Diversidade de anfíbios e répteis Squamata na região do baixo rio Purus, Amazônia Central, Brasil / Diversity of amphibians and Squamata reptilians from lower Purus River Basin, Central Amazonia, Brazil

A região do baixo rio Purus na Amazônia Central - Brasil representa uma área de relevante interesse para conservação de anfíbios e répteis. No entanto, há pouca informação disponível sobre estes grupos taxonômicos para áreas de florestas de terra firme e florestas de várzea, principais paisagens nesta região. Nesse estudo, realizamos uma amostragem ampla em esforço e área, em dois períodos: 2004-2005 e 2009-2010. Utilizamos técnicas complementares eficientes na amostragem da herpetofauna em florestas tropicais: procura ativa limitada por tempo (PLT), armadilhas de interceptação e queda (AIQ) e armadilhas de interceptação com funis duplos (AIF). Foram registradas 160 espécies, sendo 75 de anfíbios (73 anuros e dois gimnofionos) e 85 de répteis (34 lagartos e 51 serpentes). O registro do anuro Dendropsophus allenorum foi o primeiro para o Brasil. Comparando a eficiência dos métodos de coleta, a busca ativa por coletores capacitados (PLT) foi o método mais eficaz na amostragem da herpetofauna; seguido das AIQ, eficientes na captação de anuros terrícolas e lagartos de serrapilheira nas florestas de terra firme. Não utilizamos AIQ nas áreas de várzea por estas terem solos hidricamente saturados. As AIF, apesar de menos eficientes na amostragem de anuros e lagartos, foram eficazes na captura serpentes e facilmente adaptáveis aos solos hidromórficos das várzeas. Uma maior riqueza de espécies e famílias foi encontrada nas florestas de terra firme. As florestas de várzea tiveram uma marcante ausência de famílias fossoriais e de serrapilheira. No entanto, nas florestas de várzea encontramos um maior número de espécies de anuros arborícolas (Hylidae) e de lagartos heliotérmicos maiores (Teiidae). Entretanto, avaliando separadamente cada período de amostragem, a riqueza de espécies da herpetofauna torna-se similar entre os diferentes tipos de paisagens florestais, tendendo ser maior nas florestas de terra firme. Apesar de similares em número espécies, as florestas de terra firme e de várzea foram diferentes quanto ao conjunto das espécies. A diversidade complementar de anfíbios e répteis Squamata entre florestas de terra firme e de várzea (diversidade beta-β), paisagens de maior abrangência local, possivelmente representa a maior contribuição para a diversidade regional da herpetofauna no baixo rio Purus (diversidade Gama-γ).

The lower Purus River Basin, Central Amazonia - Brazil, represents an area of prominent interest for conservation of amphibians and reptiles. However, there is little available information about these groups for flooded and nonflooded forests, the major landscapes in this region. We sampled a representative area over two periods: 2004-2005 and 2009-2010. We used efficient and complementary techniques for sampling the herpetofauna in rainforests: time constrained audio-visual search (TAVS), pitfall traps with drift fence (PFDF) and double-ended funnel traps with drift fence (FTDF). We recorded a total of 160 species, including 75 amphibians (73 frogs and two caecilians) and 85 reptiles (34 lizards and 51 snakes). The occurrence of the anuran Dendropsophus allenorum represents the first record for Brazil. Comparing the efficiency of the sampling methods, the TAVS was the best method in sampling efficiency for the majority of the herpetofauna species; followed by the PFDF, efficient in sampling terrestrial frogs and litter lizards in the nonflooded forests. We did not use the PFDF in the flooded forests because the soil was water saturated. Despite its low efficiency in sampling terrestrial frogs and litter lizards, the FTDF, was efficient in snake capture and easily adaptable to the saturated soil in flooded forests. The greatest richness of species and groups was found in the nonflooded forests. Families of fossorial and litter species were mostly absent from the flooded forests. However, in the flooded forests we found a large number of arboreal frogs (Hylidae) and of larger heliothermic lizards (Teiidae). When we evaluated each sample period separately, we found a similar richness of the herpetofauna between the different types of forest landscapes, with a bias towards higher diversity in the nonflooded forests. In spite of similar species numbers, the nonflooded and flooded forests had different species assemblages. The total amphibian and Squamata reptilian diversity between the nonflooded and flooded forests (beta-β diversity), sites with more widespread landscapes, possibly represents the major contribution to the regional herpetofauna diversity in the lower Purus River Basin (Gama-γ diversity).

Mercury concentration in the spectacled caiman and black caiman (Alligatoridae) of the Amazon: implications for human health.

Mercury (Hg) concentrations in the Amazon are generally high, but no studies have been published on Hg concentrations in caimans (Alligatoridae) from the region. Aiming for sizes representative of caimans traded for food in the Amazon, we measured Hg concentration in tail muscle of spectacled caiman (Caiman crocodilus crocodilus) and black caiman (Melanosuchus niger) from the Purus River basin. The information on Hg concentration in caimans from this area is important because of the potential health risk to humans and other animals that eat them as well as the potential use of these top-level predators as bioindicators. There were no significant interspecific or sex differences in Hg concentrations. The mean Hg concentration was 291.2 µg/kg in C. c. crocodilus and 193.9 µg/kg in M. niger. A significant positive correlation between Hg concentration and size was found for M. niger (p = 0.005) but not for C. c. crocodilus. Our Hg sample from M. niger corresponded to the size of M. niger collected for commercial trade, but our Hg sample from C. c. crocodilus turned out to be significantly smaller than the trade samples (p = 0.004), but this difference is not pertinent in the absence of a correlation between size and Hg concentration for this species. Although there are no standards for reptile meat, both species had mean Hg concentrations lower than the maximum allowable level of 500 µg/kg Hg recommended by the World Health Organization and by the Brazilian Health Ministry for fish. However, by calculating daily consumptions limits and number of meals per month that can be safely consumed, we found that consumers who eat caimans frequently may be at risk for Hg-related health problems.

Ciclo ovárico y jerarquía folicular de Peltocephalus dumerilianus (Testudines: Podocnemididae) / Ovarian cycle and follicular hierarchy of Peltocephalus dumerilianus (Testudines: Podocnemididae)

Se analizaron cuarenta pares de ovarios de hembras adultas de Peltocephalus dumerilianus (Schweigger 1812), para establecer los cambios morfológicos mensuales producidos durante un año. Se llevaron a cabo exámenes macroscópicos de los oviductos y de los ovarios de especímenes que los habitantes ribereños del municipio de Barcelos, Amazonas, Brasil, utilizaron para su consumo, usando metodológicamente la medida del diámetro y conteo de los folículos ováricos y de los cuerpos lúteos. Los resultados muestran la presencia gradual de folículos acorde con la época reproductiva, resaltando que durante el último tercio del proceso, justo antes de la postura se hacen más evidentes; se analiza la relación existente entre el tamaño de la hembra y la masa ovárica, la cual es estadísticamente significativa (F (10,29)=3,655, p < 0,05). Se hace evidente la existencia de una jerarquía ovario folicular que demuestra que para esta especie solo es posible fisiológicamente una postura por año.

Forty pairs of ovaries of mature female Peltocephalus dumerilianus (Schweigger 1812) were analyzed, to establish the morphologic monthly changes that take place during one year; we examined macroscopically the oviducts and the ovaries of specimens that the riverside inhabitants of the municipality of Barcelos, Amazons, Brazil, used for their consumption. We measured the diameter and recorded the number of enlarged ovarian follicles and corpora lutea. The results show the gradual enlargement of follicles in agreement with the reproductive period, observing that during the last third of the process; just before oviposition they become more evident. The positive relationship between the size of the female and the ovarian mass, is statistically significant (F (10.29)=3.655, p < 0.05). Follicullar sizes suggest that this species nests only once a year.