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

Abstract

Boeckella hamata Brehm appears in the plankton of Lake Waihola, New Zealand, a tidally influenced lake, only at times of low salinity. To determine whether B. hamata hatches from resting eggs, allowing it to re-colonise the lake after periods of higher salinity, sediments were analysed for the presence of eggs and incubated in the laboratory at 15°C. Copepod eggs at a density of 1.3 × 104eggs m-2were recorded. Over a 4-month period, 87 nauplii hatched. Of those identified, 98% were B. hamata and 2% Gladioferens 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-colonise the plankton when conditions are favourable.