Marco A. López-Luna

Hematology and serum biochemistry comparison in wild and captive Central American river turtles (Dermatemys mawii) in Tabasco, Mexico.

Hematological and serum biochemistry analyses were determined on 51 Central American river turtles (Dermatemys mawii) during the dry and rainy seasons of 2006. Turtles came from two sites: Pantanos de Centla Biosphere Reserve and a turtle breeding farm, both located in Tabasco State, Mexico. Physical examination and body measures of animals were performed. Incidence and prevalence of hemoparasites were explored. Captive organisms were in poor physical condition while wild turtles were apparently healthy. There were differences in several hematological parameters related with the condition and the season. During the dry season captive turtles exhibited higher levels of uric acid and urea, as well as lower levels of glucose. Haemogregarina sp. was detected in 100% of the wild individuals, but not in captive individuals. Its incidence was greater during the rainy season. This is the first health assessment and hematology study of this critically endangered species.

Effect of nesting environment on incubation temperature and hatching success of Morelet's crocodile (Crocodylus moreletii) in an urban lake of Southeastern Mexico.

Incubation temperature is an important aspect in terms of biological performance among crocodiles, and several controlled experiments have demonstrated a significant relationship between incubation temperature, success in hatching and survival of hatchlings. However, a few studies have tested these relationships in the wild. The objective of this study was to determine the relationship of nest characteristics and environment (hatch year, nest basal area and height, clutch size, distance to shore line, and vegetation cover), to incubation temperature and hatching success among Morelets crocodile (Crocodylus moreletii). The study was carried out during the nesting seasons of Morelets crocodile, from 2007 to 2009 in the Laguna de Las Ilusiones, an urban lake located in Villahermosa, Tabasco, Mexico. We physically characterized 18 nests and inserted a temperature data logger in each nest chamber. At the end of the nesting season and prior to hatching, we recovered the crocodile eggs and data loggers and calculated hatching success, under laboratory conditions. We related the environmental variables of the nest with the mean and fluctuation (standard deviation) of nest temperature, using linear models. We also related the environmental variables affecting the nest, to mean nest temperature and fluctuation in incubation temperature and to hatching success, using linear models. Although we found differences in incubation temperature between nests, mean incubation temperature did not differ between years, but there were differences in nest thermal fluctuation between years. The mean incubation temperature for 11 nests (61.1%) was lower than the suggested Female-Male pivotal temperature (producing 50% of each sex) for this species, and all hatchlings obtained were males. There were no differences in clutch size between years, but hatching success varied. Our study indicates that hatching success depends on certain environmental variables and nest conditions to which the eggs are subjected, including season, nest size and clutch size. We also discuss the importance of the fluctuation of incubation temperature on hatching success and sex determination.

Health and Aquatic Environment Assessment of Captive Central American River Turtles, Dermatemys mawii, at Two Farms in Tabasco, Mexico

Abstract Health evaluations were conducted in 2 captive colonies of Central American river turtles, Dermatemys mawii, from sites in Tabasco, Mexico: Government of the State of Tabascos turtle farm (GOV) and Arroyo Tabasquillo turtle farm (TAB). Health assessments were conducted in February, May, and August. Each assessment included a group clinical history, physical examinations, serum biochemistry panels, and bacteriological analyses. Additionally, water quality of turtle ponds was analyzed monthly at each site. High frequency of shell lesions and other clinical signs related to a harmful aquatic environment were found at both farms. Serum biochemistry results include levels of urea in both farms that repeatedly exceeded reference values for this species and values greater than normal for total protein, uric acid, and triglycerides at TAB. Bacteriological results showed potentially pathogenic microorganisms in lesions, including Staphylococcus aureus, Escherichia coli, Proteus vulgaris, Serratia spp., Klebsiella spp., and Candida spp. Water quality in both farms was poor; water at TAB presented the worse quality due to its high levels of total ammonia nitrogen (median 1.092 mg/l), nitrite (median 0.011 mg/l), fecal coliform (median 4600 MPN/100 ml), and water transparence (median 0.05 m) and low level of dissolved oxygen (median 0.6 mg/l). In general, the health of captive turtles was compromised at both farms, the most likely factors being inadequate water management, overcrowding, and dietary problems.

Expression of the Sox9, Foxl2, Vasa, and TRPV4 genes in the ovaries and testes of the Morelet's crocodile, Crocodylus moreletii

The Sox9 gene is important for determining sex in vertebrates, as well as for maintaining testis morphology and fertility during adult life. In the same way, Vasa is an important gene for the maintenance of the germinal lineage and has been highly conserved throughout evolution, as it is expressed in germ cells of both vertebrates and invertebrates. In the particular case of crocodiles, the expression of Sox9 during gonadal morphogenesis and in the testes of 3-month-old Alligator mississippiensis has been studied. However, it is interesting to carry out studies on other species of crocodiles in relation to their particular mechanism for sex determination influenced by temperature. In this work, we investigated the expression of the Sox9, Vasa, Foxl2, and TRPV4 genes in the ovaries and testes of 5-year-old juvenile crocodiles from Crocodylus moreletii. As expected, Sox9 expression was found in males, but surprisingly, it was also found in females. For the first time, the expression of Vasa was reported in spermatogonia, oogonia, and oocytes of 5-year-old crocodiles. Foxl2 is important for the development and maintenance of the ovary during adult life in vertebrates; moreover, Foxl2 protein and transcripts are both highly expressed in the ovaries compared to the testes. A possible upstream regulator of the Sox9 gene in reptiles has not yet been discovered; as such, the expression of the TRPV4 ion channel was evaluated. The TRPV4 ion channel was expressed in the cytoplasm of Sertoli and follicular cells and was therefore proposed as a possible regulator of SOX9.

A Distinctive New Species of Mud Turtle from Western México

Abstract The genus Kinosternon in Mexico is represented by 12 species of which only 2 inhabit the lowlands of the central Pacific region (Kinosternon chimalhuaca and Kinosternon integrum). Based on 15 standard morphological attributes and coloration patterns of 9 individuals, we describe a new microendemic mud turtle species from the central Pacific versant of Mexico. The suite of morphological traits exhibited by Kinosternon sp. nov. clearly differentiates it from other species within the genus Kinosternon by a combination of proportions of plastron and carapace scutes, body size, and a large yellow rostral shield in males. The new species inhabits small streams and ponds in and near the city of Puerto Vallarta, Jalisco. Unfortunately, natural populations are unknown so far. The habitat is damaged by urban growth, and only one female is known. The available information would suggest that Kinosternon vogti sp. nov., is one of the most threatened freshwater turtle species. An urgent conservation program is necessary as well as explorations in the area to find viable populations of the species.

Thermal fluctuation within nests and predicted sex ratio of Morelet's Crocodile.

Understanding the interplay between thermal variations and sex ratio in reptiles with temperature-dependent sex determination is the first step for developing long-term conservation strategies. In case of crocodilians, the information is fragmentary and insufficient for establishing a general framework to consider how thermal fluctuation influence sex determination under natural conditions. The main goal of this study was to analyze thermal variation in nests of Crocodylus moreletii and to discuss the potential implications for predicting offspring sex ratio. The study was carried out at the Centro de Estudios Tecnológicos del Mar N° 2 and at the Sistemas Productivos Cocodrilo, Campeche, Mexico. Data was collected in the nesting season of Morelets Crocodiles during three consecutive seasons (2007-2009). Thermal fluctuations for multiple areas of the nest chamber were registered by data loggers. We calculate the constant temperature equivalent based on thermal profiles among nests to assess whether there are differences between the nest temperature and its equivalent to constant temperature. We observed that mean nest temperature was only different among nests, while daily thermal fluctuations vary depending on the depth position within the nest chamber, years and nests. The constant temperature equivalent was different among and within nests, but not among survey years. We observed differences between constant temperature equivalent and mean nest temperature both at the top and in the middle of the nest cavities, but were not significantly different at the bottom of nest cavities. Our results enable examine and discuss the relevance of daily thermal fluctuations to predict sex ratio of the Morelets Crocodile.