A fluviarium with controlled water velocity and quality for preference–avoidance experiments with fish and invertebrates
Sustainable management of aquatic ecosystems includes maintaining adequate water quality for aquatic fauna. Inadequate water quality may elicit a response in fish and mobile invertebrates. For example, discharges of water of an inadequate quality may create barriers to movement, potentially affecting migration and recruitment of fish and invertebrate species. If adults avoid such discharges, spawning migrations may be affected, while partial or complete recruitment failure may occur if juveniles avoid such discharges. As a result, the capacity of habitats beyond the discharge point to act as spawning or nursery areas may be reduced, with potential effects on population genetics as well as stock size.
The effect of environmental variables on movement of aquatic organisms can be examined using preference-avoidance behaviours. Fluviariums, or paired channels of a laboratory stream, have been used to examine such preference-avoidance behaviour in fish, including choices associated with various water quality parameters. The sharp gradient in fluviariums provides aquatic organisms with a choice of (usually) two water qualities, sharply demarcated at a relatively narrow boundary zone. A detailed description of a recently constructed fluviarium, however, is missing from the literature.
The fluviarium described in this paper integrates hydrodynamic design and extensive control of water quality to provide consistent experimental conditions, while at the same time being affordable. The system described was designed and used to examine acid avoidance behaviour in juvenile fish and prawns, as part of a larger study on migration barriers in aquatic environments. An assessment of the fluviarium with juvenile snapper, Pagrus auratus, showed that the system worked as desired. The design described here, however, can be used or modified to study behavioural responses of aquatic biota to a wide variety of environmental variables, including habitat quality or combinations of two or more environmental variables.
This work is part of grant no. 1998/125 from the Australian “Fisheries Research & Development Corporation”. Their support is gratefully acknowledged.