Long Term Presence Of Island Mass Effect At Tiputa Channel, Rangiroa Atoll

Abstract

The purpose of this study was to investigate the long term presence of the Island Mass Effect occurring north of Tiputa Channel, Rangiroa Atoll over a 16 year period in relation to environmental influences. Ocean water near Tiputa Channel was compared to open ocean water 46 km to the north. Over a 16 year record, 75.7% of the time, chlorophyll-a in the coastal waters outside Tiputa Channel was higher than 46 km to the north by an average increase in chlorophyll-a of 16%. Primary correlates of the Island Mass Effect at Rangiroa were found to be increased sea surface temperature and decreased photosynthetically available radiation. In situ observations in Tiputa Channel over a four day period in April of 2014 were examined to determine the characteristics of the water flowing through the channel. These data shows that water in the lagoon is different having higher temperature, lower salinity, lower density, and higher particulate load compared to ocean water, likely adding the fuel for the localized Island Mass Effect. Understanding forces governing the Island Mass Effect at Rangiroa is important for understanding future changes to ocean productivity brought about by a warming climate and changing environmental conditions.