Special Issue Survey of Cetaceans in Captive Care

352 CouquiaudOpen System—Open or flow-through systemsdo not require mechanical filtration devices.Pumped seawater from the nearby ocean, or taporgroundwater for freshwater species, flowsdirectly into the pools and is discharged withoutbeing recirculated. The exchange is continuous,and the control of temperature, colour, concentrationof suspended particles, and bacteria dependson the frequency of the water replacement (Spotte,1991). Raw seawater, however, often is pumpedthrough a silt-screen to remove the largest particlesand therefore reduce turbidity. To obtain veryclean water, some facilities, such as two surveyedfacilities in Hawaii, pump seawater through naturallava substrate, which acts as a primary filter.Water is discharged back into the sea, usuallyat a location far away from the pumping station,or into waste or storm drains if local regulationsallow. The quality of the water discharged shouldcomply with regulations and not affect marineorganisms living near the discharge point or downcurrent.Open System with Chlorine—This system isthe same as above, with the addition of a smallamount of chlorine to limit algal and bacterialgrowth. If chlorinated water is discharged intonatural waters, it can be dechlorinated unless italready complies with regulation levels. Nondechlorinatedwater will be discharged away fromshore to limit its effect on living organisms.Semi-Closed and Closed SystemsFacilities located near the sea where water qualityis such that it needs to be treated, as well as thosefacilities located inland, use semi-closed (alsocalled semi-open) or closed systems. Since thesesystems involve the partial or total recirculation ofwater, they both require mechanical, chemical, andbiological filtration. Both systems use natural orartificial seawater or freshwater (if appropriate).Semi-Closed System—A semi-closed systemrelies on the continuous replacement of water lostthrough evaporation or waste; however, replacementoccurs at a lower rate than in open systems.Typically, less than 10% of the total volume isreplaced every 24 h (Geraci, 1986; Spotte, 1991).The rest of the water is treated as it is in a closedsystem.Closed System—All water is recycled throughfilters, sterilised, and returned to the pool (Spotte,1991). On occasion, partial water replacementoccurs to replace water lost through evaporationand recycling. (See “Water Purification” sectionfor more details.)Saltwater and Seawater—There are variouskinds of “sea water” in controlled environments.Saltwater is made of tap water, groundwater, oravailable natural freshwater mixed with marinesodium chloride (NaCl). Artificial seawater can bemade from the same sources of freshwater mixedwith commercial mixes of sea salts available in bulkfrom marine supply houses (Faulk, 1990). Artificialseawater usually is recirculated because it is expensiveto produce. The composition of artificial seawaterhas to be very close to natural seawater becausethe presence of some trace elements, such as copper,zinc, manganese, or potassium, may be essential tothe health of the animals (Manton, 1986). It doesnot have an impact on marine mammals, but it iscrucial for keeping fish and invertebrates alive. Tapwater or freshwater might have to be filtered beforeadding salts because the ions or chlorine present inthis water may change the composition of the artificialseawater and might jeopardize animal health.Refer to Dierauf (1990) and Faulk (1990) for brandnames of ocean salts. Natural seawater delivered bytrucks also can be used to fill and top-off pools.Freshwater—Only four cetacean species canlive permanently in freshwater (see CetaceanSpecies Information Table in Chapter 2). Tapwater, groundwater, or freshwater from a nearbywater body (e.g., lake, river) can be used in open,semi-closed, or closed systems. If tap water isused, the amount of chlorine in the water should bechecked before adding any more. The compositionof natural freshwater has to be analysed to ensureits suitability. A high concentration of metal ionsand pollutants could make it unfit for use.Marine cetacean species cannot be kept permanentlyin freshwater. When necessary, a veterinarianmay recommend that a dolphin be kept in freshwaterfor very short periods of time for rehydrationpurposes. When this occurs, the LSS preferablywill allow the medical pool to be filled with freshwater.The danger is that after some time, a degenerationof epidermal cells will occur. Necrosis andulceration of the epidermis will result if the animalis not returned to seawater (Manton, 1986).Water ParametersTemperatureWater temperature is monitored to ensure the comfortof the animals and that all mechanical systemsare operating efficiently. If the water temperaturerises or drops slowly but steadily, it can reveal amalfunction in the system (Faulk, 1990).In natural facilities, water temperature cannot beregulated; therefore, the species housed should beadapted to that type of climate. Similar recommendationsare applicable for artificial outdoor facilities.It is not recommended to keep coldwater species intropical climates or vice versa. Despite this, with theincrease in new facilities, cetaceans more frequentlyare being placed in unnatural climates (Geraci,1986; survey). Institutions located in tropical regions