PLANKTON COMPOSITION AND POTENTIAL OF CONTAMINATING ALIENSPECIES VIA BALLAST WATER DISCHARGED IN COLOMBO HARBOR

Abstract

Colombo harbor is one of the key harbors in south Asia due to its strategic location in the main east-westshipping route. Therefore, Colombo port and adjacent marine environment is under risk of introducing alienspecies through the discharge of ballast water. When new species introduced to a particular location,existing composition will be altered. The present study was to investigate existing plankton speciescomposition in Colombo harbor and adjacent marine environment and also to study the potential ofcontaminating alien species via ballast water discharge. Species abundance and composition wereinvestigated for all the samples obtained from inner harbor, entrance, north harbor and south harbor. Amongthe 64 plankton species recorded, fish eggs had the highest abundance in inner harbor (1095 numbers/m3)and nauplii larvae had the highest abundance in all the three outer harbor sites (6782, 8562 and 4242(numbers/m3) respectively). Plankton abundance showed significant differences (p =0.001) with respect totheir location. Chlorophyll-a concentration showed a strong positive relationship (r2 = 0.890) with totalplankton abundance. Further, 26 new zooplankton and dinoflagellate species were also recorded from theinner harbor area that were not recorded in the literature. Among these there were two species found inship’s ballast water namely Microsetella sp and Prorocentrum sp.

Keywords: Ballast water, alien species, Colombo harbor, plankton1. INTRODUCTIONday.through ballast water discharge.