(LATO) IN LOWERED SEAWATER pH - Central Visayas Campus ...

Ilustrisimo, C. A., I. C. Palmitos, R. D. Señagan. 2013. “Growth Performance of
Caulerpa lentillifera in Lowered Seawater pH”. A Research Paper. Philippine Science
High School – Central Visayas Campus, Talaytay, Argao, Cebu.
ABSTRACT
Ocean acidification, as a result of increased atmospheric carbon dioxide (CO2)
concentrations, is predicted to lower the pH of seawater over the next 100 years
(Clark et al. 2009). The aim of the study was to determine the growth performed by
Caulerpa lentillifera as the test species in lowered seawater pH. To verify the growth
performance of the species, an acidic environment was made with a range of lower
seawater pH (pH 2.7 -3.3, 3.7-4.3, 5.7-6.3 and 7.7 to 8.3). Acidity was adjusted by
adding a reagent grade of hydrochloric (HCl) acid. Species treated with pH 7.7 to 8.3
were held as the controlled group. Experimental conditions (temperature, salinity,
dissolved oxygen, and pH) were observed daily as accounted by Battistoni et al.
(2007). Different physical changes (weight and color) were also observed. The
amount of chlorophyll a content of the seaweed after the treatment was examined by
reading its absorbance at 645 nm and 662 nm using UV-Vis spectrophotometer.
Lowering pH resulted in a decrease in survival of the species. Species treated in pH
7.7 to 8.3 contains 11.92 mg/L chlorophyll a and was the highest amount of
chlorophyll a content, followed by pH 5.7 to 6.3 which was 11.66 mg/L, pH 2.7 to 3.3
which was 0.1551 mg/L and lastly, pH 3.7 to 4.3 containing 0.1198 mg/L. The
statistical results proved that there was a significant difference on the weights of the
samples in the three trials among the four groups. The study concluded that lowering
seawater pH (ocean acidification) will result to a decrease in weight and chlorophyll a
content of C. lentillifera, implying a negative effect on the growth of the species.
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