We examined life cycle plasticity in two populations of the copepod Paralabidocera antarctica, one of which inhabits the coastal sea ice belt of Antarctica and the other of which has been isolated in a nearby saline lake for several thousand generations. Similarities in the life cycles of the two populations included long overwintering phases (>5 months) by late-stage nauplii, rapid development through the copepodid stages, and a short adult life span of 2-3 weeks. Adults appeared in late spring or early summer and spawned and died soon after. However, the life cycle of the lacustrine population was much less tightly regulated than at the marine site; animals were rarely found living within the lake ice, and synchrony in the developmental cycle was diminished. It is likely that a combination of factors, including ice hardness, a lack of predation threat, and a consistent food supply has freed the lacustrine population from the constraints imposed by living within the ice cover. Instantaneous growth rates calculated for the marine site showed a variable growth rate (0.04-0.14 d-1). The lacustrine population in general had faster growth rates than the marine population (0.10-0.26 d -1) and reached maturity at a smaller size. This is attributed, in part, to the higher environmental temperatures experienced by the lacustrine population.

Item Type:	Refereed Article
Research Division:	Biological Sciences
Research Group:	Ecology
Research Field:	Marine and estuarine ecology (incl. marine ichthyology)
Objective Division:	Environmental Management
Objective Group:	Management of Antarctic and Southern Ocean environments
Objective Field:	Biodiversity in Antarctic and Southern Ocean environments
UTAS Author:	Swadling, KM (Associate Professor Kerrie Swadling)
UTAS Author:	Gibson, JAE (Dr John Gibson)
ID Code:	29375
Year Published:	2004
Web of Science® Times Cited:	15
Deposited By:	Zoology
Deposited On:	2004-08-01
Last Modified:	2007-11-02
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