A test of the cumulative effect of river weirs on downstream migration success,speed and mortality of Atlantic salmon (Salmo salar) smolts: An empirical study     

Matthew Newton  James Barry  Jennifer A. Dodd  Martyn C. Lucas  Patrick Boylan  Colin E. Adams 《Ecology of Freshwater Fish》2019,28(1):176-186

This study investigated the cumulative impact of weirs on the downstream migration of wild Atlantic salmon (Salmo salar) smolts in the River Foyle, Northern Ireland. In spring of 2013 fish were released in two tributaries of similar length; one tributary (impacted) had seven low‐head weirs along the migration pathway and the other was devoid of such structures (un‐impacted). Salmon smolts fitted with acoustic transmitters were monitored via a passive acoustic telemetry array during downstream migration. In 2014 the study was repeated only in the impacted tributary. Overall freshwater survival rates were high (>94%). There was no significant difference in mortality, movement pattern, delay or travel speeds between rivers or between years at any phase of migration. Escapement of salmon smolts through Lough Foyle (a marine sea lough) to the open ocean was low, approximately 18% in each year. Escapement did not differ between impacted and un‐impacted rivers. This study showed no postpassage effects of weirs on mortality, migration speed or escapement of downstream migrating smolts. This suggests that the elevated mortality at low‐head obstacles described in other studies is not inevitable in all river systems. Migration through rivers with natural riffle‐pool migration may result in similar effects as those from low‐head weirs. Causes of apparent high mortality in the early part of marine migration in this study, are unknown; however similar studies have highlighted the impact of fish predators on smolts.  相似文献   

Life stage‐specific,stochastic environmental effects overlay density dependence in an Atlantic salmon population     

Hannele M. Honkanen  Patrick Boylan  Jennifer A. Dodd  Colin E. Adams 《Ecology of Freshwater Fish》2019,28(1):156-166

Atlantic salmon populations appear to fluctuate stochastically through time. It is suspected that both density‐dependent and density‐independent factors cause these fluctuations but the relative importance of each, and the life stages at which they operate, is not well known. In this study, a long‐term data set on Atlantic salmon migrants returning to the Foyle catchment, Ireland, was used to determine the role of density‐dependent and life stage‐specific environmental factors regulating population size. A Ricker density‐dependent model showed that spawning adult population size significantly predicted variation in the resultant filial generation; however, a large amount of variation (ca. 68%) remained unexplained. It was shown that environmental factors were significant in explaining some of the remaining variance and that these influences were linked to specific life stages. Three life stages—spawning and incubation, fry emergence and marine survival—were shown to have significant environmental effects that resulted in changes in the returning cohort strength. It is concluded that these life stage‐specific environmental effects are likely to contribute to the stochastic variation in population size resulting from the application of traditional stock–recruitment models. The identification and quantification of these effects should allow improved model accuracy.  相似文献   

Psychology. Monkey see, monkey read     

Platt ML  Adams GK 《Science (New York, N.Y.)》2012,336(6078):168-169

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Impact of sludge residence time on the relative biodegradation and biosorption of sulfonamide antibiotics in activated sludge   总被引：1，自引：0，他引：1  

YANG Cheng  GUO Jin song  Belinda S.M. Sturm  Rachael F. Lane  Craig D. Adams  Ray E. Carter 《保鲜与加工》2012,(6):63-71

Four sequencing batch reactors (SBR) are operated with sludge residence time （SRT）of 2, 8, 14, and 20 days to analyze the impact of SRT on removal of sulfanomide (5 μg/L). In batch experiments, three treatments (active biomass, inhibited biomass, and controls of no biomass) are performed in 100 mL batch reactors in triplicate that simulated one SBR cycle, and are investigated to distinguish biodegradation, biosorption, and volatilization losses, respectively. The results show that biomass removed an average 2.14±0.60 μg/g SS of sulfamethoxazole, 1.14±0.63 μg/g SS of sulfadiazine, 2.33±0.67 μg/g SS of sulfadimethoxine, 2.45±0.85 μg/gSS of sulfamerazine, with 63%, 83%, 35%, 55% of the removal respectively due to sorption. When SBRs (3 L total volume) are spiked continuously with 5 μg/L sulfamethoxazole for 60 days, 10%, 41%, 51%, 58% is removed with SRTs of 2d, 8d, 14d, 20d, respectively. Removal increased significantly with SRT, but the normalized mass removed per gram of biomass decreases. Growth of filamentous organisms with a 2-d SRT increases the sorption capacity of this sludge, although biodegradation is the dominant mechanism for removal. Higher biomass concentrations established by longer SRTs are more significant for biodegradation than species diversity, which do not vary with SRT. As wastewater treatment plants implement longer SRTs for nutrient removal, they will also achieve improved removal of some pharmaceuticals.  相似文献   

Predator and prey events at the entrance of a surface-oriented fish collector at North Fork Dam,Oregon     

Collin D. Smith  John M. Plumb  Noah S. Adams  Garth J. Wyatt 《Fisheries Management and Ecology》2021,28(2):172-182

Quantifiable estimates of predator–prey interactions and relationships in aquatic habitats are difficult to obtain and rare, especially when individuals cannot be readily observed. To overcome this observational impediment, imaging sonar was used to assess the cooccurrence of predator-size fish and juvenile salmonids, Oncorhynchus spp., at the entrance to a floating surface collector (FSC) in the forebay of North Fork Dam on the Clackamas River, Oregon (USA). Imaging sonar can be used to transform active sound waves into visual data, making it possible to obtain continuous underwater observations on the presence and interspecific interactions between predator-size fish and prey (juvenile salmonids). Hourly counts of smolt-size fish tracks, diel phase, water clarity and river discharge were used as covariates within a zero-inflated Poisson model to determine how these factors may influence the number of predators in front of the FSC. Both the number of smolt-size fish tracks and diel phase had the strongest effects on the number of predator-size fish tracks, with more predator-size fish tracks observed during the daytime, and as the number of smolt-size fish tracks increased. Additionally, the presence of predator-size fish may affect the abundance and direction of travel of juvenile salmonids, as fewer smolt-size fish were observed when predators were present, and a greater proportion of smolt-size fish were observed travelling away from the FSC when predator-size fish were present. This study provides estimates of predator and prey fish abundance in the vicinity of surface collection systems at moderate-sized hydropower projects and could help resource managers better understand mechanisms that can influence the survival and passage behaviour of juvenile salmonids using surface collection structures at dams.  相似文献   

Rewetting and litter addition influence mineralisation and microbial communities in soils from a semi-arid intermittent stream     

Rebecca E.S. McIntyre  Mark A. Adams  Pauline F. Grierson 《Soil biology & biochemistry》2009,41(1):92-101

Nitrogen (N) and carbon (C) mineralisation are triggered by pulses of water availability in arid and semi-arid systems. Intermittent streams and their associated riparian communities are obvious ‘hot spots’ for biogeochemical processes in arid landscapes where water and often C are limiting. Stream landscapes are characterized by highly heterogeneous soils that may respond variably to rewetting. We used a laboratory incubation to quantify how N and C mineralisation in rewetted soils and sediments from an intermittent stream in the semi-arid Pilbara region of north-west Australia varied with saturation level and substrate addition (as ground Eucalyptus litter). Full (100%) saturation was defined as the maximum gravimetric moisture content (%) achieved in free-draining soils and sediments after rewetting, with 50% saturation defined as half this value. We estimated rates and amounts of N mineralised from changes in inorganic N and microbial respiration as CO₂ efflux throughout the incubation. In soils and sediments subject to 50% saturation, >90% of N mineralised accumulated within the first 7 d of incubation, compared to only 48% when soils were fully saturated (100% saturation). Mineralisation rates and microbial respiration were similar in riparian and floodplain soils, and channel sediments. N mineralisation rates in litter-amended soils and sediments (0.73 mg N kg⁻¹ d⁻¹) were only one-third that of unamended samples (3.04 mg N kg⁻¹ d⁻¹), while cumulative microbial respiration was doubled in litter-amended soils, suggesting N was more rapidly immobilized. Landscape position was less important in controlling microbial activity than soil saturation when water-filled pore space (% WFPS) was greater than 40%. Our results suggest that large pulses of water availability resulting in full soil saturation cause a slower release of mineralisation products, compared to small pulse events that stimulate a rapid cycle of C and N mineralisation-immobilization.  相似文献   

Gentamicin concentrations in synovial fluid obtained from the tarsocrural joints of horses after implantation of gentamicin-impregnated collagen sponges     

Ivester KM  Adams SB  Moore GE  Van Sickle DC  Lescun TB 《American journal of veterinary research》2006,67(9):1519-1526

OBJECTIVE: To determine synovial fluid gentamicin concentrations and evaluate adverse effects on the synovial membrane and articular cartilage of tarsocrural joints after implantation of a gentamicin-impregnated collagen sponge. ANIMALS: 6 healthy adult mares. PROCEDURES: A purified bovine type I collagen sponge impregnated with 130 mg of gentamicin was implanted in the plantarolateral pouch of 1 tarsocrural joint of each horse, with the contralateral joint used as a sham-operated control joint. Gentamicin concentrations in synovial fluid and serum were determined for 120 hours after implantation by use of a fluorescence polarization immunoassay. Synovial membrane and cartilage specimens were collected 120 hours after implantation and evaluated histologically. RESULTS: Median peak synovial fluid gentamicin concentration of 168.9 microg/mL (range, 115.6 to 332 microg/mL) was achieved 3 hours after implantation. Synovial fluid gentamicin concentrations were < 4 microg/mL by 48 hours. Major histologic differences were not observed in the synovial membrane between control joints and joints implanted with gentamicin-impregnated sponges. Safranin-O fast green stain was not reduced in cartilage specimens obtained from treated joints, compared with those from control joints. CONCLUSIONS AND CLINICAL RELEVANCE: Implantation of a gentamicin-impregnated collagen sponge in the tarsocrural joint of horses resulted in rapid release of gentamicin, with peak concentrations > 20 times the minimum inhibitory concentration reported for common pathogens that infect horses. A rapid decrease in synovial fluid gentamicin concentrations was detected. The purified bovine type I collagen sponges did not elicit substantial inflammation in the synovial membrane or cause mechanical trauma to the articular cartilage.  相似文献   

Analysis of a practice management computer software program for owner compliance with recall reminders          下载免费PDF全文

Adams VJ  Waldner CL  Campbell JR 《The Canadian veterinary journal. La revue veterinaire canadienne》2006,47(3):234-240

The purpose of this study was to describe clients' level of compliance with reminders that are computer generated and to identify factors associated with owner response to a recall. Client response to a recall notice revealed that clients responded to reminders for vaccination about 3 times less often than for the other recall codes combined (dental procedures, laboratory tests, medical progress examinations, and neutering). These results suggest that veterinarians need to move away from annual vaccination reminders and toward the promotion of preventive veterinary services, such as annual wellness examinations, screening laboratory testing, and routine dental procedures. Once a practice has committed to and set up the required computer systems to promote preventive veterinary care, the stage is set for the implementation and monitoring of recommendations and reminders. This type of practice philosophy and marketing coincides perfectly with an approach to maximizing compliance in all aspects of veterinary medicine.  相似文献   

Vascular endothelial growth factor expression in canine intracranial meningiomas and association with patient survival     

Platt SR  Scase TJ  Adams V  Wieczorek L  Miller J  Adamo F  Long S 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2006,20(3):663-668

BACKGROUND: Vascular endothelial growth factor (VEGF) is a regulator of angiogenesis and vascular permeability. In human patients with meningiomas, increased VEGF expression is predictive of postsurgical recurrence. The objectives of this study were to evaluate VEGF expression in canine intracranial meningiomas and to determine whether an association between VEGF expression and patient survival existed. METHODOLOGY: Tumor tissue from 17 dogs with histologically confirmed intracranial meningiomas was obtained surgically. All dogs then were treated with radiotherapy. Immunohistochemistry was performed on 5-microm sections of paraffin-embedded tumor tissue with rabbit anti-human VEGF polyclonal antibody. The extent, intensity, and distribution of VEGF staining for each section were assessed with light microscopy by means of a semiquantitative scale. Survival was analyzed by the Kaplan-Meier procedure. Survival rates among groups were compared by log-rank tests with the significance set at P < or = .05. FINDINGS: VEGF expression was detected in all tumors, with >50% of cells staining positively in tissues from 15/17 dogs. Shorter survival times were associated with greater VEGF expression (P = .01). CONCLUSIONS: VEGF expression can be measured in canine intracranial meningiomas and may be associated with poor outcome. SIGNIFICANCE: The extent of VEGF expression in canine intracranial meningiomas may be used as a prognostic marker and suggests a potential future target for therapy.  相似文献   

Canine limbal melanoma: 30 cases (1992-2004). Part 2. Treatment with lamellar resection and adjunctive strontium-90beta plesiotherapy--efficacy and morbidity     

Donaldson D  Sansom J  Adams V 《Veterinary ophthalmology》2006,9(3):179-185

OBJECTIVES: To evaluate the efficacy of lamellar resection and adjunctive 90Sr-beta plesiotherapy in the management of canine limbal melanoma and the frequency and morbidity of early and late-onset side effects following treatment. DESIGN: Retrospective study. ANIMALS STUDIED: Thirty dogs treated for limbal melanoma at the Animal Health Trust (AHT), between 1992 and 2004. METHODS: Medical records were reviewed and information collected on the radiation dose administered, duration of follow-up, and the frequency of early- and late-onset ocular side effects. Follow-up information was obtained by re-examination of patients or completion of a telephone interview with the referring veterinary surgeons or the owners. RESULTS: Recurrence of limbal melanoma occurred in 1 of 30 cases (3%; 95% CI: 0.2-14%). One or more side effects occurred in 16 of 30 cases (53%; 95% CI: 28.1-74.9). The occurrence of side effects was not associated with the number of sites treated or the total surface dose of radiation. Short-term side effects were reported in 16/30 cases (53%) and included corneal scarring (12/30), corneal neovascularization (6/30), conjunctivitis with or without granulation tissue formation (5/30), lipid keratopathy (1/30), and localized bullous keratopathy (2/30). Long-term side effects were reported in 6 of 30 cases (20%) cases and included deep scleral thinning (5/30), focal scleromalacia (3/30), globe perforation (2/30), lipid keratopathy (3/30), localized bullous keratopathy (1/30), and sectoral cortical cataract (1/30). CONCLUSIONS: Lamellar resection and adjunctive 90Sr-beta plesiotherapy is relatively easy to perform, is minimally invasive, and extremely well tolerated by patients. The treatment is highly efficacious in the management of canine limbal melanoma. Modification of the radiation dosimetry, in particular reducing the total dose of radiation and the dose per radiation fraction, is necessary to reduce the incidence of late onset side effects.  相似文献