Artificial light at night and the predator-prey dynamics of juvenile Atlantic salmon (Salmo salar L.) in freshwater

Newman, Rhian 2015. Artificial light at night and the predator-prey dynamics of juvenile Atlantic salmon (Salmo salar L.) in freshwater. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Artificial Light at Night (ALAN) is among the fastest growing anthropogenic influences on the natural environment. ALAN has been suggested to affect the behaviour and physiology of nearly all vertebrates and invertebrates by reducing the distinction between day and night, and by altering the cues that activate nocturnal behaviours. Information is particularly scarce for freshwater ecosystems, many of which are close to sources of ALAN. This thesis examines the behavioural and physiological impact of broad spectrum ALAN on Atlantic salmon (Salmo salar L.) and their invertebrate prey. After reviewing available literature of the effects of ALAN on freshwaters (Chapter 1), a series of empirical field and laboratory experiments examined the impact of ALAN on i) invertebrate drift in an experimentally artificially lit stream (Chapter 2) to determine the influence of ALAN on the primary food source of Atlantic salmon; ii) the dispersal behaviour (Chapter 3) and cortisol stress response in dispersing Atlantic salmon fry (Chapter 4); and iii) the diel pattern of foraging and refuging in Atlantic salmon parr (Chapter 5). ALAN impacted the drifting behaviour of invertebrates from contrasting taxa with a divergent effect of ALAN between taxa and functional feeding groups (FFGs), with some increasing and others decreasing under part-lighting. In dispersing Atlantic salmon fry, ALAN disrupted the timing and periodicity of nocturnal dispersal behaviour, at all experimental light intensities (1 – 8 lux). However, this behavioural change was not the result of a cortisol stress response. Finally, ALAN affected activity levels of Atlantic salmon parr through disrupting the amount and timing of refuging behaviour, with fish housed under high intensity ALAN found to refuge 28 % more than those in the control treatment. These results highlight the complex nature of the response of both Atlantic salmon and their invertebrate prey to ALAN, whereby the influence of ALAN can be difficult to generalise between taxa and species’ life stages. Moreover, this thesis provides evidence to inform proposed mitigation strategies and advocates an increase in natural unlit areas.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Biosciences
Subjects:	Q Science > QH Natural history > QH301 Biology Q Science > QL Zoology
Date of First Compliant Deposit:	30 March 2016
Last Modified:	16 May 2022 10:44
URI:	https://orca.cardiff.ac.uk/id/eprint/79119

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