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Abstract

Despite potentially reducing predation
mortality, behavioural responses of native species to
introduced predators may still have sub-lethal
impacts. In video-recorded laboratory trials, we
examined the effects of introduced brown trout,
Salmo trutta, on the short-term behaviour of a
threatened, lake-dwelling galaxiid fish and confirmed
a suspected diel pattern in habitat use by this species.
We found that Galaxias auratus followed a distinct
diel pattern in the use of complex habitats and open
water, which was significantly altered by the presence
of brown trout. In trials without the introduced
predator, G. auratus used complex habitats (rocks or
macrophytes) during the day, and open water during
the night. In trials with brown trout present, G. auratus
spent significantly less time in open water and
rarely ventured out of the macrophytes. However,
when given the option of using only rocky substrate
or open water, which is the more common situation in
the lakes to which this galaxiid is endemic, the fish
reduced the amount of time they spent in the open
water during the night, but still spent more time in
open water than when macrophytes were available.
Spending the daylight hours amongst the cover of
rocks or macrophytes is most likely an adaptation to
reduce the risk of predation by visual predators, and
the pattern of reduced use of open water habitats in
the presence of brown trout is an acute response to
the close proximity of the introduced predator. The
difference in the nocturnal use of macrophytes and
rocks when trout are present may be related to
differences in feeding opportunities or success within
these habitats.

Item Type:	Article
Authors/Creators:	Stuart-Smith, RD and White, RWG and Barmuta, LA
Keywords:	Habitat complexity Brown trout Galaxias auratus Predation risk Diel pattern
Journal or Publication Title:	Environmental Biology of Fishes
Publisher:	Springer Netherlands
ISSN:	0378-1909
DOI / ID Number:	https://doi.org/10.1007/s10641-007-9256-z
Additional Information:	The original publication is available at www.springerlink.com
Item Statistics:	View statistics for this item

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