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Ecotoxicological assessment of ocean warming and acidification on Perna Viridis in Singapore
Author
Low, Yvonne May Ling
Supervisor
Goh, Beverly
Abstract
Human activities such as the continued burning of fossil fuels and changing land use are releasing gigatonnes of CO2 into the atmosphere. As a result of the increase in atmospheric CO2 concentration, a greenhouse effect is created. The direct consequences of an increased concentration of atmospheric CO2 include rising global temperature, warming of the ocean waters and acidification of the oceans (lowering of seawater pH). Indirect consequences may include disturbances to the physiological and biological processes in marine organisms. Warming of the ocean waters and lowering of the seawater pH are environmental stresses that could impact the well-being of marine-dwelling organisms. This dissertation aims to examine the short-term effect of increasing seawater temperatures and decreasing seawater pH on the Neutral Red retention time of lysosomes of the green mussels (Perna viridis). Green mussels were subjected to temperature stress at 25oC (control), 28oC, 30oC and 32oC. With increasing seawater temperatures, the Neutral Red retention time of the lysosomes in the green mussels were significantly reduced. Computed probit graphs of the EC50 dose-response relationship for temperature stress was 31.3oC and 30.8oC at 48 hour and 120 hour exposure period, respectively. This indicated that mussel lysosomal membranes were susceptible to damage at high temperatures. In a separate experiment, the green mussels were kept in acidified seawater at pH 8.2 (control), pH 7.5, pH 6.5 and pH 5.6. The Neutral Red retention time of the lysosomes in the green mussels also showed decreased dye retention time during the experimental period. Computed probit graphs of the EC50 dose-response relationship for increased seawater acidification was pH 6.1 and pH 6.4 at 48 hour and 120 hour exposure period, respectively. This showed that chronic exposure of green mussels to low seawater pH (pH 6.5 and below) impairs the integrity of the mussel lysosomal membranes. The temperature and pH regimes selected for this dissertation represents predicted ocean warming scenarios and the likely decrease in seawater pH as a result of ocean CO2 absorption or leakage from geological sequestration. Findings from this study suggest that environmental stressors such as elevated seawater temperature and increased seawater acidification can impair the functional abilities of the lysosome membranes of green mussels. Such stress-response evaluation of marine organisms can allow for the development of bio-monitoring tools in areas with high biological productivity and in water bodies that are prone to industrial and domestic waste pollution.
Date Issued
2013
Call Number
QL430.6 Low
Date Submitted
2013