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  • 1
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5096 | 1256 | 2011-09-29 15:24:47 | 5096 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: At high stream discharges salmonid eggs can he displaced from the gravel and may drift downstream. It has been suggested that developing salmonid eggs may be killed by ”physical shock”, especially during the period before ”eyeing”. Similarly, a progress report by the International Pacific Salmon Fisheries Commission (1966) states that salmonid eggs are most sensitive during the period between fertilisation and blastopore closure. However, it would seem unlikely that this sensitivity actually begins at the time of fertilisation because, in nature, a period, perhaps measured in hours, must occur during which the newly-fertilised eggs are exposed to physical shock during the deposition of gravel over them as a result of the cutting activity of the female fish. The present report describes simple channel experiments designed to answer the two questions: 1. After release of eggs from the gravel, does the process of drifting downstream, which implies some physical shock through movement and impact, decrease the survival of salmonid eggs? 2. Is the survival rate-influenced by the stage of development of the eggs?
    Keywords: Ecology ; Fisheries ; Limnology ; Freshwater ecology ; Rivers ; Freshwater fish ; Life cycle ; Channels ; Experimental research ; Fish eggs ; England ; Grassholme
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 33
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  • 2
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5092 | 1256 | 2011-09-29 15:25:26 | 5092 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: Aspects of reported nutrient levels and their ecological implications for Malham Tarn are discussed. Discussion centres upon the data given here as appendices, involving possible evidence of a long-term increase in the concentrations of some nutrients (especially nitrate) of significance for the Tarn's ecology and conservation. Further comparative tests of some methods of chemical analysis employed in obtaining those data are reported.
    Keywords: Biology ; Ecology ; Limnology ; Freshwater ecology ; Freshwater lakes ; Nutrients (mineral) ; Nitrates ; Phosphorus ; Alkalinity ; Methodology ; Ultraviolet radiation ; Hydrology ; England ; Malham Tarn
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 42
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  • 3
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5097 | 1256 | 2011-09-29 15:24:43 | 5097 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: It is of value to know the approximate distance of travel at different stream discharges and/or water velocities, of salmonid eggs which have been displaced from redds by spates. This report describes studies in 20 m of stream channel upstream of the fish trap in Dubby Sike. Observations were made on the relation- ships between discharge and water depth and velocity and also on the relationships between water velocity and the settlement of artificial trout eggs. The main aim was to test the hypothesis that, at any given water velocity, eggs would drift smaller distances in a natural stream than in the experimental channels.
    Keywords: Ecology ; Fisheries ; Limnology ; Freshwater ecology ; Rivers ; Freshwater fish ; Channels ; Experimental research ; Fish eggs ; England ; Grassholme
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 31
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  • 4
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5124 | 3949 | 2011-09-29 15:23:13 | 5124 | Freshwater Biological Association
    Publication Date: 2021-07-08
    Description: A review article looking at the type of information requirements commonly shared by scientists and their use of traditional information services. Areas covered include primary requirements of IFE (Institute of Freshwater Ecology) staff, pure versus applied research, informal and personal sources of information, and traditional library and information services. It goes on to describe how research into information systems and technology may improve the wider accessibility and use of information to the scientific community. Technologies covered include online databases, telecommunications, gateways, expert systems, optical technology and applications of CDROM.
    Keywords: Ecology ; Environment ; Information Management ; Freshwater ecology ; Research institutions ; Research ; Information scientists ; Information services ; Annual reports ; England ; Lake District
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 55-67
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  • 5
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5238 | 1256 | 2011-09-29 15:13:42 | 5238 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: This report presents five batches of data which have been despatched to the Joint Research Centre, Ispra. The data as been allocated to various ECDIN (Environmental Chemicals Data and Information Network) files. The data comprises environmental chemicals in the freshwater environment, taking in paricular consideration: aquatic toxicity, bioaccumulation, metabolism and elimination biodegradation.
    Keywords: Chemistry ; Ecology ; Limnology ; Data ; Data processing ; Data collections ; Chemical compounds ; Toxicity ; Bioaccumulation ; Biodegradation ; Metabolism
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 8
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  • 6
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5287 | 1256 | 2011-09-29 15:12:00 | 5287 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: Restoration of water-bodies from eutrophication has proved to be extremely difficult. Mathematical models have been used extensively to provide guidance for management decisions. The aim of this paper is to elucidate important problems of using models for predicting environmental changes. First, the necessity for a proper uncertainty assessment of the model, upon calibration, has not been widely recognized. Predictions must not be a single time trajectory; they should be a band, expressing system uncertainty and natural variability. Availability of this information may alter the decision to be taken. Second, even with well-calibrated models, there is no guarantee they will give correct projections in situations where the model is used to predict the effects of measures designed to bring the system into an entirely different ”operating point”, as is typically the case in eutrophication abatement. The concept of educated speculation is introduced to partially overcome this difficulty. Lake Veluwe is used as a case to illustrate the point. Third, as questions become more detailed, such as ”what about expected algal composition”, there is a greater probability of running into fundamental problems that are associated with predicting the behaviour of complex non-linear systems. Some of these systems show extreme initial condition sensitivity and even, perhaps, chaotic behaviour, and are therefore fundamentally unpredictable.
    Keywords: Ecology ; Limnology ; Pollution ; Eutrophication ; Algal blooms ; Phytoplankton ; Freshwater lakes ; Models ; Growth ; Modelling ; Equations ; Bacteria ; Prediction ; Netherlands ; Veluwemeer Lake
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 44-58
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  • 7
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5285 | 1256 | 2011-09-29 15:11:44 | 5285 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: The ”Vollenweider model” is a sophisticated mathematical statement about the long-range behaviour of (mainly temperate) lakes and their ability to support phytoplankton chlorophyll. Misapplication of the model, against which Vollenweider himself warned, has led to many misconceptions about the dynamics of plankton in lakes and reservoirs and about how best to manage systems subject to eutrophication. This contribution intends to frame the most important issues in context of the phosphorus- loading and phosphorus-limitation concepts. Emphasis is placed on the need to distinguish rate-limitation from capacity-limitation, to understand which is more manageable and why, to discern the mechanisms of internal recycling and their importance, and to appreciate the respective roles of physical and biotic components in local control of algal dynamics. Some general approaches to the management of water quality in lakes and reservoirs to eutrophication are outlined.
    Keywords: Ecology ; Limnology ; Pollution ; Eutrophication ; Algal blooms ; Phytoplankton ; Models ; Phosphorus ; Ecosystem management ; Nutrients (mineral) ; Plant growth ; Growth regulators ; Freshwater lakes
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 4-29
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  • 8
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5289 | 1256 | 2011-09-29 15:08:12 | 5289 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: Results from long-term investigations on biomanipulation show that indirect effects are at least as important as direct effects are for the stability of biomanipulation. Three types of indirect effects can be distinguished: (1) a change in quantity or quality of the resource base, (2) behavioural change of the prey, and (3) development of anti-predator traits. Although indirect effects of type (2), (e.g. a change in the pattern of vertical migration of zooplankton), and type (3), (e.g. development of helmets and neck teeth in Daphnia), are important mechanisms, the most essential indirect effects regarding biomanipulation belong to type (1). An example of the latter will be demonstrated: the complex of indirect effects of enhanced grazing by large herbivores on the phosphorus metabolism of the lake. It is concluded that control of the indirect effects is absolutely necessary to stabilize biomanipulation measures, but this is much more difficult than the control of direct effects and needs deeper insights into the structuring mechanisms of food webs. Proper management of fish stocks, in combination with the control of phosphorus load and/or the physical conditions, seems to be the most promising way of controlling the indirect effects of biomanipulation.
    Keywords: Ecology ; Limnology ; Eutrophication ; Freshwater lakes ; Biomanipulation ; Water quality control ; Food webs ; Phosphorus
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 82-93
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  • 9
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5290 | 1256 | 2011-09-29 15:08:14 | 5290 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: In the mesotrophic-eutrophic Saidenbach Reservoir in Saxony, the nanoplankton and cyanobacteria have increased at the expense of diatom dominance, due to a doubling of the external phosphorus load in the last 15 years. However, the phosphorus sedimentation flux is still very high (up to 80% of the input), corresponding to more than 2 g m2 d-1 in terms of dry weight. There is a strong correlation between the abundance of diatoms in the euphotic zone and their sedimentation flux (with a delay of about 2 weeks). Only about 25% of the deposited material could be clearly attributed to plankton biomass; the remainder resulted from flocculation and precipitation processes or directly from the inflow of clay minerals. The ash content of the deposited material was high (73%). Thus the sedimentation flux can be considered to operate as an internal water-treatment/oligotrophication process within the lake. The neighbouring Neunzehnhain Reservoir still has a very clear water with a transparency up to 18 m depth. Though the sediment was not much lower than Saidenbach sediment in total phosphorus and total numbers of bacteria, sulphide was always absent and the ratio of Fe 2+ to Fe 3+ was very low in the upper (0- 5 cm) layer. Thus the external and internal phosphorus loads do not attain the critical level necessary to induce a ”phosphorus - phytoplankton” feedback loop.
    Keywords: Ecology ; Limnology ; Pollution ; Eutrophication ; Freshwater lakes ; Water quality control ; Phosphorus ; Water reservoirs ; Phytoplankton ; Growth ; Sedimentation ; Sediment composition ; Germany
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 94-106
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  • 10
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5295 | 1256 | 2011-09-29 15:07:49 | 5295 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: In a small lake, intermittent destratification was installed after several other physico-chemical and physical in-lake therapy measures (phosphorus immobilization, permanent destratification) had been tested without great success. If an aerobic sediment-water interface can be maintained, intermittent destratification removes cyanobacteria and prevents optimal development of other members of the photoautotrophic plankton. During growing seasons, increasing abundances of small-bodied herbivores (Bosmina) and Daphnia may have accounted for relatively low phytoplankton biomass as well. Intermittent destratification is a very fast-working in-lake measure and seems to be applicable even in relatively shallow lakes (〈 15 m), in which permanent destratification seems to be risky.
    Keywords: Ecology ; Limnology ; Pollution ; Eutrophication ; Algal blooms ; Destratification ; Ecosystem management ; Water quality control ; Phosphorus ; Eutrophic lakes ; Inhibitors ; Phytoplankton ; Zooplankton ; Biomass ; Germany ; Fischkaltersee
    Repository Name: AquaDocs
    Type: book_section , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 163-184
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