Dolphins might be one of the most charismatic animals that plough through the oceans and seas. In general, they are social animals that enjoy living in pods. These marine mammals are considered one of the most intelligent species on the planet. Although they are mainly piscivores, their diet varies between species, feeding on fish, cephalopods and crustaceans. They are bio-indicator species, sentinels of the ecosystem’s health.
Dolphins hold an ecological niche in the marine environment comparable to humans; each of us occupies the top position in our respective trophic chains.
The Mediterranean Sea – and particularly the Aegean – holds unique biodiversity that is being affected by anthropogenic impacts. The main threats include: overexploitation of resources, unmeasured urbanisation, degradation of the surrounding lands (agriculture, etc.), marine traffic, chemical and noise pollution, bycatch and the proliferation of invasive species. These unconcerned practices have direct effects on the ecosystem equilibrium, richness and health; resulting in coral bleaching, loss of species and impoverishment of the seas in general.
Plastic is currently one of the most massively produced and widely used materials worldwide. Yet, it constitutes a global issue.
Microplastics are small plastic pieces less than five millimeters long that can be harmful to the marine environment and aquatic life.
Microplastics may come from the degradation of bigger plastic items. They may also be a constituent in goods used in daily life that are known as “microbeads”. These are microscopic pieces of polyethylene (the most common plastic) that health and beauty products contain in general. It is very likely that you are brushing your teeth and cleaning your face using microplastics, therefore, introducing them through the pipe system where they will eventually end up in the sea/ocean.
Archipelagos’ stranding response team is involved in recording and studying stranding events in and around Samos.
The content of the different gastrointestinal-compartments of the animal is collected in order to study diet and the presence of macro/micro plastics. The microplastic analysis process consists of filtration, microscope analysis, data collection and statistical study.
Through the microscope phase, the filtered slides are looked at in order to determine the number, shape/kind, color and approximate size of every microplastic found.
It is worth mentioning that not only microplastics are found inside the bodies of our specimens. Some bigger pieces that appear such as straws, plastic wrappers, balloons, and pellets have also been found.
Through my research in this area, I focused on the analysis of the plastic content of a young individual of Stenella coeruleoalba. It was initially found during a live-stranding situation, but her general health conditions were so compromised that the first aid response was unsuccessful. She died on the same night of August 2017 at Karlóvasi in NW Samos, while being heavily infested with parasites.
This unfortunate event gave us the chance to study her in a more detailed manner and to determine the (micro)plastic content in her GI system.
The results were alarming. The total amount found is 1377 microplastics, being 1052 of them white fibers. (See the graphs below)
Further analysis of these fibers will be done in university laboratories, in order to assess the chemical load and type of fibers.
In retrospect, would it be just a coincidence that the sea is full of plastic as well as these marine animals? Would we find a reflection on us from what is affecting them? Would current plastic over-exploitation and careless utilization of single-use-plastics pollute not just our environment but also ourselves?
Paula Romero de Blas
University of La Laguna, Canary Islands