Environment: Lake Rotorua has highest levels of plastic pollution of all NZ lakes

Lake Rotorua was found to have the highest levels of plastic pollution of all the New Zealand lakes in the study. Photo / Andrew Warner

Lake Rotorua has high levels of plastic pollution and the highest levels of all the New Zealand lakes, according to results just released in a global analysis of plastic pollution levels in freshwater lakes.

University of Waikato Associate Professor and freshwater ecologist Dr Deniz Özkundakci says: “Lake Rotorua showed levels of plastic pollution comparable with lakes in Europe and the USA. However – and of concern – the density of population around Lake Rotorua is a lot smaller than some other significantly polluted lakes from the study,”

Overall, the study revealed high levels of plastic pollution in New Zealand lakes, which Dr Özkundakci says is disappointing.

Dr Özkundakci holds the Toihuarewa Waimāori - Bay of Plenty Regional Council Chair in Lake and Freshwater Science at the university. He collaborates extensively with other organisations, iwi and stakeholders to promote awareness of freshwater science and support local aspirations related to lakes.

Associate Professor and freshwater ecologist Dr Deniz Özkundakci. Photo / University of Waikato

He said that while it was expected New Zealand lakes would have some plastic pollution, the results were disappointing for a country that has a relatively low population density, and given Kiwi’s high level of personal responsibility for waste reduction.

The global results showed that not even the most remote lakes around the world were untouched by plastic pollution.

Led by Dr Veronica Nava, a research fellow at the University of Milan-Bicocca’s Department of Earth and Environmental Sciences, 79 researchers from the Global Lake Ecological Observatory Network (GLEON) contributed samples for the study of 38 lakes across 23 countries and 6 continents. A number of New Zealand scientists also contributed to the work.

The study measured levels of small plastic particles, – microplastics through to macroplastics measuring a maximum of 10mm in diameter.

One of the more alarming results was the first data showing plastic pollution in some lakes is higher than the plastic ‘garbage patches’ in the ocean, the study said.

New Zealand lakes didn’t have levels to rival the ocean ‘garbage patches’ but Lake Rotorua was found to have the highest levels of plastic pollution of all the New Zealand lakes in the study.

“However, not a single lake in the research was unaffected by plastic pollution no matter how far it was from human activity, " Dr Özkundakci said.

“Plastic debris in freshwater systems is severely understudied in New Zealand. The invitation to contribute to a global study was an important opportunity to get baseline data on some of our lakes,” he said.

He would like to see the work built on for a larger survey of local lakes.

The study Plastic debris in lakes and reservoirs was published in the scientific journal Nature on Wednesday, July 12.