Epiphytic diatom composition on the leaf blades of Enhalus acoroides in Almeria, Biliran, Philippines during the northeast monsoon of 2012–2013

Abstract

Epiphytic algae, particularly diatoms, are an important food source and contribute more to primary productivity for grazers in seagrass ecosystems than the grass on which these grow.  Their proliferation, however, could impair seagrass photosynthesis. This study aimed to assess epiphytic diatom assemblages on the leaves of the seagrass species Enhalus acoroides in the coastal areas of Almeria, Biliran to provide baseline data of community composition and abundance of diatoms growing on this species. Epiphyte samples were scraped-off from the leaf surfaces of the seagrass within a three-month sampling period, and identified and counted under a compound light microscope. Diatoms found were Bacillaria paxillifera, Cocconeis sp., Cyclostephanos sp., Navicula sp. 1, Navicula sp. 2, Pleurosigma sp., Thalassiothrix sp., and Thalassiosira sp., as well as planktonic Chaetoceros affinis and Rhizosolenia imbricata that might have attached to some epiphytic mucus-secreting species. Seagrass blades that were mostly devoid of epiphytic diatoms were found in a sampling station in the vicinity of beach resorts. Overall, however, the relative abundance of all diatoms observed on Enhalus between stations was similar, and cell densities on the leaves were low. There were only eight to ten genera present on the leaves from each station. The genus Navicula dominated all sampling stations, constituting an average of 46% of total diatoms.