Biochemical changes, specifically in hemocyanin and glucose concentrations in hemolymph, glycogen in the digestive gland, were studied throughout the

Age and growth of bull shark, Carcharhinus leucas, was investigated in the southern Gulf of Mexico (Veracruz and Campeche, Mexico) from December 1993 through June 1997. Ninety-five specimens were obtained from commercial fishery catches, and vertebrae were examined from 20 males, 61 females and 14 individuals unidentified to sex. Vertebrae were examined using five different techniques to enhance the visibility of growth rings: i) alizarin red stain, ii) crystal violet stain, iii) X-ray, iv) silver nitrate stain, and v) without staining. Verification of temporal growth ring forma - tion was done by the indirect method of marginal increment analysis. An isometric relationship was found between growth and length of centrum, is described by a linear equation. Age-at-maturity was 10 years (204 cm total length, TL) for females and 9-10 years (190-200 cm TL) for males. The old- est female was 28 (256.0 cm TL), and the oldest male was 23 (243.0 cm TL). The von Bertalanffy growth parameters were estimated for the species (L∞ = 256.4 cm TL, k = 0.1397 per year and to = -1.935), for males (L∞ = 248.4 cm TL, k = 0.1692 per year and to = -1.03), and for females (L∞ = 262.1 cm TL, k = 0.1235 per year and to = -2.44). Sexual differences for each particular growth curve were found, L∞ being the parameter that showed the greatest difference between males and females; females attain a larger size.

Snakebite envenoming is a set of intoxication diseases that disproportionately affect people of poor socioeconomic backgrounds in tropical countries. As it is highly dependent on the environment its burden is expected to shift spatially with global anthropogenic environmental (climate, land use) and demographic change. The mechanisms underlying the changes to snakebite epidemiology are related to factors of snakes and humans. The distribution and abundance of snakes are expected to change with global warming via their thermal tolerance, while rainfall may affect the timing of key activities like feeding and reproduction. Human population growth is the primary cause of land-use change, which may impact snakes at smaller spatial scales than climate via habitat and biodiversity loss (e.g. prey availability). Human populations, on the other hand, could experience novel patterns and morbidity of snakebite envenoming, both as a result of snake responses to environmental change and due to the development of agricultural adaptations to climate change, socioeconomic and cultural changes, development and availability of better antivenoms, personal protective equipment, and mechanization of agriculture that mediate risk of encounters with snakes and their outcomes. The likely global effects of environmental and demographic change are thus context-dependent and could encompass both increasing and or snakebite burden (incidence, number of cases or morbidity), exposing new populations to snakes in temperate areas due to “tropicalization”, or by land use change-induced snake biodiversity loss, respectively. Tackling global change requires drastic measures to ensure large-scale ecosystem functionality. However, as ecosystems represent the main source of venomous snakes their conservation should be accompanied by comprehensive public health campaigns. The challenges associated with the joint efforts of biodiversity conservation and public health professionals should be considered in the global sustainability agenda in a wider context that applies to neglected tropical and zoonotic and emerging diseases.