Do fish respond to enhanced in-stream detritus? Using ecology to inform restoration — ASN Events

Do fish respond to enhanced in-stream detritus? Using ecology to inform restoration (#30)

Gabriel L Cornell 1 , Barbara J Downes 1 , Robin Hale 1 , John R Morrongiello 1
  1. Melbourne University, PARKVILLE, VIC, Australia

In-stream habitat restoration generally focusses on providing large, expensive structures for
large, adult fishes. Many of these projects fail to achieve their intended outcomes because
they rely on a “build it and they will come” approach, which often ignores how fish will likely
respond to restoration attempts. Here, we experimentally explore how native fish respond
to in-channel habitat modification, and demonstrate the potential application of a novel,
low-effort method of restoring fish populations. Pairs of wooden garden stakes were placed
in a degraded, sand-affected stream, which effectively trapped passing detritus and locally
increased detrital loads. Over the course of a year, we assessed the response of the fish
community to this increase in detritus. Greater abundance of river blackfish, mountain
galaxias and southern pygmy perch were recorded at sites with enhanced detritus. This
positive response of fish, however, was contingent on the time of year, the life-stage of
individuals, the age of the treatments and the broader stream habitat conditions. The
complexity of our results highlights the importance of understanding the ecological
constraints on a fish community before attempting to undertake restoration. 

#ASFB2018