Relationship of free-living nematode communities to some environmental variable in an organic shrimp farms, Ca Mau province

Abstract

Free-living nematode communities (FLNC) in the Tam Giang's organic shrimp farms ponds (TGOSFP), Nam Can district, Ca Mau province were investigated in three seasons (March - dry, July - transfer (trans) and November - wet season) of 2015. Our findings underlined that the FLNC were expressed by high density and diversity. The environmental condition in the TGOSFP was characterized by a high percentage of TN, TOC, low pH, and anaerobic condition in sediment that was not optimal conditions for shrimp farming. The results of CCA analysis showed that main environmental parameters such as TN, TOC, depth, DO, salinity, and pH almost completely governed the abundances of dominant genera such as Desmodora. Sahatieria, Terschellingia, Dichromadora, Pomponema, Halalaimus, Ptycholaimellus, and Sphaerotheristus. Subsequently, the results of Pearson correlation confirmed that the abundances of genus Sabatieria, Terschellingia were significantly positively correlated with TOC, TN, and depth. In contrast, Desmodora. Halalaimus, and Ptycholaimellus were negative correlations with organic enrichment (TOC and TN). However, most genera were positively correlated with salinity. The combination of dominant nematode genera and maturity index (MI) value indicated that the ecological quality status of sediment (EcoQ) in TGOSFP was moderate to poor EcoQ. The attribute of FLNC and their correspondence with environmental characteristics can be considered as a good tool for environmental monitoring.