INCLUENCE OF FOOD SOURCE FACTORS ON ABUNDANCE VARIATION OF MACROINVERTABRATES IN THE OMARU RIVER CATCHMENT

Abstract

 For sustainable riverine environmental management, it is nessesary to understand distribution of stream organisms along environmental gradients within a river catchment. Here this study investigated inveretebrate community responses to narrow enveironment and food source gradients in the Omaru River catchment based on comprehensive sampling of stream macroinvertabrates and a machine learning technique. Sampling of macroinvertebrates and attached algae was carried out at the 33 upstream and 17 downstream sites from 1st to 15th November, 2018. As a result, chlorophyll a displayed significant positive correlation with the browser abundance in the downstream area (r = 0.524, p = 0.031), but not with the scraper abundance. Random forests revealed that while variable importance and predictive ability of chlorophyll a remained less, canopy cover slightly improved model accuracy for abundance prediction of invertebrate community.