Effects of the optical habitat on foraging and predator avoidance behavior of Galaxias maculatus

Increasing concentrations of colored dissolved organic matter (CDOM) due to land-use permafrost thawing and landscape vegetation are darkening Northern Hemisphere freshwaters. In addition, mining activities increase water turbidity. In Chile, the same phenomena are observed, and melting glaciers are also responsible for increased turbidity. CDOM and turbidity are part of the optical habitat of fish, as is the color of the riverbed. For visual predators such as invasive trout species in Chilean rivers, turbidity is a key factor in foraging. Higher turbidity has been shown to negatively affect their foraging success. However, the effect of CDOM on salmonid foraging has never been studied. Combined, CDOM and turbidity could reduce trout predation on native Galaxias maculatus in invaded Chilean rivers. However, CDOM and turbidity could affect predator avoidance behavior by Galaxias. It’s not known whether a darker, more lurking environment could potentially shield galaxias from predation, or reduce their response time to predators’ visual cues. Nor is it known whether changes in optical habitat will reduce foraging efficiency. We aim to assess the effect of the optical habitat on G. maculatus foraging and predator avoidance behavior in trout invaded Chilean rivers, something never done before.

Faculty Supervisor:

Eva Enders;Isabelle Laurion

Student:

Partner:

Universidad Austral de Chile

Discipline:

Life Sciences

Sector:

Environmental Science and Technology; Sustainability & the Environment

University:

Université du Québec : Institut national de la recherche scientifique

Program: