How do different concentrations of aluminum and zinc affect the survival, body size, morphology and immune system of Physalaemus cuvieri (Fitzinger, 1826) tadpole?

The assessment of amphibian responses as bioindicators of exposure to chemical pollutants is an important tool for conservation of native species. This study aimed to investigate the effects of chronic aluminum (Al) and zinc (Zn) exposure on survival, body size, morphology (malformations), and immune system (leukocyte profile) in P. cuvieri tadpoles. Ecotoxicological analyses were performed utilizing chronic toxicity tests in which 210 tadpoles at the 25th Gosner developmental stage were exposed to Al and Zn. Individuals of P. cuvieri were maintained in glass containers containing various concentrations of aluminum sulfate (0.1, 0.2, or 0.3 mg/L) and zinc sulfate (0.18, 0.27 or 0.35 mg/L), and tests were performed in triplicate. After 14 days, amphibians were weighed, measured and survival rate, malformations in the oral and intestine apparatus, leukocyte profile, and ratio between neutrophils and lymphocytes determined. The differing concentrations of Al and Zn did not produce lethality in P. cuvieri where 95% of the animals survived 326 hr following metal exposure. Individuals exposed to Zn achieved greater body growth and weight gain compared to controls. Aluminum increased weight gain compared controls. These metals also produced malformations of the oral and intestine apparatus and enhanced occurrence of hemorrhages, especially at the highest doses. Lymphocytes were the predominant cells among leukocytes, with lymphopenia and neutrophilia observed following Al and Zn treatment, as evidenced by elevated neutrophil/lymphocyte ratio, an important indicator of stress in animals. Data suggest that further studies need to be carried out, even with metal concentrations higher than those prescribed by CONAMA, to ensure the conservation of this species.

2,4-D-based herbicide underdoses cause mortality, malformations, and nuclear abnormalities in Physalaemus cuvieri tadpoles.

Amphibians are considered bioindicators of the environment due to their high sensitivity and involvement in terrestrial and aquatic ecosystems. In the last two decades, 2,4-D has been one of the most widely used herbicides in Brazil and around the world, as its use has been authorized for genetically modified crops and therefore has been detected in surface and groundwater. Against this background, the aim of this work was to investigate the effects of environmentally relevant concentrations of 2,4-D-based herbicides on survival, malformations, swimming activity, presence of micronuclei and erythrocyte nuclear abnormalities in Physalaemus cuvieri tadpoles. The amphibians were exposed to six concentrations of 2,4-D-based herbicides: 0.0, 4.0, 30.0, 52.5, 75.0, and 100 µg L-1, for 168 h. At concentrations higher than 52.5 µg L-1, significantly increased mortality was observed from 24 h after exposure. At the highest concentration (100 µg L-1), the occurrence of mouth and intestinal malformations was also observed. The occurrence of erythrocyte nuclear abnormalities at concentrations of 30.0, 52.5, 75.0 and 100 µg L-1 and the presence of micronuclei at concentrations of 52.5, 75.0, and 100 µg L-1 were also recorded. These effects of 2,4-D in P. cuvieri indicate that the ecological risk observed at concentrations above 10.35 µg L-1 2,4-D may represent a threat to the health and survival of this species, i.e., exposure to 2,4-D at concentrations already detected in surface waters in the species' range is toxic to P. cuvieri.

Mortality and toxicity of a commercial formulation of cypermethrin in Physalaemus gracilis tadpoles.

This study evaluated the lethal, sublethal, and toxic of a commercial formulation of cypermethrin in the anuran species Physalaemus gracilis. In the acute test, concentrations of 100-800 µg L-1 were tested over 96 h. In the chronic test, cypermethrin concentrations recorded in nature (1, 3, 6, and 20 µg L-1) were tested for mortality and then used for the micronucleus test and erythrocyte nuclear abnormalities over a 7-days period. The LC50 determined for P. gracilis for the commercial cypermethrin formulation was 273.41 µg L-1. In the chronic test, a mortality of more than 50% was observed at the highest concentration (20 µg L-1), as it caused half of the tadpoles studied to die. The micronucleus test showed significant results at concentrations of 6 and 20 µg L-1 and recorded the presence of several nuclear abnormalities, indicating the genotoxic potential of the commercial cypermethrin formulation for P. gracilis. Cypermethrin presented a high risk to the species, indicating that it has the potential to cause several problems in the short and long term and to affect the dynamics of this ecosystem. Therefore, it can be concluded that the commercial formulation of cypermethrin had toxicological effects on P. gracilis.

Bird Fauna Composition in a Protected Area in Southern Brazil.

The integrity of natural landscapes is affected by human actions, mainly by the intensification and expansion of agriculture. Factors such as fragment size and the structure of the environment can determine changes in the structure and composition of bird assemblages. In this study we evaluated the bird species composition in three structurally different forest environments, defined as the Core areas, Edge areas, and Buffer areas. The surveys were performed in the Natural Park of Sertão (NPS) and its surroundings in the southern limit of the Atlantic Forest, southern Brazil. To record species composition of birds, the point count method was used. The bird species were categorized according to feeding habits, habitat use, and sensitivity to forest fragmentation. A total of 131 species of birds distributed in 18 orders and 38 families were recorded. The species composition varied between the three areas and there was a significant difference in diversity between the Core and Edge areas and the Core and Buffer areas. Omnivorous species were found more in the Buffer areas than in the Core areas. Species that use the Broad habitat were more frequent in the Buffer and Edge areas than in the Core areas. Species that use the Forest habitat were found more in the Core areas than in the Buffer areas. Most recorded species (66%) have low sensitivity to forest fragmentation. The assemblage patterns found in this study, notably the differences among the three areas in diversity and species composition, can be explained by the ecological traits and the sensitivity levels of birds to forest fragmentation, which in turn seem to reflect different forest structures in the NPS and its surroundings. Although the Edge and Buffer areas have greater diversity, the Core areas showed great importance in maintaining species that are more sensitive to forest fragmentation. Even the largest fragments (such as the NPS), considering the regional context, may have bird species that are widely distributed and less sensitive to forest fragmentation. Forested habitat species may no longer occur or be restricted to the core area of the fragments. For conservation of bird fauna in the NPS, the maintenance of the core areas is essential, especially for those species that require a structurally preserved environment.

Toxicity and genotoxicity of imidacloprid in the tadpoles of Leptodactylus luctator and Physalaemus cuvieri (Anura: Leptodactylidae).

Imidacloprid is a neonicotinoid insecticide used to control agricultural pests around the world. This pesticide can have adverse effects on non-target organisms, especially in aquatic environments. The present study evaluated the toxicity of an imidacloprid-based insecticide in amphibians, using Leptodactylus luctator and Physalaemus cuvieri tadpoles as study models. Spawning of both species were collected within less than 24 h of oviposition from a non-agricultural land at Erechim, Rio Grande do Sul state, Brazil. Survival, swimming activity, body size, morphological malformations, and genotoxic parameters were analyzed at laboratory conditions. A short-term assay was conducted over 168 h (7 days) with five different concentrations of imidacloprid (3-300 µg L-1) being tested. The insecticide did not affect survival, although the tadpoles of both species presented reduced body size, malformed oral and intestine structures, and micronuclei and other erythrocyte nuclear abnormalities following exposure to this imidacloprid-based compound. Exposure also affected swimming activity in L. luctator, which reflected the greater sensitivity of L. luctator to imidacloprid in comparison with P. cuvieri. The swimming activity, body size, and malformations observed in L. luctator and the morphological malformations found in P. cuvieri indicated that even the lowest tested concentration of the insecticide were harmful to amphibians. At concentrations of over 3 µg L-1, P. cuvieri presents a smaller body size, and both species are affected by genotoxic cell damage. This demonstrates that imidacloprid is potentially toxic for the two study species at environmentally relevant concentrations.

Morphological, behavioral and genotoxic effects of glyphosate and 2,4-D mixture in tadpoles of two native species of South American amphibians.

Pesticide contamination is an important factor in the global decline of amphibians. The herbicides glyphosate and 2,4-D are the most applied worldwide. These herbicides are often found in surface waters close to agricultural areas. This study aims at evaluating the chronic effects caused by glyphosate + 2,4-D mixture in Boana faber and Leptodactylus latrans tadpoles. The combined solution of the glyphosate and 2,4-D, in 5 different concentrations, was applied for 168 h. Herbicide mixtures did not affect the survival of the exposed tadpoles but growth and swimming activity were altered; besides causing several damages in the mouth and intestine. The erythrocytes showed micronuclei and other nuclear abnormalities. There is an ecological risk in the exposure of tadpoles of B. faber and L. latrans from the mixture of glyphosate + 2,4-D. Therefore, the approach used in this study provides important information on how commonly used pesticides can affect non-target organisms.

Cypermethrin- and fipronil-based insecticides cause biochemical changes in Physalaemus gracilis tadpoles.

Insecticides used for agricultural pest control, as cypermethrin-based insecticide (CBI) and fipronil-based insecticide (FBI), are constant threats to non-target aquatic organisms. This study aimed to investigate the effect of different concentrations of cypermethrin and fipronil on neurotoxicity and oxidative stress in Physalaemus gracilis. Physalaemus gracilis tadpoles were exposed to five insecticide concentrations and a control treatment, with six replicates. During the experimental period, the tadpole mortality rate was evaluated and after 168 h, the neurotoxic enzyme activity and metabolite quantification related to the antioxidant system were measured. Tadpoles reduced acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities when exposed to 20 µg L-1 CBI and at all FBI concentrations, respectively. Glutathione S-transferase (GST) and superoxide dismutase (SOD) activities showed an increase from concentrations of 6 µg L-1 and 20 µg L-1 of CBI, respectively. After exposure of P. gracilis tadpoles to FBI, inhibitions of AChE and BChE were observed at the highest concentrations evaluated (500 and 1500 µg L-1). SOD activity decreased from 50 µg L-1 of FBI; however, catalase (CAT) and GST activities and carbonyl protein levels increased, regardless of the evaluated dose. We observed that both insecticides promoted oxidative stress and neurotoxic effects in P. gracilis tadpoles. These results suggest that biochemical biomarkers can be used for monitoring toxicity insecticides for the purpose of preservation of P. gracilis.

Genotoxic effects of glyphosate on Physalaemus tadpoles.

Genotoxicity studies have revealed that pesticides bind to genetic material in non-target vertebrates, thereby impairing the genetic integrity of these animals. The main objective of this study was to determine the genotoxic damage in erythrocytes of two native South American amphibian Physalaemus cuvieri and Physalaemus gracilis, both species exposed to a glyphosate-based herbicide. We evaluated the presence of micronuclei (MN) and erythrocyte nuclear abnormalities (ENA) as biomarkers for potential genotoxic compounds. Tadpoles were exposed to doses permitted by Brazilian legislation and concentrations found naturally in Brazilian and Argentinian waters (500, 700 and 1000 µg/L). Glyphosate-based herbicide caused micronuclei formation and several types of erythrocyte nuclear abnormalities in both Physalaemus species. The total frequency of MN and ENA demonstrated the occurrence of cell damage at all tested concentrations. Glyphosate herbicide can be considered a genotoxic that may impact the genetic integrity of native populations of P. cuvieri and P. gracilis.

Can environmental concentrations of glyphosate affect survival and cause malformation in amphibians? Effects from a glyphosate-based herbicide on Physalaemus cuvieri and P. gracilis (Anura: Leptodactylidae).

Herbicides are the most common agrochemicals used in crops. Among them, glyphosate is the most widely applied in the world. Herbicides, especially organophosphates, have been shown to be hazardous to non-target species, including amphibians. The present study evaluated the acute and chronic effects of glyphosate-based herbicide (GBH), Roundup original® DI on tadpoles from two South American native species, Physalaemus cuvieri and P. gracilis. Spawnings were collected in the natural environment and maintained in the laboratory under controlled conditions. Acute and chronic toxicology trials began at stage 25 of Gosner (Herpetological 16:183-190, 1960). In an acute toxicity assay, seven GBH concentrations between 100 and 4500 µg a.e./L were tested over 96 h. For the chronic trials, tadpoles were subjected to both doses allowed by Brazilian legislation and to concentrations found in natural environment waters from Brazil and Argentina, between 65 and 1000 µg a.e/L over 14 days. Glyphosate had lethal effects on both studied species. Tadpoles showed shorter lengths and lower masses; that is, those that survived suffered chronic effects on growth and weight. The GBH maximum acceptable toxicant concentration for mortality and malformation was lower than the allowed level for Brazilian waters. The GBH tested in this study presented a high environmental and acute risk for the two studied species.

Morphological and biochemical traits and mortality in Physalaemus gracilis (Anura: Leptodactylidae) tadpoles exposed to the insecticide chlorpyrifos.

Organophosphate insecticides such as chlorpyrifos are commonly detected in surface waters around the world, where they are highly toxic to many organisms. The frog Physalaemus gracilis uses water sources located in open fields as reproductive sites, where it is exposed to insecticides. The study aimed to evaluate the lethal and sublethal effect of a commercial chlorpyrifos formulation on P. gracilis tadpoles (Anura: Leptodactylidae). In acute toxicity tests, five chlorpyrifos concentrations between 750 and 2,000 µg L-1 were tested. Chronic toxicity, swimming activity, morphological and enzymatic changes, as well as levels of non-protein thiols (NPSH), carbonyl proteins and lipid peroxidation were evaluated at five insecticide concentrations between 11 and 500 µg L-1. The highest mortality rate of P. gracilis tadpoles occurred at 24 and 48 h, with an LC50 of 893.59 µg L-1. At all chlorpyrifos concentrations, tadpoles displayed reduced mobility and spasms. Morphological anomalies were observed in the mouth and intestine, especially at the highest concentrations used. Acetylcholinesterase activity decreased at 250 and 500 µg L-1, catalase activity increased at all concentrations, and superoxide dismutase and glutathione S-transferase increased from 90 µg L-1 to 30 µg L-1, respectively. We also observed increases in NPSH levels at chlorpyrifos concentration starting at 30 µg L-1 and increases in carbonyl proteins from 90 µg L-1 of pesticide. Taken together, these data suggest that the insecticide chlorpyrifos presents acute and chronic risks for P. gracilis, causing neurotoxic effects and oxidative damage, culminating in high risk for this species.

Toxic effects of pyrethroids in tadpoles of Physalaemus gracilis (Anura: Leptodactylidae).

Pyrethroid insecticides are one of the most commonly used pesticide groups, but these compounds have brought risks to non-target species, such as amphibians. This study evaluated the toxicological effects (mortality, swimming activity and oral morphology) caused to a South American species of anuran amphibian, Physalaemus gracilis, exposed to the pyrethroids cypermethrin and deltamethrin. Total spawnings of this anuran were collected in the natural environment and transported to the laboratory where they were kept under controlled conditions. Chronic assays were defined between 0.1 and 0.01 mg L-1 of cypermethrin, and 0.009 and 0.001 mg L-1 of deltamethrin. For cypermethrin, a further chronic toxicity test was performed at 0.05 and 2.0 mg L-1, with hatchlings at stages S.20-S.25. Cypermethrin and deltamethrin were lethal enough to kill over 70% of exposed tadpoles in 1 week at concentrations that can be found in nature (0.01-0.1 mg L-1). The exposure effects also influenced swimming activity and caused changes in oral morphology, which would make it difficult for the animals to survive in their natural habitat. Both pyrethroids presented a risk for P. gracilis, so they should be re-evaluated for non-target wild species.

Is fish embryo test (FET) according to OECD 236 sensible enough for delivering quality data for effluent risk assessment?

Over the past few years, the fish embryo test (FET) has become widely accepted as an animal-friendly protocol for ecotoxicological research. As Organisation for Economic Co-operation and Development (OECD) 236, the FET has been widely applied for simple mixture exposures under the Registration, Evaluation, Authorisation, and Restriction of Chemicals regulation of the European Union; and now its use is spreading worldwide as a supposedly reliable whole-effluent test (i.e., the testing of complex mixture exposures). However, comparative peer-reviewed data regarding the FET's efficiency for whole-effluent tests are virtually nonexistent. The primary objective of the present study was to make the first comparative test between the FET according to OECD 236 and other standard and slightly modified standard fish protocols used worldwide for whole-effluent tests. For that, we used an untreated hospital effluent considered to be highly toxic but disposed of in municipal sewerage. The base methods were OECD 203 (juvenile), US Environmental Protection Agency method 2000.0 (larvae), and OECD 236 (embryo). We also evaluated the addition of 3 virtually costless sublethal metrics (immobility, nonhatching, and pericardial edema) that could enhance the sensitivity of OECD 236. We observed acute toxicity in all 8 methodologies tested, with a clear escalation in sensitivity (larvae > juvenile ≥ embryo). Larvae were the most sensitive life stage for whole-effluent tests. The addition of sublethal metrics to OECD 236 enhanced its previous sensitivity in over 30%. Thus we conclude that OECD 236 acts below its potential and that the embryonic stage (as used in the FET) may not be the most sensitive life stage for whole-effluent tests. Environ Toxicol Chem 2018;37:2925-2932. © 2018 SETAC.

Acute and chronic toxicity of pesticides on tadpoles of Physalaemus cuvieri (Anura, Leptodactylidae).

Brazil is the largest consumer of pesticides in the world. However, knowledge on how these pesticides affect wildlife is scarce. Among the vertebrates, amphibians are particularly important in research to assess the impact of pesticides because of the correlation between pesticide and the decline of these species. This study aimed to evaluate the acute and chronic toxicity of commercial formulations of pesticides, i.e., atrazine (herbicide), cypermethrin (insecticide), and tebuconazole (fungicide) in Physalaemus cuvieri tadpoles. Eggs were collected in nature and cultivated under controlled conditions in the laboratory. Toxicity tests were carried out under standard conditions to determine the lethal concentration (LC50) after 96 h of exposure and to determine the effect of sublethal concentrations after 7 days. In addition, we performed swimming activity tests on tadpoles exposed to sublethal concentrations. The lethal concentration (LC50) was 19.69 mg/L for atrazine, 0.24 mg/L for cypermethrin and 0.98 mg/L for tebuconazole. In the acute test, atrazine showed lower toxicity than cypermethrin and tebuconazole for P. cuvieri. Swimming activity was affected at sublethal doses of atrazine and cypermethrin, but was not after exposure to tebuconazole. Cypermethrin was the insecticide that most altered the swimming activity of the individuals tested. The risk evaluation analysis indicated risks for tadpoles exposed to three tested pesticides, specially cypermethrin.

Lethal and Sublethal Effects of the Herbicide Atrazine in the Early Stages of Development of Physalaemus gracilis (Anura: Leptodactylidae).

Water sources used as reproductive sites by crying frog, Physalaemus gracilis, are extensively associated with agroecosystems in which the herbicide atrazine is employed. To evaluate the lethal and sublethal effects of atrazine commercial formulation, acute and chronic toxicity tests were performed in the embryonic phase and the beginning of the larval phase of P. gracilis. Tests were started on stage 19 of Gosner (Herpetologica 16:183-190, 1960) and performed in 24-well cell culture plates. Acute tests had a duration of 96 h with embryo mortality monitoring every 24 h. Chronic assays contemplated the transition from the embryonic to larval stages and lasted 168 h. Every 24 h the embryos/larvae were observed for mortality, mobility, and malformations. The LC50 of atrazine determined for P. gracilis embryos was 229.34 mg L-1. The sublethal concentrations did not affect the development of the larvae but were observed effects on mobility and malformations, such as spasmodic contractions, reduced mobility, malformations in mouth and intestine, and edema arising. From 1 mg L-1 atrazine, the exposed larvae began to have changes in mobility and malformations. The atrazine commercial formulation has caused early life effects of P. gracilis that may compromise the survival of this species but at higher concentrations than recorded in the environment, so P. gracilis can be considered tolerant to this herbicide at environmentally relevant concentrations.

Toxicity of cypermethrin and deltamethrin insecticides on embryos and larvae of Physalaemus gracilis (Anura: Leptodactylidae).

It is important to establish the toxicity pesticides against non-target species, especially those pesticides used in commercial formulations. Pyrethroid insecticides are widely used in agriculture despite their toxicity to aquatic animals. In this study, we determine the toxicity of commercial formulation of two pyrethroid insecticides, cypermethrin and deltamethrin, in two life stages of Physalaemus gracilis, a frog that breeds in agricultural ecosystems and has potential contact with pyrethroid pesticides. The acute toxicity test (96 h) was carried out with embryos of stage 17:18 and larvae of stages 24:25. Embryos were more resistant to both pesticides than larvae. In embryo mobility assays, we found that both pesticides caused spasmodic contractions, suggestive of neurological effects. In acute toxicity assays, we found that P. gracilis is more resistant to these insecticides than other studied species.

Anuros da Reserva Natural Salto Morato, Guaraqueçaba, Paraná, Brasil / Anurans of Reserva Natural Salto Morato, municipality of Guaraqueçaba, State of Paraná, southern Brazil

O objetivo do presente estudo é apresentar a lista de espécies de anfíbios da Reserva Natural Salto Morato (RNSM), uma reserva de Mata Atlântica no Estado do Paraná, sul do Brasil. O parque está localizado no litoral norte do Paraná, na divisa com o Estado de São Paulo. Nós amostramos ambientes lênticos e lóticos, bromélias e serrapilheira durante os meses de setembro de 2006 a março de 2007. Na RNSM foram registradas 42 espécies de anfíbios anuros, pertencentes a nove famílias, sendo uma espécie endêmica da área de estudo. Nós registramos 14 modos reprodutivos dos anuros na área de estudo. Na RNSM, 50% das espécies de anuros ocorreram em mais de 50% das amostragens, 26% das espécies foram registradas entre 25-50% das amostragens e 24% das espécies foram raras, ocorrendo em menos de 25% das amostragens. A RNSM até o presente momento é a área com a maior diversidade de anfíbios e de modos reprodutivos do Paraná. Esses fatores evidenciam a importância da RNSM para a conservação dos anfíbios.

Here we present a survey of amphibian species of the Reserva Natural Salto Morato (RNSM), an Atlantic rainforest reserve in Paraná, southern Brazil. We sampled lentic and lotic water bodies, phytotelmata and leaf litter from September 2006 to March 2007. We found 42 species from nine families, one of which is endemic to the study area. Additionally, we recorded 14 reproductive modes. In the RNSM, 50% of anuran species occur in more than 50% of samples, 26% of species occurred between 25 and 50% of samples, and 24% were rare, occurring in less than 25% of samples. The reserve holds the highest diversity of amphibians and reproductive modes in Paraná. Our results emphasize the importance of RNSM for amphibian conservation.

Ecologia e história natural de uma taxocenose de serpentes no Núcleo Santa Virgínia do Parque Estadual da Serra do Mar, no sudeste do Brasil / Ecology and natural history of a snake assemblage at Núcleo Santa Virgínia, Parque Estadual da Serra do Mar, southeastern Brazil

O objetivo deste estudo foi obter informações sobre a história natural e a ecologia de uma taxocenose de serpentes na Mata Atlântica do alto da Serra do Mar, no Núcleo Santa Virgínia do Parque Estadual da Serra do Mar, nordeste do Estado de São Paulo, Brasil. Os principais aspectos estudados foram riqueza, abundância relativa, padrões de atividade diária e sazonal, utilização do ambiente e dieta. Também são fornecidas informações adicionais sobre outros aspectos da história natural das espécies. Um total de 148 indivíduos, de 27 espécies, 19 gêneros e quatro famílias foi encontrado dentro dos limites do Núcleo Santa Virgínia. As espécies mais frequentemente encontradas foram Bothrops jararaca, Xenodon neuwiedii e Liophis atraventer. A maior parte das espécies é predominantemente diurna e terrícola. Dentre os fatores abióticos analisados para a área de estudo, o mais relacionado à abundância das serpentes foi a temperatura mínima, seguido da temperatura média e da pluviosidade. A maioria das espécies encontradas apresenta dieta concentrada em uma categoria de presa ou restrita a poucos tipos de itens alimentares. Aparentemente, anfíbios anuros são o principal recurso alimentar para as taxocenoses de serpentes da Mata Atlântica do alto da Serra do Mar. Os nossos resultados indicam que a estrutura da taxocenose de serpentes do Núcleo Santa Virgínia reflete principalmente as características ecológicas da linhagem mais representada na taxocenose.

The objective of this study was to describe the natural history and the ecology of a snake assemblage in the Atlantic rainforest, at Núcleo Santa Virgínia, Parque Estadual da Serra do Mar, located on the northeastem of the state of São Paulo, southeastern Brazil. We describe richness, relative abundance, daily and seasonal activity, and substrate use, besides additional aspects of the natural history of the snakes. A total of 148 individuals, of 27 species, 19 genera and four families, were found within the area of the Núcleo Santa Virgínia. Species that were sampled more frequently were Bothrops jararaca, Xenodon neuwiedii and Liophis atraventer. Among the abiotic factors analyzed, minimum temperature, followed by mean temperature and rainfall are apparently the most important in determining snake abundance and/or activity. Most species presented a diet concentrated on one prey category or restricted to a few major food items. Frogs seem to be the most important food resource for snake assemblages in the Atlantic rainforest on the top of Serra do Mar. Our results indicate that the structure of the Núcleo Santa Virgínia snake assemblage reflects mainly the ecological characteristics of each of the lineages that compose the assemblage.