Organic matter degradation and bacterial communities in surface sediment influenced by Procambarus clarkia

Abstract

To alleviate excessive organic matter (OM) accumulation in sediments and reduce the risk of endogenous water pollution and eutrophication in aquaculture ponds, an 84-day experiment investigated the effect of the red swamp crayfish Procambarus clarkii on the OM degradation and bacterial communities in sediments. The experiment established two groups, P. clarkia treatment and control (represented as PG and CG, respectively), with three replicates for each group. At the end of experiment, the total, light fraction, and heavy fraction organic matter concentrations in the sediment of the PG group were significantly lower than those of the CG group. Significantly higher oxidation–reduction potential (ORP) and more extensively degraded OM, indicated by fatty acids, were observed in the PG group. Compared to the CG group, the average OM removal efficiency induced by crayfish in the PG group was 15.24%. Using 16S ribosomal RNA (rRNA) high-throughput sequencing, we investigated the differences in benthic bacterial communities between the PG and CG groups. Linear discriminant analysis (LDA) effect size (LEfSe) analysis revealed that Nitrospirae, Nitrospira, Alphaproteobacteria, OLB14, Nitrospirales, Rhodobacterales, Rhizobiales, Micrococcales, Nitrospiraceae, Rhodobacteraceae, Nitrospira, Rhodobacter, Thermomonas, and Denitratisoma were significantly enriched in the PG group. Four significantly different functional groups related to OM degradation were determined between the PG and CG groups according to the functional annotation of procaryotic taxa (FAPROTAX) analysis. These four functional groups, aerobic chemoheterotrophy, manganese oxidation, dark iron oxidation, and dark sulfide oxidation, showed significantly higher relative abundances in the PG group. Overall, P. clarkia effectively increased the ORP values of sediments to provide favorable conditions for OM degradation and changed the composition and function of bacterial communities to improve bacterial abilities for OM decomposition, thereby promoting OM degradation in the sediment.

Occurrence, Ecological and Health Risks of Organic Pollution of the Waters from a Tropical Lake System

“…The effect of renewal of these waters by meteorite waters would be shown more in SDS, where their COD mean value, although significant, is the lowest observed over the study period. In this season, the clear increase in the basicity of these waters [31,32] and salinity [34,35], as well as the drop in their level [33] relative to the previous season, would have contributed to the presence of matter within them. This would have been the opposite of the increase in their reductive character, further favouring their degradation and mineralization [37].…”

“…Their basic character would have been conducive to the presence of organic matter within them [31,32]. The same would be true of the very shallow depth of this lake system favouring exchanges between the water column and surface sediments [33] and the low salinity of these waters [34,35]. However, the relatively high temperature and the reductive character of these waters would contribute to the partial degradation and mineralization of organic matter within them [36,37].…”

“…The basic character of these waters in this season would also have contributed to a relative importance of organic matter within them by partial inhibition their degradation [31,32]. This would also have been the case for their relatively high salinity in this season [34,35]. However, the more pronounced reductive character and the relatively high temperature of these waters would have partially favoured the degradation of organic matter in these waters in this season [36,37].…”

“…However, the renewal of these waters would cause a clear drop in their COD values. This fact would also have been reinforced by the drop in their basicity and salinity [31,32,34,35], as well as by the increase in the water volume of this lake site. On the other hand, the decrease in the reductive character [37] would have contributed to the presence of organic matter in these waters in these two seasons.…”

Influences of the Integrated Rice-Crayfish Farming System with Different Stocking Densities on the Paddy Soil Microbiomes

“…The red claw crayfish C. quadricarinatus is distinguished by its considerable size, swift growth rate, robust disease resistance, stronger adaptability, and significant economic value, making it an integral choice for integrated rice-crayfish farming since its introduction to China in 1992 [13,14,[17][18][19]. As typical benthic organisms, crayfish can influence aquatic ecosystems, playing a crucial role in biogeochemical cycles and altering benthic bacterial communities at the sediment-water interface [20][21][22][23][24][25]. Meanwhile, exogenous artificial nutrition input in the integrated rice-fish farming system can also have significant impacts on the agroecosystem.…”