cotton using marine pectinase

Bioscouring refers to the enzymatic removal of impurities from cotton fibre, which endows it with improved hydrophilicity for further wet processes. In this study, the efficacy of pectinase from newly isolated marine bacteria Bacillus subtilis, isolated from marine sediment; collected from Chinchani beach, Tarapore, India has been evaluated for scouring of cotton fabric and compared with conventional alkaline scouring of cotton. Use of Citrus limetta peel powder as pectin substrate for enzyme production renders pectinase production process more economically viable. Scouring carried out with pectinase dose of 10% (2.8 IU/g of the fabric) on the weight of the fabric at pH 7, 60 °C for 120 min yielded hydrophilic fabric. Physicochemical and mechanical properties of the pectinase scoured fabric were similar to alkaline scoured fabric. Scouring with pectinase preserves fiber's structure and prevents it from deterioration as observed from tensile strength, FTIR and SEM studies against alkaline scoured fabric. Enhanced dye uptake was also observed in case of pectinase scoured cotton fabric as compared to alkaline scoured fabric.     

Preparation of polyethylene glycol/polyacrylamide adduct and utilization in cotton finishing

Highly concentrated aqueous solutions of acrylamide (Am) were polymerized in presence of polyethylene glycol (PEG) using ammonium persulfate as initiator under different conditions including ammonium persulfate concentration (0.02–0.06 g/gAm) temperature (60–95 °C), Am/PEG400 ratio (1/1–1/5 g/g), PEG molecular weight (400–6000). At optimum reaction conditions a PEG 400/PAm adduct was prepared with a % total conversion of 99.7 in 2 min using ammonium persulfate (0.05 g/gAm), Am/PEG (1/2 g/g) at 70 °C. The structure of the adduct was confirmed by FT-IR spectra. The adduct was utilized as a finishing additive for cotton fabric in presence and absence of dimethyloldihydroxy ethylene urea (DMDHEU) by the bad – dry – cure method. In absence of DMDHEU, the adduct improves the fabric tensile strength, stiffness and oily stain release rating without affect the wettability along with decreasing the fabric resiliency compared to the blank sample. Inclusion DMDHEU the finishing bath (50 g/l) results in improving the fabric resiliency and stiffness as well as decreasing the strength, wettability and oily stain release compared to those of fabric treated with adduct in absence of DMDHEU. However, at an adduct concentration of 40 g/l and in presence of 50 g/l DMDHEU the fabric properties are in general, superior to those of blank fabric.     

Assessment of biotic condition of Atlantic Rain Forest streams: A fish-based multimetric approach

We developed a preliminary fish-based multimetric index (MMI) to assess biotic condition of Atlantic Rain Forest streams in Southeastern Brazil. We used least-disturbed sites as proxies of reference conditions for metric development. To determine the disturbance gradient we used an Integrated Disturbance Index (IDI) that summarized the multiple disturbances measured at local/regional catchment scales in a single index, describing the totality of exposure of the streams to human pressures. For our 48 sites, nine were least-disturbed (IDI < 0.25), five were most-disturbed (IDI > 1.35) and 34 were intermediate. Initially, we considered 41 candidate metrics selected primarily from previous studies. We screened this pool of candidate metrics using a series of tests: range test, signal-to-noise test, correlation with natural gradients, responsiveness test, and redundancy test. After screening, we selected six metrics for the MMI: % Characiform individuals, % water column native individuals, % benthic invertivorous individuals, % tolerant species, % intolerant species, and % detritivorous individuals. Metrics such as diversity, dominance, species richness and biomass that have been historically used for assessing ecosystem condition failed one or more screening tests. We conclude that an IDI and rigorous metric screening are critical to the MMI development process and for meaningful assessments of stream condition.     

Changes in riverine benthic diatom community structure along a chloride gradient

The application of salt is the primary means of deicing roads and highways in colder regions of north-eastern North America. This has increased the chloride concentrations of many lake and stream ecosystems. While this salinization has been documented, less is known about how increased salinity alters benthic communities in downstream ecosystems. Natural thresholds, at which there are large scale changes in community composition, have not yet been established for many types of contaminants, including chloride. The diatom community, which is sensitive to small changes in the ambient environment, has the potential to be a strong indicator of salinization effects on stream ecosystems. In this study, we sampled diatom communities in 41 streams across a salinity gradient throughout south central Ontario, Canada. We sampled benthic diatom assemblages in early May following complete snowmelt, when stream water chloride concentrations ranged from 5 to 502 mg/L. Based on redundancy analysis, we confirmed a strong association between the species composition of the diatom community and water conductivity, a commonly used index of stream salinity. Taxa indicator threshold analyses (TITAN) indicated the community changed substantially at chloride concentrations greater than 35 mg/L. We also found that, an indicator taxa, Meridion circulare, was extremely sensitive to high concentrations of salt and negatively correlated with chloride. In a wide synoptic survey of streams of our region, we found that streams in most developed watersheds exceed tolerance thresholds for benthic diatom communities. This work suggests that current chloride concentrations in urban watersheds are greatly exceeding the benthic community thresholds, for which improved management and regulatory practices are needed. Salinization thus appears to be an important feature of urban streams and needs to be considered as an important ecological driver in future studies.     

Extent estimates and land cover relationships for functional indicators in non-wadeable rivers

Functional indicators are being increasingly used to assess waterway health but their responses to pressure in non-wadeable rivers have not been widely documented or applied in modern survey designs that provide unbiased estimates of extent. This study tests the response of river metabolism and loss in cotton strip tensile strength across a land use pressure gradient in non-wadeable rivers of northern New Zealand, and reports extent estimates for river metabolism and decomposition rates. Following adjustment for probability of selection, ecosystem respiration (ER) and gross primary production (GPP) for the target population of order 5–7 non-wadeable rivers averaged −7.3 and 4.8 g O₂ m⁻² d⁻¹, respectively, with average P/R < 1 indicating dominance by heterotrophic processes. Ecosystem respiration was <−3.3 g O₂ m⁻² d⁻¹ for 75% of non-wadeable river length with around 20% of length between −10 and −20 g O₂ m⁻² d⁻¹. Cumulative distribution functions of cotton strength loss estimates indicated a more-or-less linear relationship with river km reflecting an even spread of decay rates (range in k 0.0007–0.2875 d⁻¹) across non-wadeable rivers regionally. A non-linear relationship with land cover was detected for GPP which was typically <5 g O₂ m⁻² d⁻¹ where natural vegetation cover was below 20% and greater than 80% of upstream catchment area. For cotton strength loss, the relationship with land cover was wedge-shaped such that sites with >60% natural cover had low decay rates (<0.02 d⁻¹) with variability below this increasing as natural cover declined. Using published criteria for assessing waterway health based on ER and GPP, 232–298 km (20–29%) of non-wadeable river length was considered to have severely impaired ecosystem functioning, and 436–530 km (42–50%) had no evidence of impact on river metabolism.     

Nutrient retention function of a stream wetland complex—A high-frequency monitoring approach

The ability of riverine ecosystems to retain nutrients depends on different hydrological, chemical and biological conditions including exchange processes between streams and wetlands. We investigated nutrient retention in a stream wetland complex on the time scale of daily hydrological exchange between both systems. Daily mass balances of NO₃-N, NH₄-N, TP and SRP were calculated with data obtained by two automated measurement stations in a stream reach upstream and downstream of a wetland. The pattern of hydrological exchange between stream and wetland was used to classify characteristic hydrological periods like floods, base and low flows. The nutrient retention function of the stream wetland complex varied considerably during phases of similar hydrologic conditions. Despite re-wetting measures in the wetland, an overall net export of all nutrients except for NH₄-N characterised the whole growing season. Nitrate retention occurred during summer flood (retention in the wetland, 23 kg NO₃-N d^?1, 17% of the input load) and low flow (retention in the stream, 1 kg NO₃-N d^?1, 2% of the input load). TP retention during summer could be assigned to sedimentation (0.7 kg TP d^?1, 7% during flooding in the wetland, 0.2 kg TP d^?1, 4% during low flow in the stream). SRP retention was only intermittent. We concluded that the nutrient retention of streams and wetlands can only be optimised by restoration measures that regard both systems as one functional unit in terms of nutrient retention.     

Comparing the sensitivity of diverse macroinvertebrate metrics to a multiple stressor gradient in Mediterranean streams and its influence on the assessment of ecological status

Biological indicators are increasingly being used as integrative measures of the ecosystem health in streams, particularly those using macroinvertebrate assemblage composition. Monitoring biological quality of rivers has not a long tradition in some Mediterranean European countries like Spain. Several macroinvertebrate metrics have been recently proposed to assess ecological status in Mediterranean streams, so it is necessary to compare the use of proposed biological quality metrics to select the most appropriate ones.In the present work, two classic richness metrics (total number of families and number of the Ephemeroptera, Plecoptera and Trichoptera families), three indices (IBMWP, IASPT and t-BMWQ) and two multimetric indices, recently proposed to be used in Mediterranean streams (ICM-9 and ICM-11a or IMMi-L), were compared by the analysis of the sensitivity of these metrics to a multiple stressor gradient which reflected the main pressures present in the study area. For this purpose, data from 193 sites sampled in spring (95 reference sites and 98 disturbed sites) belonging to five different Mediterranean stream types present in 35 basins were studied.The results showed that the adjusted regression coefficients (r²) for all seven metrics in the exponential regression models were higher than linear ones, thus indicating an exponential relationship between metrics and the environmental alteration. The two studied multimetric indices presented higher regression coefficients (r² = 0.590–0.669) than the three indices (r² = 0.524–0.574) and the two metrics (r² = 0.471–0.525), therefore showing a better response to a stressor gradient in Mediterranean streams. Within the multimetric indices group, ICM-11a showed the highest regression coefficients. Based on the results obtained, we suggest using the ICM-11a, apart from the IBMWP, to assess ecological status in Mediterranean streams.     

Development of dual fish multi-metric indices of biological condition for streams with characteristic thermal gradients and low species richness

Biological indicators based on fish assemblage characteristics are used to assess stream condition worldwide. Fish-based bioassessment poses challenges in Southern New England, the USA, due to the effects of within-watershed thermal gradients on fish assemblage types, low regional species richness, and lack of minimally disturbed sites. Dual multi-metric indices (MMI) of biological condition were developed for wadeable streams based on fish assemblage characteristics sampled across watershed landscapes with varying levels of human disturbance. A coldwater MMI was developed using streams with drainage area of ≤15 km², and a mixed-water MMI for streams with drainage areas of >15 km². For each MMI development, candidate metrics represented by ecological classes were sequentially tested by metric range, within-year precision, correlation with stream size, responsiveness to landscape-level human disturbances, and redundancy. Resultant coldwater and mixed-water MMI were composed of 5 and 7 metrics, respectively. Stream sites tended to score similarly when the two MMI were applied to transitional sites, i.e., drainage areas of 5–40 km². However, some sites received high scores from the mixed-water MMI and intermediate scores from the coldwater MMI. It was thus difficult to ascertain high-quality mixed-water streams from potential coldwater streams which currently support mixed-water assemblages due to ecological degradation. High-quality coldwater streams were restricted to stream sites with drainage areas ≤15 km². The newly developed fish-based MMI will serve as a useful management tool and the dual-MMI development approach may be applicable to other regions with thermal gradients that transition from coldwater to warmwater within watersheds.     

Proton production from nitrogen transformation drives stream export of base cations in acid-sensitive forested watersheds

The biogeochemical cycles of nitrogen (N) and base cations (BCs), (i.e., K⁺, Na⁺, Ca²⁺, and Mg²⁺), play critical roles in plant nutrition and ecosystem function. Empirical correlations between large experimental N fertilizer additions to forest ecosystems and increased BCs loss in stream water are well demonstrated, but the mechanisms driving this coupling remain poorly understood. We hypothesized that protons generated through N transformation (PPR_N)—quantified as the balance of NH₄⁺ (H⁺ source) and NO₃⁻ (H⁺ sink) in precipitation versus the stream output will impact BCs loss in acid-sensitive ecosystems. To test this hypothesis, we monitored precipitation input and stream export of inorganic N and BCs for three years in an acid-sensitive forested watershed in a granite area of subtropical China. We found the precipitation input of inorganic N (17.71 kg N ha⁻¹ year⁻¹ with 54% as NH₄⁺–N) was considerably higher than stream exported inorganic N (5.99 kg N ha⁻¹ year⁻¹ with 83% as NO₃⁻–N), making the watershed a net N sink. The stream export of BCs (151, 1518, 851, and 252 mol ha⁻¹ year⁻¹ for K⁺, Na⁺, Ca²⁺, and Mg²⁺, respectively) was positively correlated (r = 0.80, 0.90, 0.84, and 0.84 for K⁺, Na⁺, Ca²⁺, and Mg²⁺ on a monthly scale, respectively, P < 0.001, n = 36) with PPR_N (389 mol ha⁻¹ year⁻¹) over the three years, suggesting that PPR_N drives loss of BCs in the acid-sensitive ecosystem. A global meta-analysis of 15 watershed studies from non-calcareous ecosystems further supports this hypothesis by showing a similarly strong correlation between ∑BCs output and PPR_N (r = 0.89, P < 0.001, n = 15), in spite of the pronounced differences in environmental settings. Collectively, our results suggest that N transformations rather than anions (NO₃⁻ and/or SO₄²⁻) leaching specifically, are an important mediator of BCs loss in acid-senstive ecosystems. Our study provides the first definitive evidence that the chronic N deposition and subsequent transformation within the watershed drive stream export of BCs through proton production in acid-sensitive ecosystems, irrespective of their current relatively high N retention. Our findings suggest the N-transformation-based proton production can be used as an indicator of watershed outflow quality in the acid-sensitive ecosystems.     

Valuation of the loss of plant-related ecosystem services caused by water stress in the wetland of China’s Yellow River Delta

China’s Yellow River Delta is ecologically important because of its role as an eco-tone between terrestrial and aquatic ecosystems. However, water stress caused by drought or flooding creates ecological risks for this important ecosystem. In this study, we assessed community biodiversity, plant biomass, and the plant total nitrogen, total phosphorus, and potassium contents to quantify the potential loss of ecosystem services value arising from water stress. The annual ecosystem services and function value of the wetlands totaled 3.68 × 10⁸ Yuan, of which biomass production and local climate regulation accounted for 39.4% and 49.5% of the total, respectively. The area with the highest value (>2 Yuan m⁻²) lies along both banks of the downstream reaches of the river, whereas areas with the lowest values (<1.5 Yuan m⁻²) were located on the northern bank, near the Bohai Sea coastline. We defined scenarios based on three levels of water stress: drought, sufficient water, and flooding. The potential annual value loss in the drought scenario was 3.60 × 10⁸ Yuan, versus 2.78 × 10⁸ Yuan in the flooding scenario. The minimum loss (with sufficient water) was 2.06 × 10⁸ Yuan. The wetland’s soil water content should therefore be managed to protect the vegetation and minimize the ecological risks (and associated ecosystem service value losses) caused by water stress. Our approach provides a tool for assessing the potential loss of ecosystem services and functions and for calculating ecological compensation payments for wetland damage.     

Scale matters: Indicators of ecological health along the urban–rural interface near Columbus,Georgia

Ecological data obtained from field plots can provide detailed information about ecosystem structure and function. However, this information typically reflects processes that occur over small spatial areas. Accordingly, it is difficult to extrapolate these data to patterns and processes that take place at regional scales. Satellite imagery can provide a means to explore environmental variables over a larger area. Therefore, our main objective was to examine the utility of a regional ecological assessment tool using landscape indicators of ecosystem health in a rapidly developing area of West Georgia near the city of Columbus. Indicator variables included in the assessment were: population density and change, road density, percent forest land-cover, forest patch density, landscape Shannon's Diversity Index, proportion of all streams with roads within 30 m, proportion of area that has agriculture on slopes >3%, proportion of all streams with adjacent agriculture, and proportion of all streams with adjacent forest cover. Cluster analysis was used to combine these variables into different groups, and resulting cluster means were used to rank regional areas according to degree of environmental impact. To assess the spatial accuracy of this tool results were compared to those obtained from a separate plot-level field-based forest condition study. Results derived using the landscape ecological assessment tool suggest that rural areas were the least environmentally impacted (or most healthy) of all areas in West Georgia, and support the findings from the field study. Results for developing areas were mixed between the two different studies and may be attributed to differences in scale. Overall, it appears that this tool is useful for broad generalizations about a given landscape, but is not detailed enough for site-specific management goals due to its inherent coarse spatial resolution (30 m × 30 m). However, these site-specific goals may be achieved using higher resolution (1 m × 1 m) satellite imagery and warrants further research. In any case, this tool is a useful asset for anyone needing a rapid diagnosis of ecosystem health in an inexpensive and timely manner.     

Shade tree cover criteria for non-point source pollution control in the Rainforest Alliance coffee certification program: A snapshot assessment of Costa Rica's Tarrazú coffee region

Management of non-point source pollution is of great importance in the context of coffee agriculture, as this land use often coincides with headwater streams that influence water quality at the basin scale. Sustainability certification programs, such as the Rainforest Alliance (RA), provide management guidelines that promote non-point source pollution control in coffee. One of these practices is the maintenance of shade trees within farms, required by RA at a minimum of 40% shade tree cover. Here we assess the effectiveness of this practice in Tarrazú, a high elevation coffee growing region in Costa Rica. We monitored indicators of non-point source pollution in streams with both high and low shade tree cover. Streams with High Shade Tree Cover (HSTC, N = 5 subwatersheds) had 35–55% cover, approximating or exceeding the RA recommendation of at least 40%; and streams with Low Shade Tree Cover (LSTC, N = 5 subwatersheds), had 18–31% cover. We monitored the ten study streams during the dry (April & December), transition (July), and peak (October) rainfall seasons of 2013, and compared responses using t-tests. We found support for the effectiveness of shade tree cover in controlling non-point source pollution: HSTC streams had significantly (p = 0.042) lower mean annual turbidity and significantly (p = 0.004) lower turbidity during the transition season. HSTC streams also had significantly (p = 0.05) lower conductivity values during the transition period, although this trend was weaker through the year. Subwatersheds with HSTC streams were characterized by a higher percentage of RA-certified coffee than LSTC streams. Our study provides evidence of the benefits of RA shade tree cover criteria for managing water quality within high elevation tropical agro-ecosystems, especially if implemented at the watershed scale. These results contribute to our understanding of the role of agroforestry certification on tropical ecosystem conservation, and are the first account of the effectiveness of a specific coffee certification guideline on non-point source pollution control.     

Ecological restoration design of a stream on a college campus in central Ohio

Straightened stream channels and altered and drained wetlands have adversely impacted streams and rivers throughout Midwestern USA, where some of the most dense drainage and riparian ecosystem alteration in the world have occurred. A segment of Grave Creek on The Ohio State University's Marion (OSU Marion) campus in Ohio, USA, with its lack of riparian ecosystems, illustrates the transformation of a natural fluvial ecosystem to an unstable and “simplified” aquatic environment that requires continued maintenance and provides little value to the surrounding landscape or to the university. However, the straight ditch, available adjacent riparian land and existing hydric soil give OSU Marion a great opportunity to demonstrate a project of stream and wetland restoration on a college campus. To restore the natural ecological stability of OSU Marion's “back yard” and to provide habitat improvement to Grave Creek and its surrounding landscape on the OSU Marion campus, we have designed a restoration of 1.1 km of Grave Creek meandering to the east of the existing sewer, using the two-stage channel techniques, and about 0.6–0.8 ha of adjacent wetland. We estimate that restoration on this scale will cost about US$ 200,000–300,000, not including monitoring of the results. To fulfill this project, it is likely that an opportunity for using this restoration in a stream/wetland loss mitigation will present itself in this region of Ohio while a long-term pre- and post-construction monitoring plan and more detailed design would be expected as the next step.     

Diatom biomonitoring of streams: Reliability of reference sites and the response of metrics to environmental variations across temporal scales

Benthic diatoms are widely used indicators of human impacts on stream ecosystems because they are very responsive to changing environmental conditions. However, little research has explicitly focused on their reliability with regards to temporal variation in assemblage structure and environmental conditions. We examined variability in diatom-environment relationships at bi-weekly, monthly, and yearly time scales from 7 reference, 7 agricultural, and 2 acid mine drainage (AMD)-impacted streams, and how nutrient and pH fluctuations may affect the interpretation of diatom metrics and the Diatom Model Affinity (DMA) index. Reference streams had less bi-weekly variability in NO₃-N concentrations than non-reference streams. The % eutraphentic diatoms and DMA scores were more strongly correlated with seasonal means of NO₃-N and PO₄-P concentrations than with same day concentrations. Most nutrient indicator metrics had strong correlations with watershed land use. All 14 non-AMD streams experienced substantial increases in NO₃-N and decreases in temperature from November to May, which were associated with high species turnover, substantial changes in community structure, reduced diversity and richness, increased relative abundances of high nutrient diatoms, and decreases in low nutrient diatoms and DMA scores. The % acidophilic diatoms and DMA scores were significantly correlated with increased pH associated with greater precipitation at AMD sites from December to April (r = ?0.77, r = 0.62, respectively; P < 0.01). Yearly, DMA scores for all reference streams were consistently in the minimally impaired category, whereas scores for non-reference streams varied among impairment categories. Reference sites serve as reliable benchmarks for diatom ecological integrity during the summer. In this region, June to October is a recommended time period for diatom sampling in monitoring programs because subsequent shifts in hydrologic regimes, nutrients, and diatom assemblages occurred, affecting all sites and masking among stream differences attributable to agricultural land uses.     

The Biological Sediment Tolerance Index: Assessing fine sediments conditions in Oregon streams using macroinvertebrates

Fine sediments in excess of natural background conditions are one of most globally common causes of stream degradation, with well documented impacts on aquatic communities. The lack of agreement on methods for monitoring fine sediments makes it difficult to share data, limiting assessments of stream conditions across jurisdictions. We present a model that circumvents these limitations by inferring fine sediments in Oregon streams through sampling of macroinvertebrates. Tolerances to fine sediments (<0.06 mm diameter) were calculated for 240 macroinvertebrate taxa, from a calibration dataset of 446 sites across Oregon, as well as an independent validation dataset of 50 samples. Weighted averaging methods were used to infer fine sediment levels in streams by weighting the tolerances of modeled taxa observed in a sample by their abundances. The final model, the Biological Sediment Tolerance Index (BSTI), showed a strong relationship to measured fine sediments (calibration r² = 0.49, validation r² = 0.58). Root-mean-squared-error was small in the calibration dataset (2% fines), but larger in the validation dataset (14% fines). Repeatability was assessed by examining variability in BSTI at 14 sites across Oregon. Because field methods for sampling macroinvertebrates are standardized across resource agencies in Oregon and the responses of macroinvertebrates represent the actual effects of fine sediments on stream ecosystems, the BSTI may offer water resource managers’ a cost-effective method for assessing fine sediment conditions in their ongoing efforts to improve water quality across the state.     

Substratum associations of benthic invertebrates in lowland and mountain streams

The preferences of aquatic invertebrate species for specific substrata at the river bottom have been subject of many studies. Several authors classified the substratum preferences of species or higher taxonomic units. Most of these compilations, however, are based on literature analyses and expert knowledge as opposed to the analysis of original data. To enhance our knowledge of invertebrate substratum preferences, we applied a ‘Multi-level pattern’ analysis based on almost 1000 substrate-specific invertebrate samples. The samples were taken in 18 streams in Germany, the Netherlands and Austria, comprising a total of 40 sampling sites and equally covering lowland and mountain streams. The main objectives of our analysis were (I) to derive substratum preferences of taxa in lowland and mountain streams, (II) to compare the preferences with existing data and (III) to compare species substratum associations between lowland and mountain streams. Of the 290 taxa analyzed, 188 were associated significantly to specific substrata. Twenty-five taxa in lowland streams and 51 taxa in mountain streams prefer one or two substratum types (of nine substratum types considered in total). In contrast, 112 species (mountain streams n = 84, lowland streams n = 28) are associated significantly with a broader range of substrata. We compared the classifications derived from our data analysis with those provided in the freshwaterecology.info database (www.freshwaterecology.info). Our results support the existing classifications of substratum preferences in most cases (70%). For 25 species, substratum preferences for both lowland and mountain streams were derived, many of them indicating different substratum associations in the two stream groups. As substratum preferences differed between closely related species, preferences should always be given at the species level as opposed to coarser taxonomic units.