The effectiveness of integrated floating treatment wetlands (FTWs) and lake fountain aeration systems (LFAS) in improving the landscape ecology and water quality of a eutrophic lake in Indonesia

Abstract

Concerns over the impacts of floating cage aquaculture (FCA) systems on ecosystem health have led to the exploration of alternative green technologies as a way of improving water quality and preventing eutrophication problems in Lake Maninjau, Indonesia. This lake has been suffering from frequent harmful algal blooms (HABs) and hypoxic conditions due to excess nutrient and organic inputs from FCA. These have caused mass fish kills and decreased the local fish population. The main goal of this study was to assess the effectiveness of using integrated floating treatment wetlands (FTWs) and a lake fountain aeration system (LFAS) to improve lake water quality and enhance ecological conservation. The FTWs, which resembled artificial islands (AFIs) and covered an area of 23.75 m2, were planted with Echinodorus palaefolius. An LFAS was installed at the front of the FTWs. The impacts of the FTWs were evaluated from July to December 2018, while those of the LFAS was evaluated from October to November 2018. Lower nutrient and chlorophyll-a concentrations were observed within and around the FTWs and LFAS. Also, the LFAS increased the dissolved oxygen concentrations in the water to more than 100% at night. The results suggested that FTWs and LFAS could be used to prevent eutrophication and lake hypoxia. The plants in the FTWs grew much faster in the parts that were facing the waves, with their higher plant biomass suggesting that more nutrients had been removed from the lake. Also, the FTWs and LFAS, which resembled floating gardens, help to make the lake landscape more attractive and increase its amenity value. The improved water quality and habitat provision provided by these systems has attracted more local fish and other wildlife to the FTWs. The overall improvement in lake water quality and ecosystem health has the potential to ensure better provision of essential lake ecosystem services.