Biological control of streptococcal infection in Nile tilapia Oreochromis niloticus (Linnaeus, 1758) using filter-feeding bivalve mussel Pilsbryoconcha exilis (Lea, 1838)

Abstract

Since bivalve mussels are able to graze heavily on bacteria, in this paper it is hypothesized that when mussels are cultured with fish, the filtering efficiency of the mussels will keep the bacterial population below a certain threshold and thus assist in reducing the risk of bacterial disease outbreaks. The ability of the filter-feeding bivalve mussel Pilsbryoconcha exilis to control Streptococcus agalactiae was tested in a laboratory-scale tilapia culture system. Juvenile Nile tilapia (Oreochromis niloticus), the bivalve mussel as well as the bacteria were cultured at different combinations using four treatments: treatment-1: mussel and bacteria but no fish, treatment-2: tilapia and mussel but no bacteria, treatment-3: tilapia and bacteria but no mussel, and treatment-4: tilapia, mussels, and bacteria. All treatments were run in three replicates; stocking rates were 10 tilapia juveniles; five mussels; and about 3.5 9 10 5 colony forming units (CFU) ml À1 of bacteria in 50-L aquaria with 40-L volume. The mussel reduced the bacterial population by 83.6-87.1% in a 3-week period whereas in the absence of the mussel, the bacterial counts increased by 31.5%. Oresence of the mussel also resulted in significantly higher growth and lower mortality of tilapia juveniles than when the mussel was absent. The results of this experiment suggest that the freshwater mussel P. exilis could control the population of S. agalactiae in a laboratory-scale tilapia culture system. Future studies should focus on the dynamic interactions among fish, mussels, and bacteria as well as on how input such as feed and other organic materials affect these interactions.

Summer mortality syndrome bacterial pathogens in farmed Nile tilapia (Oreochromis niloticus)

“…The source of the hemorrhages throughout the body could be the hemolysin produced by the Aeromonas retrieved bacteria, which hemolyzes red blood cells (RBCs), in addition to the elastase enzyme, which significantly contributes to vascular injury because the blood arteries are primarily made up of elastic and collagenous fibers. The clinical symptoms seen in this study almost the same as those identified by previously ( Ahmed and Shoreit, 2001 ; El-Ashram, 2002 ; Pretto-Giordano et al , 2010 ; Yardimci and Aydin, 2011 ; Noor El-Deen et al , 2014 ; Soliman et al , 2014 ; Othman et al , 2015 ; Dar et al , 2016 ; Omar et al , 2016 ; Abd El-Tawab et al , 2017 ; El-Barbary, 2017 ; Laith et al , 2017 ; Osman et al , 2017 ; Pech et al , 2017 ; Saleh et al , 2017 ; Amrullah et al , 2018 ; Khalil and Emeash, 2018 ; Hamouda et al , 2019 ; Hassan et al , 2020 ).…”

Prioritizing sites for conservation based on similarity to historical baselines and feasibility of protection

“…; Othman et al. ). This filter feeding improves stream clarity and increases macroinvertebrate resources in the river (Vaughn ), which could potentially increase the recreational value of the river.…”

Shell morphology, growth and longevity of Unio tumidus (Bivalvia: Unionidae) from an archaeological site and contemporary population inhabiting the Oder estuary

“…Trophic changes in the Szczecin Lagoon waters observed in the recent decades (Wolnomiejski & Witek, 2013), caused by increased intensity of agricultural production and nutrient migration to surface waters (Burzyńska, 2019), may result in future elimination of numerous species sensitive to increased levels of nitrogen and phosphorus compounds. Such changes in the environmental conditions especially affect mussels (Cope et al, 2008), which are one of the most endangered groups of animals (Lopes-Lima et al, 2017;Böhm et al, 2020) How significant for the aqueous environment the freshwater mussels are is shown by the fact that they highly support water purification by filtering off bacteria from the water column (Othman et al, 2015). The most common factors considered in the assessment of the mussel resources and planning of conservation works include the present state of the population or variability over short periods of time.…”