Utilization of Duckweeds (Lemna minor) as an extractive species in rearing juvenile rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) using the open system

Abstract

Integrated Multi-Trophic Aquaculture (IMTA) is a system that utilizes extractive species to utilize nutrients that are wasted from aquaculture activities. Lemna minor, commonly called duckweed, is a floating aquatic plant widely used to improve water quality in a body of water. The study aims to determine the potential of the Lemna minor as an inorganic extractive species in utilizing inorganic nitrogen from wastewater from rearing rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) juvenile using the open system. In this study, rainbow trout were used as the fed species with an initial weight of 25 ± 2.0 g. Freshwater mussels (Anodonta sp.) with an initial weight of 58.00 ± 2.0 g were used as an organic extractive species. Lemna minor with different biomass weights (Treatment 1: 270 g and Treatment 2: 360 g) acting as inorganic extractive species were used in the experiment. The water temperature during the study period was around 13 oC. The use of Lemna minor with different stocking densities had a significant effect (P < 0.05) on the values of pH, DO, nitrate, and T. Phosphorus in the filtration tanks. Overall, using Lemna minor as an inorganic extractive species reduced the concentration of ammonium and T. phosphorus from media-rearing rainbow trout juveniles. This study reveals that using different species with different trophic levels as extractive species can improve water quality in the IMTA system.