Brown trout redd superimposition in relation to spawning habitat availability

The relationship between redd superimposition and spawning habitat availability was investigated in the brown trout (Salmo trutta L.) population inhabiting the river Castril (Granada, Spain). Redd surveys were conducted in 24 river sections to estimate the rate of redd superimposition. Used and available microhabitat was evaluated to compute the suitable spawning habitat (SSH) for brown trout. After analysing the microhabitat characteristics positively selected by females, SSH was defined as an area that met all the following five requirements: water depth between 10 and 50 cm, mean water velocity between 30 and 60 cm s)1, bottom water velocity between 15 and 60 cm s)1, substrate size between 4 and 30 mm and no embeddedness. Simple regression analyses showed that redd superimposition was not correlated with redd numbers, SSH or redd density. A simulation-based analysis was performed to estimate the superimposition rate if redds were randomly placed inside the SSH. This analysis revealed that the observed superimposition rate was higher than expected in 23 of 24 instances, this difference being significant (P menor que 0.05) in eight instances and right at the limit of statistical significance (P = 0.05) in another eight instances. Redd superimposition was high in sections with high redd density. High superimposition however was not exclusive to sections with high redd density and was found in moderate- and low-redd-density sections. This suggests that factors other than habitat availability are also responsible for redd superimposition. We argue that female preference for spawning over previously excavated redds may be the most likely explanation for high superimposition at lower densities.

Landfill Leachate Toxicity to Oncorhynchus mykiss (Rainbow Trout) at the Merrick Landfill

At the Merrick Landfill, located outside of North Bay (Ontario, CA), an investigation into the potential for an environmental impact to the Little Sturgeon River as a result of landfill leachate discharge was undertaken using toxicity testing using 96 hour acute lethality on Oncorhynchus mykiss (Rainbow Trout). Landfill leachate may present a risk to receiving environments as it is comprised of an array of chemicals including organics, ammonia, and metals. Testing was conducted in three phases, firstly testing was completed on site throughout an existing natural attenuation zone where the presence of several groundwater seeps down gradient of the site had been identified to determine the effectiveness of the existing leachate control features at reducing the environmental risks. These tests indicated that the existing capture strategies were largely effective at reducing toxicity risks to the receiving environment. Testing was also completed on two pilot-scale hybrid-passive treatment systems to determine their effectiveness for leachate treatment. Summer performance of a constructed gravel wetland system was also shown to be effective at reducing the toxicity of the landfill leachate at the site. Lastly in order to support evaluation of leachate treatment requirements, a toxicity identification evaluation (TIE) was performed to determine the principle cause of toxicity within the leachate. Based on water chemistry analyses of samples collected at various locations at the site, the TIE identified ammonia toxicity as the primary source of toxicity in the leachate, with a secondary focus on metal toxicity.

Effects of thinning and a wildfire on sediment production rates, channel morphology, and water quality in the upper South Platte River watershed /

"Spring 2004."

Green River - Hams Fork regional coal environmental impact statement : draft /

April 1980.

The Blind Sucker River [electronic resource] /

Electronic text and image data.

Poudre River Bulletin

Mode of access: Internet.

Landfill Leachate Toxicity to Oncorhynchus mykiss (Rainbow Trout) at the Merrick Landfill

At the Merrick Landfill, located outside of North Bay (Ontario, CA), an investigation into the potential for an environmental impact to the Little Sturgeon River as a result of landfill leachate discharge was undertaken using toxicity testing using 96 hour acute lethality on Oncorhynchus mykiss (Rainbow Trout). Landfill leachate may present a risk to receiving environments as it is comprised of an array of chemicals including organics, ammonia, and metals. Testing was conducted in three phases, firstly testing was completed on site throughout an existing natural attenuation zone where the presence of several groundwater seeps down gradient of the site had been identified to determine the effectiveness of the existing leachate control features at reducing the environmental risks. These tests indicated that the existing capture strategies were largely effective at reducing toxicity risks to the receiving environment. Testing was also completed on two pilot-scale hybrid-passive treatment systems to determine their effectiveness for leachate treatment. Summer performance of a constructed gravel wetland system was also shown to be effective at reducing the toxicity of the landfill leachate at the site. Lastly in order to support evaluation of leachate treatment requirements, a toxicity identification evaluation (TIE) was performed to determine the principle cause of toxicity within the leachate. Based on water chemistry analyses of samples collected at various locations at the site, the TIE identified ammonia toxicity as the primary source of toxicity in the leachate, with a secondary focus on metal toxicity.

Study of nephrocalcinosis in rainbow trout (Oncorhynchus mykiss), from fry to brood stock

For survey incidence of nephrocalcinosis in rainbow trout fish, during winter 1385, samplings were performed in three fish farm with different water source: river, spring and recirculation system by using well water. In this survey 5 specimens from each 8 groups and in general 120 specimens of this fish were caught by random sampling, and also amounts of O2, CO2, pH and temperature of water were measured. Then blooding and renal tissue sampling performed that renal samples were fixed in 10% buffered formalin and blood samples after separating serum stored in -200C. Renal specimens transferred to pathology laboratory, pathological slides were prepared and stained by hematoxylin & Eosin method. From 120 specimens, 6 cases of fish represent nephrocalcinosis. Pathologic signs include: renal epithelial necrosis, dilated ureters, dense basophilic materials inside the dilated tubules and cast formation in some renal tubules. From 6 cases of nephrocalcinosis, 3 cases (7/5%) were related to recirculation system and 2 (5%) case were related to river water and 1 (2/5%) case was related to spring water. In survey amount of urea, creatinine and Uric acid between different weight groups, distinguished that difference between creatinine middling in different weight groups were significant and also in between healthy and afflicted fish, significant statistical difference were only in creatinine amount between healthy and afflicted fish in each farm. Amounts of O2, pH and temperature of water in three farms were in normal range and only rate of water CO2 in ponds of recirculatory system were very higher (25 mg/lit) than other farms. May be, this reason led to high number of nephrocalcinosis in recirculatory system, than other farms, nemley 7/5% of fish that caught from this farm .This subject is related to the role of CO2 in creating nephrocalcinosis which is descript in references.

Effect of temperature on genomic and some biological indices during embryonic and larval development of Caspian trout Salmo trutta caspius Kessler, 1877

Since 1966 especially recent decade, Caspian trout (Salmo trutta caspius Kessler, 1877) considered as a strategic endemic species for Caspian Sea fisheries resources also coldwater aquaculture in Iran. Nowadays habitat condition effects on this subspecies during life stages, artificial breeding and incubation period noticed by research and execution sessions of fisheries in Iran. Incubation duration of Caspian trout from artificial fertilization followed by green egg and eyed egg, hatching and yolk sac absorption identified as most sensitive stages for fish and any pollution, stress and deviation by natural life conditions of embryo up to larvae could provide possible mortalities and observable or hidden alterations. Among all vital factors for Caspian trout welfare even in conservation plans and stocks rehabilitation programs or recent attempts for domestication of this fish for introduction to cold water aquaculture industry, water temperature as the most important physical factor which might conserve or induce stress to rearing environment condition is not considered yet. In hatcheries activities, the temperature for incubation and rearing Caspian trout eggs is determining by available water temperature and wide range of temperatures in governmental or private farms is using depend on the water resources availability. Also global climate change consideration and increase temperature trend accompany with group of physical and chemical factors provided by fish farm discharges and other source points entered to the migration pathway of Caspian trout in spawning season were not investigated before. Natural spawning migration pathway is upstream of Caspian tout south and south west rivers especially in Cheshmehkileh upstream in Tonekabon, Iran directed this research focus on the mentioned location. For simulation of natural spawning bed for Caspian trout, water supplied from the upstream of Daryasar branch as headwater of Cheshmehkileh River which provided REDD water condition for in vitro incubation. Green eggs treatments of wild and F1 cultured brooders both 3+ were incubated. Incubation implemented in dark, constant temperature (4, 8, 12 degree centigrade) and DO–pH–temperature digital monitoring in 3 recycling incubators ended to yolk sac absorption and entering larval stage. Hatching success, possible genome alterations by HSP70 gene expression and comet assay implemented as diagnostic tools in 3 life stages of eyed egg– Alevin and Larvae. Numbers and diameters of larvae white fiber muscles measured by histology experiment and Hematoxylin–eosine staining. Results stated significant effect of incubation temperature on hatching success, genome and white fiber muscles of wild and F1 samples. Hatching success measured as 31% and 38% for cultured and wild cold treatments, 79% and 91% for normal and 64% and 73% for warm cultured and wild treatments respectively. Considerable mortality occurred for cold treatment and 8 degree centigrade stated the best thermal condition in normal incubator according to hatching success in wild Caspian trout samples.

A Hydrogeologic Evaluation of the Waterloo Area in the Upper Jefferson River Valley, Montana

The Upper Jefferson River is one of the most dewatered rivers in Montana. The river exists in an intermontane basin filled with sediment transported from the Highland Mountains to the west, the Tobacco Root Mountains to the east, and the Jefferson River from the south. The Upper Jefferson River Valley is highly dependent on the Jefferson River as the main industry in the valley is agriculture. A majority of the valley is irrigated and used to grow crops, and a good portion is also used for cattle grazing. The residents of the Upper Jefferson River Valley use the aquifer as the main source of potable water. The Jefferson River is also widely used for recreation. This study took place in the Waterloo area of the Upper Jefferson River Valley, approximately 20 miles south of Whitehall, Montana. The Waterloo area provides significant groundwater base flow to the Jefferson River, which is particularly important during the late irrigation season when the river is severely dewatered, and elevated surface-water temperatures occur, creating irrigation water shortages and poor trout habitat. This area contains two springfed streams, Willow Springs and Parson’s Slough, which discharge to the Jefferson River providing cool water in the late season as well as providing the most important trout spawning habitat in the valley. The area is bordered on both the east and west by irrigation ditches, and about 60% of the study area is irrigated. Tile drains were installed in the study area in close proximity to Parsons Slough causing some concern by neighboring residents. This study evaluated relationships between surface water, groundwater, and irrigation practices so that water managers and others can make informed management decisions about the Upper Jefferson River. Data was collected via a network of groundwater wells and surface-water sites. Additionally, water-quality samples were taken and an aquifer test was conducted to determine aquifer properties. The field data were analyzed and a groundwater budget was created in order to evaluate the aquifer. Results of the groundwater budget show that seepage from the irrigation canals and irrigation recharge have the biggest influence on recharge of the aquifer. There is significant groundwater outflow from the aquifer in the spring-fed streams as well as discharge to the Jefferson River. In comparing previous study results to this study’s results, there is no evidence of the water table decreasing due to irrigation practice changes or tile drain installation. However, given the amount of recharge irrigation practices contribute to the aquifer, if significant changes were made, they may affect groundwater elevations. Also lining the irrigation ditches would have a significant impact on the aquifer, as the amount of seepage would be greatly reduced.

Geographic Variation of Notified Ross River Virus Infections in Queensland, Australia, 1985-1996

The spatial and temporal variations of Ross River virus infections reported in Queensland, Australia, between 1985 and 1996 were studied by using the Geographic Information System. The notified cases of Ross River virus infection came from 489 localities between 1985 and 1988, 805 between 1989 and 1992, and 1,157 between 1993 and 1996 (chi2(df = 2) = 680.9; P < 0.001). There was a marked increase in the number of localities where the cases were reported by 65 percent for the period of 1989-1992 and 137 percent for 1993-1996, compared with that for 1985-1988. The geographic distribution of the notified Ross River virus cases has expanded in Queensland over recent years. As Ross River virus disease has impacted considerably on tourism and industry, as well as on residents of affected areas, more research is required to explore the causes of the geographic expansion of the notified Ross River virus infections.