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.

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.

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.

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.