Phosphorus as a driver of nitrogen limitation and sustained eutrophic conditions in Bolinao and Anda, Philippines, a mariculture-impacted tropical coastal area

Charissa M Ferrera; Atsushi Watanabe; Toshihiro Miyajima; Maria Lourdes San Diego-McGlone; Naoko Morimoto; Yu Umezawa; Eugene Herrera; Takumi Tsuchiya; Masaya Yoshikai; Kazuo Nadaoka

doi:10.1016/j.marpolbul.2016.02.025

Phosphorus as a driver of nitrogen limitation and sustained eutrophic conditions in Bolinao and Anda, Philippines, a mariculture-impacted tropical coastal area

Mar Pollut Bull. 2016 Apr 15;105(1):237-48. doi: 10.1016/j.marpolbul.2016.02.025. Epub 2016 Feb 28.

Affiliations

¹ Department of Mechanical and Environmental Informatics, Graduate School of Information Science and Engineering, Tokyo Institute of Technology, O-okayama 2-12-1 W8-13 Meguro, Tokyo 152-8552, Japan. Electronic address: cmferrera@gmail.com.
² Department of Mechanical and Environmental Informatics, Graduate School of Information Science and Engineering, Tokyo Institute of Technology, O-okayama 2-12-1 W8-13 Meguro, Tokyo 152-8552, Japan.
³ Marine Biogeochemistry Group, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8564, Japan.
⁴ Marine Science Institute, University of the Philippines, Diliman, Quezon City 1101, Philippines.
⁵ Faculty of Fisheries, Nagasaki University, 1-14 Bunkyo, Nagasaki 852-8521, Japan.
⁶ Institute of Civil Engineering, University of the Philippines, Diliman, Quezon City 1101, Philippines.
⁷ Japan International Cooperation Agency, Tokyo 102-8012, Japan.

PMID: 26936120
DOI: 10.1016/j.marpolbul.2016.02.025

Abstract

The dynamics of nitrogen (N) and phosphorus (P) was studied in mariculture areas around Bolinao and Anda, Philippines to examine its possible link to recurring algal blooms, hypoxia and fish kills. They occur despite regulation on number of fish farm structures in Bolinao to improve water quality after 2002, following a massive fish kill in the area. Based on spatiotemporal surveys, coastal waters remained eutrophic a decade after imposing regulation, primarily due to decomposition of uneaten and undigested feeds, and fish excretions. Relative to Redfield ratio (16), these materials are enriched in P, resulting in low N/P ratios (~6.6) of regenerated nutrients. Dissolved inorganic P (DIP) in the water reached 4μM during the dry season, likely exacerbated by increase in fish farm structures in Anda. DIP enrichment created an N-limited condition that is highly susceptible to sporadic algal blooms whenever N is supplied from freshwater during the wet season.

Keywords: Bolinao; Eutrophication; Fish feed; Mariculture; Nutrient ratios; Phosphorus.

MeSH terms

Animals
Environmental Monitoring*
Eutrophication
Fishes
Fresh Water
Nitrogen / analysis*
Philippines
Phosphorus / analysis*
Water Pollutants, Chemical / analysis*

Substances

Water Pollutants, Chemical
Phosphorus
Nitrogen