Bruno Díaz López

Bottlenose Dolphin Research Institute | BDRI · Research and Education

Bottlenose dolphins (Tursiops truncatus) are an extremely vocal mammalian species and vocal communication plays an important role in mediating social interactions. Very little is known about how wild bottlenose dolphins use whistles in different contexts and no data exist for context specificity of whistle characteristics. This study describes, for...

A first attempt at analysing interactions between bottlenose dolphins and gillnets along the northeastern coast of Sardinia (Italy) was conducted between October 1999 and December 2004. A new approach was used: combining interviews with fishers with boat-based direct observations and behavioural and group size analysis. Fishers on monitored boats n...

The main response of top predators to human-induced environmental changes is often behavioral. Although human activities regularly impose a disturbance on top predators, they can also be a source of reliable and concentrated food resources for species with a high degree of behavioral plasticity. This study represents the first assessment of the inf...

There is increasing evidence that animal personality can affect many aspects of an individual's behaviour, life history and fitness. However, there have been few studies about the link between personality and social organization in the context of wild mammals in their own natural environments. This article reports on ecologically relevant data, lin...

Owing to the worldwide growth of aquaculture over the last years, new habitats have been created through the supplement of nutrients. This addition of nutrients affects the whole marine food web, resulting in predator species such as bottlenose dolphins becoming attracted to these areas. During this 5-year-long study that was carried out along the...

The Iberian harbour porpoise (Phocoena phocoena) reaches a larger body size than most other harbour porpoise populations and is genetically distinct, albeit closely related to the population in Northwest Africa. Currently comprising an estimated 3000–4000 individuals, genetic evidence and strandings data suggest that the population has declined in...

This study addresses existing gaps in our understanding of the ecology of killer whales by investigating their habitat use dynamics in the Atlantic coastal waters of North Africa, the Iberian Peninsula, and the Gulf of Biscay. Despite previous research on their distribution during the Atlantic Bluefin tuna migration in the Strait of Gibraltar and a...

The assessment of free-ranging cetacean health through the study of skin conditions using photographs has gained prominence in recent years. However, little attention has been given to the relationships between cetacean skin conditions, species, and body condition. To explore this relationship among baleen whale species along the northwestern coast...

The Iberian harbour porpoise (Phocoena phocoena meridionalis) population faces unique challenges, characterized by low population size and limited genetic diversity, underscoring the urgency of conservation efforts. However, a dearth of ecological information on this population hampers targeted conservation measures. This study addresses this knowl...

Due to anthropogenic pressures, estuarine systems are among the most broadly impacted areas for marine top predator species. Given this, it is crucial to study the interaction between the vulnerable marine species that inhabit these regions with environmental and anthropogenic variables. This study aims to determine whether nutrient pollution is re...

While dolphins have been widely studied in many parts of the world, their nocturnal activity remains vaguely known due to the technical constraints of nighttime monitoring. New techniques to estimate dolphin detection probability have been developed using the predominance of acoustic communication in these species. This is the principle of Passive...

To create protection measures for a species, it is necessary to know its distribution. Through the study of environmental variables that determine the presence of a species, it is possible to obtain information on their distribution. Among the species that need to be protected are bottlenose dolphins. Although this species is widely studied around...

Out of all types of energy, acoustic energy propagates in water the most efficiently making it the optimal way to transfer information. This fact is widely taken advantage of by members of the Delphinidae family who use whistles for communication. The bottlenose dolphin (Tursiops truncatus) is a well-studied species in the Ría de Arousa (NW Spain),...

Biological rhythms are a natural periodic regularity associated with both external abiotic factors and endogenous control mechanisms that impact the life of organisms. This association enables animals to improve physical and behavioral performance in response to environmental alternations and brings important adaptive gains. Understanding the behav...

Marine mammals spend most of their life underwater, but have to come to the surface to breath, which makes the study of their diving behaviour really important to know these animals better. Many cetacean species are threatened by human activities, and one of the most important anthropogenic threats for whales is noise pollution, which can impair th...

The use of photographs to assess the health of free-ranging cetaceans has been increasingly used over the last years. To explore the potential threats on baleen whales feeding along the Northwestern coast of Spain (Galicia), we used a non-invasive method through the analysis of photographs to assess markings of natural and anthropogenic origin on t...

Cetaceans exhibit an exceptional capacity for vocal learning and variation in acoustic parameters even within the same species. The effect of geographical distance on the variation of bottlenose dolphin (Tursiops truncatus) whistle parameters had been widely studied. However, many studies have not utilized long-term data sets to reduce bias of indi...

Identifying variation in interbirth interval, weaning age and reproductive seasonality is essential to increase knowledge about female reproductive success in long-lived mammals. While variability in reproductive success between populations has been accounted for habitat differences, relatively few studies have focused on this topic. Here, we used...

Here, we describe the epimeletic behavior of an adult Risso’s dolphin towards a deceased newborn calf of the same species across several days with photographs, acoustic monitoring, and video recordings. Boat-based observation surveys were conducted from April 2014 to October 2021 along the southern coast of Galicia (northwest Spain) as part of a lo...

We investigated the presence and diversity of cetaceans in the Mediterranean Sea, analysing the data collected by 32 different research units, over a period of 15 years (2004–2018), and shared on the common web-GIS platform named Intercet. We used the encounter rate, the species prevalence, and the Shannon diversity index as parameters for data ana...

Increases in marine traffic represent a growing issue for marine wildlife, posing threats through the impacts of ship strikes and noise pollution. Baleen whales are especially vulnerable to these impacts, yet regional and species-specific information on exposure to such threats is lacking. This study uses AIS and observational data to provide the f...

An understanding of animal grouping patterns is essential to increase knowledge about their social systems. We used a 5-year continuous dataset to investigate grouping behavior in a free-ranging highly social mammal, the bottlenose dolphin. Our objective was achieved by examining the relationships between a set of oceanographic, climatic, topograph...

The common bottlenose dolphin (Tursiops truncatus) is a cosmopolitan delphinid, regularly present in the Mediterranean Sea. According to previous studies, this dolphin tends to form resident geographical units scattered on the continental shelf. We investigated how the physiographic characteristics of the area of residence, with special reference t...

A fundamental question in animal behaviour is the role of vocal communication in the regulation of social interactions in species that organise themselves into social groups. Context dependence and seasonality in vocalizations are present in the communication of many species, although very little research has addressed this dependence in marine mam...

The Persian Gulf is positioned in the heart of the Middle East as one of the most critical water bodies. Indian Ocean humpback dolphins (Sousa plumbea) are distributed in nearshore waters and are therefore highly vulnerable to a variety of anthropogenic pressures. To our knowledge, there is a little information and data available about habitat use...

Our oceans are the lifeblood of our planet, covering more than 70% of the planet's surface, driving the climate, regulating temperature and ultimately sustaining all living organisms. They also serve as the basis for much of the global economy, supporting sectors such as shipping, renewable energy, tourism and fisheries and employing millions of pe...

Ecopath with Ecosim has been used to create mass-balance models of different types of ecosystems around the world to explore and analyse their functioning and structure. This modelling framework has become a key tool in the ecosystem approach to fisheries management, by providing a more comprehensive and holistic understanding of the interactions b...

Despite the important role of marine mammals in marine ecosystems and the imperative for their conservation, there is still a great lack of information on the diversity, distribution, and density of these animals in the Saudi waters of the Arabian Gulf. To fill this gap, an integrative data-collection approach including fishermen’s questionnaires,...

Knowledge of the habitat use of wildlife in highly impacted areas is essential to identify areas of biological importance and to implement appropriate conservation measures. The Arabian Gulf represents one of the most extreme marine environments and is considered one of the regions in the world with the greatest anthropogenic impact. Information on...

Eutrophication risk determination requires a continuous acquisition of nutrient data to establish environmental trends. In the context of the MarRISK project, a portable module has been designed to autonomously measure inorganic nutrients together with other parameters such as temperature and salinity along coastal transects.

The expansion of fisheries and its increased efficiency are causing severe detrimental impacts on marine species and ecosystems, that can be categorised into operational and ecological effects. While impacts directly caused by fishing activities have been extensively documented, it is difficult to set an empirical link between fisheries and changes...

We described the spatial segregation of two species of cetaceans, the common dolphin and the bottlenose dolphin. We also document the first direct observation of interspecific killing of a common dolphin by bottlenose dolphins and of interspecific necrophilia in cetaceans. The study was conducted from 2014 to 2019 in the Ría de Arousa (Northwest Sp...

Knowledge of the habitat use of wildlife in highly impacted areas is essential to identify areas of biological importance and to implement appropriate conservation measures. The Arabian Gulf represents one of the most extreme marine environments and is considered one of the regions in the world with the greatest anthropogenic impact. Information on...

Resulta ser apremiante que, dada la incertidumbre sobre los efectos de las actividades humanas y el cambio climático en especies amenazadas de carácter migratorio, como el rorcual azul, sea necesario alcanzar una mayor comprensión sobre la ecología de estas especies. El proyecto BALAENATUR: seguimiento del rorcual azul dentro de la red Natura 2000,...

Cover image: Underwater photo of a common bottlenose dolphin in Sardinia Island (Italy) to illustrate dolphins' personality research. CetusGeo Dolphin & Whale Emagazine # 7 - Dolphin Research Australia

We like to think humans are pretty special. Yet, for ethologists, pet owners, and anyone else who’s ever bonded with an animal, the existence of non-human personalities might not be breaking news. Personality describes consistently expressed (repeatable) behavioural differences between individuals of the same species that are otherwise similar to o...

The four currently recognised species of Sousa are all threatened on the IUCN Red List. To date they have not been included in any of the available software platforms that have been developed for the automated matching of cetaceans from photo-ID data. Because of their unique morphology, existing algorithms are unlikely to be successful and new algo...

Ecopath with Ecosim has been used to create mass-balance models of different type of ecosystems around the world to explore and analyse their functioning and structure. This modelling framework has become a key tool in the ecosystem approach to fisheries management, by providing a more comprehensive and holistic understanding of the interactions be...

Identifying foraging variation within a population and assessing its relationship with social structure is essential to increase knowledge about the evolution of social systems. Here, we investigated individual foraging variation in bottlenose dolphins and its potential influence on their social organization. We used generalized affiliation indices...

This study describes personality differences between wild bottlenose dolphins and quantifies, for the first time in marine mammals, the influence of personality on social structure. There is increasing evidence that animal personality can affect many aspects of an individual’s behaviour, life history, and fitness. This study reports on ecologicall...

Methion S, Díaz López B. 2019. Individual foraging variation drives social organization in bottlenose dolphins. Behavioral Ecology DOI:10.1093/beheco/arz160 Poster presented at the World Marine Mammal Conference

The Emirate of Abu Dhabi is strategically located within the Arabian Gulf in a combination of geographical, oceanographic and ecological conditions which enable the presence of a rich cetacean fauna. Although the preservation of suitable habitats is necessary, the persistence of cetacean species in Abu-Dhabi waters cannot occur without a better und...

Marine ecosystems, especially those located in coastal areas are heavily affected by human activities. Research conducted in these areas should be aimed at improving the conservation of threatened species and habitats. Environmental factors have been used to understand species distribution and the latter has proven to be a fundamental tool to promo...

Special Areas of Conservation (SACs) are an increasingly used conservation tool to protect the oceans and its biodiversity. The harbour porpoise (Phocoena phocoena) is elegit to such protection by Annex II of the EU’s Habitats Directive; particularly the Iberian harbour porpoise, a genetically distinct population, is in need of such conservation me...

Cetaceans frequently display skin marks which can be caused by diseases, parasites, and interactions among conspecifics and with human activities. For the present study, we used one year of photo-identification data for resident bottlenose dolphins of the Ría de Arousa (NW Spain). The aims of this study were to assess the types of skin marks found...

Social network analysis is important for studying the evolution of social systems. The aim of this study is to describe the social structure of a resident population of common bottlenose dolphins (Tursiops truncatus). Data were collected between January and June 2017 onboard a research vessel in the Ria de Arousa (Galicia, North West of Spain). Dol...

Interaction between bottlenose dolphins and fisheries is a growing problem worldwide. The fisheries sector in the Ría de Arousa (Galicia, NW Spain) is one of the most important of Europe, however the effect of fisheries activities on the behaviour of bottlenose dolphins (Tursiops truncatus) remains poorly known in the area. This study is a first ap...

Understanding the dynamics between bottlenose dolphin (Tursiops truncatus) behavior and anthropogenic behavior is essential for the creation and implementation of effective conservation strategies for the species. Due to a general trend towards coastal urbanization, bottlenose dolphins encounter frequent disturbances due to human activities, facing...

Understanding the physical processes and environmental variables influencing cetacean movements on a small scale is necessary to discern the ways in which these top predators utilize their habitat. In this study we analyze the variables related to the presence of common bottlenose dolphins (Tursiops truncatus) in two adjacent but environmentally di...

Atypical pigmentation, which is rarely observed in the wild, may influence social interactions between animals and can be detrimental for survival. Hypopigmentation, which is the lack of pigment in a part or on the entire body, is a type of atypical pigmentation pattern that can be either acquired (e.g. vitiligo) or congenital resulting from the in...

Eutrophication can cause adverse effects in the coastal ecosystems, this leads to an accelerated proliferation of opportunistic microbial and macroalgae communities, altering the trophic structure of the marine ecosystems and deteriorating water quality. The determination of eutrophication risk requires a continuous acquisition of time series of nu...

Since the beginning of my career as marine mammal scientist in 1999, I realized that a research study is only as good as the methods used to sample and analyse the data collected at sea. In this respect, to study the ecology and behaviour of marine mammals is not very different from any other research on land mammals' or birds' ecology. During all...

The world's ecosystems are altered to different extents by anthropogenic activities. Marine habitats, especially coastal areas, are subjected to an increasing pressure derived from human activities on both land and ocean. Information about species distribution is fundamental to develop effective conservation and management measures and counteract n...

1. In the coastal environment, marine mammals are exposed to one of the fastest-growing food production sector, i.e. the shellfish farming industry. Identification of critical habitats, such as foraging grounds in highly human-impacted areas, is essential to species conservation. Therefore, understanding the variables that influence a species’ fora...

Recent studies show that human impacts on marine ecosystems are threatening marine biodiversity. A greater emphasis on predicting how predators might respond to changes in the marine environment is needed because the effects of human activities are spatially heterogeneous. Here we analyse rorqual whales distribution data in a highly impacted upwell...

The impact of commercial fisheries on marine top predators is currently the focus of considerable international concern. In spite of the recognition of the competition between fisheries and marine predators for the same resources, few comprehensive assessments of the level of overlap between marine predators and fisheries have been conducted. Data...

El delfín común (Delphinus delphis) es la especie de cetáceo más abundante y observada con más frecuencia en aguas del Atlántico Noreste. Aunque estudios recientes sobre la distribución de esta especie en aguas atlánticas muestran que el Noroeste de la Península Ibérica es un área importante para su distribución, hay una falta de información sobre...

This study presents the first robust estimates of abundance and demographic parameters of common bottlenose dolphins (Tursiops truncatus) in a highly affected coastal ecosystem along the northeastern Atlantic. Seasonal abundance, apparent survival and temporary emigration rates were estimated using Pollock's robust design models. Photographic ident...

Determining the drivers that are responsible for the fine-scale distribution of cetacean species is fundamental to understand better how they respond to changes in their environment. We utilized information theoretic approach to carry out a comprehensive investigation of the key environmental and anthropogenic correlates of habitat use and relative...

Determining the drivers that are responsible for the fine scale distribution of cetacean species is fundamental to understand better how they respond to changes in their environment. Coastal cetaceans regularly exist in sympatry; nevertheless, ecological studies have been often based on a single species approach while ignoring the potential effects...

Behavioural studies are essential for defining critical habitat for a population’s survival. It is crucial to identify foraging habitats, especially in areas under high anthropogenic pressure, to protect cetacean populations in need of conservation. We present here an innovative study combining behavioural sampling and the use of a multi-model appr...

The short beaked common dolphins (Delphinus delphis) is the species of cetacean most commonly seen in the NE Atlantic. Recent studies such as the CODA and SCANS III surveys and other surveys carried out in the early 2000s, showed that the waters off NW Spain are an important area for the species. However, there is a lack of information on habitat u...

Because bioacoustics is a recent discipline, the importance of behavior and sociality on the vocal production of marine mammals is not very well known. The aim of this study is to determine the importance of intra-population variability on the whistles characteristics of free-ranging bottlenose dolphins (Tursiops truncatus). A boat-based campaign h...

The interaction between cetaceans and gillnets and purse seine fisheries is common in European waters.Gill nets and purse seines fishing activities affect the survival of many cetaceans, including the bottlenose dolphin. Along th NW Spain, more particularly the Ría of Arousa, there is a resident population of common bottlenose dolphins in an area c...

La interacción entre el hombre y los cetáceos, siempre ha suscitado una atracción especial a lo largo de la historia. Desde tiempos de la antigua Grecia comenzando por los relatos idílicos de Homero (700-800 A.C) y posteriores descripciones con un corte más científico de Aristóteles (350 A.C), se habla de la relación existente entre estos animales...

Humpback dolphins threats in the Arabian Gulf

Study of the evolution of natural marks present on the dorsal fin of free ranging common bottlenose dolphins resident in the Ría of Arousa, NW Spain.

Determining the drivers that are responsible for the fine scale distribution of cetacean species is fundamental to understand better how they respond to changes in their environment. Coastal cetaceans regularly exist in sympatry; nevertheless, ecological studies have been often based on a single species approach while ignoring the potential effects...

Owing to the worldwide growth of marine aquaculture over the last years, new habitats have been created through the supplement of nutrients. This addition of nutrients affects the whole marine food web, resulting in predator species such as bottlenose dolphins becoming attracted to these areas. The primary aim of this 9-yr study was to identify and...

Association patterns of resident bottlenose dolphins in the Ría of Arousa, NW Spain.

Infanticide is considered a conspicuous expression of sexual conflict amongst mammals, including bottlenose dolphins. Although reported previously in this species, confirmed cases of infanticide and associated epimeletic behaviour are very rare and their socio-behavioural context remains poorly understood. Here, we provide evidence of epimeletic an...

The Arabian Gulf is one of the most heavily impacted water bodies raising serious concerns about the conservation status of many marine species. A limited coastal range and near-shore distribution make Indian Ocean humpback dolphins particularly vulnerable to mortality and traumatic injuries from heavy maritime traffic and gill-netting practices. P...

Bioacoustics is a relatively new area of cetacean research. However, due to technical, financial, and logistical issues, it is relatively poorly studied outside of captive animals. This study examined the whistle characteristics of bottlenose dolphins, Tursiops truncatus, in Ria de Arousa, Galicia, Spain from April to October 2014. The effects of g...

Shellfish farming is an expanding segment of marine aquaculture, but the impact of this industry on coastal cetacean species is only beginning to be considered. The interaction between mussel farming and coastal cetaceans in one of the world’s leading producers of this bivalve (Galicia, NW Spain) was studied. Specifically, the habitat use of common...

Recently, aquaculture has generated worldwide interest as a result of the overexploitation of wild stocks combined with a growing international demand for fish and seafood products. Wild fish attracted to the marine fish farms, together with the presence of the farmed fish, are powerful attractants to predators that normally feed on similar or iden...

The waters of the southern Arabian Gulf are the most extreme marine environ-ment on the planet with temperatures ranging from 16 oC during the winter to over 36oC in the summer. We initiated a dolphin monitoring programme in the coastal waters of the Emirate of Abu Dhabi in the United Arab Emirates in 2014 in order to define the distribution, abund...

Monitoring changes in bottlenose dolphin communities and then identifying the causes for them forms the core of conservation research and are further integral components of the information needed to manage human impacts on dolphin populations. Mediterranean bottlenose dolphin populations are affected by man’s use of coastal waters, particularly by...

El presente estudio, llevado a cabo en aguas de la ría de Arousa entre abril y noviembre del 2014, se centra en la descripción de las características y las tasas de producción de los silbidos emitidos por los delfines mulares. Grabaciones y observación del comportamiento de los delfines se llevaron a cabo a bordo de una embarcación de 12m. Mediante...

Aunque las rías gallegas albergan una de las concentraciones de polígonos de bateas más altas a nivel mundial se desconoce el impacto de dicha industria en depredadores superiores como los delfines mulares. Entre los meses de marzo 2014 y agosto 2015 en la ría con mayor número de bateas, la ría de Arousa, se llevó a cabo un enfoque multidisciplinar...