Plants contribute to cleaning up polluted lagoon waters

Plants that absorb pollution

A lagoon in danger

Moorea, Tahiti... Whenever we think of French Polynesia, we picture fine sandy beaches, lush wilderness, and turquoise, crystal clear waters... but this little slice of paradise is in danger – and the threat this region faces is all the more worrying because it can’t be seen with the naked eye. The threat? Pollution.

In Opunohu Bay in Moorea, the local people grow pineapples and market gardening is highly diversified across the other islands in the region. But organic farming isn’t very well developed at all here, and pesticides are still widely used. During heavy rains, these chemicals run off into the rivers and down into the lagoon. The resulting pollution affects the water, the coral reefs, and the algae that live in perfect harmony with the coral, as well as the aquatic plants and fish that call the lagoon their home. So how can we get back to having clean water and rebalance this ecosystem? Plants could well be the answer to our problems once again!
 

Identifying local depolluting plants

Plants capable of purifying polluted waters... that’s the idea representing tremendous hope for protecting aquatic life. It’s also a major challenge. When we want to decontaminate water, soil, or any other environment using plants (a process known as phytodepollution), it’s vital the selected plant has the right properties to adapt to the environment it’s going to be immersed in, including the chemical characteristics of the pollutants, climatic factors, the type of water or soil, plus many other factors.

The goal in French Polynesia is to identify local species that possess these miraculous virtues to clean up the lagoon by purifying the run-off water upstream. To achieve this considerable feat, Klorane Botanical Foundation has teamed up with two entities from the French National Centre for Scientific Research (CNRS): the Bio-Inspired Chemistry and Ecological Innovations Laboratory (ChimEco) and the Centre for Island Research and Environmental Observatory (CRIOBE), as part of an innovative scientific programme.
Klorane Botanical Foundation is already involved in another phytodepollution project with the ChimEco Laboratory in the Cévennes in mainland France. The plant chosen there is water mint, which has extraordinary properties for depolluting rivers contaminated by heavy metals.

From trials to full-scale cleaning

Initial tests in aquariums

The ChimEco Laboratory began lab trials to identify plants likely to retain the specific herbicides used in pineapple fields. To find out which ones worked, they began their lab trials in aquariums, in the hope of finding the most effective aquatic plants in French Polynesia at depolluting. Priority was given to invasive plants, which were tested dead to avoid any risk of them escaping into the wild!

Upscaling

At the same time, the team has been working on finding a process that could translate into efforts on the ground in French Polynesia. In practice, this means successfully identifying the best plant to capture pollution as closely as possible to the fields and which is already adapted to the local terrain, conditions and climatic hazards. Trials will take place in rivers by testing out different variables, including the gradient, dimensions, installation formats... Samples will be taken monthly to assess the results and identify any successes that could be rolled out on a larger scale. CRIOBE, which has been active in the local region for 50 years now, will lead operations. This is also an opportunity to develop discussions with farmers to support them in moving towards more rational use of bio-pesticides.

These plants could be game changers! 
Local spinach, water spinach, taro, and even water poppy are just some of the indigenous plants being investigated. Some are already being used in private pools to filter water... 

Preserving water, flora and fauna – a global priority

The biodiversity and waters of the Opunohu valley and the islands of French Polynesia are in danger! All across the globe, water pollution is increasing to the point of becoming a major issue for the planet, just as coral reefs are being weakened by climate change in many areas. It’s vital we take urgent action to protect water resources and threatened ecosystems.