South Georgia is renowned for the abundance of Antarctic krill (Euphausia superba) and a range of krill predators. Variability in krill availability at a range of scales, and the consequences of this for predator-prey interactions, mean that quantifying the spatially explicit demand for krill by those predators is essential to understanding the mechanisms underlying ecosystem changes in the region. In this thesis demand within a distinct study box to the northwest of the island has been assessed. The thesis has three sections; (1) the number of predators; (2) the distribution of predators; and (3) the demand for krill by those predators. (1) Predator densities with confidence intervals were determined from appropriately designed shipboard transect survey; counts of Antarctic fur seals (Arctocephalus gazella), macaroni penguins (Eudyptes chrysolophus), gentoo penguins (Pygoscelis papua), and Antarctic prions (Pachyptila desolata) were adjusted for sea state, distance from observer and dive behaviour. Providing the first at-sea predator density estimates for the region. (2) A comparison of the distribution of female Antarctic fur seals engaged in pup-rearing (using satellite telemetry) and the whole population that were not restricted to a single part of the population (from shipboard transect survey) was undertaken. Using two general additive models based on the relationship between seal distribution (one derived from transect and the other from telemetry) and the physical environment indicated that the spatial distribution of lactating females is representative of the general population. (3) Using the derived predator density, the local krill demand estimate was 2581 tonnes krill per day, a consumption rate of 0.45% per day of the concurrently estimated krill biomass (using shipboard acoustics). Antarctic fur seals accounted for 75% of this demand. This level of demand was less than the increase in biomass resulting from krill growth. However, based on the length-specific demand, determined from concurrent predator diet samples demand exceeded growth for krill >48mm.

Proteins are a highly diversified group of molecules, andfor their study, advanced analytical tools are required. Inparticular, a need for high-throughput techniques has emergedin order to enable the characterization of large sets ofproteins. In this thesis, improved techniques for proteinseparations as well as new tools for the mass spectrometricanalysis of proteins are described. In the work, presented in the first part of the thesis, arefined extract containing proteases from Antarctic krill (Euphausia superba) was separated and characterized bymeans of capillary electrophoresis (CE) and mass spectrometry(MS). Tailored CE separations of the krill extract revealed thepresence of approximately 50 components. In addition, adetailed CE and MS analysis of fractions, containing individualkrill proteases has been carried out. Trypsin-like proteasesfrom krill exhibited a 12-fold and a 60-fold higher digestionefficiency at 37 °C and 2 °C respectively compared todigests performed with bovine trypsin. Furthermore, thecleavage specificity of the trypsin-like proteases wasstudied. In the last part of the thesis, novel concepts forchip-based nanoelectrospray (nanoESI) and matrix-assisted laserdesorption/ionization (MALDI) mass spectrometry are described.First, a micromachined silicon chip with a two-dimensionalmatrix of out-ofplane nanoESI needles for high-throughputanalysis was fabricated. A two-fold improvement insignal-to-noise reproducibility was obtained. Second, achip-based target for MALDI was developed, which featured pairsof elevated 50×50 µm anchors in close proximity. Theanchors were individually addressable with sample solution. Theminiaturized sample preparations at close distance to eachother allowed a simultaneous ionization of a physicallyseparated sample and standard by one single laser pulse. Thisresulted in a twofold reduction of relative mass errors.Moreover, ion suppression of the analyte was significantlyreduced. The effective utilization of the sample resulted in adetection limit of ca 200 zeptomole of angiotensin I. Key words:Proteins, peptides, proteases, Antarctickrill,Euphausia superba, capillary electrophoresis,fluorosurfactants, mass spectrometry, nanoelectrospray, ESI,MALDI, chip, high-throughput, reproducibility, sensitivity andmass accuracy.

<p>Proteins are a highly diversified group of molecules, andfor their study, advanced analytical tools are required. Inparticular, a need for high-throughput techniques has emergedin order to enable the characterization of large sets ofproteins. In this thesis, improved techniques for proteinseparations as well as new tools for the mass spectrometricanalysis of proteins are described.</p><p>In the work, presented in the first part of the thesis, arefined extract containing proteases from Antarctic krill (<i>Euphausia superba</i>) was separated and characterized bymeans of capillary electrophoresis (CE) and mass spectrometry(MS). Tailored CE separations of the krill extract revealed thepresence of approximately 50 components. In addition, adetailed CE and MS analysis of fractions, containing individualkrill proteases has been carried out. Trypsin-like proteasesfrom krill exhibited a 12-fold and a 60-fold higher digestionefficiency at 37 °C and 2 °C respectively compared todigests performed with bovine trypsin. Furthermore, thecleavage specificity of the trypsin-like proteases wasstudied.</p><p>In the last part of the thesis, novel concepts forchip-based nanoelectrospray (nanoESI) and matrix-assisted laserdesorption/ionization (MALDI) mass spectrometry are described.First, a micromachined silicon chip with a two-dimensionalmatrix of out-ofplane nanoESI needles for high-throughputanalysis was fabricated. A two-fold improvement insignal-to-noise reproducibility was obtained. Second, achip-based target for MALDI was developed, which featured pairsof elevated 50×50 µm anchors in close proximity. Theanchors were individually addressable with sample solution. Theminiaturized sample preparations at close distance to eachother allowed a simultaneous ionization of a physicallyseparated sample and standard by one single laser pulse. Thisresulted in a twofold reduction of relative mass errors.Moreover, ion suppression of the analyte was significantlyreduced. The effective utilization of the sample resulted in adetection limit of ca 200 zeptomole of angiotensin I.</p><p><b>Key words:</b>Proteins, peptides, proteases, Antarctickrill,<i>Euphausia superba</i>, capillary electrophoresis,fluorosurfactants, mass spectrometry, nanoelectrospray, ESI,MALDI, chip, high-throughput, reproducibility, sensitivity andmass accuracy.</p>