Significance of river–aquifer interactions for reach-scale thermal patterns and trout growth potential in the Motueka River, New Zealand

摘要: To assess whether reaches of the Motueka River (New Zealand) that gain water from groundwater were likely to represent significant cold-water refugia for brown trout during periods high temperatures, temperature was monitored more than 18 months in two gaining and three predicted be losing groundwater. These data used predict (Salmo trutta) growth reaches. Groundwater inputs had a small effect on at reach-scale modelling suggests differences observed unlikely result appreciable growth. Several coldwater patches identified within study reach up 3.5°C cooler mainstem, but these generally shallow provide refuge adult trout. The exception Hinetai Spring, which mean close 16°C period January–March, when temperatures mainstem regularly exceeded 19°C. Trout plume mouth Stream, would allow them thermoregulate are unfavourable while still being able capitalise food resources available mainstem.