I hoped we’d see Spanish Terrapins (Mauremys leprosa) and European Pond Terrapins (Emys orbicularis) once we have been in Portugal in early April. We did however within the Algarve we additionally noticed very massive numbers of North American sliders (Trachemys scripta) in a freshwater lake behind the saline lagoon and seashore at Quinta do Lago (a part of the Ria Formosa Nationwide Park). I spent ages trying by the images to be able to try to determine what we had been seeing basking within the spring sunshine. I then discovered a paper from 2018 which describes an in depth survey of the Nationwide Park, which extends alongside the coast of the Algarve, performed between 2011 and 2013. Over that interval the commonest species was M. leprosa (79% of all captures). Then got here E. orbicularis (12%) with launched North American species on 9%. That paper clearly demonstrated for the primary time that the launched terrapins have been breeding. I additionally found that the lake, surrounded by a golf course and vacation residences, is used as a spot to launch rescued native terrapins. Whether or not that lake is typical of different freshwater lakes and ponds of the Ria Formosa Nationwide Park I have no idea but it surely was clear to us that launched sliders vastly outnumbered M. leprosa whereas just a few E. orbicularis have been evident.
The authors of the 2018 paper raised the alarm in view of proof that North American sliders compete for meals and basking websites with E. orbicularis. All through its vary E. orbicularis is lowering in numbers and is now labeled as Close to Threatened within the IUCN Purple Checklist. The query is that if and can something be performed to regulate the variety of launched terrapins in Portugal.
I ought to level out that I’m following British terminology for freshwater chelonians in utilizing ‘terrapin’ for all these species, fairly than the North American ‘turtle’. Nevertheless, to complicate issues, Emys orbicularis was typically referred to as the European Pond Tortoise. ‘Spanish Terrapin’ can be deceptive because the species additionally happens in North Africa. In Portugal and elsewhere, Mediterranean Pond Terrapin can be used as a reputation for M. leprosa.
We additionally travelled inland and on one reservoir and a slow-moving river noticed solely the 2 native species.
I’m puzzled by the presence in the identical places of E. orbicularis and M. leprosa, as I used to be at Butrint in Albania, the place E. orbicularis and the Balkan Terrapin (Mauremys rivulata) reside facet by facet. Are these pairs of species not in competitors? And if not why not?
Sliders in Europe symbolize both the declining remnants of the as soon as monumental trans-Atlantic commerce in ‘child terrapins’ within the north or a thriving feral inhabitants within the south. Because the child terrapins grew, they have been launched by house owners unable to deal with them. Nevertheless, earlier than that stage was reached solely when phrase unfold on the right way to rear them efficiently. Till then just about all died from being stored too chilly and from being given unsuitable meals poor in nutritional vitamins and calcium. Nevertheless, when stored correctly the lovable child grows very quickly.
The sliders we noticed symbolize the 2 phases of the commerce. Initially—and other than ones captured within the wild for the sellers promoting to newbie herpetologists—those which got here in have been Purple-eared Sliders (Purple-eared terrapins, Trachemys scripta elegans). The late Nineteen Fifties noticed the beginning of the mass commerce in Britain. What we didn’t know was that these terrapins have been being bred on ‘turtle farms’ within the southern USA and that they have been fed the waste from hen carcasses. It didn’t take all that lengthy for Salmonella from the hen and contaminated water to make its presence felt, each within the USA and in Europe. Finally that commerce was banned. However then a second wave, I feel additionally coinciding with the mutant ninja turtle craze, this time of one other subspecies of slider, introduced the Yellow-bellied Slider (Trachemys scripta scripta) to pet retailers. It was these two kinds that have been current at Quinta do Lago. In distinction to 2011-2013 information when Purple-ears predominated (98% of the sliders), Yellow-bellied have been as least as widespread, if not barely extra so, than the Purple-ears, as could be anticipated.
Of the sliders I may see clearly, I didn’t spot any apparent hybrids between the 2 subspecies. This might imply that lots of the massive terrapins are of the unique inventory or it may point out assortative mating.
The EU banned the import, sale, breeding or trade of all types of T. scripta in 2015, a place maintained in Britain after Brexit.
Martins BH, Azevedo F, Teixeira J. 2018. First copy report of Trachemys scripta in Portugal Ria Formosa Pure Park, Algarve. Limnetica, 37, 61-67. DOI: 10.23818/limn.37.06