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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 5 (1997), S. 0 
    ISSN: 1526-100X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Extensive land loss, which is mostly wetland loss, has taken place during this century in the Mississippi River delta and other river deltas. Our purpose was to evaluate the effectiveness of constructing “artificial” crevasses, or cuts in the natural levee, made by the U.S. Fish and Wildlife Service in the Delta National Wildlife Refuge (DNWR) to slow or reverse this type of land loss. Land growth of the crevasses was determined from aerial photographs and was related to crevasse-site characteristics. The newly constructed crevasses create emergent wetlands after 2 years of subaqueous growth at about 4.7 ha/year and an average cost of $21,377 per crevasse. The present total cost per hectare declines with age as new land builds, and it will equal $48 per hectare if all the open water in the receiving ponds fills in. At these rates, the net land loss rates in the DNWR measured from 1958 to 1978 would be compensated for by the building of 63 crevasses, 24 of which are already in place.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 72 (1950), S. 4953-4955 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 72 (1950), S. 5015-5017 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 68 (1946), S. 574-577 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Infections of gill amoebae that manifest as amoebic gill disease (AGD) occur in Atlantic salmon in Tasmania. The treatment of choice is freshwater bathing; however, the effectiveness of this treatment has declined over time. In this experiment, cage trials of chloramine-T (Cl-T) to treat AGD in Atlantic salmon were conducted over 3 months, and involved an initial bath in either freshwater or seawater with Cl-T, followed by a second bath 6 weeks later. Amoeba densities were reduced to 50–80% of original values for both treatments. Neoparamoeba sp. density was not affected by bathing, and was not significantly different over the course of the experiment. Lesion prevalence was higher for Cl-T-treated fish than for freshwater-treated fish, with overall prevalence levels of 14.30±1.00% and 8.03±0.57% respectively. This was also seen for gross gill scores. In the fortnight after each of the two baths, Cl-T-treated fish had significantly higher lesion levels, although this difference was then resolved by 4 weeks post bathing. The use of Cl-T in seawater is at least as effective as freshwater at reducing amoebae density, and may be a more practical alternative when freshwater is in short supply.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 36 (2005), S. 0 
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Amoebic gill disease (AGD) is a significant disease of Atlantic salmon farmed in South East Tasmania. The commercial treatment for the disease is a freshwater bath for up to 4 h. Previous studies have shown that the chemical composition of the freshwater, in particular total water hardness, affects the efficacy of the treatment. The aim of this study was to determine if other water chemistry parameters, such as dissolved organic carbon (DOC), interact with total water hardness to affect treatment success. Firstly, the relative survival of isolated gill amoebae incubated for up to 3 h with hard or soft water (346.0 and 34.6 mg L−1 CaCO3 respectively) with low or high concentrations of humic or tannic acid (5 and 50 mg L−1 respectively) was determined. Secondly, fish with AGD were bathed for 2.5 h in hard or soft water (249.3 and 35.3 mg L−1 CaCO3) containing either 5 or 20 mg L−1 humic acid. The number of viable amoebae surviving on the gills and number of gill lesions were determined. It was found that the concentration of DOC used in this study that represents the levels commonly found around SE Tasmania is unlikely to have any commercial significance in the reduction in amoebae on the gills of Atlantic salmon. However, this study provided further support that freshwater selected for bathing AGD-affected salmonids should be chosen primarily on its total water hardness.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Growth and survival of juvenile greenlip (39.03 (SD 3.80) mm (n=524)) and blacklip (31.92 (SD 4.19) mm (n=531) abalone were investigated at high dissolved oxygen levels (95–120% saturation) between 17 and 19°C. Abalone were fed the same artificial diet and each species was contained in groups of approximately 30 individuals within triplicate tanks for each of six treatments and were exposed to flow through water adjusted to give experimental conditions for up to 75 days. Blacklip abalone held at 16.9°C and 97% oxygen saturation grew in shell length significantly faster than all other treatments of blacklip abalone held at 19°C, and significantly faster than blacklip abalone maintained at 111% oxygen saturation and 17.5°C. Both temperature and oxygen saturation significantly affected the survival of this species. Blacklip abalone held at 19°C had significantly lower survival for both 96% oxygen saturation and 120% oxygen saturation, compared with blacklip abalone maintained at either 110% oxygen saturation and 19°C, or for any 17°C treatment. No significant differences were noted for greenlip abalone within the range tested in terms of growth rate, food consumption rate or survival, indicating that greenlip abalone tolerated these conditions better than did blacklip abalone.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Atlantic salmon with amoebic gill disease (AGD) were treated with chloramine-T to compare its effectiveness with that of freshwater bathing. In 250-L tank trials, treatment of seawater with chloramine-T reduced amoeba density on the gills to levels significantly lower than when treated with seawater alone. There was no further change in amoeba levels in fish bathed for 3 or 6 h compared with 1 h of treatment. Plasma lactate levels in fish bathed in chloramine-T for 6 h showed no differences across treatments. In 1000-L tank trials using freshwater alone or seawater with chloramine-T, significant reductions in amoeba density occurred compared with pre-bath levels. Histological analysis of gill tissue revealed AGD lesion levels to increase, then to return to pre-bath levels within 1 week for freshwater-treated fish, while chloramine-T- and seawater-treated fish had higher levels of AGD lesions from 2 weeks post bathing. Immunodot-blot data indicated an initial significant increase in prevalence of lesions in seawater and chloramine-T-treated fish, which declined to levels significantly lower than pre-bath levels by 3 weeks post bathing, compared with the freshwater-treated fish, which had significantly lower levels than controls by 2 weeks post bathing. At reducing amoeba density, it is apparent that bathing AGD-affected Atlantic salmon in seawater with chloramine-T proved at least as effective as freshwater.
    Type of Medium: Electronic Resource
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