Integration of aquatic ecology and biological oceanographic knowledge for development of area-based eutrophication assessment criteria leading to water resource remediation and utilization management: a case study in Tha Chin, the most eutrophic river of Thailand

Abstract

This research was carried out in Tha Chin Watershed in the central part of Thailand with attempts to apply multidisciplinary knowledge for understanding ecosystem structure and response to anthropogenic pollution and natural impacts leading to a proposal for an appropriate zonation management approach for sustainable utilization of the area. Water quality status of the Tha Chin River and Estuary had been determined by analyzing ecological, hydrological, and coastal oceanographic information from recent field surveys (during March 2006 to November 2007) together with secondary data on irrigation, land utilization, and socio-economic status.Results indicated that the Tha Chin River and Estuary was eutrophic all year round. Almost 100% of the brackish to marine areas reflected strongly hypertrophic water condition during both dry and high-loading periods. High NH(4)(+) and PO(4)(3-) loads from surrounding agricultural land use, agro-industry, and community continuously flew into the aquatic environment. Deteriorated ecosystem was clearly observed by dramatically low DO levels (ca 1 mg/l) in riverine to coastal areas and Noctiluca and Ceratium red tide outbreaks occurred around tidal front closed to the estuary. Accordingly, fishery resources were significantly decreased. Some riverine benthic habitats became dominated by deposit-feeding worms e.g. Lumbriculus, Branchiura, and Tubifex, while estuarine benthic habitats reflected succession of polychaetes and small bivalves. Results on analysis on integrated ecosystem responses indicated that changing functions were significantly influenced by particulates and nutrients dynamics in the system.Based on the overall results, the Tha Chin River and Estuary should be divided into 4 zones (I: Upper freshwater zone; II: Middle freshwater zone; III Lower freshwater zone; and IV: Lowest brackish to marine zone) for further management schemes on water remediation. In this study, the importance of habitat morphology and water flow regimes was recognized. Moreover, nearshore extensive shrimp culture ponds, irrigation canals, and surrounding mangrove habitats belonging to local households seemed to act as effective natural water treatment system that can yet provide food resources in turns. These remediation-production integrated functions should be deserved depth considerations for water quality development of the Tha Chin areas.

Impacts of nutrients and related environmental factors on distribution and size structure of Noctiluca scintillans populations of the Eutrophic Tha Chin Estuary, Thailand

“…Nutrient loads have caused eutrophication problems and frequent red tide outbreaks in the inner Gulf of Thailand (Suvapepun 1989;Chongprasith & Srinetr 1998). The very high nutrient levels generally found in the lower river and the estuarine zones have initiated hypertrophie conditions and red tides throughout the year (Meksumpun & Meksumpun 2008). Very high loads of dissolved inorganic nitrogen and orthophosphate phosphorus of 145.54 and 36.141 day"\ respectively, have been reported recently (Thaipichitburapa et al 2010). Nutrients have been emphasized by various ecologists as an important factor influencing the growth of Noctiluca (Pithakpol et al 2000;Sriwoon et al 2008) where in a study on red Noctiluca, nutrients played an indirect role, stimulating the growth of other phytoplankton.…”

Spatio-Temporal Variations in Water Quality of the Chao Phraya River, Thailand, between 1991 and 2008

“…cluster A) but also the other rivers in the region, i.e. Bangpakong [13], Mae Klong [20] and Tha Chin [21], in which all selected parameters, except temperature, were below the national standard of surface water quality of Thailand at the lowest level, i.e. fairly clean used [22].…”

“…chemical agents and heavy metal) also caused a reduction in DO and are increase in BOD in the lower Chao Phrya River [23,24]. Meanwhile, high NH3-N and derivatives are commonly loaded from surrounding agricultural land uses [20,21].…”

Influence of environmental factors on abundance and temporal variation of benthic fauna resources in the eutrophic Tha Chin estuary, Samut Sakhon province, Thailand

“…The highest AVS (0,755 mg/g) found during the mediumloading period (approximately three months after large inflows) could imply deteriorated conditions of the bottom deposits due to high organic accumulation and an anaerobic decomposition process. According to the categorization of AVS impacfing on benthic resources of the Tha Chin river basin by Meksumpun & Meksumpun (2008), the AVS levels during this period were harmful to the living invertebrate benthic resources,…”

“…Unfortunately, wastewater from anthropogenic activities has affected water quality, especially in the lower river basin and estuary. The lower river and estuarine zones have been reported to be in a hypertrophie condition (Meksumpun & Meksumpun 2008). Although distinguishable deterioration of the water quality occurred, some evidence suggested the eco-potential of self-remediation (Thaipichitburapa et al 2010).…”