An Assessment of the Ecological Impacts from Low Intensity Shrimp Farm Wastewater in the Bang Pakong River Region of Thailand Using Stable Isotope Analysis

Sustainable Aquaculture;Thailand;Stable Isotopes;Wastewater;Natural Resources and Environment

Kempke, SarahWiley, Michael ;

University of Michigan

关键词: Sustainable Aquaculture;    Thailand;    Stable Isotopes;    Wastewater;    Natural Resources and Environment;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/89961/KempkeThesis-Final_2_9-12%5b1%5d.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Eutrophication of receiving water is often cited as a significant environmental impact ofshrimp aquaculture. However, it is difficult to trace sporadic nutrient inputs from harvestsand to separate effects of aquaculture effluent from other nutrient sources. This studyattempted to trace impacts of shrimp wastewater in Thailand, where shrimp farmingdominates much of the coastal landscape and economy. Stable isotopes of N and C, C:Nratios, and water quality analysis were used to evaluate the impact of shrimp farm effluentfrom small scale farms using semi intensive management with minimal treatment ofdischarged water. Farms discharge into the Chucachur Canal, a tributary to the Bang PakongRiver in the Northern Gulf of Thailand. There were exceptionally high levels of nutrients inthe canal, stemming both from shrimp aquaculture and from other agricultural sources. TPexceeded Thai standards for all sampling points and days; NH3 exceeded Thai standardsnear a pig farm source on all days, as well as in a plume of shrimp wastewater on a daywhen a farm was harvested. Multiple linear regression on stable isotope data indicated thatinsolation was the most influential variable determining δ15N and δ13C in plants in the canal.This analysis also indicated that levels of NO2 and NH3 contributed to the variation inisotope ratios measured in periphyton and hyacinth, respectively. Overall, δ15N isotoperatios indicated that although nitrogen inputs did explain some isotopic concentrations inplants, isotope ratios were driven more by physical processes like insolation and availableoxygen than by inputs of particular δ15N signatures from shrimp farms. My results indicatethat although it is likely that shrimp farming on the canal does impact the environment,other factors significantly influence it as well, with other anthropogenic inputs such as pigfarming having a more significant and continual impact than temporal pulses of nutrientsfrom pond harvests.