krillgrowth 9192pal 22oct91-29feb92 Instantaneous growth rate and molting frequency experiments on Antarctic krill held on in seawater tables at ambient temperatures for short periods Animal: sex or larval stage, total length, molt period, telson length of animal and molt if molted Experimental: temperature of seawater, time observed animals for presence of molts 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 Growth experiments were conducted weekly when krill were found. Eight larvalIGR experiments (1 solely larvae, 7 with juveniles and subadults) were conducted from 22 Oct to 18 Jan, and three adultIGRs from 28 Jan to 29 Feb during 9192pal. 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 (adults and subadults) or 500 ml (larvae, juveniles) 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 molt and animal were preserved together in 10% formalin. At the end of the experiment, the non- molters preserved together. For small krill (< 15 mm) the total length and lengths of the telson of all animals and their molts and the total lengths of the non-molters were measured under a binocular microscope back at University of California at Santa Barbara. For adults, total length was measured with digital calipers, and telson lengths under the microscope. 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 throughout the season to observe growth during different environmental conditions. Growth rates of AC0 or AC1 krill were of particular interest. IGR experiments in the 9191pal season and on the 91nov cruise were numbered sequentially without regard to whether the experiments was done on larval or adult krill or on station or at sea. Thus the 9192 sequence is 1, 7-13, 16-18, interrupted by experiments conducted on the cruise (91nov, #2-6) and two experiments on the same collection (#14, 15). Experiments on young krill (AC0 and AC1) were conducted from late October to mid- January and are labeled larval IGRs. Growth rates for adults were measured from late January to late February. antarctic krill, growth rates, molting frequency ascii, comma separated variable There are 4 summary files for each study plus individual files for each experiment. 1) adultIGR.details and larvalIGR.details give 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 and larvalIGR.sum are summaries of results, with experiment number, event number, trawl number, day/month started, local time started, grid location, average temperature (ĄC), number of molters, number of animals in experiment, duration of experiment, molting frequency (% per day). If krill were not collected by trawling, the trawl number was either a dive number (D#) or dnet (dipnet). 3) in directories called AIGR and LIGR are located files containing the length measurements and sexual or stage identification for each experiment: sex (im immature; F female; M male; J/SA juvenile or subadult; MM mature male; MF mature female) or stage of the individual (furcilia 1-6), animal total length (mm), molt period, animal telson length (mm), molt telson length (mm), comments (dead animals; problems; etc) ~lter/lterdata krill mac and robin's mac /9192pal/* adultIGR.details adultIGR.sum larvalIGR.details larvalIGR.sum /adultIGR/* AIGR(experiment number)ev(event number).dat [16-165; 17-222; 18-285] /larvalIGR/* [1-3; 7-7; 8-11; 9-55; 10-65; 11-95; 12-116; 13-140] Robin M. Ross, Langdon B. Quetin none Robin M. Ross, Langdon B. Quetin Langdon B. Quetin, Tim Newberger, T. Moylan, Robin M. Ross, K. Hacecky, K. Haberman, M. Amsler, J. Mahoney C. Wyatt-Evens C. Wyatt-Evens, CT. Shaw, Robin M. Ross Langdon B. Quetin and Robin M. Ross Langdon B. Quetin Individual files on experiments submitted 10 Jan 1996. *IGR.details submitted 23 Dec 1996 *IGR.sum submitted 23 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. Initial measurements of telson lengths were made by T. Moylan as part of an REU project for experiments #1, 8, 9, 10, by L. Serold for an independent research project for experiments #11, 12, 13, 16, 17, 18, and by C. Wyatt-Evens for experiment #7. Subsequently C. Wyatt-Evens remeasured all telson lengths. Comparison of the results showed that although the average % growth per intermolt period was the same for the two sets of measurements, the variance was decreased when just one person measured all the animals.