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  • 1
    Electronic Resource
    Electronic Resource
    A mathematical model of the aerobic deterioration of big-hale silage and its implications for the growth of Listeria monocytogenes (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 50 (1995), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Aerobically spoiled silage has often been shown to harbour dangerously high levels of Listeria monocytogenes. This paper investigates the dynamics of aerobic deterioration in a silage bale as it occurs close to a site of damage to the cover. The underlying aim was to enable prediction of the extent of the silage that may become suitable for Listeria growth during the course of storage. In order to meet these objectives, a model was formulated that represents the microbiology of the deterioration process and the transport of oxygen and heat through the silage. The geometry of the system was exploited to ensure that the model is computationally tractable. The model was used to evaluate the effect of silage pH and puncture size on the risk of Listeria contamination. Although the hazardous fraction was seen to be relatively insensitive to the initial pH of the silage, it increased rapidly with puncture size. However, a small puncture can result in the ‘loss’ of a considerable fraction of the bale because of the relatively long time scale over which bales are stored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1995.tb02328.x
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  • 2
    Electronic Resource
    Electronic Resource
    Aerobic deterioration of grass silage: the need to couple models and experiments (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 49 (1994), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A mathematical model of the aerobic stability of grass silage is presented. The model is shown to predict as well as more complex models previously published. Sensitivity analysis performed on model parameters suggests that current understanding of the temperature dependence of yeast growth needs to be advanced in order to produce more accurate models of deterioration. Inhibition of yeast growth by organic acids is identified as a critical process worthy of further investigation. We discuss how model validation experiments must identify different yeast species and track their growth separately. Such experiments should also attempt to minimize or measure heat losses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1994.tb02023.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The influence of differential swimming speeds on composition of multi-species fish shoals (2005)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 67 (2005), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The importance of species-specific swim speeds for the formation of multi-species fish shoals in a Canadian freshwater system was investigated. Swim speed was positively correlated with total length and differed between species but was unrelated to shoal size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0022-1112.2005.00768.x
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  • 4
    Electronic Resource
    Electronic Resource
    Fish don’t read textbooks: juvenile salmon prove ignorant of foraging theory (2003)
    Oxford, UK; Malden, USA : Blackwell Science Ltd/Inc
    Journal of fish biology 63 (2003), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The rules governing the selection of feeding patches by foraging animals is an area of intense interest. Much work has focussed on the development of theoretical models that predict when individuals should switch patches. Tests of these models have often been conducted in laboratory environments, but it is not clear how much influence patch-switching decisions have on population-level parameters such as growth and distribution in more complex natural environments. We used juvenile Atlantic salmon as a model species to investigate the effects of randomly fluctuating food levels on growth and site selection. We used PIT technology to monitor in detail individuals’ patterns of patch use and activity in an artificial stream, at natural densities. This allowed us experimental control of food supplies and sufficient replication, while retaining many features of a natural system. Only a few individuals of high social rank switched patches as predicted by an appropriate foraging model; otherwise, although frequent, patch-switching was not related to food availability. Thus, while laboratory experiments indicate that this species has the potential to choose foraging sites on the basis of food availability, it is unlikely that this behavioural mechanism is of great importance in natural systems; further tests of foraging models under natural conditions are essential if we are to understand their effects at the level of populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2003.0216y.x
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  • 5
    Electronic Resource
    Electronic Resource
    Is there always an influence of shoal size on predator hunting success? (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 52 (1998), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Theoretical and empirical studies predict that there should be a decrease in hunting success of predators with increasing prey group size. Most of these studies investigated situations in which predator and prey were in full view of each other before, during and after an attack. In this study, single rock bass Ambloplites rupestris were given an opportunity to launch surprise attacks at shoals of creek chub Semotilus atromaculatus that ranged in size from two to 13 fish. There was no significant influence of either shoal size or attack distance on predator success rate and no significant relationship between attack distance and shoal size. Furthermore, it was found that the leading fish of a shoal was attacked significantly more often than fish in other shoal positions, indicating that predation risk was not shared equally among shoal members. Also, leading fish in larger shoals (eight to 13 fish) were not more likely to survive a predator attack than ones in small shoals (two to seven fish).The consequences of these results are discussed in the general context of antipredator benefits of grouping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1998.tb02012.x
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  • 6
    Electronic Resource
    Electronic Resource
    Refuge use in sticklebacks as a function of body length and group size (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 56 (2000), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A change in anti–predator strategy from hiding to grouping outside a refuge was observed in large three–spined sticklebacks. No such change in strategy was seen in small fish. The body–length dependence of this strategy change is discussed in the context of metabolic constraints.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.2000.tb00891.x
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  • 7
    Electronic Resource
    Electronic Resource
    Refuge use by fish as a function of body weight changes (1999)
    Springer
    Acta ethologica 2 (1999), S. 29-34 
    Details
    ISSN: 1437-9546
    Keywords: Key words Gasterosteus aculeatus ; Foraging behaviour ; Refuge use ; Weight change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Refuge use provides a good model for the study of trade-offs between the benefits of predator avoidance and the costs of lost feeding opportunities. We manipulated the latter costs by subjecting similar-sized three-spine sticklebacks to 2 days of food deprivation followed by a 2-day re-feeding period and recorded associated changes in body weight and refuge use. Food deprivation resulted in a decrease and re-feeding in an increase in the duration of refuge use by fish. Emergence times of fish from the refuge were extremely variable (with a ratio of 1:127 between the shortest and the longest ones) but individual ranks were highly consistent between different days of testing, suggesting that emergence times were individually characteristic. Percentage weight change of fish in response to the experimental treatments also showed a high level of inter-individual variation ranging from 0–17%. A significant positive correlation was found between the percentage weight lost and the percentage decrease in emergence time from a refuge after food deprivation and similarly between the percentage weight gained and the percentage increase in refuge use after re-feeding. The relationship between energy turnover and behavioural strategies is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00012229
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  • 8
    Electronic Resource
    Electronic Resource
    Group size and relative competitive ability: geometric progressions as a conceptual tool (2000)
    Springer
    Behavioral ecology and sociobiology 47 (2000), S. 113-118 
    Details
    ISSN: 1432-0762
    Keywords: Key words Assortative shoaling ; Competition ; Gasterosteus aculeatus ; Group size ; Group composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Contrary to the assumptions of many previous theoretical models, group size has recently been shown in experiments to have an effect on the relative (as well as absolute) competitive abilities of group members. Here we introduce a novel and effective mathematical tool for describing how relative competitive ability will change for any two specified individuals within a group as group size changes. We show that there is no simple general rule for describing how relative competitive ability will change with group size. A subsequent empirical test of the model helps to illustrate that very specific knowledge of the system under study is needed in order to produce robust predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050001
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