Diet composition of two larval headwater stream salamanders and spatial distribution of prey

相似文献   

A novel bacterial community index to assess stream ecological health

相似文献   

Increasing extent of periods of no flow in intermittent waterways promotes heterotrophy

相似文献   

Land‐use legacy and the differential response of stream macroinvertebrates to multiple stressors studied using in situ experimental mesocosms

相似文献   

The cold‐water climate shield: delineating refugia for preserving salmonid fishes through the 21st century

The distribution and future fate of ectothermic organisms in a warming world will be dictated by thermalscapes across landscapes. That is particularly true for stream fishes and cold‐water species like trout, salmon, and char that are already constrained to high elevations and latitudes. The extreme climates in those environments also preclude invasions by most non‐native species, so identifying especially cold habitats capable of absorbing future climate change while still supporting native populations would highlight important refugia. By coupling crowd‐sourced biological datasets with high‐resolution stream temperature scenarios, we delineate network refugia across >250 000 stream km in the Northern Rocky Mountains for two native salmonids—bull trout (BT) and cutthroat trout (CT). Under both moderate and extreme climate change scenarios, refugia with high probabilities of trout population occupancy (>0.9) were predicted to exist (33–68 BT refugia; 917–1425 CT refugia). Most refugia are on public lands (>90%) where few currently have protected status in National Parks or Wilderness Areas (<15%). Forecasts of refuge locations could enable protection of key watersheds and provide a foundation for climate smart planning of conservation networks. Using cold water as a ‘climate shield’ is generalizable to other species and geographic areas because it has a strong physiological basis, relies on nationally available geospatial data, and mines existing biological datasets. Importantly, the approach creates a framework to integrate data contributed by many individuals and resource agencies, and a process that strengthens the collaborative and social networks needed to preserve many cold‐water fish populations through the 21st century.     

Ammonia removal from a waste air stream using a biotrickling filter packed with polyurethane foam through the SND process

This paper presents the results of a bench-scale biotrickling filter (BTF) on the removal of ammonia gas from a waste stream using a simultaneous nitrification/denitrification (SND) process. It was found that the developed BTF could completely remove 100 ppm ammonia from a waste stream, with an empty bed retention time of 60 s and 98.4% nitrogen removal through the SND process under the tested conditions. It was elucidated that both autotrophic and heterotrophic bacteria were involved in the nitrogen removal trough the SND process in the BTF. Additionally, the elimination capacity of total nitrogen by the BTF increased from 3.5 to 18.4 g N/m³ h with an inlet load of 20.6 g N/m³ h (73.6%). The findings of this study suggest that the BTF can be operated to attain complete ammonia removal through the SND process, thereby making the treatment of ammonia-laden gas streams both short and cost-effective.     

ALGAL COMMUNITIES OF SPRINGS AND STREAMS IN THE MT. ST. HELENS REGION,WASHINGTON, U.S.A. FOLLOWING THE MAY 1980 ERUPTION1

Mt. St. Helens, a volcanic peak in the Cascade Range in southern Washington erupted violently on May 18, 1980, causing enormous damage to both terrestrial and aquatic ecosystems. The initial explosion evaporated, scoured or buried all springs and streams in the blast impact area. Ash fall and erosion from defoliated hillsides subsequently filled most of the lotic habitats with organic debris and volcanic ash. Recolonization of springs and streams by algae occurred quickly in areas where erosion through the ash progressed down to bedrock. Within 15 months or less of the eruption, algal communities were established throughout the blast impact area. However, as a result of the initial and continued disturbance these communities remained in an early successional stage. Floral assemblages were highly variable except that they were composed mostly of diatoms, with Achnanthes minutissima dominating most lotic sites. Springs showed the most rapid development toward stable floras.     

Physicochemical stream bed characteristics and recruitment of the freshwater pearl mussel (Margaritifera margaritifera)

1. The freshwater pearl mussel (Margaritifera margaritifera) is endangered and of conservation importance. We used its survival/mortality during the critical post‐parasitic phase as a biological indicator for the habitat quality of the stream substratum. 2. We established and tested biological, physical and chemical methods of assessing the stream bed in 26 streams from seven European countries. We analysed penetration resistance, texture, the concentrations and ratios of C, N, S, P, Fe, Mn in fine material <100 μm, and redox, pH and electric conductivity at the surface and at 5 and 10 cm into the substratum. 3. Sites with high stream bed quality (promoting pearl mussel populations with good juvenile recruitment) had coarser and better sorted substrata with significantly lower quantities of fines, and a higher Mn concentration in the fines, than poor quality sites. Redox potential (Eh) at sites without recruitment differed markedly between the free‐flowing water at the surface and at 5 and 10 cm in the bed, whereas no differences were detectable at good quality sites. This was also true of electric conductivity and, to a lesser extent, pH. The stream bed at sites lacking pearl mussel recruitment had a more variable and higher penetration resistance, indicating clogging of the interstitial macropore system by the deposition of mud and compaction of the stream bed. 4. Our results show that habitat quality for pearl mussels depends strongly on the exchange between the surface and the interstices, which is governed by physicochemical characteristics of the stream substratum. Combined measurements of penetration resistance, depth gradients of Eh and texture were most suitable for assessing stream bed quality, while water chemistry was insufficient because of the decoupling of interstitial and free‐flowing water at poor quality sites.     

Age-Related Changes of NADPH-Diaphorase Positivity in the Rat Rostral Migratory Stream

Summary Accumulating evidence confirms that nitric oxide (NO), a versatile diffusible signaling molecule, contributes to controling of adult neurogenesis. We have previously shown the timing of NADPH-diaphorase (NADPH-d) positivity within the rat rostral migratory stream (RMS) during the first postnatal month. The present study was designed to describe further age-related changes of NO presence in this neurogenic region. The presence of NO synthesizing cells in the RMS was shown by NADPH-d histochemistry and neuronal nitric oxide synthase (nNOS) immunohistochemistry. The phenotypic identity of nitrergic cells was examined by double labeling with GFAP and NeuN. Systematic qualitative and quantitative analysis of NADPH-d-positive cells was performed in the neonatal (P14), adult(5 months) and aging (20 months) rat RMS. 1. Nitrergic cells with different distribution pattern and morphological characteristics were present in the RMS at all ages examined. In neonatal animals, small, moderately stained NADPH-d-positive cells were identified in the RMS vertical arm and in the RMS elbow. In adult and aging rats a few labeled cells could be also detected in the RMS horizontal arm. NADPH-d-positive cells in adult and aging rats were characterized by long varicose processes and displayed dark labeling in comparison to the neonatal group. 2. Double immunolabeling has revealed that nNOS-immunoreactivity co-localized with that of NeuN. This indicates that nitrergic cells within the RMS are neurons. 3. Quantitative analysis showed that the number of NADPH-d-positive cells increases with advancing age. The presence of NO producing cells in the RMS of neonatal adult and aging rats indicates, that this proliferating and migratory area is under the influence of NO throughout the entire life of the animals.