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  • 1
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5344 | 1256 | 2011-09-29 15:02:55 | 5344 | Freshwater Biological Association
    Publication Date: 2021-07-10
    Description: Remarkably little has been published on the feeding habits of the non-salmonid fishes of British fresh waters. The following report briefly summarizes the results obtained from the examination of the stomach contents of some 2,700 fish, belonging to 19 species, which were obtained during 1939. The results of all examinations of gut contents were analysed, species by species, upon a simple basis of the presence of different types of food. Foodstuffs were divided up into six main categories— fish, molluscs, insects, crustaceans, higher plants together with filamentous algae, and diatoms—and the occurrence of members of any of these categories was recorded for each fish.
    Keywords: Biology ; Fisheries ; Limnology ; Coarse fish ; Feeding ; Feeding behaviour ; Fishery surveys ; Food organisms ; Gutting ; England
    Repository Name: AquaDocs
    Type: book , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 315-322
    Format: 33
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  • 2
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5345 | 1256 | 2011-09-29 15:02:58 | 5345 | Freshwater Biological Association
    Publication Date: 2021-07-10
    Description: It has been estimated that in England and Wales fresh water covers some 340 square miles of which about one quarter is inhabited mainly by salmon and trout; in Scotland the lakes cover an area of 340 square miles. The principal object of this publication is to make available in handy form some of the methods, especially those involving the use of manures, by which crops of fish from water can be increased. The cultivation of water which this implies may be compared directly to the cultivation of farm land: the conditions for growth are made as favourable as possible, the seed is sown in the form of young fish, and after one or perhaps two growing seasons the crop is harvested. There are however many waters about the country where marketable fish are already available and can be removed without prejudice to, and indeed to the advantage of, sporting fisheries. In such cases it is necessary only to remove the fish and to rely on the natural processes of reproduction of those which are left to repopulate the water. Farming waters in the true sense is the concern of the greater part of this publication; the removal of crops of otherwise unwanted fish is considered in the last two sections on perch trapping and eel fisheries.
    Keywords: Biology ; Fisheries ; Limnology ; Freshwater fish ; Fish culture ; Fish ; Freshwater aquaculture ; Pond construction ; Fish ponds ; Food consumption ; Food fish ; UK
    Repository Name: AquaDocs
    Type: book , FALSE
    Format: application/pdf
    Format: application/pdf
    Format: 315-322
    Format: 36
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  • 3
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5348 | 1256 | 2011-09-29 15:03:15 | 5348 | Freshwater Biological Association
    Publication Date: 2021-07-10
    Description: The need for research upon the coarse fishes of Britain, questions of the breeding and rearing of large numbers of young fish, more especially roach, was established back in 1937. The investigation which was begun in 1939 at Barrington in Cambridgeshire was therefore, with the full approval of the National Federation of Anglers, devoted to the general life histories of as many species as possible. Now, five years later, the results of the investigation are presented in the hope that they will provide a basis of knowledge upon which sound policies can be devised for the improvement of fish stocks and the increase of sport. In this report the scientific data, which will be published in full elsewhere, have been condensed as much as possible, but nothing of importance has been omitted and nothing has been concealed.
    Keywords: Biology ; Fisheries ; Limnology ; Coarse fish ; Fishery surveys ; Fish physiology ; Food composition ; Competition ; Angling ; England
    Repository Name: AquaDocs
    Type: book
    Format: application/pdf
    Format: application/pdf
    Format: 40
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  • 4
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5346 | 1256 | 2011-09-29 15:03:10 | 5346 | Freshwater Biological Association
    Publication Date: 2021-07-10
    Description: Parallel trials form a most important part of the technique of scientific experimentation. Such trials may be divided into two; categories. In the first the results are comparable measurements of one kind or another. In the second the data consist of records of the number of times a certain 'event' has occurred in the two sets of trials compared. Only trials of the second category are dealt with here. In this paper all the reliable methods of testing for significance the results of parallel trials of a certain type with special reference to fishery research are described fully. Some sections relate to exact, others to approximate tests. The only advantage in the use of the latter lies in the fact that they are often the more expeditious. Apart from this it is always preferable to use exact methods.
    Keywords: Biology ; Fisheries ; Limnology ; Freshwater fish ; Methodology ; Mathematical analysis ; Inland fisheries ; Equations ; Statistical analysis
    Repository Name: AquaDocs
    Type: book
    Format: application/pdf
    Format: application/pdf
    Format: 55
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  • 5
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5259 | 1256 | 2011-09-29 15:09:27 | 5259 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: In recent collaborative biological sampling exercises organised by the Nottingham Regional Laboratory of the Severn-Trent Water Authority, the effect of handnet sampling variation on the quality and usefulness of the data obtained has been questioned, especially when this data is transcribed into one or more of the commonly used biological methods of water quality assessment. This study investigates if this effect is constant at sites with similar typography but differing water quality states when the sampling method is standardized and carried out by a single operator. An argument is made for the use of a lowest common denominator approach to give a more consistent result and obviate the effect of sampling variation on these biological assessment methods.
    Description: Bilateral study of methods 2 - Pollution Report No.8
    Keywords: Biology ; Limnology ; Pollution ; Sampling ; Samplers ; Methodology ; Standardization ; Rivers ; Invertebrate larvae ; England ; Trent River
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 19
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  • 6
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    Freshwater Biological Association | Ambleside, UK
    In:  http://aquaticcommons.org/id/eprint/5270 | 1256 | 2011-09-29 15:10:29 | 5270 | Freshwater Biological Association
    Publication Date: 2021-07-09
    Description: At the present time hydrobiological indicators are widely used for the control of surface water quality. Results of the applying of methods suggested at the 1st Soviet-American seminar (1975), development of improved methods and estimation of their usefulness for various conditions are presented in this report. Among the criteria permitting an estimation of the degree and character of changes in water quality and their connection with the functioning of river ecosystems in general, the biological tests of natural waters appears to be the most universal one and is being carried out in two main directions — ecological and physiological. This study summarises approaches in both directions.
    Keywords: Biology ; Limnology ; Pollution ; River water ; Rivers ; Water quality ; Water quality control ; Indicators
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 6
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  • 7
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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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  • 8
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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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  • 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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