krillGrowth 98jan.b 28 January to 13 February 1998 Instantaneous growth rate and molting frequency for Antarctic krill experiments krill held on board ship at ambient temperatures for short periods Animal: sex, total length, molt period, telson length of animal and molt if molted Experimental: temperature of seawater, time observed animals for presence of molts, dead animals 1) molting frequency (%/day): 100 * number molters/number of experimental animals/duration of experiment in days. the inverse of the molting fequency is the intermolt period in days 2) percent growth per intermolt period (% growth/IMP): 100 * (animal telson - molt telson)/molt telson Four experiments were conducted during 98jan.b aboard the Laurence M. Gould. The number of experiments was less than planned because of the shorten cruise. Because of delays in shipyard, the LMG was not available for research until late January. Facilities aboard the Abel J (used 18-24 Jan) were not adequate for conducting growth rate experiments. Only krill in good physiological condition were used in IGR experiments, i.e. swimming, no white sections in abdomen. Krill were used from either standard tows or targeted tows. All lively swimming krill were gently placed in a large volume of cold seawater, and then 100 randomly selected krill were gently placed in individual 2-liter vessels in a flowing seawater table at ambient temperature. Temperature was recorded, and animals were checked every 12 hours for molts over the following 4 days. Dead or unhealthy animals were noted. Once an animal molted, both animal and molt were removed from the vessel. The total length of the fresh animal was measured with digital calipers, then molt and animal were preserved together in 10% formalin. The lengths of the telson of the animal and the molt were measured under a binocular microscope at Palmer Station. At the end of the experiment, the total lengths of all non-molters were measured, and the non-molters preserved together. Total length is from the tip of the rostrum to the end of the uropods, not including spines (Standard Length 1, Mauchline 1981). Dead or dying animals were excluded from experimental totals, but their total lengths recorded. Instantaneous growth rate (IGR) experiments were conducted across the grid to observe growth both on and off shore and at the northern and southern area of the sampling region. For this cruise, the distribution was limited by time to two outer shelf (600.180, 300.160), one mid-shelf (200.100) and one inner shelf (200.000) experiment. [expt-event: 1-84;2-215;3-298;4-338] Only adult IGR experiments were conducted during this cruise. No larvae were collected. Antarctic krill, growth rates, molting frequency ascii, comma separated variable There are 2 summary files for each study plus individual files for each experiment. 1) adultIGR.details gives the details of the experimental checking, with experiment number, initial temperature, local time of checking for periods 1-8, temperature of seawater at time of checking periods 1-8, and number of molters at time of checking periods 1-8. 2) adult IGR.sum is a summary of results, with experiment number, event number, trawl number, day/month started, local time started, grid location, average temperature (°C), number of molters, number of animals in experiment, duration of experiment, molting frequency (% per day). 3) in a directory called AIGR are located files containing the length measurements and sexual identification for each experiment: sex (im immature; F female; M male; J/SA juvenile or subadult; MM mature male; MF mature female), animal total length (mm), molt period, animal telson length (mm), molt telson length (mm), comments (dead animals; problems; etc) ~lter/lterdata Velella (mac) /98janb/krillGrowth adultIGR.details adultIGR.sum /adultIGR AIGR(experiment number).dat Robin M. Ross, Langdon B. Quetin none Robin M. Ross and Langdon B. Quetin Marine Science Institute, UCSB, Santa Barbara, CA 93106 (805) 893-2096 robin@icess.ucsb.edu or langdon@icess.ucsb.edu L. B. Quetin, J.L. Jones, C. Tracy Shaw, D. Conlin, J. Kneebone, K. Grimm The research team checking or taking down the experiment measured total lengths on live animals. CT Shaw measured telson lengths of both animals and molts on preserved samples; telson length of the animal and its matching molt were measured by the same individual. Individuals cross-calibrated their measurements to ensure that the data were consistent and comparable both within and between years. Measurement of total length on live animals yields the required precision for this measurement. RM Ross and C. Tracy Shaw Robin M. Ross and Langdon B. Quetin Langdon B. Quetin AIGR and individual files on experiments submitted 27 Dec 1996. adultIGR.details submitted 27 Dec 1996 adultIGR.sum submitted 27 Dec 1996 IGR experiments with this protocol conducted with Antarctic krill wer reported in: Quetin, L. B. and R. M. Ross. 1991. Behavioral and physiological characteristics of the Antarctic krill, Euphausia superba. Amer. Zool. 31: 49-63. Ross, R. M. and L. B. Quetin. 1991. Ecological physiology of larval euphausiids, Euphausia superba (Euphausiacea. Memoirs of the Queensland Museum 31: 321-333. Prior comparisons of the results of live and preserved animals showed that although the average % growth per intermolt period was the same for the two sets of measurements, the variance was decreased when done in a more stable environment and by 1-2 individuals.

Datafile Form V1.2 for describing a data file.