ZOOPLANKTON COMMUNITY STRUCTURE AND COPEPOD EGG-PRODUCTION IN COASTALWATERS OF THE CENTRAL GREAT-BARRIER-REEF LAGOON

We describe zooplankton community structure and copepod egg production in the vicinity of the coastal boundary zone of the Great Barrier Ree f lagoon, Australia. The abundance and egg production rate of constitu ents of the zooplankton assemblage characteristic of the coastal zone rapidly increase subsequent to events such as flooding and upwelling. Our sampling spanned two summer monsoonal seasons, the first of which (1990-91) was very wet. The second monsoonal season (1991-92) was very dry and was characterized by intrusive upwelling events from the Cora l Sea. Chlorophyll a concentrations did not rise in the wet year, prob ably because of light limitation, but did rise as a result of upwellin g. Terrestrial run-off in the wet year had a greater apparent effect o n zooplankton abundance-patterns than did upwelling in the dry year, e xcept where coastal trapping allowed sufficient time for increases in zooplankton abundance to occur. Egg production rates by the copepods A crocalanus gibber and Acrocalanus gracilis showed haphazard spatial di fferences. Nitrogen-specific egg production ranged between 0.03 and 0. 21 day-1 for A.gibber, and between 0.13 and 0.41 day-1 for A.gracilis. The egg production rate by A.gibber was food limited for most of the year and showed a poor correlation with temperature.