Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2017
Erindi/veggspjald / Talk/poster V55
Höfundar / Authors: Krystal Mannion (1), Coralie Delarue (1), Jeroen Koolmees (1), Fia Finn (1,2), Stefán Óli Steingrímsson (1)
Starfsvettvangur / Affiliations: 1. Hólar University College, Department of Aquqculture and Fish Biology, 2. University of Iceland, Institute of Life and Environmental Science
Kynnir / Presenter: Stefán Óli Steingrímsson
Food availability and predation risk, are two principal factors that influence the way animals exploit and compete for resources in time and space. This project examines the role of intraspecific competition on diel activity patterns and foraging of juvenile Arctic charr (Salvelinus alpinus) by manipulating the abundance of drifting invertebrate prey (high/low food availability) and measuring individual behaviour. In a semi-natural field experiment, 64 fish were tagged, weighed, measured and randomly assorted into 8 enclosures exposed to either unmanipulated food availability (high) or filtered food availability (low). Overall, the low food treatment experienced an average 47.7% reduction in drift density (prey/m³). All individuals were monitored for six 24hr cycles, over the course of two weeks, during which individual behaviour (diel activity, space use, and foraging mode) and environmental conditions (water temperature, light intensity, water current velocity, and depth) were recorded. All individuals were then observed in controlled laboratory conditions for behavioural variation (i.e. boldness) by measuring repeated responses in shelter emergence, open field activity, and sociability test arenas. We predicted that, for individuals to meet energetic demands, low food availability may cause fish to (i) increase their overall time spent searching for food, and (2) feed more during the day, when foraging is riskier but more efficient. We also expect that diel activity patterns, foraging and growth may be related to phenotypic differences among individuals.