Euphausia superba Dana was collected at stations encompassing 3" of latitude in icecovered waters west of the Antarctic Peninsula in winter of 1992 (July-August), and in the same region the previous summer (December-January). There was no significant change in any biometric index (dry weight vs length, carbon vs dry weight, nitrogen vs dry weight, or body C:N). Rates of ammonium excretion in winter were not significantly different from those previously reported for E. superba in summer. It was clear that E. superba fed as a carnivore in winter. Copepod body parts consistently occurred in M 1 guts. During winter shipboard experiments, freshly caught krill ingested copepods and produced faeces at rates comparable to those measured in summer. The low ratio of N:P excretion (2.02) also suggests carnivorous feeding. A physiological model of carbon and nitrogen metabolism indicates that E. superba must feed during winter to maintain its observed C : N ratio and rate of ammonium excretion. On a diet of less than 1 Metridia gerlachei female copepod per day, a 20 mm knll can grow with a growth efficiency comparable to that achieved in summer. We suggest that starvation, body shrinkage and reduced metabohsm are unusual behaviors for knll in winter, and that carnivory sustains growth until ice algae become available as food in late winter and early spring.

Molting success and survivorship increased during naupliar development in the marine calanoid copepod Calanus pacificus studied in the laboratory. However, both rates decreased with age within each instar Simulations of the development of different naupliar stage I11 (NIII) age-groups suggest that mortality can shorten estimated cohort development times below the minimum possible in individual nauplii. The magnitude of this reduction depends strongly on differences in initial mortality rate among instars. The suggestion that copepod generation times in the field are independent of food availability can be reconciled with the well-established relationship between stage durations and food concentration if a distinction is made between individual and cohort development rates. Individual development rates decrease at low food levels, but with the death of a sufficiently large fraction of slowdeveloping individuals, cohort development rates may remain maximal.

Calanoldes acutus (Giesbrecht) in 0 to 290 m stratified samples collected repetitively at 23 stations in Gerlache Strait, Antarctica, in November 1989 consisted of stage 111 to V1 copepodites (C111 to CVI) All stages except CV decreased in abundance through the 3.5 wk sampling period. Vertical distnbutions of all copepodite stages remained consistent, with no evidence of die1 vertical migrahon. Centers of mass were as follows: female CVl, 44 m; CV, 66 m; CIV, 127 m; male CVI, 189 m. Progressive ovarian maturation in adult females was not correlated with ambient chlorophyll a concentrations. Mean daily egg production at 16 stations over a 3 d period in late November was a hyperbolic function of 0 to 150 n~ integrated chlorophyll a concentrations.

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