The Diversity of Phytoplankton in a Combined Rice-Shrimp Farming System in the Coastal Area of the Vietnamese Mekong Delta

Nguyen Dinh Giang Nam,Minh N Nguyen,Nigel K Downes,Nguyen Thanh Giao,Nguyen Hieu Trung,Le Hoang Hai Anh,Nguyen Vo Chau Ngan

doi:10.3390/w14030487

Abstract

An assessment of varying density, species composition and dynamics of phytoplankton in a combined rice-shrimp culture was carried out in My Xuyen district, Soc Trang province in the Vietnamese Mekong delta. Water was sampled six times at six separate locations within the culture system, on days 1, 20, 34, 57, 68, and day 81 of the rice-shrimp crop cycle. The results showed the abundance of 95 phytoplankton species belonging to five phyla including Cyanophyta, Chlorophyta, Bacillariophyta, Euglenophyta, and Pyrrophyta. The values of Shannon–Wiener index indicated high phytoplankton diversity, while the water quality ranged from medium to good. A Cluster Analysis showed that the phytoplankton density variation can be divided into three distinct periods. The initial phase of crop growth was dominated by Pandorina morum, Pediastrum simplex, Eudorina elegans, Oscillatoria limosa, and Anabaena circinalis. The midstage, reproductive phase of crop growth was dominated by Scenedesnus acuminatus, Pediastrum duplex, Closterinm setaceum, Scenedesnus quadricauda, and Actinastnum hantzschii. Whereas Scenedesnus acuminatus, Scenedesnus quadricauda, Closterinm closterioides, Staurastrum arcuatum, Euglena nhrenbergii, and Phacus lnsmorensis were dominant at the end of crop cycle. The findings provide useful information on phytoplankton assemblages in a typical rice-shrimp culture, which has recently gained popularity as an adaptive livelihood system.

Highlights

Introduction published maps and institutional affilAquaculture is the fastest growing food-producing sector in Vietnam
The global demand for aquaculture products continues to grow, as the natural stocks from captured fisheries continue to decline. This is especially true for the Vietnamese Mekong delta (VMD)
This may be an indication of decreasing water quality as this phylum is often indicative of organic water pollution [26]

Summary

Introduction

Introduction published maps and institutional affilAquaculture is the fastest growing food-producing sector in Vietnam. The global demand for aquaculture products continues to grow, as the natural stocks from captured fisheries continue to decline. This is especially true for the Vietnamese Mekong delta (VMD). According to the General Statistics Office of Viet Nam [1], the total aquaculture production was 3513.3 thousand tons, in which a total shrimp production was 628.2 thousand tons in 2015. The aquaculture and shrimp production in Vietnam for the year 2020 was. In comparison to the year 2015, respectively [2] As it is rapidly increasing, aquaculture plays a crucial role in improving the livelihood of people in the coastal provinces of the VMD, such as Ca Mau, Kien Giang, and Soc Trang

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