December 18th, 2024
Decades after their initial discovery, a team of NIWA scientific divers, including freshwater ecologist Mary de Winton, who participated in the original studies in the 1990s, returned to the tranquil waters of Otago's Lakes Whakatipu, Wānaka, and Hāwea. Their mission: to search for the elusive deep-water bryophytes, a rare community of moss and liverwort species known to thrive in the lakes' abyssal zones. This undertaking, commissioned by the Otago Regional Council (ORC), aimed not only to revisit these unique ecosystems but also to establish a foundation for ongoing monitoring and research.
The deep-water bryophytes of Otago are a botanical anomaly. Typically found in moist terrestrial environments, these plants have carved out a niche in the depths of alpine lakes, where conditions diverge drastically from their usual habitats. The team's findings confirmed that, despite significant environmental changes over the past 30 years, these plant communities continue to thrive, submerged up to 50 meters below the water's surface.
The success of this survey, as detailed by ORC’s Scientist - Lakes, Hugo Borges, extends beyond the mere cataloging of plant species. The use of advanced technology, including a remotely operated vehicle, allowed for an extensive exploration of the lakebed. This approach has generated hours of footage, providing a rich resource for future analysis. The insights gained from this and subsequent surveys will be instrumental in understanding the ecological dynamics of Otago's lakes, particularly in relation to water quality and environmental health.
The establishment of a regular dive programme, slated to occur every three years, marks a significant step towards the long-term study of these submerged plant communities. This initiative underscores the importance of deep-water bryophytes as indicators of ecological change, offering a unique lens through which to view the impacts of factors such as water transparency, sedimentation rates, and temperature fluctuations.
The findings from the initial study serve as a baseline for ongoing research, critical for tracking the health of Otago's underwater ecosystems. As the world grapples with the challenges of environmental conservation, the work of NIWA and the ORC highlights the significance of safeguarding these hidden bastions of biodiversity. Through their efforts, Otago's alpine lakes continue to be a source of wonder, offering invaluable insights into the resilience and adaptability of life in extreme conditions.