“Small pieces of plastics could be toxic for the organisms”

© Cristina Fossi/University of Siena

Cristina Fossi’s research  aims  to determine the effects of microplastics on marine animals. Aboard of Tara, she is collecting krill and other microorganisms. During other sampling campaigns, she is collecting whale biopsy. For the professor on ecotoxicology in Italy, the only way to solve the problem of macro and microplastics in the Mediterranean is to work on a global scale: all countries must enforce the Barcelona Convention and follow the Marine Litter Action Plan.


What kind of research are you doing at the University of Sienna?

Our group is a biomarker lab from Sienna. For the past 20 years we have been involved in a study of the impact of contaminants on Mediterranean marine organisms. In the last 5 years we have focused especially on the potentially impact of microplastics in the Mediterranean, and in particular in the Pelagos area. In fact we  published in 2012  the first paper on the impact of the microplastics on whales. We think it’s a very important topic because it’s probably one of the species that can be largely impacted by microplastics. Each time a whale opens its mouth, it  filters 70 000 litters of water. So that’s one of the largest filter feeder species of microplastics in the world!

How do you collaborate with Tara?

Here on board, we are doing research in collaboration with Maria Luiza Pedrotti and Gabriel Gorsky at the Oceanographic Laboratory of Villefranche-sur-Mer We are trying to identify the effects of contaminants transported by the microplastics throughout the whole food chain.  All these small pieces of plastics could be toxic for the organisms:  The plastic itself is full of contaminants, particularly plastic additives, such as phthalates, biphenyl A, PBDEs.  When they are eaten by a fish and arrive in its stomach, the contaminants are released and produce  toxic effects on its organism: they can have an impact on the fish endocrine system, on its sexual hormones.

Also, microplastics can  absorb and transport contaminants like POPs (Persistent Organic Chemicals) or mercury. Our topic is to investigate the presence and effects of POPs in the marine organisms, in the Pelagos food chain. Here on Tara, we have started collecting several planktonic organisms with the nets: small crustacean like Meganyctiphanes norvegia– what we call krill. It’s very important because it’s the food of the whales! This species can be a bio indicator to understand the impact on the marine food chain, in particular on the whales. That’s why we are storing all the samples in liquid nitrogen. How do we proceed? We use some biomolecular techniques to investigate response of the organisms to the contaminants. For example we will measure the increase or decrease of the level of a protein, or the DNA damage. We use several techniques from PCR real time to WB, gene expression and so on, to study effects of contaminants in organisms.

I think we have already collected 22 samples in different nets: invertebrates and vertebrates. The final idea would be to create 2 maps: one on the presence of the microplastics and one on the effects of the microplastics on marine wildlife. We are expecting that where there is a high level of microplastics, there is also probably a high level of contaminants in marine organisms and so, a high level of toxicological effects.

What have you noticed in terms of toxicology for marine mammals?

Two years ago, we  published a paper with a very provocative title: “The Pelagos Sanctuary for Mediterranean mammals: Marine Protective Area or Marine Polluted Area?” The case study was striped dolphins and we analysed 3 different populations: one in Pelagos, one in Gibraltar and a last one in the South of the Mediterranean. Through this study, we have shown that the Pelagos dolphins are the most polluted of the Mediterranean, in terms of contaminants and biomarkers, so the biological effects are quite dramatic. For example, there is a very strong induction of some enzymes, which means that these animals are exposed to 3 times more POPs than the others. We have also observed endocrine-perturbing effects – variations of estrogen receptors that could have consequences on reproduction. So the Pelagos is an area under pressure and we really should keep an eye on it and take care of it.

 How do you proceed to get samples from marine mammals?

The cetacean investigation is very complex and depends on the species that we’re studying.  For example, for fast swimming cetaceans, like dolphins, it’s much easier than with whales. We have to collect a small piece of skin anddo a blubber biopsy. It’s an extremely precious sample that can help us to do a toxicological check up of the animal. It can give us a lot of information, such as the contamination level of the animal, the measure of the biomarkers, as well as the biological response to these contaminants. In addition, we collect genetics information and data on its diet.

If a bottlenose dolphin, a striped dolphin or a pilot whale come close to the boat, we can use an aluminium tool, a kind of a harpoon. The animal doesn’t get hurt. When we need to do a biopsy on a larger animal, like a sperm whale or fin whale, we use what we call “remote sampling”. We have to shoot a dart with a crossbow. It’s not that easy because we have to localize the animal, approach it quickly with a zodiac before it dives, and finally try to shoot it up to the dorsal fin. Then the dart is pulled out,  floats in the water, and we have to retrieve it and store it rapidly in  liquid nitrogen. For me, biopsy is the only way to detect the impact of contaminants in cetaceans.


Noëlie Pansiot


Related items : 

- Interview of another scientist, Rachel Cable, by Noelie Pansiot. 

- Gaby Gorsky, chief scientist of Tara Mediterranean.

- Onboard and offshore team during Tara Mediterranean.