Physicochemical and microbiological assessment of oyster farms in Ilocos Sur, Philippines

Chris Paul Pagaoa; Charo Rojas; Berlin Agsalog; Olieve Karenth Barcesa

doi:10.31893/multiscience.2026050

Keywords:

oyster farming

water quality

sustainable aquaculture

physicochemical analysis

microbial contamination

Abstract

Oyster farming in the Philippines plays a crucial role in the livelihoods of local communities, particularly in rural coastal areas of Ilocos Sur. However, the industry faces environmental degradation, limited market demand, and a prolonged cultivation period, which hinder its profitability and sustainability. This study evaluated the physicochemical and microbiological quality of water in six selected oyster farms using standardized analytical techniques. Surface water samples were collected and analyzed for temperature, pH, turbidity, total coliforms, and fecal coliforms. Physicochemical parameters were measured using the SPARK Science Learning System, while microbial quality was assessed through multiple tube fermentation technique. Results indicate that the temperature range from 28.1 to 30.1°C and pH levels of 7.56 to 7.79 obtained from all farms are within the DENR standards and suitable for oyster culture. However, turbidity in most farms exceeded the permissible level of 5 NTU, which is dangerous for oyster health. More importantly, many of these farms' fecal and total coliform counts are alarming, far higher than the DENR standard of 70 MPN/100 mL. The conditions are generally suitable for oyster farming. However, special attention is required concerning water turbidity and microbial contamination. These factors have related implications for such farms' sustainability and the harvested oysters' safety. Regular water quality monitoring, farm management improvement practices, community education for environmental protection measures, and strict enforcement of regulation measures against potential contamination risks are recommended.
References
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7. Dove, M. C., & O'Connor, W. A. (2007). Salinity and temperature tolerance of Sydney rock oysters Saccostrea glomerata during early ontogeny. Journal of Shellfish Research, 26(4), 939–947. https://doi.org/10.2983/0730-8000(2007)26[939:SATTOS]2.0.CO;2
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11. Jeamsripong, S., Thaotumpitak, V., Anuntawirun, S., Roongrojmongkhon, N., & Atwill, E. R. (2022). Meteorological and water quality factors associated with microbial diversity in coastal water from intensified oyster production areas of Thailand. Water, 14(23), 3838. https://doi.org/10.3390/w14233838
12. Ko, G. W., Dineshram, R., Campanati, C., Chan, V. B., Havenhand, J., & Thiyagarajan, V. (2014). Interactive effects of ocean acidification, elevated temperature, and reduced salinity on early-life stages of the Pacific oyster. Environmental Science & Technology, 48(17), 10079–10088. https://doi.org/10.1021/es501611u
13. Lebata-Ramos, M. J. H. L., Solis, E. F. D., & Almeida, M. J. C. (2023). Grow-out culture of oyster Magallana bilineata (Röding, 1798) using pouches: A comparison of growth and survival in the river and earthen pond. The Philippine Agricultural Scientist, 106(1).
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21. Philippine Statistics Authority. (2021). Ilocos Region's aquaculture fisheries production grows in 1st quarter 2021 (Results from the Fisheries Production Survey, 1st quarter 2021).
22. Rabanal, H. R. (2000). Aquaculture in the Philippines (1898–1998). In R. D. Guerrero III (Ed.), 100 years of Philippine fisheries and marine science (pp. 70–115). Philippine Council for Aquatic and Marine Research and Development.
23. Rahman, M. S., & Rahman, M. S. (2020). Effects of elevated temperature on prooxidant-antioxidant homeostasis and redox status in the American oyster: Signaling pathways of cellular apoptosis during heat stress. Environmental Research, 110428.
24. Robert, R., Vignier, J., & Petton, B. (2017). Influence of feeding regime and temperature on development and settlement of oyster Ostrea edulis (Linnaeus, 1758) larvae. Aquaculture Research. https://doi.org/10.1111/are.13297
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26. Rodrigues, I. C., Santos-Ferreira, N., Silva, D., da Silva, C. C., Inácio, Â. S., Nascimento, M. S. J., & da Costa, P. M. (2023). A one-year systematic study to assess the microbiological profile in oysters from a commercial harvesting area in Portugal. Microorganisms, 11(2), 338. https://doi.org/10.3390/microorganisms11020338
27. Silva, M., Nascimento, I., Gomes, J., Farias, F., Santos, D., Anchieta de Melo, T., & Serra, I. (2021). Microbiological analysis of water and fish of fish farms in the protection area of the western lowlands of Maranhão, Brazil. Aquaculture Research. https://doi.org/10.1111/are.15451
28. Silva, O. L., Veríssimo, S. M., da Rosa, A. M., Iguchi, Y. B., Nunes, E. D., Moraes, C. M., Cordeiro, C. A., Xavier, D. D., Pinto, A. S., Peixoto Joele, M. R., Brito, J. D., Juen, L., & Rocha, R. M. (2020). Effect of environmental factors on the microbiological quality of oyster farming in Amazon estuaries. Aquaculture Reports, 18, 100437.
29. Sudradjat, A. (2006). Effect of salinity, temperature, and food value of four microalgae to oyster, Crassostrea iredale larval growth. Indonesian Aquaculture Journal, 1, 135–143.
30. Venugopal, V., & Gopakumar, K. (2017). Shellfish: Nutritive value, health benefits, and consumer safety. Comprehensive Reviews in Food Science and Food Safety, 16(6), 1219–1242. https://doi.org/10.1111/1541-4337.12312

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

How to cite

Pagaoa, C. P., Rojas, C., Agsalog, B., & Barcesa, O. K. (2025). Physicochemical and microbiological assessment of oyster farms in Ilocos Sur, Philippines. Multidisciplinary Science Journal, 8(2), 2026050. https://doi.org/10.31893/multiscience.2026050

[1] Andalecio, M. N., Duncan, P. F., Peralta, E. M., Napata, R. P., & Laureta, L. V. (2014). Consumers’ behavior towards cultured oysters and mussels in Western Visayas, Philippines. Aquaculture, Aquarium, Conservation & Legislation International Journal of the Bioflux Society (AACL Bioflux), 7(2).

[2] Ballesteros, E. R., Andrade, V. D., Barbieri, E., Pinto, A. B., Oliveira, R. S., & Oliveira, A. J. (2016). Qualidade microbiológica de ostras (Crassostrea sp) e de águas coletadas em cultivos e em bancos naturais de Cananéia (SP). Boletim do Instituto de Pesca.

[3] Bhaja, P., & Kundu, R. (2012). Status of the seawater quality at a few industrially important coasts of Gujarat (India) off the Arabian Sea. Indian Journal of Geo-Marine Sciences, 41(1), 90–97.

[4] Campbell, V. M., Chouljenko, A., & Hall, S. G. (2022). Depuration of live oysters to reduce Vibrio parahaemolyticus and Vibrio vulnificus: A review of ecology and processing parameters. Comprehensive Reviews in Food Science and Food Safety, 21(4), 3480–3506. https://doi.org/10.1111/1541-4337.12969

[5] Department of Environment and Natural Resources, Environmental Management Bureau. (2008). Water quality monitoring manual: Volume 1, manual on ambient water quality monitoring.

[6] Domingo, J. C., Raboy, M. R., & Ramos, J. C. (2021). Oyster farming in Ilocos Sur, Philippines. The Vector: International Journal of Emerging Science, Technology and Management, 30(1). https://doi.org/10.69566/ijestm.v30i1.69

[7] Dove, M. C., & O'Connor, W. A. (2007). Salinity and temperature tolerance of Sydney rock oysters Saccostrea glomerata during early ontogeny. Journal of Shellfish Research, 26(4), 939–947. https://doi.org/10.2983/0730-8000(2007)26[939:SATTOS]2.0.CO;2

[8] FAO. (2018). FAO online query panels. http://www.fao.org/fishery/topic/16140/en

[9] Guerrero, R. (2006). Eco-friendly fish farm management and production of safe aquaculture foods in the Philippines.

[10] Ilac, A. G., Foronda, J. M. S., Ayop, A. N., Europa-Morales, A. L. V., & Ruadap, M. E. V. (2024). Exploring growth of Gracilaria sp. using the raft culture method. ILMU KELAUTAN: Indonesian Journal of Marine Sciences, 29(4), 557–566. https://doi.org/10.14710/ik.ijms.29.4.557-566

[11] Jeamsripong, S., Thaotumpitak, V., Anuntawirun, S., Roongrojmongkhon, N., & Atwill, E. R. (2022). Meteorological and water quality factors associated with microbial diversity in coastal water from intensified oyster production areas of Thailand. Water, 14(23), 3838. https://doi.org/10.3390/w14233838

[12] Ko, G. W., Dineshram, R., Campanati, C., Chan, V. B., Havenhand, J., & Thiyagarajan, V. (2014). Interactive effects of ocean acidification, elevated temperature, and reduced salinity on early-life stages of the Pacific oyster. Environmental Science & Technology, 48(17), 10079–10088. https://doi.org/10.1021/es501611u

[13] Lebata-Ramos, M. J. H. L., Solis, E. F. D., & Almeida, M. J. C. (2023). Grow-out culture of oyster Magallana bilineata (Röding, 1798) using pouches: A comparison of growth and survival in the river and earthen pond. The Philippine Agricultural Scientist, 106(1).

[14] Lee, C. S., et al. (2018). Temporal and spatial variability in estuarine water quality. Marine Pollution Bulletin, 136, 489–496.

[15] Lunt, J., & Smee, D. L. (2014). Turbidity influences trophic interactions in estuaries. Limnology and Oceanography, 59(6), 2002–2012. https://doi.org/10.4319/lo.2014.59.6.2002

[16] Neta, M. T., Maciel, B. M., Lopes, A. T., Marques, E. L., Rezende, R. P., & Boehs, G. (2015). Microbiological quality and bacterial diversity of the tropical oyster Crassostrea rhizophorae in a monitored farming system and from natural stocks. Genetics and Molecular Research: GMR, 14(4), 15754–15768.

[17] Omoregie, E., Mwatilifange, N., & Liswaniso, G. (2019). Futuristic ocean acidification levels reduce growth and reproductive viability in the Pacific oyster (Crassostrea gigas). Journal of Applied Sciences and Environmental Management, 23(9), 1747–1754. https://doi.org/10.4314/jasem.v23i9.21

[18] Pagaoa, C. P. P., Rojas, C. B., Ilac, A. G., & Barcesa, O. K. P. (2024). Microbial contamination assessment and identification of Enterobacteriaceae isolated from the surface water of Govantes River, Vigan City, Ilocos Sur, Philippines. International Journal of Biosciences, 25(6), 313–322. http://dx.doi.org/10.12692/ijb/25.6.313-322

[19] Pakingking, R. V., Jr., Hualde, M. L., Peralta, E., Faisan, J. P., Jr., & Usero, R. (2022). Microbiological quality and heavy metal concentrations in slipper oyster (Crassostrea iredalei) cultured in major growing areas in Capiz Province, Western Visayas, Philippines: Compliance with international shellfish safety and sanitation standards. Journal of Food Protection, 85(1), 13–21. https://doi.org/10.4315/JFP-21-257

[20] Pereira, M. A., Nunes, M. M., Nuernberg, L., Schulz, D., & Batista, C. R. (2006). Microbiological quality of oysters (Crassostrea gigas) produced and commercialized in the coastal region of Florianópolis - Brazil. Brazilian Journal of Microbiology, 37, 159–163.

[21] Philippine Statistics Authority. (2021). Ilocos Region's aquaculture fisheries production grows in 1st quarter 2021 (Results from the Fisheries Production Survey, 1st quarter 2021).

[22] Rabanal, H. R. (2000). Aquaculture in the Philippines (1898–1998). In R. D. Guerrero III (Ed.), 100 years of Philippine fisheries and marine science (pp. 70–115). Philippine Council for Aquatic and Marine Research and Development.

[23] Rahman, M. S., & Rahman, M. S. (2020). Effects of elevated temperature on prooxidant-antioxidant homeostasis and redox status in the American oyster: Signaling pathways of cellular apoptosis during heat stress. Environmental Research, 110428.

[24] Robert, R., Vignier, J., & Petton, B. (2017). Influence of feeding regime and temperature on development and settlement of oyster Ostrea edulis (Linnaeus, 1758) larvae. Aquaculture Research. https://doi.org/10.1111/are.13297

[25] Rodolfo, R. S., & Lapus, M. R. (2021). Strengthening disaster risk governance to manage disaster risk.

[26] Rodrigues, I. C., Santos-Ferreira, N., Silva, D., da Silva, C. C., Inácio, Â. S., Nascimento, M. S. J., & da Costa, P. M. (2023). A one-year systematic study to assess the microbiological profile in oysters from a commercial harvesting area in Portugal. Microorganisms, 11(2), 338. https://doi.org/10.3390/microorganisms11020338

[27] Silva, M., Nascimento, I., Gomes, J., Farias, F., Santos, D., Anchieta de Melo, T., & Serra, I. (2021). Microbiological analysis of water and fish of fish farms in the protection area of the western lowlands of Maranhão, Brazil. Aquaculture Research. https://doi.org/10.1111/are.15451

[28] Silva, O. L., Veríssimo, S. M., da Rosa, A. M., Iguchi, Y. B., Nunes, E. D., Moraes, C. M., Cordeiro, C. A., Xavier, D. D., Pinto, A. S., Peixoto Joele, M. R., Brito, J. D., Juen, L., & Rocha, R. M. (2020). Effect of environmental factors on the microbiological quality of oyster farming in Amazon estuaries. Aquaculture Reports, 18, 100437.

[29] Sudradjat, A. (2006). Effect of salinity, temperature, and food value of four microalgae to oyster, Crassostrea iredale larval growth. Indonesian Aquaculture Journal, 1, 135–143.

[30] Venugopal, V., & Gopakumar, K. (2017). Shellfish: Nutritive value, health benefits, and consumer safety. Comprehensive Reviews in Food Science and Food Safety, 16(6), 1219–1242. https://doi.org/10.1111/1541-4337.12312

Abstract

References

How to cite