Abstract. Nematode communities in Ba Lai river, Ben Tre province were investigated in September of 2015 (eight stations from estuary to upstream). The results showed that the nematode communities have characterized by high density and biodiversity, providing useful information of nematode assemblages in freshwater habitas, in particular inland river. Also the results indicated that the distribution of nematode communities in Ba Lai river was strongly discriminated between in and outside of dam with two groups. The Ba Lai dam may be reasons for cause the nematodes distribution discontinuity. Present study is a pioneering attempt to record the impact of the dam on benthic -invertebrate in Viet Nam.

Camellia is a large genus in the tea family of Theaceae. In this genus, several species serve different purposes, such as, medicinal and ornamental plants and beverage production. Thus, country-wide cultivation of various species of Camellia genus sought to alleviate poverty and promote economic development in many regions. However, studies on evaluating its genetic resources as a foundation for the conservation and development of this plant are yet to start. Currently, using DNA barcoding often serves as a highly reliable approach to identifying and characterizing numerous plants. In the presented study, a total of 10 Camellia accessions collected from Dong Bua village, Tam Quan commune, District Tam Dao, and Vinh Phuc province, Vietnam, underwent study during 2020–2022 at Ho Chi Minh City University of Food Industry, Vietnam. Evaluation of two DNA barcoding regions, namely, rbcL and trnH-psbA, transpired for their ability to distinguish the Camellia accessions belonging to different species in Vietnam. The results revealed a significant difference in the DNA sequences of the rbcL and trnH-psbA regions among the Camellia species. In addition, the trnH-psbA barcode region also showed higher effectiveness versus the rbcL region in recognizing various species of Camellia. The results authenticated the potential of DNA barcoding in the management, conservation, and development of the genetic resources of Camellia in Vietnam.