First Data on Testate Amoeba Composition in Tropical Karst Wetlands of Northern Vietnam in Relation to Type of Biotope and Season: New Bioindication Potentialities

Abstract

The first data on testate amoeba composition from Trang An and Van Long wetlands (Ninh Binh province, Vietnam) was obtained. Sixty-three species and subspecies belonging to 9 genera and 6 families were identified from 108 samples collected from these wetlands. Arcella conica, Difflugia pulex, and D. sarissa were recorded in Vietnam for the first time. Species diversity of wetland Van Long (52 species) was higher than Trang An (36). The number of identified species and subspecies was highest in periphytonic samples (49), followed by planktonic (46) and benthic samples (29). The most species-rich genera were Difflugia, Arcella, and Centropyxis in both investigated wetlands. The most frequently occurred testaceans were C. aculeata, D. schurmanni, A. hemisphaerica, A. megastoma arcuata. C. aculeata, D. schurmanni, and D. elegans were the most common species in all investigated types of biotopes including plankton, benthos, and periphyton. The species accumulation curves for Trang An and Van Long wetlands were not saturated and well fitted by equations S = 3.77N0.56 and S = 16.96N0.30, respectively. Mean species richness per sample of Trang An wetland was statistically higher than Van Long wetland. The difference in species richness per sample between planktonic and periphytonic samples collected in Trang An wetland was statistically insignificant. In contrast, statistically significant difference in species richness per sample was observed among planktonic, benthic and periphytonic samples collected in Van Long wetland. Species richness per sample in plankton and periphyton was statistically higher than in benthos, while the statistically significant difference between two first ones was not observed. The difference in species richness between samples collected in the rainy (September 2017) and the dry seasons (June 2018) was not statistically significant in Trang An wetland. By contrast, in Van Long wetland, mean species richness per sample in the rainy season was statistically higher than at the end of the dry season. The results of detrended correspondence analysis (DCA) revealed distinct testate amoeba species in association with plankton, periphyton, and benthos habitats in the studied wetlands. These species should be considered as bioindicators for each of these types of biotopes.