Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Movement of non-native rainbow trout in an estuary with periodic summer hypoxia.

Abstract

Many present-day aquatic ecosystems are defined by anthropogenic activities such as the introduction of non-native species, habitat loss, and eutrophication. On Prince Edward Island, Canada, non-native rainbow trout (Oncorhynchus mykiss) have established in highly agricultural coastal watersheds. We used acoustic telemetry with continual oxygen and temperature monitoring to explore the relationship between rainbow trout movements, low dissolved oxygen, high temperature, and other environmental parameters in the eutrophic Dunk River estuary. We tested the hypothesis that rainbow trout capitalize on increased productivity from nutrient stimulation but face a trade-off with disturbed water quality. We divided the salinity transition gradient into zones representing the transition from freshwater to seawater and established that temperature and hypoxia increased with salinity. During hypoxic periods, movements decreased, and residence increased in low salinity habitat (< 1 Practical Salinity Units, PSU) Movement between zones increased from September to November, when conditions improved. A boosted regression tree model showed that dissolved oxygen, discharge, and temperature were related to occupancy which was greatest at dissolved oxygen levels > 6 mg L-1, discharge averaging 2 m3 s-1, and temperatures below 23°C. This study provides insights into the success of rainbow trout in eutrophic estuaries.