Exploring the environmental history of New Zealand’s lakes
Posted at 6:00am Thursday 13 Feb, 2020 | By Julie Perry Upper Clutha Community Trust
The first Royal Society speakers for 2020 were from the Lakes380 project, which is gleaning information from the clues left in sediment taken from the lake bed. The presenters were Susie Wood (Cawthron Institute), Marcus Vandergoes (GNS Science) and Marc Schallenberg (University of Otago).
There are 3,800 lakes in New Zealand, many of which are deteriorating in health. This project involves analysing sediment cores taken from 10 percent of our lakes — hence Lakes380. Lake sediments are natural archives that provide information on current and historical aquatic communities, water quality, vegetation changes, human impacts, climate systems and environmental changes. The project will improve our understanding of the lakes by providing information about their current state, regional variability and how things have changed over time.
To date, over 180 lakes have been sampled, with more than 600 cores and 15,000 samples taken. The scientists involved with the project are using environmental DNA (eDNA) combined with carbon dating, pollen analysis, microscopic identification of aquatic organisms and core scanning techniques to deduce the story of NZ's lakes. Each sample can capture up to 1,000 years of history.
What has been found so far is that as New Zealand's original native forests were cleared by European settlement and replaced with grasses, pine and non-native trees, algae in many lakes increased markedly, particularly bloom forming cyanobacteria. The samples from some lakes show how the introduction of perch caused a dramatic change in the types of bacteria present in those lakes.
By improving our understanding of how and why lake communities and water quality has changed, knowledge gathered by the project will be used to help predict future changes in the lakes and to ensure that protection and restoration efforts are ecologically appropriate.
The Lakes380 project is the biggest scientific study of New Zealand's lakes ever undertaken and is funded by a five-year Endeavour Fund grant from the Ministry of Business, Innovation and Employment. The Lakes380 team will be returning to Wānaka in March 2020 with a large boat and special equipment to collect core samples from lakes Wānaka and Wakatipu at a depth of around 120 metres.
The core samples are currently kept in refrigerated storage at GNS science in Lower Hutt and it is hoped that these will ultimately form the basis of a national archive to support future research.
For more information see www.lakes380.com