Zooplankton community composition of Darwin Harbour, Northern Territory

The composition of the zooplankton community in a macrotidal (8m), tropical estuarine system (Darwin Harbour, Northern Territory, Australia) was studied over a 2 year period.In all, 32 copepod species were recorded, with small euryhaline marine copepod species such as Parvocalanus crassirostris, Bestiolina similis and Oithona aruensis dominating the zooplankton. Salinity, temperature, silica, particulate phosphorus (PP), total dissolved nitrogen (TDN), dissolved organic nitrogen (DON), particulate nitrogen (PN) and total chlorophyll a were measured. Environmental variables were correlated with salinity, which had the strongest influence on community structure. Sites were grouped into three sample sets: River (BR - Blackmore River and ER - Elizabeth River); Inner Harbour (MA - Middle Arm and EA - East Arm); Middle (MH) and Outer (OH) Harbour. There was a significant drop in species richness from harbour to river sites. Samples were taken day and night at another site, B, to determine diurnal patterns.Seasons were designated as: Wet 2003 (December 2002 and February 2003), Dry 2003 (June and September 2003), Wet 2004 (December 2003 and February 2004), and Dry 2004 (July and October 2004).Plankton biomass was partitioned into 350µm size fractions. Average abundance (individual m-3) was measured and relative abundance (%) was calculated for the zooplankton community. Plankton abundances ranged between 30,000 and 110,000 m-3, and there were significant year, season and site differences. To describe biodiversity and determine the environmental factors that have the greatest impact on community structure. Copepod species: Acrocalanus gibber, A. gracilis, Arcatia pacifica, A. erythraea, A. fossae, A. sinjiensis, Bestiolina similis, Canthocalanus pauper, Corycaeus andrewsi, C. catus, C. dahli, C. dubius, C. pacificus, C. subtilis, Eucalanus pileatus, Euterina acutifrons, Labidocera minuta, Microstella sp., Oithona aruensis, O. attenuate, O. fallax, O. simplex, O. nana, O. nishidai, O. rigida, Onacea paraclevei, Paracalanus indicus, P. aculaeatus, P. aculaeatus minor, P. indicus, Parvocalanus crassirostris, Pseudodiaptomus sp., P. annandalei, P. griggae, P. mertoni, Tortanus barbartus; Calanoid, Cyclopoid, and Harpacticoid nauplii and copepodites.Other zooplankton components: Holoplankton (Chaetognatha, Euphausiid calyptosis, Appendicularia, Ostrocoda, Pteropoda, Salpida, decapod larvae); and Meroplankton (barnacle larvae, Bivalva, fish larvae, fish egg, Gastropoda, Polychaete, Brachyuran Zoea).A subset of the data has been provided to the Ocean Biogeographic Information System (OBIS, http://iobis.org/OBISWEB/DisplayMetaData.jsp?content=meta/1463.html).