Sensory Biology as a Risk Factor for Invasion Success and Native Fish Decline

Abstract

Native freshwater fish populations are among the world’s most threatened taxa due to the combined effects of habitat degradation and invasive alien species. Habitat degradation negatively impacts native species, whereas invasive species tend to possess adaptations, such as thermal and salinity tolerance, that are more suited to the degraded environment. Sensory ecology may also be a contributing factor. Most threatened native species are visual feeders, whereas invasive species found in degraded systems often have nonvisual specializations. Behavioral and distributional characteristics of the invasive Western Mosquitofish Gambusia affinis and the New Zealand native Inanga Galaxias maculatus illustrate the potential for sensory biology to influence foraging success, distribution, and species interaction between degraded and clear habitats. Behavioral trials measured the change in feeding rate in clear (0 NTU) and turbid (100 NTU) water over 30 min for Inanga and Western Mosquitofish feeding on brine shrimp Artemia salina nauplii. These experiments showed that Western Mosquitofish maintained similar feeding rates between clear and turbid water, whereas the native species exhibited a marked decline in feeding efficiency in turbid water. Across a strong natural turbidity boundary, the alien species was found to dominate turbid habitat less than 1 m from clear water, where both species were found. Accounting for sensory biology as a potential contributing factor in the establishment of invasive fish species in degraded habitat may help to identify invasive species risk and to shape strategies for rehabilitating native species.

Received February 23, 2017; accepted July 3, 2017 Published online October 6, 2017

ACKNOWLEDGMENTS

This research was supported by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada to M. Abrahams and a postdoctoral award from the New Zealand Foundation for Research, Science, and Technology to D. Bassett.