Effects of Stigeoclonium nanum , a freshwater periphytic microalga on water quality in a small-scale recirculating aquaculture system

Abstract

Recirculating aquaculture systems (RAS) are becoming important for aquaculture due to land and water supply limitations and due to their low environmental impact.Bacteria are important in RAS as their role in nutrient recycling has been the main mechanism for waste removal in these systems. Besides bacteria, the presence of microalgae can benefit the water quality through the absorption of inorganic nitrogen (ammonium and nitrate) and phosphorus from the water. However, reports on the inclusion of microalgae in RAS are very scarce. The objective of this study was to determine the effect of microalgae on water quality (total ammonia nitrogen, nitrite, nitrate and phosphate) and bacterial composition in a freshwater small-scale RAS. A periphytic microalga, Stigeoclonium nanum, was used in this study. A rapid fingerprint analysis, denaturing gradient gel electrophoresis (DGGE), was used to determine the bacterial community composition in the water. The results showed that ammonia concentrations were not significantly different (p > 0.05) between RAS with microalgae (RAS+A) and RAS without microalgae (RAS-A). However, nitrite, nitrate and phosphate were significantly lower in the RAS+A than the RAS-A (p < 0.05). Pielou's evenness and Shannon diversity index of bacterial community between the treatments were not different (p > 0.05); however, the bacterial composition between the treatments was significantly different (p < 0.05). K E Y W O R D Sammonia, bacterial community, microalgae, nitrate, recirculating aquaculture system, Stigeoclonium nanum, water quality

Application of microalgae Scenedesmus acuminatus enhances water quality in rice-crayfish culture

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Unlocking the richness of microalgae biodiversity for potential applications

“…The absence or abundance of algae can lead to the interruption of this food chain due to the low evenness, which means that the community has a few abundant species that are dominating the community and could consequently result in the loss of the following consumers in the food chain [16]. The functionality of an environment is considered preserved when evenness is high, and the community contains various species that equally exist, with no one species gaining the upper hand and dominating an ecosystem [17][18][19].…”

Abatement of water nutrient load in a fish culture system using the aquatic trophic levels

“…Therefore, the discharges from aquaculture systems should be kept to minimum levels to mitigate the subsequent environmental impacts (Gilles et al, 2014). Several biological strategies and techniques have been used to improve the quality of aquacultural effluents including combined extensive and intensive fish ponds (Jaeger et al, 2021), artificial freshwater wetlands, aquaponics (Huang et al, 2019; Nuwansi et al, 2019; Zhimiao et al, 2019), using macroalgae and microalgae as biofilters (Ansari et al, 2017; Mohamed Ramli et al, 2018), and bio‐flocculation technology (Deb et al, 2017, 2020).…”