Pond nutrient storage across permanence and temporal gradients

Abstract

Our goal was to understand how range shifts in detrivorous larval caddisflies could affect nutrient storage along a pond permanence gradient in the Mexican Cut Preserve (Gunnison County, Colorado). As part of a larger project quantifying other ecological impacts and interactions arising from the caddisfly range shift, this study focused on measuring nutrient distributions along the permanence gradient. First, through an observational study, we measured levels of nitrogen and phosphorus in the water column and took samples of benthic organic matter (BOM) and sedge for analysis at a later date. By sampling these nutrient compartments with respect to time and pond permanence, we will be better able to understand the magnitude and timing of nutrient storage in oligotrophic subalpine ponds. Second, we designed an experiment to quantify the effects of caddisflies on pond nutrient distribution. We created an in- situ cage experiment to compare the effects of two Limnephilid caddisfly species: L. externuns and L. picturatus. This allowed us to understand the nutrient cycling that caddisflies are responsible for within these ponds. This experiment also serves to contextualize our nutrient observations with respect to larval caddisfly activity and the ongoing research on caddisfly distributional shifts and nutrient excretion.