krillgrowth 04Jan Instantaneous growth rate and molting frequency experiments on Antarctic krill held on in seawater tables at ambient temperatures for short periods. 8 to 28 January 2004 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, number of molts per period 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 calculated for individuals. Two growth experiments were planned each of the 5 transect lines, one on the inner shelf and one of the outer shelf. Thirteen IGR experiments were conducted. Only krill in good physiological condition were used in IGR experiments, i.e. swimming, no white sections in abdomen. All lively swimming krill were gently placed in a large volume of cold seawater, and then 50 - 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 molt and animal were preserved together in 10% formalin. At the end of the experiment, the non-molters were preserved together. 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 1980). Dead or dying animals were excluded from experimental totals, but their total lengths recorded. Instantaneous growth rate (IGR) experiments were conducted to observe any alongshore or on/off shore gradients in growth due to different environmental conditions and/or size class. Larger krill are generally found seaward of smaller, young-of-the-year krill on the inner shelf. ascii, comma separated variable. There are 2 summary files for each study plus individual files for each experiment. 1) IGR_details gives details of the checking of experiments, 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) 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 IGRdata are located files containing the length measurements and sexual or stage identification for each experiment: sex (i immature; F female; M male; 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), calculated percent per intermolt period for that individual, comments (dead animals; problems; etc). Molt period is recorded based on 16 intervals in the 4 day period, not 8. ~lter/lterdata; Velella on the MSILter apple network /04Jan/* IGR_details IGR_sum IGRdata/* IGR(experiment number).csv 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 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 R.Ross, B. Cheng, A. Kaiser, S. Talley, R. Cadiz, J. Watts. Total length was measured on live krill prior to preservation by R.Ross, B. Cheng, A. Kaiser, S. Talley, R. Cadiz, J. Watts. Telson lengths of animal and molt were measured on preserved animals at Palmer Station by J. Sprague and K. Schwager during austral spring 2004 for all experiments. Team Langdon B. Quetin and Robin M. Ross RM Ross November 2, 2006 IGR experiments with this protocol conducted with Antarctic krill were 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. Ross, R. M., L. B. Quetin, K. S. Baker, M. Vernet, R. C. Smith. 2000. Growth limitation in young Euphausia superba under field conditions. Limnol. Oceanogr. 45(1): 31-43. Same individual measured the telsons of both the molt and the animal. Measurer cross-calibrated with previous measurers to ensure consistency across years. Antarctic krill, growth rates, molting frequency Datafile Form V1.2 for describing a data file.