Growth and Nutrient Removal Efficiency of Sweet Wormwood (Artemisia annua) in a Recirculating Aquaculture System for Nile Tilapia (Oreochromis niloticus)

Abstract

The maintenance of optimal water quality for fish production is one of the major challenges in aquaculture. Aquaponic systems can improve the quality of water for fish by removing the undesirable wastes and in turn produce a second marketable crop. However, there is no information on the growth and nutrient removal capability of Artemisia annua in aquaponic systems. This study evaluated the effect of plant density on water quality, the growth of A. annua and Oreochromis niloticus in a small scale aquaponic system in Kenya. The aquaponic system consisted of three treatments representing different plant densities (D1: 48 plants/m2, D2: 24 plants/m2 and D3:0 plants/m2). The high plant density system contributed significantly (p < 0.05) to the removal of all nutrients. The removal efficiency of ammonia was significantly higher in D1 (64.1 ± 14.7%) than in D2 (44.5 ± 6.8%) and D3 (38.0 ± 12.1%). Nitrates and nitrites were inconsistent, whereas phosphorus increased gradually in all treatments. The productivity of plants was higher in D1 than D2. Fish growth rates were significantly higher in D1 (0.35 ± 0.03 g/d) and D2 (0.32 ± 0.02 g/d) than in D3 (0.22 ± 0.04 g/d). The results show that A. annua can be cultivated in aquaponic systems due to its nitrogen removal capabilities.

Efficiency of pumpkin (Cucurbita pepo), sweet wormwood (Artemisia annua) and amaranth (Amaranthus dubius) in removing nutrients from a smallscale recirculating aquaponic system

“…The trend in ammonia and nitrate levels suggest that microbial activity that oxidizes ammonia and converts nitrates to nitrogen gas favoured the removal of nutrients from the hydroponic subsystem. Similar media-based aquaponic studies demonstrated that microbial organisms play a significant role in removing nutrients from aquaculture wastewater (Gichana et al 2019;Boxman et al 2017;Hu et al 2015;Trang and Brix 2014). Gichana et al (2019) demonstrated that plant uptake did not contribute significantly to the overall removal of nutrients in a media-based system because a hydroponic subsystem without plants played a role in the removal of nutrients from the effluent water.…”

“…Similar media-based aquaponic studies demonstrated that microbial organisms play a significant role in removing nutrients from aquaculture wastewater (Gichana et al 2019;Boxman et al 2017;Hu et al 2015;Trang and Brix 2014). Gichana et al (2019) demonstrated that plant uptake did not contribute significantly to the overall removal of nutrients in a media-based system because a hydroponic subsystem without plants played a role in the removal of nutrients from the effluent water. In Trang and Brix (2014), plants absorbed only 6% of nitrogen and 7% of phosphorus while 45% of nitrogen and 9% of phosphorus was unaccounted for suggesting that the unaccounted nitrogen and phosphorus was probably bound in the media substrate or lost through denitrification.…”

“…The low DO levels in the sump can be attributed to biological processes including fish respiration, oxidation of ammonia in the sand filter in addition to organic load production in the system (Espinosa-moya et al 2018;Wongkiew et al 2017). Furthermore, DO levels decreases in the biofilters and hydroponic subsystems due to the activities of microbial organisms including nitrifiers and heterotrophs as well as absorption by plant roots (Gichana et al 2019;Wongkiew et al 2017). Plant roots require oxygen to carry out metabolic processes such as aerobic respiration (Schroeder and Lieth 2004).…”

“…The indigenous vegetables have high micronutrient content, medicinal properties and economic values (Abukutsaonyango 2007). Although previous aquaponic trials have grown herbal and indigenous plants in aquaponic systems (Henze and Ulrichs 2015;Oladimeji et al 2018;Gichana et al 2019), there is still not enough information about growth and efficacy of the plants in aquaponic systems. Hence, the use of these plants as part of the biofilters in aquaponic systems should be further explored.…”

The Duckweed, <em>Lemna minor</em> Modulates Heavy Metal-induced Oxidative Stress in Nile Tilapia

“…Introduction of aquatic phytoremediation plant species and adsorbents should be performed in land management plans in order to reduce risks due to their contamination [22]. Therefore, plants represent an alternative remediation approach has escalated in the last few decades, [23][24][25][26][27][28][29].…”