Zooplankton Assemblage in Hambanota Port and Adjacent Coastal Waters of Sri Lanka

Abstract

Present study was to investigate zooplankton assemblage in Hambantota port and
adjacent coastal waters in Sri Lanka. Samples were collected from the port before the
commencement of commercial operations in order to have baseline information on
zooplankton assemblage that can be used in the future to study any community change.
Species composition, abundance, spatial distribution and diversity of zooplankton were
investigated over a period of six months from January 2011 to June 2011. Monthly
samples were collected from both inner-harbor and outer-harbor. Physico-chemical
parameters such as temperature, pH, salinity, density, conductivity, nitrate,
orthophosphate, DO, BOD5 and Ch a were also measured. Zooplankton diversity, species
richness and evenness were calculated using Shannon-Weiner diversity index (Hˊ ),
Simpson‟s index (D) and Pielou‟s evenness (E). A total of 72 zooplankton types were
identified throughout the research project mainly Calanus sp., Paracalanus sp.,
Sapphirina sp., Acartia tranteri, Barnacle nauplii, Crustacean cypris larvae, Oikopleura
sp., Tunicate larvae, Brachionus calyciflorus calyciflorus, Brachionus forficula, Fish
larvae, Discorbis sp., Actinula larvae and Sagitta sp.. Copepod nauplii dominated the
zooplankton. According to percentage occurrences arthropods (71%), protozoans (10%)
and ichthyoplankton (9%) were abundant in the inner harbor. In the outer harbor also
arthropods (66%), ichthyoplankton (11%) and protozoans (7%) were recorded in higher
numbers. Highest species diversity (Hˊ =2.685), highest species richness (S=39) and
highest evenness (E=0.856) were recorded from outer harbor locations (HFHB1 and
HPM). Several species such as Ceratium furca, Chaetoceros sp., Thalassiosira sp.,
Rhizosolenia sp. and Protoperidinium sp. known to form harmful algal blooms were also
observed in this study.

Key words: Zooplankton assemblage, Hambantota port, Ballast water, Invasive Alien
Species (IAS)