REPRODUCTION AND CONSERVATION OF THE MAGDALENA RIVER TURTLE (Podocnemis lewyana) IN THE CLARO COCORNÁ SUR RIVER, COLOMBIA

Abstract

Citation / Citar este artículo como: Ceballos CP, RomeRo i, Gómez-saldaRRiaGa C, miRanda K. Reproduction and conservation of the magdalena River turtle (Podocnemis lewyana) in the Claro Cocorná sur River, Colombia. acta biol. Colomb. 2014;19(3):393-400. ABSTRACTThe Magdalena River Turtle, Podocnemis lewyana, is an endangered and endemic turtle from Colombia. Among the most important information needed to conserve endangered species is to identify, monitor, and protect the sites used by the species to reproduce and grow. In this study we report, for the first time, the reproductive output and the nesting beaches of P. lewyana in the Claro Cocorná Sur River, a tributary of the Magdalena River drainage. We systematically examined a river transect of 8 km with 14 sandy beaches during two nesting seasons in one year. We recorded a yearly production of 47 clutches, 957 eggs, and two preferred nesting beaches: Alto Bonito with 51 %, and Bélgica with 28.3 % of this reproductive output. AAFUVER, a community-based organization, has led a headstarting program since 2010 to decrease in-situ egg mortality due to predation on nesting beaches. AAFUVER collects and incubates the eggs ex-situ, raises the hatchlings for one to five months and then releases them into the same river. To understand potential effects of such egg manipulation, we monitored and compared in-situ and ex-situ incubation temperatures. We found exsitu temperatures below the pivotal temperature known for P. lewyana and below the temperatures in nesting beaches. Finally, we monitored hatchlings growth under AAFUVER captive conditions, and found that hatchlings duplicated their body mass during the first three months of age. Egg weight was strongly associated to body weight at hatching, however this association is lost by the third month of age. We strongly encourage supporting this community-based conservation program, and the protection of the Claro Cocorná Sur River as an important nesting and growth habitat for the conservation of P. lewyana.

Histological description of the reproductive tract of male and female hatchlings of the Magdalena river turtle (Podocnemis lewyana).

“…This is, the pivotal temperature of 33.4 °C produces both sexes in similar proportions, while higher temperatures produce mainly females and lower temperatures produce mainly males . Its reproductive cycle has not been studied in detail, however it is known that there are two nesting seasons: between December and March, and between June and August (Gallego-García and Castaño-Mora, 2008;Ceballos et al, 2014). Its average clutch size varies between 20 to 22 eggs, with an egg weight varying between 18-38 g and an egg size between 31-50 mm long x 21-44 mm width (Páez et al, 2012;Ceballos et al, 2014).…”

ANTHROPOGENIC IMPACTS ON YELLOW-SPOTTED RIVER TURTLE Podocnemis unifilis (REPTILIA: PODOCNEMIDIDAE) FROM THE BRAZILIAN AMAZON

“…For the turtle species, egg size can be determined by biological patterns of females, mainly related to their age, among other factors. Because these animals do not have parental care, the apparent energetic effort employed for reproduction can ensure better development of the offspring; thus, larger eggs may have greater hatching success and generate larger neonates (Valenzuela, 2001;Loehr et al, 2004, Warner et al, 2010Ceballos et al, 2014). Conditions of soil moisture and temperature that cause water loss in the egg may lead to a lower vitelline absorption and, then, generate smaller neonates (Ferreira-Junior, 2009a;FerreiraJunior, 2009b).…”

“…Several studies (Fachín-Terán, 1993;Fachín-Terán et al, 1995;Rebelo and Pezzuti, 2000;Fachín-Terán and Von Mulhen, 2003;Fachín-Teran et al, 2004;Caputo et al, 2005;Fachín-Terán and Von Mulhen, 2006;Ceballos et al, 2014) on the influence of egg collection, adult chelonians hunting and effects of habitat destruction reported that the decline of chelonians populations is more strongly associated with increased activities that alter mainly the landscapes of Amazon floodplains. In the Araguari river basin (eastern Amazon), the nesting of P. unifilis occurs from September to November, eggs hatching occurrs in December and the mean incubation period is of 63.5 ± 5.2 days.…”

Effects of Incubation Temperature on Sex Determination in the Endangered Magdalena River Turtle,Podocnemis lewyana

“…Species with TSD are particularly vulnerable to climate change because higher temperatures could bias natural sex ratios (Janzen 1994;Neuwald and Valenzuela 2011). The TSP has not been studied in P. lewyana; yet, artificial incubation of eggs is a current conservation practice to avoid egg mortality in some populations (Romero 2011;Ceballos et al 2014b), and the effect that this may have on sex determination is unknown. Furthermore, the TSP is ideally evaluated based on embryonic stages (Yntema 1978(Yntema , 1979Bull and Vogt 1981;Pieau and Dorizzi 1981); however, such destructive sampling is not always possible in endangered species (Le Blanc et al 2012).…”

“…We incubated eggs under temperatures that were 100% feminizing and 100% masculinizing in a different P. lewyana population (Páez et al 2009) to test whether sex ratios differed in our population (Ceballos et al 2014b) and to obtain a baseline for comparison with our shift experiments. We estimated the onset and duration of the TSP using 6 shift-twice treatments (masculinizing-feminizing-masculinizing temperatures) as described below.…”