Chlorophyll-a Enhancement Induced by Monsoonal Island Wakes in the Western Region of Camiguin Island, the Philippines
Janell Carmina A Sihay1*, Cristy S. Acabado2, and Cesar L. Villanoy1
1Marine Science Institute, University of the Philippines Diliman,
Quezon City, National Capital Region 1101 the Philippines
2Institute of Marine Fisheries and Oceanology, College of Fisheries
and Ocean Sciences, University of the Philippines Visayas,
Miag-ao, Iloilo 5023 the Philippines
ABSTRACT
Satellite-derived observations of chlorophyll-a (Chl-a) concentration reveal patterns of enhancement, particularly at the west side of Camiguin Island in Bohol Sea, the Philippines. Previous studies have linked basin-scale chlorophyll variability with interannual rainfall anomalies due to the El Niño–Southern Oscillation. However, the role of other mesoscale processes such as upwelling, eddies, and island effects remains unexplored. Here, we analyzed ocean data to determine the related processes to the observed enhancement. We determined the spatiotemporal variability and distribution of Chl-a in the Bohol Sea. We found that Chl-a varies most on the seasonal scale following monsoon forcing. The west Camiguin enhancement is prominent during the northeast monsoon (NEM). We found that strong NEM winds drive mixing, upwelling, and particle entrainment (i.e. Chl-a as a proxy for phytoplankton). The monsoonal physical processes create favorable conditions for finer-scale enhancement through island wakes generated from the interaction of winds and currents with Camiguin Island.
INTRODUCTION
Chlorophyll-a (Chl-a) is a photosynthetic pigment widely used as a proxy for phytoplankton. Synoptic observation of this pigment through satellite remote sensing reveals distribution patterns strongly linked with physical ocean processes and conditions across spatiotemporal scales (Mann 1992; Daly 1993). The physical ocean phenomena drive upper ocean mixing that determines the availability of light and nutrients (Sathyendranath et al. 2019). Most of the Chl-a variability has been observed at the mesoscale (10–100 km, seasonal to interannual; Talley et al. 2011; Du et al. 2023) and forced by processes such as eddies, upwelling, fronts, internal waves, and island wake effects (Vance and Doel 2010). . . . . read more
