Special Issue Survey of Cetaceans in Captive Care

6. Life Support Systems 355al., 1999). Erysipelothrix rhusiopathiae is anotherpathogenic bacterium, which also is presumed to bein food. It causes erysipelas, which can be lethal inits septicemic form (Dunn, 1990; Sweeney, 1993).The main bacteria that is monitored is coliformbacteria, which can cause water contamination. Itcan be recognized, though, that pathogens could bepresent in marine mammal pools when coliformsare low in number or absent (Spotte, 1991). Faecalcoliform bacteria, Escherichia coli, is released inthe water through dolphin faecal matter. A high concentrationof E. coli can be harmful to animals andindicates an unbalanced sterilisation system or waterexchange. Measurements are obtained by the MTF(Multiple Tube Fermentation) method. The concentrationsof these bacteria is expressed in MPN (MostProbable Number). Another method called MF(Membrane Filtration) can be used and is expressedin number of colony-forming units/100 ml of water(Spotte, 1991). Coliform count should be performedweekly (E. coli is the most significant of the familyEnterobacteriacae, which also includes most speciesof Citrobacter, Enterobacter, and Klebsiella)(Arkush, 2001; Spotte, 1991). Results above 100MPN require a correction of the sterilisation systemor an increase in the changing of water (Sweeney &Samansky, 1995).A weekly count of total bacteria should beevaluated against the historical norm of the location.If the tests indicate a contamination, they willbe repeated and the source identified (Sweeney,1993).A water- and soil-borne bacterium, Burkholderiapseudomallei (formerly named Pseudomonaspseudomallei), endemic to Southeast Asia, but nowrecognized in humans and animals worldwide, canbe found in dolphinarium waters, especially afterheavy rains when soil is washed into the pools. Itis responsible for a dangerous infectious diseasecalled melioidosis, which is lethal in most cases(Liong et al., 1985; Reeves et al., 1994; Sweeney,1986). A vaccine is now available for melioidosis(Kennedy-Stoskopf, 1990), but it is still recommendedthat the presence of this bacterium bemonitored closely in regions at risk.Where pools holding cetaceans have sandybottoms, regular inspections will be undertakento ensure that bottom sediments do not becomeanoxic (Anonymous, 1992b).AlgaeAlgae are single-celled (e.g., phytoplankton) orsimple multi-celled (e.g., macrophyte or seaweed)organisms commonly found in surface water andproduce their own food through photosynthesis.Excessive algal growth may cause the water to haveundesirable odours or tastes, and decay of algaecan deplete the oxygen in the water (Anonymous,1999). Algal growth is favoured by warm temperatureand daylight Ultra-Violet (UV) rays (Sweeney& Samansky, 1995), and it occurs on all submergedsurfaces. It is not dangerous for the dolphins, butit is unsightly—especially in concrete pools. Inpools and lagoons made of natural materials, thealgae only needs to be removed once in a while.Chlorine, ozone, copper, biological filtration, andUV disinfection can control algae.The following table presents a summary ofwater tests that are carried out on a regular basisby many surveyed facilities. Sweeney (1993) recommendedkeeping records on site for at leastthree years in a digital format.Table 6.2. Frequency and targeted range of water quality measurementsMeasurement Frequency RangeAir temperature 2 x day N/AWater temperature 2 x day see Cetacean Species Information TableSalinity Daily 25-35 ‰pH Daily 8.2; if chlorination, 7.5-7.6Turbidity Daily £ 0.5 NTUDissolved oxygen Weekly 5.0-8.8 ppm DOColiform bacteria Weekly £ 100 MPN/100 ml; more frequent if > 200 MPN until level dropsbelow 100Total bacteria Weekly see historical norm of locationAmmonia Weekly £ 0.05 mg/l of waterNitriteNitrate Weekly £ 1 mg/l rapidly converted to nitrate£ 10 mg/lFree chlorine 2-3 x day £ 0.2 ppmTotal chlorine£ 0.5 ppmAlkalinity Weekly 100-150 mg/l