Laguna de Bay is the largest inland body of freshwater in the country and provides support system to more than 13.6 million people, around two million of which do not have access to proper sewage systems. As a consequence, water contamination continues to be a threat to the vitality of this important water resource.
Results of a research conducted by SEARCA graduate alumna Dr. Michelle Grace V. Paraso revealed that there are high levels of an estrogenic endocrine-disrupting compound in Laguna de Bay that poses a threat to fish health. These and other important details of her dissertation were presented in the SEARCA Special Graduate Seminar held on 3 August 2011.
Analysis of water samples gathered from 16 sites in the east and west parts of the lake revealed the presence of a natural estrogen called 17-beta estradiol (E2). Alarmingly, the levels of E2 found in Laguna de Bay were much higher than in surface waters in other Asian countries. These bio-pollutants are correlated to the hormone excretions found in animal and human feces and urine carried as surface run-off that flow into the lake.
Male common carp were raised in fish cages along the bay and were later examined and compared with a reference group raised in the UPLB Limnological Research Station. Signs of estrogen exposure were evident in the caged fish as shown by changes in their sexual characteristics. These changes include reproductive abnormalities such as delay in maturation of germ cells, development of lesions in the testis, and presence of an egg yolk protein precursor called vitellogenin, which are usually found only in female fish. The size and frequency of hepatic melanomacrophage aggregates, which are biomarkers of pollution in aquatic ecosystems, also increased.
While the study confirmed estrogenic pollution in the lake and effects of exposure in male carps, Dr. Paraso cautioned that it is too early to establish that the bio-pollutants adversely affect the overall fish population or raise any concern regarding fish consumption.
Nonetheless, Dr. Paraso emphasized that with Laguna de Bay being regarded as a viable water source for Metro Manila, “environmental laws, particularly those that focus on proper waste management, as well as basic sewage treatment systems need to be strictly enforced.”
Dr. Paraso finished her PhD in Environmental Science at the University of the Philippines Los Baños (UPLB) in April 2011 under the SEARCA Graduate Scholarship Program. She currently works as Associate Professor of the UPLB College of Veterinary Medicine. (Jesselle S. Laranas)
The point of view taken by this article is entirely that of the presenter's and does not reflect in any way, SEARCA’s position.