Aquatic Sciences Meeting, Albuquerque 2001

PC07 Spatial and Temporal Connections

Date: Wednesday, February 14, 2001

Location: Southwest Hall

Ji, C, H, THE CHINESE UNIVERSITY OF HONG KONG, SHATIN, N.T., Hong Kong POC, chji@cuhk.edu.hk

Wong, C, K, THE CHINESE UNIVERSITY OF HONG KONG, SHATIN, N.T., Hong Kong POC,

STUDIES ON THE RESTING EGGS OF PLEOPIS POLYPHEMOIDES AND PSEUDEVADNE TERGESTINA

The marine podonids Pleopis polyphemoides and Pseudevadne tergestina alternate between gamogenesis and parthenogensis. Both species are seasonally abundant in zooplankton community of Tolo Harbour, Hong Kong. In this study, resting eggs of P. polyphemoides were collected from both bottom sediments and net samples, while resting eggs of P. tergestina were collected from bottom sediments only. Hatching of resting eggs occurred over a wide range of temperature and salinity. For P. polyphemoides, resting eggs from net samples had much higher hatching rates than resting eggs from sediment. The highest hatching rate of ~70% was recorded at 25C and 20‰ for resting eggs from net samples. Hatching rates for resting eggs from sediment were usually less than 40%. For resting eggs of P. tergestina, the highest hatching rate of 35% was recorded at 17C and 20‰. Hatching times for the resting eggs of both species were shorter at higher temperatures. Hatching times were generally shorter for P. tergestina than for P. polyphemoides. Hatching of resting eggs and seasonal appearance of marine cladocerans in Tolo Harbour will be discussed.

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Aquatic Sciences Meeting, Albuquerque 2001

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