Israel Maciel

• PhD
• PostDoc Position at State University of Rio de Janeiro

Mixed species groups are usually associated with group protection to avoid predation. Reports of killer whale occurrence and attacks are scarce in Brazilian waters. Here we report the first case of an attack by killer whales on a mixed group of humpbacks (Megaptera novaeangliae) and a southern right whale (Eubalaena australis). This is also the fir...

Studies show that the infection of cetaceans by socially transmitted diseases may impact the ecology and behavior of individuals and populations. Little is known about the effects of intense, short-term outbreaks of disease, typical of cetacean morbillivirus (CeMV). Understanding these effects is important in the case of resident populations expose...

Climate change alters marine environments, affecting temperature, oxygen levels, and acidity, prompting species to relocate to suitable areas. Understanding these shifts is vital for top predators like cetaceans, crucial for marine ecosystem regulation. We mapped the suitable environments for the rough-toothed dolphin (Steno bredanensis) - consider...

Impact of human activities (dredged channel, anchoring areas, and industrial pole) on Guiana dolphin (Sotalia guianensis) social structure (group size and feeding behaviours) in a coastal bay in Brazil

Two resident populations of Guiana dolphins inhabit the Costa Verde estuarine complex in southeastern Brazil. While these populations are relatively well-studied, little is known of the movement patterns between them. The present study was based on the identification of the individual dolphins that transited between the two Costa Verde populations...

Climate change harms marine ecosystems, causing habitat loss and shifts in biodiversity. Impacts on vital species like cetaceans disrupt biological communities, emphasizing the need to understand their spatial distribution for biodiversity conservation. Our study assessed potential changes to suitable habitats in Brazil of a key species, the rough-...

Marine ecosystems, especially coastal ones, are experiencing an increased pressure from human impacts. The first step to develop effective and appropriate management strategies is to understand the underlying processes of species distribution. The Guiana dolphin is a threatened coastal species, vulnerable to human-induced rapid environmental change...

Ocean warming, acidification, and deoxygenation are expected to intensify without significant climate mitigation. In tropical regions, rising ocean temperatures may push marine species to their thermal limits, leading to redistributions and cascading effects on communities and ecosystems. We evaluate how the future climate change scenarios could im...

As baleias-jubartes (Megaptera novaeangliae) são frequentemente avistadas na região do Cabo Frio, entre Arraial do Cabo e Armação dos Búzios–RJ, durante a sua temporada de migração para as áreas de reprodução, predominantemente no sul da Bahia. Apesar dessa região ser conhecida como um importante local de passagem, em anos recentes, há indícios do...

1. While cetaceans are known to produce large and complex acoustic repertoires, the challenges of exhaustively sampling sounds at sea and counting relevant signals has precluded an understanding of their true repertoire diversity. 2. Here we quantify and compare the whistle repertoires of 16 populations in the genus Sotalia, belonging to two sister...

Simple Summary This study investigated the body condition of the Guiana dolphins (Sotalia guianensis) of Sepetiba Bay, in southeastern Brazil, between 2017 and 2022. Body condition, a key indicator of animal health, was assessed using standardized photographs taken from a research vessel. These photographs were used to evaluate visible roundness, e...

The present chapter gathers five years of information on the population of Guiana dolphins in Sepetiba bay, contributing to the Observatório Socioambiental of Sepetiba bay. The information gathered here is presented in the context of intensified degradation of Sepetiba bay caused by the cumulative and synergistic action of port, industrial, tourist...

The rapid and ongoing decline in global biodiversity highlights the need for ever-effective conservation measures, which has transformed the monitoring of biodiversity into an essential diagnostic tool. Over the past few decades, studies in biodiversity monitoring have invested increasingly in the use of bioacoustics tools as a mean of obtaining da...

Shipping is the principal source of anthropogenic noise in the aquatic soundscape of many coastal areas. Noise can affect temporally or permanently the physiology, behavior, and ecology of marine mammals. As noise pollution is considered to be an important threat to Guiana dolphins (Sotalia guianensis), we focused the present study in the effects o...

Áreas Marinhas Protegidas (AMPs) são delimitações legais, criadas para proteção dos recursos naturais e serviços ecossistêmicos, de ecossistemas representativos de um bioma ou de elementos da biodiversidade, sendo considerada a melhor medida de manejo sustentável de recursos naturais e da biodiversidade. A sua efetividade se dá pelo conjunto de açõ...

Despite the importance of coastal habitats for the provision of many ecosystem services, these areas are currently among the most impacted by human activities. Impacts on coastal ecosystems may affect many key species, such as the Guiana dolphin, which inhabits Sepetiba Bay in south‐eastern Brazil, a highly degraded environment owing to a human‐ind...

Animal vocalizations have nonlinear characteristics responsible for features such as subharmonics, frequency jumps, biphonation, and deterministic chaos. This study describes the whistle repertoire of a short-beaked common dolphin (Delphinus delphis) group at Brazilian coast and quantifies the nonlinear features of these whistles. Dolphins were rec...

Shipping is the principal source of anthropogenic noise in the aquatic soundscape of coastal areas. Noise can have temporary or permanent effects on the physiology, behavior, and ecology of the marine mammals and, as noise pollution is considered to be an important threat to Guiana dolphins ( Sotalia guianensis ), we focused on this question in the...

Sepetiba bay has a Marine Protected Area (MPA) created to safeguard the population of Guiana dolphins (Sotalia guianensis). However, anthropogenic activities and the current increase in vessel traffic may cause the environment to be acoustically disturbed, and impact communication, reinforcing the need for acoustic refuges to protect the species. T...

Os assobios dos botos-cinzas (Sotalia guianensis) são importantes na comunicação. Estes sinais são adaptáveis ao ambiente e às influências antropogênicas, alterando o esforço vocal. Unidades de Conservação (UC), apresentam medidas de regulação de atividade humanas, sendo potenciais habitats favoráveis à comunicação. Avaliamos as diferenças entre di...

A pesquisa sísmica introduz altos níveis de ruído no ambiente. Os limites acústicos para cetáceos expostos a sons pulsados foi definido para resposta comportamental e potencial dano auditivo respectivamente á 160 e 180 dB re 1 µPa. Entretanto, órgãos ambientais brasileiros estão preocupados quanto a potenciais impactos mesmo abaixo de 160 dB. Nós a...

Understanding the processes that determine the occurrence of species, especially for those exposed to human activities, is key to appropriate management. The common bottlenose dolphins, Tursiops truncatus, is well studied worldwide, but very little attention has been given to transient groups of this species and how such groups are exposed to human...

It is important to understand the processes that determine species distribution, particularly for species that have an extensive home range and are exposed to various environmental conditions. Although studies have modeled the influence of environmental conditions on dolphin distribution, there is still a gap in assessing the influence of human act...

Marine ecosystems provide vital services to humans. However, they have been further degraded due to anthropogenic activities. To minimize the impacts, the creation and establishment of Protected Areas (PAs) have been encouraged, but their effectiveness is still not clear. Sepetiba and Ilha Grande bays are two anthropized estuarine areas located in...

Understanding the processes that determine the occurrence of species, especially for those exposed to human activities, is the key to appropriate management. Despite Tursiops truncatus being well-studied worldwide, information about transient groups of this common bottlenose dolphins and how groups are exposed to human activities is lacking. Here,...

Sepetiba and Ilha Grande bays are two estuarine areas located in Rio de Janeiro State, Brazil, that have Marine Protected Areas (MPAs) to safeguard the local biodiversity. However, anthropogenic activities may cause acoustic disturbance in some areas, affecting local species. The aim of this study was to map the noisiest areas in Sepetiba and Ilha...

The social structure plays a key role in the ecology of cetaceans. It is a product of group living trade-off and may influence the genetic structure, habitat use and spread of diseases. We analyzed social network parameters of Guiana dolphin (Sotalia guianensis) at Ilha Grande Bay, a estuarine complex in SE Brazil. A total of 196 individuals were p...

Dolphins developed feeding tactics to overcome schooling fish anti-predatory behavior and the distribution of prey species may influence dolphins tactics. We analyzed the habitat suitability of feeding tactics performed by Guiana dolphin (Sotalia guianensis) at Ilha Grande Bay (IGB), in SW Brazil. Due to IGB various microhabitats, we expected the G...

Behavioral plasticity helps to understand the life history and different strategies that offspring and adults use to increase their fitness. Behavioral differences among age classes are reported for marine mammals, but few focused on behavioral events. These events help to understand the complexity of cetacean’s behavior, since they may be performe...

Anthropogenic noise can impact cetaceans, leading to masking, stress, and auditory damage, among other effects. Recent studies have emphasized the need to understand these impacts on marine organisms, for which cetaceans may be used as ecological models. However, it is unclear whether public policy-making in the countries that present the same conc...

The common bottlenose dolphin, Tursiops truncatus, is widely distributed. However, information about its ecology and behavior in Brazilian waters is scarce especially about the ‘offshore’ ecotype, an Evolutionarily Significant Unit in the Southwest Atlantic. We report for the first time the occurrence, behavior and habitat use of bottlenose dolphin...

Species distribution modelling has been used to identify critical habitats for the delimitation of Marine Protected Areas. Although Marine Protected Areas may often overlap with the distribution of key marine species, illegal human activities often continue within these areas, causing negative impacts on the local biodiversity. A generalized linear...

Social organization is an important feature of the behavior of most delphinids, including the rough-toothed dolphin (Steno bredanensis), although, even in social dolphins, specific circumstances may lead to solitary behavior. In these situations, a solitary dolphin may shift to interacting with humans. Between November 2018 and April 2019, we obtai...

Investigating the influence of coastal development on marine environments is a priority to maintain healthy seas. Cetaceans are top predators, keystone and umbrella species and thus are good candidate models to evaluate the extent of anthropogenic impacts on coastal habitats. We employed a generalized linear model with spatial eigenvector mapping (...

The recent discovery of the Araguaian river dolphin (Inia araguaiaensis) highlights how little we know about the diversity and biology of river dolphins. In this study, we described the acoustic repertoire of this newly discovered species in concert with their behaviour. We analysed frequency contours of 727 signals (sampled at 10 ms temporal resol...

Tonal whistle produced by an Araguaian boto and the longest sound in our recordings

Short call with no non-linear phenomena produced by an Araguaian boto

Short two-component calls produced by an Araguaian boto calf

Short calls with subharmonics produced by an Araguaian boto

Os objetivos do presente estudo foram analisar a ocorrência, os movimentos e a fidelidade de área da subespécie oceânica do golfinho-nariz-de-garrafa-comum (Tursiops truncatus truncatus) na região do Cabo Frio e na cidade do Rio de Janeiro através da análise de captura e recaptura dos indivíduos foto-identificados. Cruzeiros mensais foram realizado...

The recent discovery of the Araguaian river dolphin ( Inia araguaiaensis ) highlights how little we know about the diversity and biology of river dolphins. In this study, we described the acoustic repertoire of this newly discovered species in concert with their behaviour in free-ranging, human-habituated individuals. We analysed 393 signals that w...

The recent discovery of the Araguaian river dolphin ( Inia araguaiaensis ) highlights how little we know about the diversity and biology of river dolphins. In this study, we described the acoustic repertoire of this newly discovered species in concert with their behaviour in free-ranging, human-habituated individuals. We analysed 393 signals that w...

The recent discovery of the Araguaian river dolphin ( Inia araguaiaensis ) highlights how little we know about the diversity and biology of river dolphins. In this study, we described the acoustic repertoire of this newly discovered species in concert with their behaviour in free-ranging, human-habituated individuals. We analysed 393 signals that w...

In this short paper we describe a twisting movement during feeding behavior by Bryde's whales in Cabo Frio, Southeastern Brazil.

A fidelidade de área é uma das características marcantes do boto-cinza (Sotalia guianensis) ao longo de sua distribuição, posto que indivíduos da espécie ocupam uma região e/ou retornam ao mesmo local ou áreas adjacentes com frequência durante um período de tempo. Estudos sobre a ecologia e comportamento desse pequeno cetáceo vêm sendo realizado de...

Ninety-six field trips were conducted between summer 2010 and 2012 in order to understand the occurrence and habitat use of Bryde's whale (Balaenoptera edeni) in the Cabo Frio region, South-eastern Brazil. Bryde's whales were present in the study area between November and July, being observed during all seasons, but occur more frequently during the...

Um total de 96 viagens foram feitas na região do Cabo frio, entre o verão de 2010 e 2012, com o objetivo de averiguar a ocorrência de baleia-de-bryde (Balaenoptera edeni) e sua distribuição na região do Cabo Frio, Rio de Janeiro, em relação à batimetria. Baleias-de-bryde estavam presentes na área de estudo entre novembro e julho dos referidos anos,...

Bryde’s whales, Balaenoptera edeni Anderson, 1879, were observed on 17 occasions (N = 21 surveys) in the coastal waters off Rio de Janeiro in southeastern Brazil during austral summer through autumn 2014. Five whales were individually identified using photo-identification techniques. The mean interval between resightings for all individuals was 12....

Photo-identification technique was applied to Bryde’s whales off the coast of Cabo Frio region, south-eastern Brazil between December 2010 and November 2012. Twenty-five individuals were sighted on nineteen different days and, of these total, nine were individually identified using natural marks on the dorsal fin. Of these, two individuals were...

Photo-identification technique was applied to Bryde’s whales off the coast of Cabo Frio region, south-eastern Brazil between December 2010 and November 2012. Twenty-five individuals were sighted on nineteen different days and, of these total, nine were individually identified using natural marks on the dorsal fin. Of these, two individuals were see...

O golfinho-flíper (Tursiops truncatus) é uma das espécies mais populares de golfinhos, principalmente pela existência do seriado de televisão americano da década de 1960, cujo prota-gonista era um golfinho denominado Flipper e por ser uma das espécies de cetáceos mais comumente exibidas em oceanários. Também é conhecido como golfinho-nariz-de-garra...

A Baleia de Bryde (Balaenoptera edeni) é uma das Baleias me-nos conhecidas em todo o mundo, apesar de sua distribuiçãoo ser ampla,, podendo ser encontrada em águas troPicais e temPeradas dos oceanos atlântico, Pacífico e índico, entre as coordenadas 40ºn e 40ºs. Os indivíduos dessa espécie podem atingir até 15,5m e pesarem até 16 to-neladas. Em méd...