Shuttle-box systems for studying preferred environmental ranges by aquatic animals

Abstract

Animals’ selection of environments within a preferred range is key to understanding their habitat selection, tolerance to stressors and responses to environmental change. For aquatic animals, preferred environmental ranges can be studied in so-called shuttle-boxes, where an animal can choose its ambient environment by shuttling between separate choice chambers with differences in an environmental variable. Over time, researchers have refined the shuttle-box technology and applied them in many different research contexts, and we here review the use of shuttle-boxes as a research tool with aquatic animals over the past 50 years. Most studies on the methodology have been published in the latest decade, probably due to an increasing research interest in the effects of environmental change, which underlines the current popularity of the system. The shuttle-box has been applied to a wide range of research topics with regards to preferred ranges of temperature, CO2, salinity and O2in a vast diversity of species, showing broad applicability for the system. We have synthesized the current state-of-the-art of the methodology and provided best practice guidelines with regards to setup, data analyses, experimental design and study reporting. We have also identified a series of knowledge gaps, which can and should be addressed in future studies. We conclude with highlighting directions for research using shuttle-boxes within evolutionary biology and behavioural and physiological ecology.

Silver carp experience metabolic and behavioral changes when exposed to water from the Chicago Area Waterway; implications for upstream movement

“…More speci cally, there was no signi cant difference between the CAWS and control treatments for metrics including whether or not the sh shuttled, frequency of shuttles, latency to rst shuttle, and time spent the side of the shuttle box that received an input of CAWS water during the avoidance assay. Organisms can show a number of possible responses when confronted with a deleterious change in their environment 39,64 , with one possible response being a choice between different environments based on physiological preferences 10 . Many organisms exhibit environmental preferences in direct response to possible negative physiological effects that could occur while occupying sub-optimal habitat 2 .…”

“…Many organisms exhibit environmental preferences in direct response to possible negative physiological effects that could occur while occupying sub-optimal habitat 2 . One tool that can be used to quantify avoidance or preference of differing environments in a laboratory setting is a 'shuttle box' 10 . In the past, shuttle boxes have been used to quantify avoidance of noxious stimuli such as salinity, CO 2 gas, and temperature [65][66][67][68] .…”

“…Changes in swimming behavior in response to an environmental stressor has also been documented, as altered behavior can be an indicator of decreased performance in individuals 9 . In extreme cases, in an effort to avoid increased energetic costs concomitant with suboptimal habitat, sh may choose to simply swim away and avoid certain areas, exhibiting behavioral avoidance 10 . Speci cally, aquatic organisms will avoid deleterious environmental conditions and move to a more optimal location, with some species having different environmental tolerances than others 11 .…”

The interplay between sleep and ecophysiology, behaviour and responses to environmental change in fish

“…It is possible that temperature plays a role in the sleeping location selected by fish, with preference given to locations with a temperature that reduces sleep disruption or minimises potential trade-offs with energy allocation or risk of predation. Elevated temperature has been shown to increase activity in awake fish ( Little et al, 2020 ), so if sleeping fish are exposed to higher temperatures, we might expect sleep disruptions, which could affect behaviour the following day ( Pinheiro-da-Silva et al, 2017b , 2018 ) as well as alter aerobic metabolism and hormonal signalling ( Christensen et al, 2021 ). Alternatively, if exposure to elevated temperature occurs during a non-sleep period and leads to fish becoming more active, we might expect to see increased sleep the following night to allow the fish to recover from periods of high activity, or the use of increased sleep as a means to reduce overall energy expenditure ( Lesku and Schmidt, 2022 ).…”

On the relevance of animal behavior to the management and conservation of fishes and fisheries

“…Apart from movement and migration, the thermal choices of fish in the laboratory can be used to predict their ecologically optimal temperature range in the wild. A variety of behavioral arena designs have been used to do so over the years (Christensen et al 2021). In most cases, laboratory experiments are the only way to assess the 'true' thermal preferences of fishes (because other influences like food and predators can be controlled in the lab), but thermal preference behavioral tests have not proliferated widely (e.g., unlike the use of CTmax, or respirometry, to assess thermal performance), perhaps because the experiments are time-consuming and technically challenging (Speers-Roesch and Norin 2016).…”