Radiata2010(4)e

Sascha Pawlowski &

Sascha Pawlowski & Christine Krämer Observations during husbandry Despite their perceived “doing poorly” in captivity, there are cases of Diamondback Terrapins being raised or kept in pure freshwater for many years without skin problems surfacing or even losing specimens due to disease. One such instance was the adult pair of Malaclemys terrapin ssp., which we received in March of 2007. It had previously been raised and kept in pure freshwater for fourteen years (Figs. 2 and 4). Both terrapins had originally been acquired as hatchlings from the Zoo of Frankfurt/Main in 1993 and were initially kept together before being separated. A small dry patch (rock) and regular access to unfiltered natural sunlight had obviously provided the two animals with a perfect state of health, as they exhibited smooth carapaces and no signs of skin or shell necroses. We were furthermore able to acquire two groups of hatchlings (Malaclemys terrapin terrapin, Fig. 5, and Malaclemys terrapin centrata, Fig. 3) from a dealer in 2007 and 2008, respectively. These were raised in pure freshwater (drinking water quality) as well. It showed that the terrapins were eager feeders so that their raising confirmed previous observations in freshwater environments. Also in this case, the animals were able to dry on a terrestrial section under a halogen spotlight (40 and 50 W, resp.) and enjoy UV light from a small UV-A lamp (14 W). Considering the low energy output of this lamp it would appear unlikely that it had a disinfecting effect, though. The drinking water used was rather hard at a total hardness of 17.2 °dH (for details see Tab. 1), and there is a possibility that keeping these terrapins in relatively soft water (i.e, with low conductivity and low mineral and salt contents) might produce different results. This might also be the case if the terrapins were kept too cool, as this would favour skin infections. It is nothing particular to this species, however, but also known to be the case with other aquatic species, such as the Chinese three-keeled pond turtle, Chinemys reevesii (Gray, 1831), the red-bellied short-necked turtle, Emydura subglobosa (Krefft, 1876), and even the European pond turtle, Emys orbicularis (Linnaeus, 1758). It is therefore not something specific to the keeping of Diamondback Terrapins (pers. obs.). Parameter Value Unit Conductivity (at 20/25°C) 522 / 582 µS/cm pH 7.60 - Total hardness 17.2 °dH Carbonate hardness 14.0 °dH Classification hard - Calcium 105 mg/l Magnesium 11.0 mg/l Hydrogen carbonate 304 mg/l Nitrate 0.8 mg/l Nitrite < 0.03 mg/l Chloride 15.2 mg/l Copper 0.03 mg/l Other metals < 0.015 mg/l Tied organic carbon (TOC) 3.1 mg/l Herbicides indet.** µg/l Table 1. Analysis of the drinking water in Lampertheim, southern Hesse, Germany* * Analysis of drinking water, average values, 2008 (excerpt), according to Energieried GmbH & Co. KG, accessible at www.energie-ried.de/download/2008_TrinkwV2001_Auszug_Lampertheim_Buerstadt.pdf ** indet. – indeterminable, i.e., the values of individual parameters are lower than the current minimum detection levels. 22 RADIATA 19 (4), 2010

Diamondback Terrapins, Malaclemys terrapin (Schoepff, 1793) Even keeping them outdoors for periods of several months did never so far cause health problems in the shape of skin alterations and/or necroses, because the terrapins always had the opportunity to dry on land (Fig. 1). If this opportunity of drying is absent, or if the animals are weakened, for example as a result of inappropriately low temperatures (< 20 °C during their active phase), they, like other aquatic turtle species, may be afflicted by skin alterations. These would show as a whitish film that first affects only the surface, but as the disease progresses spreads to deeper skin layers, and eventually even to the musculature and organs beneath. Specimens afflicted thus are typically so weak that it will be impossible to save them. At an early stage, it is well possible to turn the situation around if the husbandry conditions are improved. Again, this is nothing specific to the keeping of Diamondback Terrapins, but likewise applies to species of the genera Chinemys, Mauremys, Emys and Emydura if they are kept in unsuitable surroundings, which is most commonly the case in indoor aquaterraria. If the animals are kept outdoors at least periodically, or in aquaterraria with a proper climate management, diseases like that should not even surface (comp. Pawlowski 2007a, b). The appearance of skin alterations is thus not a function of the salinity of their water because the addition of cooking salt (to emulate a brackish environment) alone will not prevent these external infections from forming. The disinfecting action of salt water on shell and skin surfaces, on the other hand, very probably requires concentrations well above dehydration levels (especially those of true freshwater species). Their captive care furthermore reveals that Diamondback Terrapins often take extensive sand baths (i.e., slightly covered with sand) on the terrestrial section, both in an outdoor setting (adults, Fig. 6) and in the aquaterrarium (juveniles and semiadult specimens). This may go so far that the animals bury themselves deeply in sand and remain there for several days or even weeks. It does not at all mean that they are now inactive, as they will keep on watching the closer vicinity through a hole in the sand cover and retreat to deeper levels if danger approaches (Fig. 7). Corresponding observations have also been reported for juveniles and adults from the wild, with the latter resting in the mud or on the banks at times of low tide (Brennessel 2006). Diamondback Terrapins were also found hibernating buried on land (Yearicks & Wood 1981). In the aquaterrarium, this behaviour could furthermore be witnessed under water where the animals buried themselves in the bottom substrate (fine sand). These were distinct periods of rest, however. Comparable behaviour has also been described for M. t. macrospilota (ornate Diamondback Terrapin) (Szymanski 2005). No alterations of the skin have been noted to date, although this installation does not include a spotlight that would assist drying. Lighting here consists merely of two fluorescent tubes of 30 W each. It must be said, though, that air and water temperatures are maintained at between roughly 22 and 29 °C during the period of activity. Quite by contrast: individuals that had developed a minor coating of the skin following hibernation made intense use of the sand pits, resulting in the skin reverting to its original condition within the space of a week or two. The terrapins continued to go on land and bury themselves in the sand even after that, and it did not seem to matter to them whether the sand was dry or moist. Their large hind feet make these terrapins good and active swimmers, and they often use the current created by the powerful internal filters (600 and 1,200 l/h turnover, respectively) in their respective installations (200 and 350 l in volume) to swim against it (comp. Szymanski 2005). This continued swimming keeps them fit and is therefore beneficial to their general state of health. The minimum dimensions of an indoor installation for the keeping of adult Diamondback Terrapins should be derived from those used for other species that are known to be active swimmers (genera Emydura, Chelodina; comp. Bundesministerium für Ernährung, Landwirtschaft & Forsten 1997), but rather exceed them whenever possible. RADIATA 19 (4), 2010 23