Líffræðifélag Íslands
Líffræðiráðstefnan 2015
Erindi/veggspjald / Talk/poster E2
Amy Fingerle, Nicolas Larranaga, Stefán Óli Steingrímsson
Hólar University College
Kynnir / Presenter: Stefán Óli Steingrímsson
Tengiliður / Corresponding author: Stefán Óli Steingrímsson (stefan@holar.is)
Intraspecific competition plays a key role in shaping how animals use and share habitats in space and time. However, the way individuals modify their diel activity in response to increased competition has received limited attention. We used juvenile (age 1+) Arctic charr to test the prediction that individuals at high population density are more active and distribute their foraging activity over a greater portion of the 24 h cycle than individuals at low population density. Individually-tagged fish were stocked in semi-natural stream enclosures at low (2 fish/m2) and high (6 fish/m2) density. During each of two 2-week experimental rounds, activity of all fish within each enclosure was recorded every three hours over seven 24 h cycles. At high density, fish were more active and distributed their activity over a greater portion of the 24 h cycle, with increased activity particularly at crepuscular times. Fluctuations in ecological conditions (e.g. water temperature and light intensity) also affected activity. Fish at high density grew as fast as fish at low density. This study highlights the behavioural flexibility exhibited by individuals in response to changes in ecological conditions, and suggests that intraspecific competition can cause animals to modify their activity patterns to gain access to resources and maintain growth.