Hatching of Boeckella hamata (Copepoda : Calanoida) resting eggs from sediments of a tidally influenced lake

Boeckella hamata Brehm appears in the plankton of Lake Waihola, New Zealand , a tidally influenced lake, only at times of low salinity. To determine wh ether B. hamata hatches from resting eggs, allowing it to re-colonise the l ake after periods of higher salinity, sediments were analysed for the prese nce of eggs and incubated in the laboratory at 15 degreesC. Copepod eggs at a density of 1.3 x 10(4) eggs m(-2) were recorded. Over a 4-month period, 87 nauplii hatched. Of those identified, 98% were B. hamata and 2% Gladiofe rens pectinatus Brady. This is the first report of B. hamata resting eggs. We conclude that B. hamata in Lake Waihola can use resting eggs to re-colon ise the plankton when conditions are favourable.