In search of mussels

In search of mussels

What’s happening with Waikato’s freshwater mussels? University of Waikato student Michele Melchior’s 10-week summer research project looked at two species of native freshwater mussels to find out.

Her project, supervised by Associate Professor Kevin Collier from the School of Science, was called “Monitoring Methods for Freshwater Mussels” and involved conducting mussel monitoring surveys to determine the distribution and abundance of two freshwater mussel species - Echyridella menziesii and Echyridella aucklandica.

Michele conducted surveys in wadeable streams at 41 tributary sites in the lower Waikato River catchment. Sites were selected based on stream accessibility, clarity, depth, and landowner permission. She carried out tactile and visual searches using underwater viewers, and used a standardised monitoring protocol developed by Waikato Regional Council as a basis to assess mussel populations within the streams.

“Freshwater mussels across New Zealand are under threat and are rapidly disappearing from our waterways,” she says.

“The data gathered from this research is important for the Waikato Regional Council as it can be used as an insight into the factors that may be affecting the health of freshwater mussels and aquatic ecosystems in general.”

Freshwater mussels were found at 22% of the sites surveyed. E. menziesii was present at 89% of those sites, while the rarer E. aucklandica was present at 33% of the sites. A total of 122 mussels were collected. Of these, 7% were E. aucklandica and 93% were E. menziesii. Most mussels were found in streams that had fencing of some sort or a wide vegetated riparian zone next to the stream. They were never found in water with temperatures above 21 degrees Celsius.

“Freshwater mussels are important to aquatic ecosystems as their filter-feeding ability enables them to improve the water quality of our streams by filtering organic matter, bacteria, algae and pollutants, as well as stabilising suspended sediments that appear in waterways,” says Michele. “If freshwater mussels disappear, the health of our waterways will diminish.”

Michele says she applied for the Summer Research Scholarship because she’d always been interested in ecology and had previously worked as a volunteer in this field. In 2014/15 she spent three months on an internship in Alaska with the Alaska SeaLife Centre monitoring the oestrus cycle of Steller sea lions, and had also volunteered with International Bird Rescue in San Francisco in 2012, and on the Rena oil clean up in 2011.

Michele has just graduated with a Bachelor of Science in Environmental Sciences and Animal Behaviour and will start a Master of Science in B semester this year.

The Summer Research Scholarship was funded by the University of Waikato and Waikato Regional Council.

ENDS

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