(2018). Mātauranga Māori: shaping marine and freshwater futures. New Zealand Journal of Marine and Freshwater Research: Vol. 52, Special Issue: Mātauranga Māori shaping marine and freshwater futures. Guest Editors: Joanne Clapcott, Erica Williams, Anne-Marie Jackson, Daniel Hikuroa, Chris Hepburn, Jamie Ataria and Rauru Kirikiri, pp. 457-466.

Small headwater streams are abundant components of the riverine landscape where critical biochemical processes occur that provide clean water, energy, and nutrients to downstream reaches. Disturbance to these systems as a result of human land use has the potential to affect downstream health. Rates of metabolism and organic matter processing were measured in 22 small forested headwater streams in 2 regions of Tasmania, Australia, to evaluate the effects of forestry disturbance. Twelve of these streams had been subjected to recent clearfell-burn-and-sow (CBS) harvest. Benthic metabolism was measured in small in situ chambers (production ranged from <0.001 to 21.845 mg C m−2 h−1 and respiration from <0.001 to 4.976 mg C m−2 h−1), whole-system metabolism was estimated based on relative habitat abundance (gross primary production ranged from <0.001 to 0.297 g C m−2 d−1 and daily respiration from 0.003 to 0.072 g C m−2 d−1). Algal growth potential was measured on nutrient diffusing pots (chlorophyll a ...

Stream metabolism (gross primary production and ecosystem respiration) is increasingly used to assess waterway health because mean values are responsive to spatial variation in land use, but little is known about how human land use influences the temporal variability of stream metabolism. We investigated daily variation in dissolved O₂ (DO) concentrations and calculated mean and within-season variation in gross primary production (GPP) and ecosystem respiration (ER) rates at 13 stream sites across a landuse intensity gradient in the Auckland region, New Zealand, over 9 y. Based on generalized linear mixed models, mean daily GPP (0.1–12.6 g O₂ m⁻² d⁻¹) and ER (1.8–29.6 g O₂ m⁻² d⁻¹) and seasonal variation in stream metabolism were significantly related to landuse intensity with higher variability associated with higher values of a landuse stress score. Overall, mean daily rates and day-to-day variation in GPP and ER were greatest in summer and least in winter. We recommend summer monitoring over a minimum 5-d period to assess stream health. Our results show that human land use affects the mean and the temporal variability of DO and stream metabolism. This finding has important consequences for characterizing in-stream processes and the resilience of stream ecosystems. Only long-term temporal monitoring provides the data needed to assess fully how streams function.