Emerging climatic pressures: Connecting CO₂ and river ecosystems in a warming world

Abstract

This presentation introduces the Emerging Climatic Pressures (ECP) MBIE Research Programme, a five-year study of the ecological and biogeochemical effects of rising CO₂ pressures on the Waikato River and freshwater environments more generally. In terms of the carbon cycle, river corridors can be thought of as the largest nexus, or interface between the continents, oceans, and atmosphere. The ECP programme examines whether CO₂ exchanges occurring across this interface are defining emerging trends in water quality, that deviate from those expected based on total nutrient loads. Our programme therefore asks fundamental questions about the relationship between CO₂ exchange and water quality (i.e. pH, dissolved nutrients, carbonate saturation); and how future atmospheric CO₂ levels could influence ecosystem phenology (e.g. phytoplankton succession) and the habitability of freshwater for molluscs (e.g., kākahi). These scientific questions are relevant to water quality attributes that matter to communities (e.g. safety for contact recreation), industry (e.g., drinking water source contamination), and Māori (e.g., mahinga kai).