Special Issue Survey of Cetaceans in Captive Care

5. Architectural Design of Pools and Enclosures 333Sand and RocksAlthough present in nature, some elements maybe used differently in a display by both captiveand wild-born animals. Sweeney (1990) and severalvisited and surveyed facilities reported thatdolphins often swallow sand, gravel, small stones,seaweeds, and various objects dropped in thepool. Stones of large diameters, around 30 cm,are preferred. Fine crushed shells will preferablybe used rather than silica sand because shells canbe digested if swallowed. Natural and artificialrocks should not present dangerous protrusions oroverhangs. The finish and surfacing of artificialrocks will be discussed with curators according tothe potential destructive behaviour of animals andthen properly specified to the contractor prior toconstruction. The surface has to be smooth, andits quality and finish must not be porous and friable.Crumbly material can be swallowed by animals.Abrasive finishes may provoke skin damageand tooth erosion in animals (Sweeney, 1990).Rough surfaces may contribute to increased algaland bacterial growth and need therefore to befrequently and thoroughly cleaned (Sweeney &Samansky, 1995). Proper waterproofing shouldprevent the corrosion of the internal metal structure.Internal Polyvinyl Chloride (PVC) structurecan be preferred over metal, but it does not allowthe same freedom of shape. In both cases, it isFigure 5.23. Artificial rockworkFigure 5.24. Rockwork structureFigure 5.25. Artificial coral reefrecommended to fill the sculpted rock with concreteto strengthen it and avoid dirt traps.Partitions and FencesNatural and Semi-Natural Environments—Thedivision of space within a pen or a pool is madeby walls, partitions, or fences. The design andmaterials used should be convenient and safe forboth animals and trainers. Here are some examplesobserved in or reported by facilities:• In a lagoon, various types of partitions can separatethe main enclosure and the holding areas.They should be adapted to the tidal action andmaintenance requirements. Several types ofchain link fences can be used—for example,the classical type (diamond-shape pattern, plasticcoated metal) or the reinforced type (squareor rectangular pattern, stronger welded mesh).Both are convenient and cheap, but they haveto be maintained regularly to remove the algaland coral growth and to check for protruding orrusted portions. They corrode quickly and donot have a very long life span. Facilities locatedwhere fouling and coral growth is fast willensure that the fence does not collapse underthe weight of incrustation. Chain link fencesare preferred aesthetically in areas with littletidal action since they are collapsible. They arequite easy to move or replace. Mesh size willbe wide enough (10-15 cm) to allow fish andcrustaceans to swim through and to ensure thatanimals do not get their rostrum stuck betweenmeshes. A regular schedule of inspection bydivers is recommended.• Partitions can be made of stainless steel bars,which are resistant to corrosion and easy tomaintain. Since they are rigid, they cannotcollapse under tidal action unless they havearticulated parts. They can create noise in thedolphin’s environment, however, if not carefullypadded with rubber at the junctions. Theyare more costly than chain link fences, but theyalso are more durable.