The ecology and biology of marine cladocerans in Tolo Harbour, Hong Kong

This thesis studies the ecology and biology of marine cladocerans in Tolo Harbour, Hong Kong. Seasonal occurrence and distribution were investigated at four stations in the inner and channel parts of Tolo Harbour over a two-year period from March 1998 to March 2000. Four species of marine cladocerans were found in Tolo Harbour. Penilia avirostris and Pseudevadne tergestina occurred throughout the year and were seasonally abundant. They were most common during summer and autumn. Peak density > 8,000 ind.m -3 was found in the inner harbour. The body length of P. avirostris ranged from 0.38--1.04 mm and brood size of parthenogenic females ranged from 2--11. For P. tergestina, body size ranged from 0.26--0.85 mm and brood size ranged from 1--12. Pleopis polyphemoides and Pleopis schmackeri occurred only seasonally in Tolo Harbour. P. polyphemoides occurred during spring to early summer and peak density of >6,500 ind.m-3 was recorded in the inner harbour. Parthenogenic females of P. polyphemoides had body length of 0.21--0.57 mm and brood size of 1--9. P. schmackeri occurred sporadically in Tolo Harbour in early spring and summer. Peak density was only 33 ind.m -3. The body length of P. schmackeri ranged from 0.32--0.61 mm, while brood size ranged from 2--7 with a mean of 5.1. During the peak abundance of P. tergestina, gamogenic females with developing resting egg appeared in the population. Gamogenic females constituted <2% of the whole population in P. tergestina. For P. polyphemoides, gamogenic females appeared with parthenogenic individuals, and constituted as much as 46% of whole population. (Abstract shortened by UMI.).