Inshore and offshore bottlenose dolphin, Tursiops truncatus, ecotypes were distinguished through genetics, distribution, diet, morphology, diversity, and social behaviors. Although T. truncatus is a widely studied species, few studies have focused on offshore populations. Offshore biodiversity is frequently neglected due to the difficulty of data collection, and therefore, it is challenging to assess how threatened these populations are. A small, offshore population of dolphins residing around the Saint Peter Saint Paul Archipelago (SPSPA) in the middle of the Atlantic Ocean has been monitored for several years, and a decrease in the number of dolphin sightings has recently been noticed. We analyzed a comprehensive mtDNA control-region sequence dataset for this species to infer the conservation status and better understand the relationships between the SPSPA population and other offshore populations. We assessed the genetic diversity and population structure of the bottlenose dolphin from inshore and offshore populations of the Atlantic Ocean. Offshore populations are more genetically diverse and have less variation between populations than inshore populations. The offshore populations share haplotypes, indicating potential gene flow. However, the SPSPA population presented the lowest levels of genetic diversity between populations. The conservation status of the SPSPA population is concerning, and it is necessary to apply effective management strategies to guarantee its protection.

The franciscana dolphin (_Pontoporia blainvillei_), a small cetacean native to the Southwestern Atlantic Ocean (SAO), is critically threatened by bycatch in gillnet fisheries and habitat degradation. The Franciscana Management Area (FMA) Ia, located in Espírito Santo, Brazil, harbors the most endangered population of small cetaceans in the SAO. The Doce River region represents a vital habitat for this species, particularly following the 2015 mining waste spill, which further disrupted local ecosystems. Through drone-based monitoring, this study investigates the diving and surface behavior of franciscana dolphins, providing valuable insights for refining population estimates and advancing conservation strategies. The average surface time was 17 seconds (±15s), and the average dive time was 64 seconds (±26s). The diving time was almost four times longer than the surface time. These findings underscore the importance of ongoing monitoring to support effective management of this vulnerable population.

Coatis (Nasua nasua) form extensive social groups and utilize acoustic signals as one of their means of communication. The contact call, chirp, plays an important role in maintaining cohesion and exchanging information. Our objective was to evaluate possible regional differences in chirp parameters in the Atlantic Forest and Pampa biomes from southern Brazil and Uruguay, and investigate the relationship between environmental variables and this signal, testing the Acoustic Adaptation Hypothesis (AAH). We obtained audios from 184 videos of camera traps distributed in the two biomes. Temporal and spectral parameters were extracted from the chirps and organized with the respective environmental variables and location. We found significant differences for all chirps’ parameters at biome and locality levels. The environmental predictors most consistently associated with vocal variation were NDVI, latitude and wind speed, although NDVI and latitude likely reflect the same environmental gradient. Animals in environments with dense vegetation tend to vocalize at lower frequencies, probably due to attenuation generated by vegetation, whereas calls emitted in open environments tended to exhibit higher frequencies, consistent with the predictions of the AAH. These findings are consistent with the Acoustic Adaptation Hypothesis and suggest that environmental conditions may contribute to acoustic variation in coati contact calls.