Changes of Benthic Macroinvertebrates in Thi Vai River and Cai Mep Estuaries Under Polluted Conditions with Industrial Wastewater

Abstract

The pollution on the Thi Vai River has been spreading out rapidly over the two lasted decades caused by the wastewater from the industrial parks in the left bank of Thi Vai River and Cai Mep Estuaries. The evaluation of the benthic macroinvertebrate changes was very necessary to identify the consequences of the industrial wastewater on water quality and aquatic ecosystem of Thi Vai River and Cai Mep Estuaries.In this study, the variables of benthic macroinvertebrates and water quality were investigated in Thi Vai River and Cai Mep Estuaries, Southern Vietnam. The monitoring data of benthic macroinvertebrates and water quality parameters covered the period from 1989 to 2015 at 6 sampling sites in Thi Vai River and Cai Mep Estuaries. The basic water quality parameters were also tested including pH, dissolved oxygen (DO), total nitrogen, and total phosphorus. The biodiversity indices of benthic macroinvertebrates were applied for water quality assessment.The results showed that pH ranged from 6.4 -7.6 during the monitoring. The DO concentrations were in between 0.20 -6.70 mg/L. The concentrations of total nitrogen and total phosphorous ranged from 0.03 -5.70 mg/L 0.024 -1.380 mg/L respectively. Macroinvertebrate community in the study area consisted of 36 species of polychaeta, gastropoda, bivalvia, and crustacea, of which, species of polychaeta were dominant in species number. The benthic macroinvertebartes density ranged from 0 -2.746 individuals/m 2 with the main dominant species of Neanthes caudata, Prionospio malmgreni, Paraprionospio pinnata, Trichochaeta carica, Maldane sarsi, Capitella capitata, Terebellides stroemi, Euditylia polymorpha, Grandidierella lignorum, Apseudes vietnamensis. The biodiversity index values during the monitoring characterized for aquatic environmental conditions of mesotrophic to polytrophic. Besides, species richness positively correlated with DO, total nitrogen, and total phosphorus. The results confirmed the advantage of using benthic macroinvertebrates and their indices for water quality assessment.

Aquatic invertebrates and their correlation with the basic abiotic factors in the coastal water of Can Gio, Southern Vietnam

“…Similar to the species richness, the abundance of the invertebrates in the studied area was also quite low which could be due to the sandy bottom and the high water turbulence. These findings on dominant species that recorded in this study was quite similar to the previous results aquatic flora and fauna monitoring in the Can Gio Mangrove Biosphere Reserve [12,27,30] and the surrounding area as the coastal of Tien Giang Province [14,22]. However, the abundance of aquatic invertebrates was lower because of the sea waves and hard bottom beds in the coastal region.…”

“…The polychaeta contributed highest species number in the benthic macroinvertebrates, 6 species gaining 33% of the total species number (Figure 3). These results were similar to the findings of aquatic invertebrate distribution at the Eastern Delta Coast at Daietta, Egypt [24] and the Thi Vai River, Vietnam [12]. Another study on macroinvertebrates in the mangrove forests in India indicated that the polychaetes contributed highest proportion in the organism assemblage [26].…”

“…The species number and diversity of aquatic invertebrates recorded in the coastal area of Can Gio during the monitoring period varied very little among the sampling sites (Figure 4). The monitoring results of aquatic flora and fauna in the Thi Vai River and the Tien Giang coastal also showed that the species of polychaeta were more abundant than other classes [12,22]. In the present study, the species Paracalanus parvus and nauplius copepoda could be found in all locations.…”

“…Additionally, the mollusks and malacostraca were commonly found in the coastal of Can Gio. The results from previous studies in adjacent coastal areas also showed the common occurrence of these groups of species [12]. The species number and diversity of aquatic invertebrates recorded in the coastal area of Can Gio during the monitoring period varied very little among the sampling sites (Figure 4).…”

“…In Vietnam, zooplankton and benthic macroinvertebrates were recommended as excellent bioindicators for river health because of their usefulness for biological monitoring [11,12]. Nguyen et al (2014) applied a multi-metric index (MMI) which was divided into five categories, from poor to good, to assess the environmental quality [13].…”