Brazilian river dolphins communication, new study


This 2014 video says about itself:

A new species of river dolphin has been discovered by scientists working in Brazil. This is the fifth known species of its kind, and there are an estimated one thousand of the dolphins living in the Araguaia river basin.

Researchers from the Federal University of Amazonas ran genetic testing on some of the dolphins to be certain that a new species had been found. The last time a new species of river dolphin was discovered was back in 1918.

Doctor Tomas Hrbek, lead author of the study, is quoted as saying: “It is very similar to the other ones. It was something that was very unexpected, it is an area where people see them all the time, they are a large mammal, the thing is nobody really looked.” The Araguaia dolphins are smaller and reportedly have fewer teeth than the Amazon river dolphins, also called boto or pink dolphins, which are believed to be the most intelligent of the river dolphins.

From the University of Vermont in the USA:

Mysterious river dolphin helps crack the code of marine mammal communication

April 19, 2019

The Araguaian river dolphin of Brazil is something of a mystery. It was thought to be quite solitary, with little social structure that would require communication. But Laura May Collado, a biologist at the University of Vermont, and her colleagues have discovered that the dolphins can actually make hundreds of different sounds to communicate, a finding that could help uncover how communication evolved in marine mammals.

“We found that they do interact socially and are making more sounds than previously thought,” she says. “Their vocal repertoire is very diverse.”

The findings of May Collado are her colleagues were published in the journal PeerJ on April 18.

The Araguaian dolphins, also called botos, are a difficult animal to study. They are hard to find in the first place, and while the waters of the Araguaia and Tocatins rivers are clear, it is challenging to identify individuals because the dolphins are skittish and hard to approach.

Luckily, Gabriel Melo-Santos, a biologist from the University of St Andrews in Scotland and leader of the project, found a fish market in the Brazilian town of Mocajuba where the botos regularly visit to be fed by people shopping there. The clear water and regular dolphin visits provided a unique opportunity to get a close look at how the animals behave and interact, and to identify and keep track of various individuals.

The team used underwater cameras and microphones to record sounds and interactions between the dolphins at the market, and took some genetic samples. They identified 237 different types of sounds the dolphins make, but even with 20 hours of recordings the researchers don’t believe they captured the animals’ entire acoustic repertoire. The most common sounds were short, two-part calls that baby dolphins made when they were approaching their mothers.

“It’s exciting; marine dolphins like the bottlenose use signature whistles for contact, and here we have a different sound used by river dolphins for the same purpose,” says May Collado. The river dolphins also made longer calls and whistles, but these were much rarer, and the reasons for them are not yet clear. But there is some indication that whistles serve the opposite purpose than in bottlenose dolphins, with the botos using them to maintain distance rather than for group cohesion.

The acoustic characteristics of the calls are also interesting; they fall somewhere between the low-frequency calls used by baleen whales to communicate over long distances, and the high-frequency ones used by marine dolphins for short distances. May Collado speculates that the river environment may have shaped those characteristics.

“There are a lot of obstacles like flooded forests and vegetation in their habitat, so this signal could have evolved to avoid echoes from vegetation and improve the communication range of mothers and their calves,” she says.

May Collado and her colleagues next want to study whether the same diversity of communication is seen in other populations of Araguaian river dolphins that are less accustomed to humans, and compare them to their relatives elsewhere in South America. The Araguaian dolphins are closely related to two other species, the Bolivian river dolphin and Amazon river dolphin; the Araguaian dolphins were only described as a separate species in 2014, and that classification is still under debate. But there seems to be a large amount of variation in the repertoire of sounds each species makes.

The Amazon dolphins in Ecuador, studied by May Collado in 2005, are generally very quiet. “We need more information on these other species and more populations,” she says. “Why is one population chattier than others and how do these differences shape their social structure?”

May Collado says the work could help researchers gain clearer understanding of how communication evolved in marine mammals. Similar calls have been reported in pilot whales and killer whales, for example, and the similarities and differences between different species could help tease out which signals evolved first, and why.

The river dolphins are evolutionary relics, represented by just a few species around the world, and they diverged from other cetaceans much earlier than other dolphins. So these calls may have arisen first in river dolphins, then later evolved in marine dolphins into whistles and calls but in a different social context. Or was there a change in the function of the calls, with this kind of sound being used for group identity in killer whales, and individual identity in river dolphins? The calls may also have other functions in addition to identity, perhaps indicating group identity, or providing information on emotional state.

“We can’t say what the evolutionary story is yet until we get to know what sounds are produced by other river dolphins in the Amazon area, and how that relates to what we found,” she says. “We now have all these new questions to explore.”

Advertisements

Pink river dolphins of the Amazon


This 4 january 2019 video says about itself:

Pink River Dolphins Of The Amazon Rainforest‘s Hunting Secret | Earth’s Great Rivers | BBC Earth

Botos (pink river dolphins) have whiskers that help them find their prey in dark waters.

Dolphins greet new born baby


This 28 July 2018 BBC video says about itself:

When a new baby dolphin is born, his family reunites around him to welcome him as one of them.

In a stunning new insight into the lives of wild dolphins, this film follows six remarkable months in the life of the ‘Beachies’: a family of six dolphins led by mother-to-be Puck, who live in the shark-infested waters of Western Australia‘s Shark Bay. Using the latest miniature cameras to eavesdrop on the Beachies’ underwater lives, this moving story follows Puck and the challenges she faces bringing up her newborn calf Samu. From learning to fish, to the ever-present threat of a shark attack, no day is ever the same. Including rarely seen footage of young dolphins and revelatory new behaviour, this is a heart-warming and emotional portrayal of one of the ocean’s most revered creatures.

Dolphin liberation in Korea


This video says about itself:

22 June 2015

I found dolphins at Jeju island in KOREA.

From the Ulsan National Institute of Science and Technology (UNIST) in South Korea:

Dolphin liberation in Korea

May 27, 2018

Summary: Biologists have carried out a scientific investigation on dolphin liberation in South Korea.

“Dolphin liberation in South Korea has raised awareness towards the welfare of marine animals and has resulted in the strengthening of animal protection policies and the level of welfare.”

An engineering student, affiliated with UNIST has recently carried out a scientific investigation on dolphin liberation in South Korea. The paper presents the overall analysis of the social impact of the first case of dolphin rehabilitation in Asia, which occurred in 2013.

This study has been carried out by Sejoon Kim in the School of Energy and Chemical Engineering in collaboration wit Professor Bradley Tatar in the Division of General Studies at UNIST. Their findings have been published in the April issue of the journal Coastal Management and will be published online, this month.

“After the release of captive dolphins from South Korean marine parks, there has been a growing environmental movement towards the conservation and management of marine and coastal ecosystems“, says Sejoon. “Although such movement relies on a single-species conservation focus and does not encompass an entire ecosystem, it has enormous symbolic significance for the welfare of marine animals.”

The research team hopes to expand their research to areas beyond the study of dolphin liberation and carry out in-depth case studies on various topics, including the whale-eating culture in Ulsan, the public perspective of dolphin shows, as well as the establishment of new types of dolphin life experience facilities.

Bottlenose dolphins’ first time in Canadian Pacific


This video says about itself:

22 September 2016

This curious bottlenose dolphin (Tursiops truncatus) came over to see what ARC (Atlantic Reef Conservation) Reef Researchers were up to. Our research involved using a sonar imaging device, which the dolphin was fascinated with.

From BioMed Central:

Bottlenose dolphins recorded for the first time in Canadian Pacific waters

April 19, 2018

A large group of common bottlenose dolphins (Tursiops truncatus) have been spotted in Canadian Pacific waters — the first confirmed occurrence of the species in this area. The sighting is reported in a study published in the open access journal Marine Biodiversity Records.

On 29 July 2017, researchers from Halpin Wildlife Research, in collaboration with the Department of Fisheries and Oceans, Canada and the Department of Environment and Climate Change, Canada, observed a group of approximately 200 common bottlenose dolphins and roughly 70 false killer whales (Pseudorca crassidens). The sighting occurred off the west coast of northern Vancouver Island, British Columbia, Canada and may be the northern most recording for this species in the eastern North Pacific.

Luke Halpin, lead author of the paper, said: ‘It is surprising to find a warm-water dolphin in British Columbian waters, and especially to find such a large number of common bottlenose dolphins within the group.”

Halpin added: “The sighting is also the first offshore report of false killer whales in British Columbia. To see the two species traveling together and interacting was quite special and rare. It is known that common bottlenose dolphins and false killer whales seek each other out and interact, but the purpose of the interactions is unclear.”

Both common bottlenose dolphins and false killer whales typically live in warm temperate waters further south in the eastern North Pacific, but this sighting suggests that they will naturally range into British Columbia, Canada when conditions are suitable. There has been a warming trend in eastern North Pacific waters from 2013-2016 and the authors hypothesize that the trend may be the reason behind this unusual sighting.

Halpin adds: “Since 2014 I have documented several warm-water species: common bottlenose dolphins, a swordfish and a loggerhead turtle in British Columbian waters. With marine waters increasingly warming up we can expect to see more typically warm-water species in the northeastern Pacific.”

See also here.

Ancient dolphin species discovery in Ecuador


This video says about itself:

21 December 2017

A well-preserved juvenile skull recently discovered in Ecuador belongs to a new species of ancient dolphin, which researchers are calling Urkudelphis chawpipacha. The fossil was discovered near Montañita in Santa Elena Province, a tropical region of Ecuador, and is believed to be between 24 to 26 million years old.

From PLOS:

Ancient dolphin species Urkudelphis chawpipacha discovered in Ecuador

Small dolphin skull may have belonged to river dolphin ancestor from the Oligocene

December 22, 2017

Summary: An extinct dolphin species likely from the Oligocene has been discovered. The fossil is one of the few fossil dolphins from the equator, and is a reminder that Oligocene cetaceans may have ranged widely in tropical waters.

A new dolphin species likely from the Oligocene was discovered and described in Ecuador, according to a study published December 20, 2017 in the open-access journal PLOS ONE by Yoshihiro Tanaka from the Osaka Museum of Natural History, Japan, and colleagues.

Many marine fossils described in previous research have been from long-recognized temperate regions such as South Carolina, off the coast of Oregon, Hokkaido and New Zealand. Few equatorial and polar fossils are currently known.

While in the tropical region of Santa Elena Province, Ecuador, the authors of this study found a small dolphin skull, which they identified as representing a new species, Urkudelphis chawpipacha, based on facial features. The dolphin skull had a bone crest front and center on its face, above the eye sockets. This species stands apart from other Oligocene dolphins with its shorter and wider frontal bones located near the top of the head and the parallel-sided posterior part of its jaw. The authors also conducted a phylogenetic analysis which revealed that the new species may be the ancestor of the nearly-extinct Platanistoidea, or river dolphin, and may have lived during the Oligocene era.

The fossil is one of the few fossil dolphins from the equator, and is a reminder that Oligocene cetaceans may have ranged widely in tropical waters.

This study was supported by an UPSE project IN-P5-2016-1 for equipment at UPSE, and YT thanks support of a trip to Ecuador. This work has also been supported by the Agencia Estatal de Investigación (AEI) from Spain and the European Regional Development Fund of the European Union (CGL2016-76431-P) and the project CGL2015-68333 (MINECO/FEDER, UE).