September 2017 Study Finds Microplastic Pollution is Increasing on Irish Continental Shelf

NUI Galway researchers provide the first assessment of microplastic pollution in marine sediments from the Irish continental shelf 

Researchers from the School of Geography and Archaeology at NUI Galway have conducted the first study that investigates microplastic pollution of marine sediments on the Irish continental shelf. The study was published this week in the international journal Scientific Reports.

Pollution from plastic entering into the ocean is a global issue that impacts marine life at all trophic levels as well as economically important ecosystems. Microplastics (plastics smaller than 0.5mm) are widely dispersed throughout the marine environment. An understanding of the distribution and accumulation of this form of pollution is crucial for gauging environmental risk. In this study the researchers provide the first assessment of microplastic pollution in sediments and bottom waters collected from the Irish continental shelf. More specifically, this study investigated the history of microplastic deposition on the seafloor and examined how sedimentation regimes, proximity to densely populated areas, and maritime activities may impact microplastic pollution and deposition in marine sediments.

The results demonstrate that microplastic contamination is present along the western Irish continental shelf regardless of proximity to densely populated areas. The study found that a shallow layer of microplastics has formed along the Irish seafloor within marine sediments and their overlaying bottom waters. It also found a statistically significant trend of a rapid decrease in microplastic abundance with sediment depth within the fisheries near Galway Bay, which supports the assumption that microplastic deposition is increasing over time in this area. All recovered microplastics were classified as secondary microplastics as they appear to be remnants of larger items; fibres being the principal form of microplastic pollution (85%), followed by broken fragments (15%). The range of polymer types, colours and physical forms recovered suggests a variety of sources that may originate from plastic polymer fishing gear or land based contributions from nearby industry, water treatment plants, or households.

Dr Audrey Morley, senior author of the study and lecturer in Physical Geography at NUI Galway, said: “The pervasive presence of microplastics on the Irish Sea floor bares significant risks for economically important Irish fisheries, for example the Galway Bay Prawn (Nephrops Norvegicus). A previous study from Scottish fisheries has shown that prawns tend to ingest high concentrations of microplastic fibres when exposed to this type of pollution.

“Our results show that the Galway Bay Prawn fishery may be experiencing high exposure to this form of pollution with potential detrimental repercussions for this species, including reduced fitness and potential reproductive failure. However, more research is needed to understand the mechanisms influencing interactions of microplastics with individual species and ecosystems.”

This research was an NUI Galway student-led investigation by Mr Jake Martin, a graduate of the Masters Programme in Marine and Coastal Environments: Policy and Practice within the Discipline of Geography. For his achievements he has received the Professor Micheál Ó Cinnéide Award for Academic Excellence and is the lead-author of this publication.

This research was funded by a GSI Short Call from the Geological Survey of Ireland and a grant-in-aid for Ship-time on the RV Celtic Voyager from the Marine Institute of Ireland.

To read the full paper in Scientific Reports, visit: http://rdcu.be/vECw

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