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Rectangular Midwater Trawls (RMT) for krill during BROKE-West
Regular Trawl At each regular trawl station a quantitative standard double oblique tow was conducted from the surface down to 200 m (or to within 10 m of the bottom at stations shallower than 200 m). Such a depth range is considered to be the best compromise between the time available for sampling and the likely vertical depth range of krill. During the hauls, ship speed was maintained at a constant 2.5 plus or minus 0.5 knots. Wire speed of 0.7 to 0.8 m/s during paying out and of 0.3 m/sec during hauling (approx. 0.5 m/s and 0.2 m/s respectively at vertical depth change rate). The net mouth angle is remarkably constant during hauling within the speed ranges given above. When the net reaches maximum depth, the winch was stopped for about 30 seconds to allow the net to stabilise before starting retrieval. When hauling, propeller thrust was turned off when the net reached a depth of 15 to 20 m; this was to minimise the effects of the propeller action on the net operation and avoids damage of the samples. Target Trawl Whenever interesting targets were seen on the echo-sounder, or large amounts of krill were required for any purpose, target trawls were performed. Once the position of the target was marked, the ship was turned and navigated to run over the target from direction required within navigation capacity. The ship speed was lowered down to below 2.0 knots before hitting the target, so that the net could be lowered down to the desired depth whenever the net reached the target. Fine adjustments were made throughout the trawl by monitoring the echo-sounder in the aft control room. For live krill target trawl, ship speed was kept as slow as possible to avoid any damage to krill. Sample processing for all regular trawl stations: RMT-8 1.Measure the total sample volume (Drain water, then measure using water replacement; mandatory only for the regular hauls) 2.Sort out all Antarctic krill and count their number. If the sample mainly consists of krill and the volume is more than ~1L, a known portion of the whole sample was sub-sampled for the further processing. 3.Stage (TL, Carapace Length, Maturity) of all krill (or subsample), up to 50 to 150 individuals, and digestive gland size (the longest axis) of up to 50 individuals were measured using digital calipers. 4.Other zooplankton groups were immediately sorted out from the catch and their numbers were recorded. Preservation of RMT-8 samples Krill (including those used for onboard demography measurements) were fixed in 10% formalin for their further analysis. Whenever excess amount of krill catch were made, they were sampled and frozen for POP (persistent organic pollutant) measurements, preserved in 80% ethanol for genetic analysis, and frozen under -80C/ liquid nitrogen for chemical analysis. Fish were preserved in formalin, EtOH, or frozen. Squids were preserved in ethanol. RMT-1 1.The whole sample was fixed with 10 % formalin. 2.If the sample volume was too large, then a known proportion of catch was randomly sub-sampled and fixed. This work was completed as part of ASAC projects 2655 and 2679 (ASAC_2655, ASAC_2679).
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Nella Dan: AAMBER Cruise - Zooplankton and Krill data
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This data were collected on the sixth Nella Dan voyage of a long term field survey project being conducted by the Australian Antarctic Division, to collect distribution, abundance and population structure data for the krill Euphausia superba in the Prydz Bay region, Antarctica. This voyage, the Australian Antarctic Marine Biological Ecosystem Research 1986/1987 (AAMBER 86/87) cruise, operated between February and April 1987. During March, a survey of the krill population and zooplankton community was conducted, to determine the late summer distribution and abundance of krill, especially the larvae. This was done as a follow up to SIBEX II in mid-summer (Janurary) 1985. The major species investigated were Euphausia superba, Euphausia frigidia, Euphausia crystallorophias and Thysanoessa marcuria. Phytoplankton pigment analysis was also conducted at each CTD station site.
Larval krill data collected during the BROKE-West voyage
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These data were collected during the BROKE-West voyage of the 2005-2006 season. They are numbers of krill larvae per cubic metre of water at each of the stations at which data were collected. The data cover three species of Antarctic krill - Euphausia crystallorophias, Euphausia superba and Thysanoessa macrura. The superba data have been published in the Kawaguchi et al paper, "Krill demography and large-scale distribution in the Western Indian Ocean sector of the Southern Ocean (CCAMLR Division 58.4.2) in Austral summer of 2006". The data for the other species will be presented in a forthcoming paper by Kerrie Swadling. This work was completed as part of ASAC projects 2655 and 2679 (ASAC_2655, ASAC_2679).
Nella Dan: SIBEX II Cruise - Krill and zooplankton data
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This dataset contains results from the Second International BIOMASS Experiment II (SIBEX II) cruise of the Nella Dan, January 1985. This cruise is the fourth cruise out of a series of six, investigating the distribution, abundance and population structure of krill Euphausia superba in the Prydz Bay region, Antarctica. SIBEX II was co-ordinated with South Africa, Japan and France, and 66 grid sampling stations covered an area from 58 degrees to 93 degrees East and from 60 degrees South to the Antarctic coast. At each sampling station, surveys of krill and other zooplankton were taken, as well as a CTD cast and water collection for phytoplankton pigment, nutrients and primary production measurement. Species identity and abundance data were obtained. The major species investigated were Euphausia superba, Euphausia frigidia, Euphausia crystallorophias and Thysanoessa marcuria. Other pteropods and cephalopods were also studied, as well as results from hydroacoustic surveys of krill biomass. Summary results are listed in the documentation. The fields in this dataset are: species Station Number Haul Type RMT Biomass Weight Flowmeter Latitude Longitude Time Date Ice Sea State Density Sea Floor Maturity This dataset was updated by Angela McGaffin. This download file also contains the original dataset provided in 2007. There are four files available: SIBEX_II_krill.xls (original file) sibex2_krill_morphometrics.xslx sibex2_station_data.xslx sibex2_zooplankton_corrected.xls A minor data update took place on 202211-03 to add a scanned copy of the original acoustics log.
Nella Dan: ADBEX II Cruise - Hydroacoustic krill survey data
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This dataset contains hydroacoustic results from the Antarctic Division Biomass Experiment II (ADBEX II) cruise of the Nella Dan. This cruise is the third in a series of six cruises, performing a long term survey of krill and other zooplankton distribution and abundance. Australia was to have participated in the Second International Biomass Experiment I (SIBEX I), but withdrew due to resupply problems. ADBEX II is a reduced sampling program of what was to have been sampled during SIBEX I. Three transects were made off Antarctica in the Mawson region of the Australian sector, in January to March 1984, covering a survey area of 70,000 square kilometers. Quantitative and geographic krill distribution, abundance, mean and variance of the krill weight density, and total krill biomass were obtained. Biomass estimates for ADBEX II are given as 3.5 million tonnes, obtained by extrapolating over the survey area used on the SIBEX II cruise (1.28x10^6 square kilometers). Temperature, nutrient and salinty data were also obtained, as well as trawl results. Summary results are listed in the documentation. The fields in this dataset are: pressure temperature salinity volume geopotential samples deviation
Kerguelen Axis salps and Thysanoessa macrura
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Zooplankton were collected with a Rectangular Midwater Trawl (RMT 8+1 net) from 37 sampling sites on and near the Southern Kerguelen Plateau. The contents of each net were preserved in 5% buffered formaldehyde. This dataset covers the counts of the contents of the RMT8 net and includes the abundances for the euphausiid Thysanoessa macrura and the salp Salpa thompsoni. The contents were identified and counted under a Leica M165C stereo-microscope. A flow meter attached to the mouth of the RMT 8 was used to record the volume of seawater passing through the net. The count for Thysanoessa macrura includes the total of all developmental stages. For the salps abundances are shown for the 2 developmental phases - solitary individuals and aggregates.
Fish catches from Rectangular Midwater Trawl - data collected from the BROKE-West voyage of the Aurora Australis, 2006
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This dataset gives an overview of the fish (larvae) caught in the RMT 8+1 (Rectangular Midwater Trawl composed of nets with an 8 square metre and 1 square metre net opening surface area respectivly). For correct deployment procedure please see the'krill catches' document available for download at the URL given below. Columns 'sheet' : 'Samples' Station number: Station number as attributed by Krill group Trawl type: Routine or Target Trawl Start Latitude: Latitudinal position at start of trawl (decimal notation) Start Longitude: Longitudinal position at start of trawl (decimal notation) Start Date: Date at the start of the trawl Start Time: Time (UTC) at start of the trawl End Latitude: Latitudinal position at end of trawl (decimal notation) End Longitude: Longitudinal position at end of trawl (decimal notation) End Date: Date at the end of the trawl End Time: Time (UTC) at the end of the trawl Net Size: Size of the net from which the sample was collected Sample number: Individual Sample code as Used by anton van de Putte Bar Code: bar code as used by AAD Family: Taxonomic family to which the sample belongs Species: Name of species Species short: abbrivation of speciesname, format Genus species==Gen_spe example Electrona antarctica=Ele_ant SL:Standarlength of the specimen (mm) TL: Total length of the specimen (mm) Preservation: preservaion method of sample: Ethanol (sample stored in 100% ethanol), Formalin (sample stored in 4% formalin solution) -80 degrees (sample stored in deep frezer at -80 degrees C). This work was completed as part of ASAC projects 2655 and 2679 (ASAC_2655, ASAC_2679).
Feeding of Antarctic Krill
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Metadata record for data from ASAC Project 668 See the link below for public details on this project. From the abstracts of some of the referenced papers: Body shrinkage may be one of the strategies that Antarctic krill use to cope with food scarcity, particularly during winter. Despite their demonstrated ability to shrink, there are only very limited data to determine how commonly shrinkage occurs in the wild. It has been previously shown that laboratory-shrunk krill tend to conserve the shape of the eye. This study examined whether the relationship between the eye diameter and body length could be used to detect whether krill had been shrinking. By tracking individuals over time and examining specimens sampled as groups, it was demonstrated that fed and starved krill are distinguishable by the relationship between the eye diameter and body length. The eye diameter of well-fed krill continued to increase as overall length increased. This created a distinction between fed and starved krill, while no separation was detected in terms of the body length to weight relationship. Eye growth of krill re-commenced with re-growth of krill following shrinkage although there was some time lag. It would take approximately 2 moult cycles of shrinkage at modest rates to significantly change the eye diameter to body length relationship between normal and shrunk krill. If krill starve for a prolonged period in the wild, and hence shrink, the eye diameter to body length relationship should be able to indicate this. This would be particularly noticeable at the end of winter. A series of experiments was carried out to examine the relationship between feeding, moulting, and fluoride content in Antarctic krill (Euphausia superba). Starvation increased the intermolt period in krill, but had no effect on the fluoride concentration of the moults produced. Addition of excess fluoride to the sea water had no direct effect on the intermoult period, the moult weight, or moult size. Additions of 6 micrograms per litre and 10 micrograms per litre fluoride raised the fluoride concentrations of the moults produced and the whole animals. The whole body fluoride content varied cyclically during the moult cycle, reaching a peak 6 days following ecdysis. Fluoride loss at ecdysis could largely be explained by the amount of this ion shed in the moult.
Shallow Coastal Marine Fauna of the Vestfold Hills and Rauer Island Antarctica
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This dataset is a description of the shallow coastal marine fauna found in the Vestfold Hills and Rauer Island area, Antarctica. The results are from various surveys in this region over a 12 month period in 1981-82, and a full listing of species (with photographs) is given in the documentation. It includes benthic, pelagic and planktonic organisms of the coast as well as those that inhabit the ice-water interface.
Nella Dan: FIBEX Cruise - Hydroacoustic krill survey data
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This dataset contains hydroacoustic results from the First International Biomass Experiment (FIBEX) cruise of the Nella Dan. This cruise is the first in a series of six cruises, performing a long term survey of krill and other zooplankton distribution and abundance. FIBEX was an international project, done in co-operation with Japan, South Africa and France. Fourteen transects were made by Australia off Antarctica in the Australian sector (Mawson to Davis region) and Prydz Bay in January to March 1981, covering a survey area of 1.09x10^6 square kilometers. Quantitative and geographic krill distribution, abundance, mean and variance of the krill weight density, and total krill biomass were obtained. The standing stock of krill for the Prydz Bay region was calculated at the second workshop to be approximately 1.3 million tonnes, or 1.6 million tonnes if extrapolated over the survey area of the SIBEX II cruise. Temperature, nutrient and salinty data were also obtained, as well as trawl results. Summary results are listed in the documentation. A scanned copy of the acoustics log book from the voyage is available for download from the provided URL.