The environmental history of Aotearoa New Zealand provides a unique opportunity to investigate the impact of anthropogenic activities on lake health. A prehuman reference condition can be established because the first humans, Māori (indigenous people of Aotearoa New Zealand), only arrived about 750 years ago. As Māori settled the land, native forests were reduced by fire in many regions, either accidentally or for subsistence agriculture, and mammals such as rats and dogs were introduced. European settlers arrived in the early 1800s CE, further reducing native vegetation, establishing small-scale low-intensity farms, and introducing non-native mammals and freshwater fish. By the early 1900s, European farming practices intensified, with larger-scale farms and the adoption of techniques such as phosphate-based fertilizer application.
The Lakes380 project (www.lakes380.com) sampled sediment cores from about 10% of the country’s 3,200 lakes, capturing a representative cross-section of size, altitude, and land use. Using an array of scientific techniques, including sedimentary environmental DNA, the team reconstructed the environmental histories of the lakes, providing unprecedented insights into how lakes have responded to anthropogenic influences over time.
In this presentation, I will highlight two case studies: firstly, how native fish populations have responded to increasing human disturbance; and secondly, how extreme storm events influence lake ecosystems, with responses varying across periods of different land-use intensities. I conclude by highlighting how the team partnered with Indigenous communities to demonstrate that weaving different knowledge streams can enrich our understanding of lake ecosystems and lead to more sustainable lake revitalization.