Spatiotemporal distribution of organochlorine pesticides in the upper La Antigua watershed, Veracruz Mexico.

Even though the use of organochlorine pesticides has been prohibited since the last century their presence is still being recorded around the world. In the upper La Antigua watershed, Veracruz, Mexico we have reported concentrations of these contaminants in different compartments of the riverine ecosystems. This is of relevance due to their potential disruptive endocrine effect on the vertebrates drinking the water or feeding in the riverine area.

Stream food webs in tropical mountains rely on allochthonous carbon regardless of land use.

The relative importance of allochthonous and autochthonous carbon (C) as sources of energy for tropical stream food webs remains an open question. Allochthonous C might be the main energy source for small and shaded forest streams, while autochthonous C is more likely to fuel food webs draining land uses with less dense vegetation. We studied food webs in cloud forest streams draining watersheds with forests, coffee plantations, and pastures.

Effect of landscape tree cover, sex and season on the bioaccumulation of persistent organochlorine pesticides in fruit bats of riparian corridors in eastern Mexico.

Riparian forests are recognized as important ecosystems for biodiversity conservation in transformed landscapes. Many animal species that use this type of vegetation facilitate its recovery through pollination and seed dispersal. In landscapes dominated by agrosystems and cattle ranching, persistent organochlorine pesticides (OCPs) in the riparian system may have an effect on the physiology and fitness of animals.

[Relative abundance of the gray fox Urocyon cinereoargenteus (Carnívora: Canidae) in Veracruz central area, Mexico].

The gray fox, Urocyon cinereoargenteus, is a medium-size canid widely distributed in México. Most studies on this species focus on habitat use, home range, diet, intraguild competence, and lanscape distribution between urban and rural sites. In central Veracruz, gray foxes are present in fragments of cloud forest and in shaded coffee plantations; nevertheless, its abundance has not yet been compared among other vegetation types found in the area, such as sugarcane plantations.

Morphological variability of the cranium of (Carnivora: Mustelidae): a morphometric and geographic analysis.

Background: Studies of morphometric variation make it possible to delimit species and geographic intraspecific variation, mainly in species with wide distribution ranges. In the Neotropical otter, , variation in the shape of the rhinarium of three potential subspecies has been described but it is not known whether there is a pattern to the morphometric variation in the skull throughout the distribution of this species. We analyzed morphological variation in the cranium (ventral view) and the mandible (lateral view) of the Neotropical otter, comparing male and female specimens and evaluating the differences between specified geographic units utilizing methods from geometric morphometrics.

Comparison of organochlorine pesticides and PCB residues among hawksbill (Eretmochelys imbricata) and green (Chelonia mydas) turtles in the Yucatan Peninsula and their maternal transfer.

Organochlorine pesticides and PCB (POPs) concentrations were determined in the blood and eggs of green and hawksbill turtles. We compared concentrations between species, analyzed the relationship between turtle size and the POPs concentrations and the relationship between the concentrations in the blood of the nesting turtles and their eggs. We expected higher concentrations in the hawksbill turtle because of its higher trophic level, but concentrations were not higher in all the cases.

Persistent organochlorine pesticides in two hylidae species from the La Antigua watershed, Veracruz, Mexico.

Amphibians are good models for monitoring contaminants in ecosystems because they transfer xenobiotic substances throughout trophic networks. We quantified bioaccumulated POCs by capturing and sacrificing ninety-one frogs (Charadrahyla taeniopus and Ecnomiohyla miotympanum) from four riverine forests immersed in agriculture and pasture lands in the La Antigua, Veracruz, Mexico watershed. The concentrations of ∑DDTs, ∑HCHs, ∑Endosulphans, ∑Heptachlors, ∑Drines, and ∑Chlordanes were measured by gas chromatography and compared between species, sites and seasons.

Heavy metals in the habitat and throughout the food chain of the Neotropical otter, Lontra longicaudis, in protected Mexican wetlands.

Top predators like the Neotropical otter, Lontra longicaudis annectens, are usually considered good bioindicators of habitat quality. In this study, we evaluated heavy metal contamination (Hg(tot), Pb, Cd) in the riverine habitat, prey (crustaceans and fish), and otter feces in two Ramsar wetlands with contrasting upstream contamination discharges: Río Blanco and Río Caño Grande in Veracruz, Mexico, during the dry, the wet, and the nortes seasons. Most comparisons revealed no differences between sites while seasonal differences were repeatedly detected for all of the compartments.

Persistent organic contaminants and steroid hormones levels in Morelet's crocodiles from the Southern Gulf of Mexico.

Effects of endocrine disruptors on reproductive variables of top predators, such as alligators and crocodiles, have long been cited. Due to their long life span, these predators provide us with historic contaminant annals. In this study we tried to test whether lifestyle (free-ranging vs.

Gastrointestinal parasites of Howler monkeys (Alouatta palliata) inhabiting the fragmented landscape of the Santa Marta mountain range, Veracruz, Mexico.

In recent years populations of howler monkeys (Alouatta palliata) in southeastern Mexico have decreased substantially due to the transformation and loss of natural habitats. This is especially evident in the Santa Marta mountain range, Veracruz, Mexico where several studies have evaluated the impact of fragmentation on howler monkey populations in order to propose management programs for their conservation. The conditions generated by fragmentation likely change the rates of parasitic infection and could decrease howler survival.

Physiological constraints and latitudinal breeding season in the Canidae.

Physiological strategies that maximize reproductive success may be phylogenetically constrained or might have a plastic response to different environmental conditions. Among mammals, Canidae lend themselves to the study of these two influences on reproductive physiology because all the species studied to date have been characterized as monestrous (i.e.