POST-SPILL ECOLOGICAL HEALTH ASSESSMENT AT THE SOUTHERN COAST OF MACTAN ISLAND, PHILIPPINES USING MULTIMETRIC PHYTOPLANKTON INDEX FOR BIOTIC INTEGRITY
Abstract
Evaluation of ecological health status after an oil spill is crucial for effective restoration measures
of the affected aquatic ecosystems. In this study, we applied a multimetric phytoplankton index for biotic
integrity (MPI-BI) to assess the ecological health status of the southern coast of Mactan Island, Philippines
after 8, 12, 24, and 30 months from the MV Thomas Aquinas spill incident in August 2013. Phytoplankton
community analysis revealed (1) no difference in abundance, richness, and diversity between affected and
reference sites, (2) increasing trend of diversity over time after the spill, and (3) higher remotely-sensed
chlorophyll a level in affected sites. Phytoplankton relative abundance, diversity, and trophic statewere
used to derive MPI-BI. Based on MPI-BI, the health status of the affected sites wasgenerally in good
condition 8 – 30 months after. A time-series analysis of remotely-sensed and meteorological parameters
showed no difference between pre and post spill conditions, except for chlorophyll a and particulate organic
carbon. Generally, the health status of the coastal water may be affected by the oil spillage as indicated by
the increased trophic state after the spill but may be recovering from the oil spill stress.
Keywords
phytoplankton community, bioindicator, oil spill impact, multivariate analysis, remote sensing
application
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