Filtration capabilities of freshwater mussel (Lamellidens marginalis) and apple snail (Pila globosa) and their potential impacts on freshwater integrated multitrophic aquaculture systems

Abstract

Aim: The study aimed to assess the relative filtration rates of an indigenous freshwater mussel, Lamellidens marginalis and an indigenous freshwater snail, Pila globosa, and their suitability for incorporation into freshwater integrated multi-trophic aquaculture (FIMTA) systems. Methodology: An indoor experimental trial was conducted in a wet laboratory (temperature: 30.5 ± 0.5, light intensity: 2000 lux, light cycle: L: D: 12hr: 12hr). The trial was performed in glass aquaria in triplicate filled with algae rich water to assess their filtration rate. Simultaneously, the impacts of these two molluscs on inorganic nitrogen and phosphorus were evaluated. Results: L. marginalis exhibited filtration rates of 934.7± 0.07 cells min-1 mussel-1 and 13.79 ± 0.04 cells g-1 min-1) against 261.8 ± 10.15 cells min-1 snail-1 and 9.74±0.15 cells g-1 min-1 for P globosa. Similarly, the mussel also exhibited markedly higher turbidity and chlorophyll clearance capacity (p<0.05) in comparison to snail, especially during initial 6-12 hr when initial concentrations of algal population, turbidity and Chl-a were high. Notably, the oxygen consumption and ammonia excretion rates were greater for snail than mussel after 24hr and at the end of the experiment. Interpretation: The results provide quantitative information on the filtration capacity of two indigenous freshwater molluscs that have considerable local food as well as economic value and would pave the way for their utilization as ecological engineers, especially organic extractive in freshwater integrated multi-trophic aquaculture (FIMTA) system. It is concluded from the study that L. marginalis was more efficient in extracting almost four times algal cells than, P. globosa. Key words: Eutrophication, Filtration, Lamellidens marginalis, Pila globosa