Maria Isabel Carvalho Gonçalves

The distribution of odontocetes is likely to be influenced by environmental and oceanographic factors, as well as prey availability, resulting in distinct habitat-use patterns among species. Cetaceans rely on acoustic communication for essential activities such as navigation, foraging, and social interactions. In southern Bahia, Brazil, the narrow continental shelf promotes the coexistence of coastal and offshore species within a restricted area, providing an opportunity to investigate spatial segregation and acoustic niche structure. We conducted simultaneous visual and acoustic monitoring along the coast of Ilhéus between January and December 2022 to assess species distribution, acoustic presence, and acoustic niche overlap. Six odontocete species were visually identified, with the prevalence of Sotalia guianensis in nearshore habitats, whereas the sperm whales (Physeter macrocephalus) was detected and identified exclusively by acoustic monitoring. A clear spatial segregation was observed between coastal and offshore species, indicating strong habitat partitioning at a fine spatial scale. Acoustic presence was significantly higher in coastal waters and during winter, suggesting seasonal and spatial variation in habitat use. Acoustic overlap analyses indicated spectral niche partitioning, with greater frequency overlap among species occupying adjacent zones and less overlap among species with greater spatial differentiation. This study provides the first integrated characterization of spatial distribution and acoustic patterns of odontocetes in southern Bahia, offering valuable baseline information to support the monitoring and conservation of these species, where an increase in anthropogenic activities is projected.

Whale watching is a tourist activity that allows visitors to observe cetaceans. This descriptive study, with an exploratory and qualitative approach, analyzed the socio-demographic profile and types of learning, knowledge, and training needs of the tour boat crew who take visitors to see humpback whales on the southern coast of Bahia, Brazil. Data were collected through semi-structured interviews followed by content analysis. The data showed that most of the crew/drivers were male and adequately trained, although performance was low for all the workers involved. Moreover, education was characteristic of the whale watching activity. These results reveal the urgency of new studies that focus on the real training needs of the vessel crew involved in whale watching.

Aim: The urgency for remote, reliable and scalable biodiversity monitoring amidst mounting human pressures on ecosystems has sparked worldwide interest in Passive Acoustic Monitoring (PAM), which can track life underwater and on land. However, we lack a unified methodology to report this sampling effort and a comprehensive overview of PAM coverage to gauge its potential as a global research and monitoring tool. To address this gap, we created the Worldwide Soundscapes project, a collaborative network and growing database comprising metadata from 416 datasets across all realms (terrestrial, marine, freshwater and subterranean).Location: Worldwide, 12,343 sites, all ecosystem types.Time Period: 1991 to present.Major Taxa Studied: All soniferous taxa.Methods: We synthesise sampling coverage across spatial, temporal and ecological scales using metadata describing sampling locations, deployment schedules, focal taxa and audio recording parameters. We explore global trends in biological, anthropogenic and geophysical sounds based on 168 selected recordings from 12 ecosystems across all realms.Results: Terrestrial sampling is spatially denser (46 sites per million square kilometre—Mkm²) than aquatic sampling (0.3 and 1.8 sites/Mkm² in oceans and fresh water) with only two subterranean datasets. Although diel and lunar cycles are well sampled across realms, only marine datasets (55%) comprehensively sample all seasons. Across the 12 ecosystems selected for exploring global acoustic trends, biological sounds showed contrasting diel patterns across ecosystems, declined with distance from the Equator, and were negatively correlated with anthropogenic sounds.Main Conclusions: PAM can inform macroecological studies as well as global conservation and phenology syntheses, but representation can be improved by expanding terrestrial taxonomic scope, sampling coverage in the high seas and subterranean ecosystems, and spatio‐temporal replication in freshwater habitats. Overall, this worldwide PAM network holds promise to support cross‐realm biodiversity research and monitoring efforts.

After the worldwide moratorium on whaling, humpback whale populations began to recover, reoccupying former areas of use, as also observed on the Brazilian coast. Abrolhos Bank represents the area of greatest humpback whale concentration but the number of individuals to the north has increased, as has happened in the region of Serra Grande. To compare relative abundance, habitat use, and movement patterns between a well‐established breeding and a reoccupation area, visual monitoring from land‐based stations was performed: 160 days in the Abrolhos Archipelago located on the Abrolhos Bank and 133 days in Serra Grande in 2014, 2015, 2018, and 2019. While relative abundance varied annually in the Abrolhos Archipelago, it gradually increased in Serra Grande, surpassing the number registered in Abrolhos in 2019. Group composition frequency was similar between areas except for mother and calf accompanied by one or more escorts, which were more frequent in Abrolhos. Despite similar movement speed and linearity values, whales in Serra Grande had a higher reorientation rate. Monitoring different areas occupied by this population supports decisions about spatial management of the Brazilian coast in relation to the implementation of anthropogenic activities, especially in areas where whales have recently returned to occupy.

The urgency for remote, reliable, and scalable biodiversity monitoring amidst mounting human pressures on climate and ecosystems has sparked worldwide interest in Passive Acoustic Monitoring (PAM), but there has been no comprehensive overview of its coverage across realms. We present metadata from 358 datasets recorded since 1991 in and above land and water constituting the first global synthesis of sampling coverage across spatial, temporal, and ecological scales. We compiled summary statistics (sampling locations, deployment schedules, focal taxa, and recording parameters) and used eleven case studies to assess trends in biological, anthropogenic, and geophysical sounds. Terrestrial sampling is spatially denser (42 sites/M·km ² ) than aquatic sampling (0.2 and 1.3 sites/M·km ² in oceans and freshwater) with only one subterranean dataset. Although diel and lunar cycles are well-covered in all realms, only marine datasets (65%) comprehensively sample all seasons. Across realms, biological sounds show contrasting diel activity, while declining with distance from the equator and anthropogenic activity. PAM can thus inform phenology, macroecology, and conservation studies, but representation can be improved by widening terrestrial taxonomic breadth, expanding coverage in the high seas, and increasing spatio-temporal replication in freshwater habitats. Overall, PAM shows considerable promise to support global biodiversity monitoring efforts.

The population of humpback whales from breeding stock A is increasing, and little is known about the routes used by humpbacks that move north of the main calving area of Brazil, the Abrolhos Bank. The aim of this study was to describe the movements of humpback whales in a reoccupation wintering area (Serra Grande, Bahia state, Brazil) based on land-based surveys to test if movement patterns change during the season and between years, due to group composition, behavioral state, and distance to the coast. The mean leg speed of the groups sighted was 6.88 (±2.92) km/h, and leg speed was positively correlated with distance to the coast. There was an increase in leg speed and distance to the coast with increasing number of escorts in the groups with calves. The mean linearity value for group trajectory was 0.81 (±0.19) and the mean reorientation rate was 25.72 (±19.09) º/min. We observed a predominance of trajectories heading south throughout the study. Groups exhibiting more erratic movements early in the season, and groups moving south showed more linear trajectories than groups moving north, indicating the beginning of their migration back to the feeding grounds. Energy conserving strategies and social context affect the movements of humpback whales in Serra Grande, resulting in the observed patterns of the reoccupation of available and suitable habitat north of Abrolhos. Thereby, special attention should be given managing activities with the potential to disturb or displace whales using the region to calve and breed.

The coast of Brazil is an important low latitude nursery ground for humpback whales (Megaptera novaeangliae). The number of humpback whales in this region has increased and its population is reoccupying areas where it has been depleted during the whaling period. The goal of this study was to conduct land-based observations during 2014 and 2015 to characterize patterns of habitat use and relative abundance of humpback whales that migrate to one of these reoccupation areas: Serra Grande, Bahia state. The observed mean group size was 2.12 ± 0.96 individuals and did not vary through the reproductive season nor between years. Dyads (32.9%) and singletons (26.7%) were more frequently observed, and groups with calves represented 21.2% of the sightings. The mean number of whales counted per hour increased from 2014 (3.44 ± 3.35) to 2015 (5.12 ± 4.18). Habitat use varied during the season; whales used shallower waters closer to shore as the season progressed. The spatial distribution of groups with calves was dependent on the presence and number of escorts. Spatial segregation of groups with calves closer to shore is a key factor in understanding the overall distribution of whales in the area, suggesting that social strategies are affected by environmental factors, as seen in other wintering grounds. Small-scale studies from land-based stations, in areas such as this where there is no previous knowledge about the species, are cost effective. They provide information about the overall behavioural and spatial patterns while anthropogenic activity is still low, allowing habitat protection and management decisions before implementation and increase of human activities.