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EARTH SCIENCE > BIOLOGICAL CLASSIFICATION > ANIMALS/INVERTEBRATES > ARTHROPODS > CRUSTACEANS > EUPHAUSIIDS (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.

  • This video is supplementary data for the publication entitled 'Internal physiology of live krill revealed using new aquaria techniques and mixed optical microscopy and optical coherence tomography (OCT) imaging techniques'. The video is high resolution microscopy video of a live krill captured in the krill containment trap placed within the water bath. File size: 1.8 GB, 32 s duration. The optical microscopy was carried out using a Leica M205C dissecting stereomicroscope with a Leica DFC 450 camera and Leica LAS V4.0 software to collect high-resolution video. The experimental krill research project is designed to focus on obtaining life history information of use in managing the krill fishery - the largest Antarctic fishery. In particular, the project will concentrate on studies into impacts of climate change on key aspects of krill biology and ecology.

  • These data represent the results of the first study to use Earth System Model (ESM) outputs of SST and chlorophyll-a to simulate circumpolar krill growth potential for the recent past (1960-1989) and future climate change scenarios (2070-2099). Growth potential is obtained using an empirically-derived krill growth model (Atkinson et al. 2006, Limnol. Oceanogr.), where growth is modeled as a function of SST and chlorophyll-a. It serves as an approximation of habitat quality, as areas that support high growth rates are assumed to be good habitat (see Murphy et al., 2017, Sci Rep). To increase confidence in the future projections, ESMs were selected and weighted for each season based on their skill at reproducing observation-based krill growth potential for the recent past. First, eleven ESMs which provided SST and chlorophyll-a outputs were obtained from the Coupled Model Inter-comparison Project 5 archive. These included: CanESM2, CMCC-CESM, CNRM-CM5, GFL-ESM2G, GFDL-ESM2M, GISS-E2-H-CC, HadGEM2-CC, IPSL-CM5A-LR, MPI-ESM-MR, MRI-ESM1 and NorESM1-ME. For each ESM, seasonal surface averages of SST and chlorophyll-a were used to calculate growth potential for the historical scenario (1960-1989), which was then bilinearly interpolated on to the same 1°x1° grid. Satellite observation-based datasets for SST and chlorophyll-a were used to calculate observation-based growth potential for the recent past (1997-2010). These comprised seasonal surface averages of SST (from the OISST v2 daily dataset, 1/4⁰ horizontal resolution) and chlorophyll-a (the mean of the SeaWiFS and Johnson et al. (2013) corrected estimate of SeaWiFS daily datasets, 1/12⁰ horizontal resolution). Observation-based growth potential was then bilinearly interpolated onto the same grid as the ESMs. ESM skill for each season was subsequently assessed against observation-based growth potential using a Taylor Diagram. The ESMs were selected and weighted according to their performance to produce a weighted subset (see "ESM_weighting_method.pdf" file). Of the netcdfs provided, "hist_mean_ensemble.nc" represents the unweighted mean of seasonal growth potential, calculated from the initial ensemble of eleven ESMs for the historical scenario. The "hist_mean_subset.nc" file represents the analogous output of the weighted subset. Future projections of seasonal growth potential for Representative Concentration Pathways (RCPs) 4.5 and 8.5 were obtained using the weighted subset for the period of 2070-2099. These projected seasonal surface averages are provided in the "rcp45_mean_subset.nc" and "rcp85_mean_subset.nc" files. RCPs represent standard climate change scenarios developed by the Intergovernmental Panel on Climate Change, with 4.5 reflecting some mitigation of carbon emissions, and 8.5 being the "business as usual" scenario. Analogous netcdfs for the weighted subset outputs of chlorophyll-a (chl) and SST (tos) for the historical and RCP scenarios are also provided in the "chl_tos_netcdfs.zip" file so that the driving environmental variables underlying growth potential can be examined.

  • Distribution and abundance of zooplankton, krill and fish were observed on the K-axis transect using deployments of RMT1+8 net. Towing speed of the RMT1+8 were approximately 2 knots. All krill, fish and squid in the catch were sorted, identified to species and counted. The density at each station were determined from the counts per calibrated flow-meter readings attached to the net. Morphometric measures were taken and, for larger taxa. List of files K-Axis Morph combined_for data centre.xlsx: Morphological data for all krill and zooplankton captured in RMT-8 net haul. RMT data entry_v1_for data centre.xlsx: Trawl data. RMT8 filtered volume_for data centre.xlsx: Filtered volume for each haul. Map_all.tif: Map showing all trawl stations. Map_RMTR.tif: Map showing only regular trawl stations. Map_RMTT.tif: Mapn showing only target trawl stations. K-Axis description This dataset includes biological data from “K-Axis voyage, 2016 and “Voyage 3, 2015”. [Data from K-Axis voyage, 2016] Distribution and abundance of zooplankton, krill and fish were observed on the K-axis transect using deployments of RMT1+8 net. Towing speed of the RMT1+8 were approximately 2 knots. All krill, fish and squid in the catch were sorted, identified to species and counted. The density at each station were determined from the counts per calibrated flow-meter readings attached to the net. Morphometric measures were taken and, for larger taxa. -List of files- K-Axis Morph combined_for data centre.xlsx: Morphological data for all krill and zooplankton captured in RMT-8 net haul. Map_all.tif Map_RMTR.tif Map_RMTT.tif RMT data entry_v1_for data centre.xlsx: Trawl data. RMT8 filtered volume_for data centre.xlsx: Filtered volume for each haul. [Data from Voyage 3, 2015] The Australian Antarctic research and resupply vessel, RV Aurora Australis, was directed to undertake an opportunistic marine science survey for 17 days during 21 February to 10 March 2015 using ship time that became available due to unexpectedly favourable ice conditions for Mawson station resupply. The purpose of this opportunistic Marine Science work was to assess: 1. The spatial variability, particularly along the shelf break, of the prey field for penguins, flying seabirds and marine mammals in East Antarctica. 2. The small scale variability of prey in key foraging locations near to land-based colonies of penguins and flying seabirds in East Antarctica. 3. Feasibility and potential of utilising annual station resupply voyages as a cost effective means to undertake monitoring and research to better understand the ecosystem in the region. The survey completed 5 acoustic box surveys including a total of 53 RMT target and routine trawls, 6 demersal trawls, 131 phytoplankton samples from underway sampling, and 214 hourly observations of predators. These activities were successfully supervised remotely. -List of files- emm-15-22.pdf: Prelminary report of the voyage to CCAMLR WG-EMM Figure_V3_all_euphausiids.pdf: Map of Euphausiid abundance distribution. Figure_V3_Clione_antarctica.pdf: Map of Clione antarctica abundance distribution. Figure_V3_crystal_krill.pdf: Map of Euphausia crystallorophias abundance distribution. Figure_V3_frigida.pdf: Map of Euphausia frigida abundance distribution. Figure_V3_larval_fish_abundances.pdf: Map of fish larvae abundance distribution. Figure_V3_superba.pdf: Map of Antarctic krill abundance distribution. Figure_V3_tmacrura.pdf: Map of Thysanoessa macrura abundance distribution. V3_final_for data centre.xlsx: Trawl station data and density data of each taxa caught. Voyage 3 Marine Science Program Final.docx: Voyage report.

  • Echosounder data were collected on a multidisciplinary research voyage conducted from the RV Tangaroa, operated by New Zealand’s National Institute of Water and Atmospheric Research Limited (NIWA). The voyage lasted 42 days, departing from Wellington, New Zealand on January 29th , 2015 and returning to the same port on 11th March 2015. Active acoustic data were obtained continuously using a calibrated scientific echosounder (Simrad EK60, Horten, Norway). The echosounder operated at 38 and 120 kHz for the duration of the voyage with a pulse duration of 1.024 ms, a pulse repetition rate of one ping per second and a 7° beam width. The echosounder data here are a subset of that collected throughout the voyage and include only data from south of 65°S. This subset of data focuses on research questions pertaining to Antarctic blue whales and krill.

  • Microscopy imaging of live Antarctic krill using a Leica M205C dissecting stereo-microscope with a Leica DFC 450 camera and Leica LAS V4.0 software. Krill were held in a custom made 'krill trap', details provided in manuscript in section eight of this form. The data are available as a single video file. These data are part of Australian Antarctic Science (AAS) projects 4037 and 4050. Project 4037 - Experimental krill biology: Response of krill to environmental change The experimental krill research project is designed to focus on obtaining life history information of use in managing the krill fishery - the largest Antarctic fishery. In particular, the project will concentrate on studies into impacts of climate change on key aspects of krill biology and ecology. Project 4050 - Assessing change in krill distribution and abundance in Eastern Antarctica Antarctic krill is the key species of the Southern Ocean ecosystem. Its fishery is rapidly expanding and it is vulnerable to changes in climate. Australia has over a decade of krill abundance and distribution data collected off Eastern Antarctica. This project will analyse these datasets and investigate if krill abundance and distribution has altered over time. The results are important for the future management of the fishery, as well as understanding broader ecological consequences of change in this important species.

  • We checked each site by taking ice cores and observing the algae biomass to determine the likelihood of krill living under the sea ice in each location. We also used a Remotely Operated Vehicle (ROV) with cameras attached to observe the abundance of krill under the sea ice. If krill were present we used on the sea ice floe a zooplankton pump, called MASMA, according to Meyer et al. 2009, whereas at the edge of the floe column a custom-built fish pump system was used to collect krill near the surface. The Aqualife Biostream BP40 fish pump was capable of pumping up to 1300 litres per minute without harming animals that pass through the pump. For much of the voyage it was operated from the ctd room and at this increased suction head it ran at about 500 litres per minute. Krill were caught at ice stations 2, 6, 7 and 8. The Krill Sample-Overview.xls file contains information regarding how many krill were caught at each ice stations, who was involved and related information. The SIPEX II Krill Voyage Report.docx contains information about the various issues that were encountered during the voyage. It also contains information from the Bottom Krill experiment, which has its own dataset and metadata record. It is duplicated in both datasets. The larvae were used for a growth experiment using the IGR method and after length measurements frozen for carbon, nitrogen, lipids, stomach and gut content analysis. The total and carapace length were determined of juveniles as well as their digestive gland size. Animals were than dissected and tissues frozen at -80C for further analysis (see above). These condition parameters will be discussed in relation to physical and biological environmental parameters of the ice floe (e.g. sea ice thickness, snow coverage, under ice topography and biomass). When this data is analysed, the dataset will be updated to include analysed versions of the data listed in the Krill Sample-Overview.xls file. Also included in the dataset are technical documents and manuals pertaining to the fish pump that was used. Meyer B et al. 2009. Limnol Oceanogr 54:1595-1614

  • This metadata record was created in error and a DOI assigned to it before the error was noticed. The correct metadata record is available here: https://data.aad.gov.au/metadata/records/AAS_4015_Krill_Gonad_Transcriptome with the DOI doi:10.26179/5cd3c8fec9ad8.

  • Long-term experiment on increased CO2 level on krill physiology. Krill were exposed to a range of CO2 conditions 400-4000ppm over a year, and their growth, mortality, and physiology were monitored. -List of files- Ericson Krill Ocean Acidification Study Raw Data_for data centre.xlsx: This file contains data on krill growth, mortality, physiology, and biochemistry, as well as information on water chemistry throughout 1 year period of the experiment. Ericson et al. Adult krill OA MS final submission.pdf: Unpublished manuscript of the experiment including all methods of the experiment.

  • This restriction site associated DNA sequencing (RAD-seq) dataset for Antarctic krill (Euphausia superba) includes raw sequence data and summaries for 148 krill from 5 Southern Ocean sites. A detailed README.pdf file is provided to describe components of the dataset. DNA library preparation was carried out in two separate batches by Floragenex (Eugene, Oregon, USA). RAD fragment libraries (SbfI) were sequenced on an Illumina HiSeq 2000 using single-end 100 bp chemistry. As there is no reference genome for Antarctic krill, a set of unique 90 bp sequences (RAD tags) was assembled from 17.3 million single-end reads from an individual krill. We obtained over a billion raw reads from the 148 krill in our study (a mean of 6.8 million reads per sample). The reference assembly contained 239,441 distinct RAD tags. The core genotype dataset exported for downstream data filtering included just those SNPs with genotype calls in at least 80% of the krill samples and contained 12,114 SNPs on 816 RAD tags. Sample collection table (comma separated): Southern Ocean Location, Sample Size, Austral Summer, Latitude, Longitude, ID East Antarctica (Casey), 21, 2010/2011, 64S, 100E, Cas East Antarctica (Mawson), 22, 2011/2012. 66S, 70E, Maw Lazarev Sea, 38, 2004/2005 and 2007/2008, 66S, 0E, Laz Western Antarctic Peninsula, 16, 2010/2011, 69S, 76W, WAP Ross Sea, 23, 2012/2013, 68S, 178E, Ross