Micro and macroplastic ingestion by marine mammals

… “When marine mammals strand, the present a unique opportunity to obtain insights into the ecology”….. (Lusher et al. 2015).

It’s not uncommon to see reports on the news and the web about the marine mammals stranding on coastlines around the world. In the most part, their deaths are associated to natural causes. However, in many cases their deaths are attributed to marine debris, specifically large plastic items that have been ingested, caused blockages, malnutrition, starvation and eventually death. Regardless of the route of entry to the marine environment, discarded plastic can be accidently ingested by animals mistaking it for prey.

A quick Google search lead me to these reports:

It is not only large plastic items that could be present in the digestive tracts of these animals. As part of my PhD research and collaborative work with Dr. Gema Hernandez-Milian from University College Cork (UCC) we have been investigating methods for the identification of microplastics in stranded animals on Irish shores.

We were fortunate enough (not fortunate for the animals), to have three True’s beaked whales (Mesoplodon mirus) strand on the west and north coast of Ireland within two weeks of each other. A mother and calf in Co. Donegal, and an adult female in Connemara, Co. Galway.

True's beaked whale stranded in Co. Galway, May 2013

True’s beaked whale stranded in Co. Galway, May 2013 (Image: Ian O’Connor)

It is important to note that strandings of True’s beaked whales in Ireland are very rare, with only 13 record to date, check out the Irish Whale and Dolphin Group (IWDG) for more details.

A laboratory procedure was developed, to prevent contamination and to search effectively for microplastics in our samples. In short, we looked at each stomach separately, and divided the intestines into 20 equal sections. Rinsing the samples through stacked sieves, we were able to remove remains of prey, for dietary analysis, and the retained material was digested to leave non-biological material.

Any items remaining following digestion were visually analysed under a microscope, and a sub-sample were retained for FTIR analysis to find out which polymer new were looking at. For more information on this technique, read the methodology section of Lusher et al. 2013.

We found microplastics throughout the digestive tract (stomach and intestines) one female whale. We also identified macro plastic items in both the adult whales. The calf had no sign of plastics or food, but did have milk, which suggests it was still feeding from the mother.

Diagram of the stomach of True’s beaked whale (Image: Lusher et al. 2015)

As we are not vets, the cause of death could not be determined. The levels of plastic found did not appear to have caused any significant negative effects on the individuals.

To read more about the study click here.

Or you can contact me for a copy of the PDF: amy.lusher@reaserch.gmit.ie

We are carrying out this work on cetaceans stranded in Ireland, so keep an eye out for future research.

Dr. Simon Berrow from IWDG and GMIT was interviewed on TodayFM about a killer whale stranding in Co. Waterford a the beginning of the month. He discusses the work we have been doing form 11. 40 mins on-wards. Take a listen here.

 

Published by Amy Lusher

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2 thoughts on “Micro and macroplastic ingestion by marine mammals

  1. just wondering if you found a shot gun cartridge (as in the illustration) in the ‘accessory main stomach’ ? There are SO many of them coming in on the tide – the majority are coming from Canada, where they shoot thousands of guillemots every Winter.

    • Hi Rosemary,

      Sorry for the late reply, I’ve only just seen your comment. That’s really interesting about the guillemot shooting, yes it was definitely a shot gun cartridge, we couldn’t work out how the animal was exposed to it. it floats and the animal feeds at depth. I will keep this in mind 🙂 Amy

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