Dolphin DNA

Photo credit: http://blog.nus.edu.sg/lsm1303student2013/2013/04/11/deadly-alliances-male-common-bottlenose-dolphins-engage-in-sexually-coercive-mating-behaviour-in-gangs/

          I read a book one time about a girl who fell overboard during a tropical boating expedition.  Somehow the crew didn’t notice her absence and left her, stranded, in the middle of the ocean.  Worried, alone, and exhausted, the girl was rescued by a friendly dolphin, who gave her a ride back to the boat.

Regardless of how unrealistic this story is, I can’t help being captivated by the majestic beauty of these marine mammals.  When I think of Marine Biology, my mind quickly creates this heroic rescue by the dolphin pod.  So without further ado, we can proceed to the science surrounding these beautiful creatures.

Although microorganisms can be useful indicators for various aspects of marine ecology, dolphins and other large marine organisms are important to study because of their large size.  Contaminants to the marine environment can actually be identified and estimated using samples from dolphins.  Along the same lines, the health of a marine habitat can be evaluated by assessing the health of animals farther up the food chain such as dolphins.  It was with these aspects in mind that a team of nine researchers joined forces to sequence and assess the DNA of five Tursiops truncatus (bottlenose dolphin) populations.  They published their multidisciplinary results in 2015.

DNA was collected from blood samples from dolphins in the following locations:

• Beaufort, NC
• Sarasota Bay, FL
• Saint Joseph Bay, FL
• Sapelo Island, GA
• Brunswick, GA

Samples were collected from 69 dolphins total, 30 males and 39 females collectively from these five locations between 2005 and 2010.  The team evaluated 30 control genes to verify the species.  Additionally, blubber samples were examined for the presence of polychlorinated biphenyls (PCB), which are persistent organic pollutants that are banned in many countries including the US.

Photo credit: http://www.brandoncole.com/photos_bottlenose_dolphins.htm

Since this was a new technique, the capabilities of the microassay was evaluated through the completion of this project.  It identified seven genes that correctly differentiated the dolphins by sex as well as 153 genes that were expressed differently depending on whether dolphins were part of Gulf or Atlantic populations.  The researchers found that the genomes of the dolphins from the two locations in Georgia – Sapelo Island and Brunswick – did not contain significant differences, so they were regarded as one population.  Specific differences were noted between the genomes when gender was consistent and population was assessed, such as specific genomic differences between a male Gulf dolphin and a male Atlantic dolphin.  The researchers expressed concern about drawing many conclusions about the sexes individually due to low sample sizes, so statistical analysis was focused on the group of both sexes together.

Georgia dolphins were found to be significantly different than the other dolphins in 69 of the 153 genes that were assessed.  The differences among both male and female members of the respective populations each fell into four categories, as you can see in the table below.

Male	Female
Development and Differentiation	Transcription and Translation
Wound Healing and Tumor Prevention	Immune Response
Inflammatory Response	Cell Development and Growth
Metabolism of Foreign Chemicals	Metabolism of Foreign Chemicals

The differences between Georgia dolphins and other dolphins generally center around immune response, so blubber was analyzed.  The research team found that Georgia dolphins deal with more PCBs than the other populations, most likely due to their proximity to the Linden Chemicals and Plastics plant on the Georgia coast.  Not only is it clear that the Atlantic habitat off the coast of Georgia is contaminated with PCBs, we can see that these toxins are genetically – and thus, physiologically – affecting the marine organisms there.  A quick search online shows that PCBs have been linked to decreased lymphocyteresponses and negative reproductive effects in dolphins, not to mention their prey and consumers.  After identifying the PCB level in the Georgia dolphin population, the researchers were able to identify specific genes that reflect this differing level of contaminants, which will make future assessments easier.

Overall, this method of genetically analyzing Tursiops truncates is quite informative about the marine environments that were studied.  I appreciate the interdisciplinary nature of this paper, as it integrates genetics so flawlessly into the field of marine biology.  Who knows if I’ll ever befriend a dolphin, but they are fascinating to study and beautiful to see!

Reference:

Microarray applications to understand the impact of exposure to environmental contaminants in wild dolphins (Tursiops truncatus)

Dynamic Dolphins

Palm trees, sandy beaches, and blue water…Oh my! Doesn’t that just sound amazing? Well last summer (2013) I was lucky enough to experience all of those on a cruise to the Bahamas and it was absolutely wonderful. One of our stops on our trip was to Freeport, Bahamas. As most people know, when you stop somewhere while on a cruise, most people get off and go on excursions. My family decided to do this and I am so glad we did because it was probably my favorite part of the trip. You may not know this about me but I have an obsession with animals; mostly ones with fur such as dogs and cats, but I also am a big marine animal lover (one of the reasons I was dying to take marine biology). I love sea turtles and was actually able to swim with them when I went to Hawaii a few years ago, but one of my life goals had always been to swim with a dolphin. Well guess what? I can put a check mark next to swimming with dolphins on my bucket list because that life goal has now been completed! And let me tell you, it was amazing. We got to hang out with two male dolphins, who were brothers, and they were remarkably smart and cute.

                   This is a picture of me on the trip! 

This experience has only increased my interest in dolphins. I already knew dolphins are very intelligent animals known for their agility and playful behavior, but researching online I found out about an interesting study known as the Shark Bay Dolphin Project. It started in 1982 when two American researchers flew half-way around the world to a remote bay in Western Australia, at the Monkey Mia beach. There, they found a small group of wild bottlenose dolphins that would swim right into shore to be hand-fed by humans. From these few animals, their research expanded to include hundreds of Shark Bay dolphins, and their visit led to the establishment of an extensive long-term study of the population. The long-term records of the animals are being managed in a database at Georgetown University.

The main reason these dolphins are be researched is due to the unique window it provides into the dolphin society. From this research, the dolphins are being protected as well as providing information on the effects of provisioning on wild animals. Research performed includes hundreds of dolphins that are surveyed and cataloged each year. Their behavior, ecology, genetics, development, communication, and various other aspects are all being recorded, making this one of the most important dolphin research sites world-wide. What I also love about this is that it is all accomplished non-invasively, without tagging or capturing the dolphins. 

When looking at different articles about dolphins, an interesting aspect I came across is the mystery of why dolphins have evolved such big brains. Bottlenose dolphins have the largest brains outside of humans when body size is taken into account. Why do they need such large brains? The Shark Bay Dolphin Research Project has revealed that dolphins, like some large brained terrestrial mammals, lead highly complex social lives. Complex social relationships are thought to have played an important role in the evolution of large brains in elephants, apes, and humans, so it is believed to be the reason it is seen in dolphins as well.

Another study being performed in Australia can be found at Shark Bay, called the Shark Bay Ecosystem Research Project. Shark Bay is in remote Western Australia and is home to a large sea grass ecosystem. Its remote location and small human population have made it a safe place for organisms such as tiger sharks, sea turtles, and of course dolphins, to thrive.  

The male dolphins of Shark Bay are known to marine biologists for their social entanglements. Their relationships with each other are so unusual that one team of scientists argues that the dolphins live in a social system that is known to be quite unique among mammals. Researchers suggest that these complex relationships may stem in part from one simple factor: the dolphins' low cruising speed, which may lead to social smarts. Because the Shark Bay dolphin population is large and has overlapping territories, it doesn't take long for one group of dolphins moving at their normal speed to meet up with another, possibly competitive, group. In these situations, the dolphins are forced to do the two things that may enhance social cognition: make friends and form group alliances.

In yet another study, it was seen that dolphins have a large cerebellum and the findings from this research suggest this is due to motor and sensory processing. The scientists linked this information and sensory processing to echolocation (Marino). Echolocation is when high frequency sound waves are emitted by the animal and the echoes are picked up and rapidly processed.

So, it seems to be that the brain size of dolphins is still somewhat of a mystery. Is it due to social relationships, cruising speed, or echolocation? Although it may not be fully determined, it is no mystery how amazing these animals are. I hope the dolphins continue to thrive in these Australian waters. I also hope we get the chance to see them on our trip to the Outer Banks!

Here is a video I found of two dolphins playing near a boat, kind of scary how close they are! 

Reference:

Marino, L., Rilling, J.K., Lin, S.K., & Ridgway, S.H. (2000). Relative Volume of the Cerebellum in Dolphins and Comparison with Anthropoid Primates. Brain, Behavior & Evolution. Doi:10.1159/000047205

Harmful effects of oil spills on dolphins

With the recent oil spill in the Gulf of Mexico all over the news, I couldn’t help but wonder if dolphins could be hurt as bad as other marine organisms since they can at least swim away from the oil.

I was partially right. They can swim away from the spill, and their skin allows the oil to just run off them as they swim so it doesn’t cause any permanent harm.
However, they do need to breathe sometime. When they come up to the surface, if they happen to take in oil in their mouths or blowhole, it can cause serious damage to their airways, mucous membranes, or digestive tract (like a poison). Oil can also cause eye damage if it gets in their eyes.
Things only get worse from there because panicking or stressed dolphins will surface more often because they are breathing harder and need to breathe more often, which will expose them to more oil floating on the surface.

Source: www.amsa.gov

http://webcache.googleusercontent.com/search?q=cache:yneaqFyM5EcJ:www.amsa.gov.au/Marine_Environment_Protection/National_Plan/General_Information/Oiled_Wildlife/Oil_Spill_Effects_on_Wildlife_and_Non-Avian_Marine_Life.asp+oil+spill+effects+on+dolphins&cd=2&hl=en&ct=clnk&gl=us

Dolphins!

After seeing some young dolphins playing near the shore during our trip to the Outer Banks, I had no choice but to put up a post about dolphins.

I found this great video of dolphins playing with bubble rings on Youtube.



You also hear stories every now and then about dolphins playing near cruise ships, and doing jumps for the tourists.

Based on research on dolphins, it has been found that the way we treat them may affect them psychologically. Dolphin brains are very large and are second to humans based on the brain to body size relationship. Their brains are very well developed and have many of the same characteristics as our brains do. They are able to recognize themselves and are very intelligent animals.

When humans capture them and put them in captivity for entertainment purposes, they may be doing psychological damage to the dolphins. In knowing this, capturing dolphins has become an issue under ethical scrutiny. It has become an issue to figure out what effects we could be having on these delicate animals. Hopefully more research can be done in order to determine what effects we are having on dolphins. We need to protect all animals and we need to know whether we are doing harm or good.

Is Commercial Fishing Endangering Dolphins?

Local fish populations have been decreasing over the last 60 years. Scientists wanted to analyze the top predator relationship between Bottlenose Dolphins and the Trawlers.

Commercial fishing in the Mediterranean appears to be having a detrimental effect on dolphins; however, the problem is not caused by the fishermen catching the food sources the dolphins eat. Recent studies have been analyzing the gut content of dolphins accidentally caught in the nets and ones that have washed upon the shore to confirm their diets. Fisherman were relieved to find commercial fishing in the Mediterranean does not affect the nutrition of the dolphins.

It has been found that dolphins are swarming around the fisherman boats to eat the smaller schools of fish that cannot be caught in the net. This behavior is causing a decline in the dolphin population, because they accidentally get caught in the nets. On average 8 dolphins die off the coast of Israel each year, about half are accidentally caught in the nets.

The behavioral change in the female dolphins and their young catching food by commercial fishing boats have led scientist to believe they are getting an insufficient amount of nutrients and are having problems finding adequate food sources. The dolphin population have found a relatively stable environment off the coast of Israel, and fishing regulations are being imposed to keep the dolphin population stable.



Is Commercial Fishing Endangering Dolphins?