Banned toxins passed from mother to young in European dolphins

Dolphins in the northern Adriatic contain high levels of PCBs – highly toxic chemicals banned in the 1970s and 1980s – and are passing the pollutant to their young, according to new research led by a marine scientist at the University of St Andrews.

An international team of researchers evaluated PCB and other organochlorine contaminants in bottlenose dolphins (Tursiops truncatus) living in the Gulf of Trieste (northern Adriatic Sea), the northernmost part of the Mediterranean Sea and one of the most human-impacted areas in the Mediterranean.

They found that, overall, 87.5% of dolphins had PCB concentrations above the toxicity threshold for the onset of physiological effects in marine mammals, while 65.6% had concentrations above the highest threshold published for marine mammals based on reproductive impairment in seals. Such high contaminant levels are of concern, particularly in combination with other threats to dolphins, including bycatch in fisheries, disturbance by boat traffic, and prey depletion.

The research, published in the journal Science of the Total Environment, involved Morigenos – Slovenian Marine Mammal Society (Slovenia), the Sea Mammal Research Unit at the University of St Andrews (UK), the Zoological Society of London’s Institute of Zoology (UK), the Centre for Environment, Fisheries and Aquaculture Science (CEFAS, UK) and the Institute of Marine Sciences of the Italian National Research Council (Italy).

Tilen Genov, lead author of the study and a PhD student at the University of St Andrews, said: “We have been studying these dolphins for over 16 years, so we know most of them well. Through long-term re-sighting histories of identified individuals, we were able to link PCB levels in individual dolphins to parameters such as sex, reproductive output and social group membership.

“The research showed that males have significantly higher pollutant concentrations than females. This is because females offload a substantial amount of their toxicological burden to their young through gestation and lactation.

“That is also why females that have not yet had calves had significantly higher concentrations than those that had previously produced at least one calf. Such results are expected based on our knowledge of mammal physiology, but it is not very common to demonstrate this phenomenon in wild whales and dolphins.”

Dr Paul Jepson, co-author of the study and specialist wildlife veterinarian at the Zoological Society of London’s Institute of Zoology, said: “This is another study showing high or very high levels of a very toxic and persistent pollutant – PCBs – in European dolphins. PCBs have the ability to cause diseases like cancer and can also suppress reproduction.”

source: news.st-andrews.ac.uk

Find out how a dolphin can recognise their trainer

When 10 years has passed and you see with your own eyes, the proof of a unique bond between an animal and a human.

I was so flabbergasted it took my breath away and brought tears to my eyes.

Misty… the closest animal to me and the smarted dolphin I have ever trained, proved to me once again, what a special bond we had after 10 years without interacting with each other.

When I remember how we found her its breaks my heart!

She was just a baby, floating lifeless, like a piece of drift-wood in the open ocean, alone and close to dying, when we came to her rescue.

It was April the 4th 2005, she was a very sick, cast away from her family, very dehydrated body, with severe infections plus around six ulcers in her stomach, which I later observed through our endoscope camera.

After nursing her back to health, she soon became the most intelligent and responsive animal and after sleeping many nights by her side on the trainer’s platform, we developed a bond that was evident in her reaction to me, whenever we were together.

Fast forward now to two weeks ago, on a visit to see all my friends at Dolphin Cove Jamaica Ocho Rios, my one thought was how was Misty. She was 16 years old whilst I was there, so I wanted to see my young friend!  I was asked if I wanted to help feed her and naturally, with such a kind offer from the trainers who by now had heard of our history, I could not miss the chance to see Misty.

I gave her a tactile signal, which I used to give her always when we used to play, only she and I knew about it, it was our little secret… I was speechless when she responded positive and with fluency to my signal after 10 years…my heart was bursting with happiness, after she showed me that she remembered my unique signal and touch. I spent a short while with her and could tell by other unique signals and touches that she remembered each one perfectly.

It was an amazing experience and confirms my belief that not only are these beautiful animals so intelligent, but that a special bond can exist between a trainer with an honest kind heart, putting their love into how they treat their animal and an animal respecting that treatment. Often, Misty offered to perform without constant positive reinforcement, because she trusted me to reward fully at the end of the program, this was also somewhat unique to Misty and I, but it also demonstrates what can happen, if you treat the animals with love and respect.

In my experience, having a particular tactile signal (SD) for a very simple behaviour, one that only you and your dolphin knows, proves an animal can remember specific signals for many years, years that they have not been in contact with that trainer or signal. The story about my recent encounter with Misty demonstrated this perfectly to me.

A big thank you to you guys at Ocho Rios for making this experience possible, it will remain in my heart, as will Misty, forever.