Tolerance to salinity and dehydration in the Sahara Blue-eyed turtle (...) conservation

Organização: CEF/CEABN

Data: 20 dezembro 2018 :: 12h30 às 13h30

Local: Sala 2.12 - Edificio Azevedo Gomes

Tema: "Tolerance to salinity and dehydration in the Sahara Blue-eyed turtle: implications for conservation"

Orador: Mohammed ZNARI (Faculty of Science and Natural History Museum of Marrakech, Semlalia - Marrakech, Cadi Ayyad University)


Mohammed ZNARI (PhDs, Natural Sciences, University of Paris VI, France, and Cadi Ayyad university at Marrakech, Morocco) is a Professor of Ecology and Conservation Biology at the Faculty of Science, Semlalia - Marrakech, Cadi Ayyad University and the curator of Vertebrate Zoology at the Natural History Museum of Marrakech at the same university.  His research career has been focused on vertebrate ecology and conservation biology along with morphometrics and molecular phylogeography. His preferred lines of research are physiological ecology including nutritional ecology, energetics, osmoregulation, developmental and breeding biology along with different aspects of conservation ecology. He has focused his work in various vertebrate taxa, mainly arid-land reptiles and birds and mammals. His most recent work is focused on fish and amphibians in arid land freshwater ecosystems, and the effects of multiple stressors, namely driven by climate change, water scarcity and salinization. He has been involved in several international cooperative projects and has obtained several international fellowships (e.g., Averroes, Fulbright, DAAD) and international research-conservation grants.


The marginal populations of the Sahara Blue-eyed Pond Turtle, Mauremys leprosa saharica, in the southernmost species distribution range in the pre-Saharan areas of Northwest Africa, are faced with extreme environmental conditions of arid climate, which have been exacerbated by anthropogenic and climate change mediated water and land salinisation. Here, I present first data on tolerance to salinity and dehydration in a small and isolated population of M. l. saharica at Sidi El Mehdaoui oasis, Lower Draa, Southern Morocco. Turtles are able to survive in brackish waters with a salinity level as high as 25% seawater. Their voided urine was relatively hypotonic to plasma indicating that they could use their bladder water reserves for osmo- and iono-regulation until the iso-osmocity level beyond which a relative “anhomeostasy” can occur. Experimental tests showed that the osmo- and iono-regulatory abilities of these turtles are relatively limited and not enough effective to allow them to survive for long-term periods in brackish/saline waters or out of water because of dehydration indicated by progressive weight loss to a critical threshold. The increased drought, water and land salinisation and habitat fragmentation related to anthropogenic activities and climate change, represent great threats that can create conditions exceeding species’ threshold that may imperil the long-term persistence of small marginal populations. Hence, conservation measures of these highly threatened populations and their habitats are urgently needed.