Evaluating Bottom Water Quality at the Flood Control Area in An Giang Province, Vietnam Using Zoobenthos’ Diversity Index

Abstract

The aquatic environment and zoobenthos fauna are closely related

in a water body. In recent years, the use of zoobenthos to assess the

quality of surface water environment is of interest because this

method causes less environmental pollution and is less costly. The

study was conducted to evaluate the distribution of zoobenthos fauna

in the Bac Vam Nao flood control area, An Giang. Three samples of

benthos (VN1-VN3) were collected in two periods, the first in March

and the second in September 2020. The results have found eight

species belonging to three phyla of Mollusca, Annelida and

Arthropoda. In which, Mollusca phylum had the highest number of

species with six species (70%) and the lowest was Annelida and

Arthropoda with one species each (12.5%). In the dry season,

Macrobrachium sp. (Arthropoda) dominated at all three sampling

positions. In the rainy season, Mollusca is dominant with Pomacea

canaliculate, Gyraulus sp., Filopaludina (F.), Sumatrensis speciosa

species. Density of zoobenthos at three monitoring locations in the

Bac Vam Nao flood control area ranged from 170 to 290

individuals/m2

in March and from 40 to 70 individuals/m2

in

September, reaching the highest value is at the end of Than Nong

canal adjacent to Cai Tac canal (VN3) in March and the lowest at

the middle point of Than Nong canal adjacent to K26 canal (VN2) in

September. The diversity index H' of zoobenthos at three locations

in the Bac Vam Nao flood control area through two monitoring

periods in 2020 ranged from 0.36 to 2.24, classifying water quality

from mild to very polluted. The diversity of zoobenthos at the

monitoring sites is subjected to seasonal change in which the H'

index in the dry season is lower than that in the rainy season. The

current findings showed that the zoobenthos composition reflected

the bottom water quality of the study area. More studies are needed

to increase the accuracy of this assessment method.