temperature. The physical environment of the secondary enclosure, such as a room, constitutes the macroenvironment.

Water Quality

The composition of the water (water quality) is essential to aquatic animal well-being, although other factors that affect terrestrial microenvironments are also relevant. Water quality parameters and life support systems for aquatic animals will vary with the species, life stage, the total biomass supported, and the animals’ intended use (Blaustein et al. 1999; Fisher 2000; Gresens 2004; Overstreet et al. 2000; Schultz and Dawson 2003). The success and adequacy of the system depend on its ability to match the laboratory habitat to the natural history of the species (Godfrey and Sanders 2004; Green 2002; Lawrence 2007; Spence et al. 2008).

Characteristics of the water that may affect its appropriateness include temperature, pH, alkalinity, nitrogen waste products (ammonia, nitrite, and nitrate), phosphorus, chlorine/bromine, oxidation-reduction potential, conductivity/salinity, hardness (osmolality/dissolved minerals), dissolved oxygen, total gas pressure, ion and metal content, and the established microbial ecology of the tank. Water quality parameters can directly affect animal well-being; different classes, species, and ages in a species may have different water quality needs and sensitivities to changes in water quality parameters.

Routine measurement of various water characteristics (water quality testing) is essential for stable husbandry. Standards for acceptable water quality, appropriate parameters to test, and testing frequency should be identified at the institutional level and/or in individual animal use protocols depending on the size of the aquatic program. Staff managing aquatic systems need to be trained in biologically relevant aspects of water chemistry, how water quality parameters may affect animal health and well-being, how to monitor water quality results, and how water quality may affect life support system function (e.g., biologic filtration).

The specific parameters and frequency of testing vary widely (depending on the species, life stage, system, and other factors), from continuous monitoring to infrequent spot checks. Recently established systems and/or populations, or changes in husbandry procedures, may require more frequent assessment as the system ecology stabilizes; stable environments may require less frequent testing. Toxins from system components, particularly in newly constructed systems, may require special consideration such as leaching of chemicals from construction materials, concrete, joint compounds, and sealants (DeTolla et al. 1995; Nickum et al. 2004). Chlorine and chloramines used to disinfect water for human consumption or to disinfect equipment are toxic to fish and amphibians and must be removed

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