Scientists are seeing more toxic algae in our lakes and rivers compared to previous years, says NIWA.
New Zealand's warm, stable summer has created ideal conditions for the growth of the algae, also known as cyanobacteria, which can be harmful to people and animals as it may produce toxins.
Algal Ecologist Karl Safi says that his work through NIWA's Algal Services, which monitors, samples and analyses water sources for these outbreaks, has increased significantly.
"Warm, calm waters help this type of algae, commonly referred to as blue-green algae, to thrive. Shallow lakes and slow-moving rivers and streams being particularly susceptible, especially when the weather is hot. Bodies of water in the central North Island have seen a particularly dramatic increase in cyanobacterial blooms," said Dr Safi.
Cyanobacteria as a mat, Lake Ototoa. [Rohan Wells, NIWA]
Cyanobacteria play a crucial role in our ecosystem but become a problem when found in high concentrations because of the toxins they can produce. These cyanotoxins can have health risks for people and animals if exposed through touching or swallowing contaminated water and breathing in droplets of contaminated air.
Symptoms include irritation of the skin, eyes, and lungs, as well as stomach pain, headaches, diarrhoea, and dizziness. For animals such as dogs, cyanobacteria can be life threatening within a few hours.
"We ask that people keep an eye out for lakes or ponds that are discoloured, cloudy or murky, especially if blue-green in colour or with a scum on the water's surface or edge. In rivers, toxic algae generally form brown or black mats that grow on rock. There may also be a strong odour.
"We don't want to worry people, but instead help them be more aware when enjoying the outdoors this summer. So, if you notice any of these signs, be cautious when going in or near the water, and take special care of any pets," said Safi.
Visit NIWA's Algal Monitoring Service
