The hot season generaly allows for better visability, while the cold months (December to February) might sometimes have less visability, also due to the yearly algea bloom. (calypso-boracay.com)
My guess would be a vast bloom of plants possibly algea or photosynthetic plankton or something like this. (realclimate.org)
These labs harvest DHA and ARA from lab grown fermented microscopic algea (DHA) and soil fungus (ARA). (myorganicformula.com)