Effect of fish biomass on environmental DNA shedding and degradation
Carlos Henrique Dos Anjos Dos Santos1,2, Vilmar Biernaski3, Adalberto Luis Val4
1Universidade Federal Rural de Pernambuco, Unidade Acadêmica de Serra Talhada, Serra Talhda (PE), Brasil. carlos.hasantos@ufrpe.br.
Background:
Environmental DNA in freshwater samples is a promising tool for assessing the relationship between biomass and eDNA concentration. We performed a quantitative PCR in experimental tanks to verify the influence of density/biomass on the release and decay of DNA in water samples.
Methods And Results:
The three densities used were one fish (0.416 ± 0.075 g L⁻¹), two fish (0.778 ± 0.041 g L⁻¹), and three fish (1.277 ± 0.165 g L⁻¹) in triplicate. We collected water samples at 0, 24, 48, 72, and 96 h (with and without fish) for analysis. Temperature, pH, and oxygen remained constant, with only total ammonia increasing with fish density. We verified that eDNA concentrations increased with density/biomass, revealing a positive correlation in the fish assays. After 24 h, eDNA stabilized, reaching equilibrium. We observed a significant drop in the eDNA concentration within 24 h of removing the fish. The persistence of eDNA increased from high to low densities, indicating a strong correlation with the decay rate constant.
Conclusions:
Herein, the results demonstrate the potential use of eDNA samples for monitoring and managing fish in both aquaculture and wild environments. However, further studies on different types of water (black, clear, and white waters) in the Amazon are necessary to facilitate the routine application of eDNA in the region.
