Laguna Lake pollutants dangerous to some fish species - UPLB study

LOS BAÑOS, Laguna, Philippines – Pollutants in Laguna Lake have reached a level that causes abnormalities in some fish species.

This was found in a scientific study done by Dr. Michelle Grace Paraso of the University of the Philippines Los Baños-College of Veterinary Medicine (UPLB-CVM).

Titled “Estrogenic Disruption in Male Common Carp (Cyprinus carpio Linsaeus) Introduced to the East and West Sites of Laguna de Bay,” the research was funded by the UPLB-based Southeast Asian Ministers of Education Organization-Regional Center for Graduate Study and Research in Agriculture (SEAMEO SEARCA).

The Philippine government-hosted SEARCA, headed by director Gil Saguiguit Jr., is one of the 20 “centers of excellence” of SEAMEO, an inter-government treaty body founded in 1965 to foster cooperation among Southeast Asian nations in the fields of education, science and culture.

Established in 1966, SEARCA is mandated to address the agricultural and rural development needs of Southeast Asia through capacity-building interventions such as research, scholarships, training, and knowledge sharing and management.

Paraso earned her doctorate in Environmental Science from UPLB in 2010-2011 as a SEARCA scholar.

In her research, the UPLB-CVM associate professor analyzed water samples gathered from 16 sites in the east and west bays of the lake. She presented her findings in a recent SEARCA-sponsored seminar.

Results showed the presence of high levels of a natural estrogenic endocrine-disrupting compound called 17-beta estradiol (E2) that poses a threat to fish health.

Estrogen, as defined, is a substance – as sex hormone – tending to promote estrus or a state of sexual excitability and stimulate the development of secondary sex characterization in the female.

“Alarmingly, the levels of E2 found in Laguna de Bay were much higher than those in surface water in other Asian countries,” Paraso said.

These bio-pollutants are correlated to the hormone excretions found in animals and human feces and urine carried as surface runoff that flows into the lake, she added.

In her study, the UPLB-CVM scientists raised male common carp in fish cages along the bay. She later examined and compared them with a reference group raised at the UPLB Limnological Research Station in Los Baños.

She reported: “Signs of estrogen exposure in the caged fish were evident in the 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 vitellogenin, which is usually found only in female fish.”

While the study confirmed estrogenic pollution in the lake and effects of exposure in male carp, Paraso cautioned that it is too early to establish that the bio-pollutants adversely affect the overall population or raise any concern regarding fish consumption.

Nonetheless, she recommended that with Laguna de Bay being considered as a viable source of domestic water supply 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.”