Dr Katrin Schmidt

Dr Katrin Schmidt

Research Assistant

School of Geography, Earth and Environmental Sciences (Faculty of Science and Engineering)


I'm currently employed as a Research Assistant in the NERC-Project: 'Quantifying the contribution of sympagic versus pelagic diatoms to Arctic food webs and biogeochemical fluxes: application of source-specific highly branched isoprenoid biomarkers' (PI: A. Atkinson, Co-PI: S. Belt). This is one of seven UK funded contributions to the 'Multidisciplinary drifting Observatory for the Study of Arctic Climate' (MOSAiC) led by the Alfred Wegener Institute, Germany.


1988-1994, Study of Biology at the University of Rostock, Germany (1993-1994, Master thesis)

1994-1999, PhD Marine Biology, Inst. for Baltic Sea Research Warnemuende, Germany; Danish Institute for Fisheries Research, Charlottenlund, DK

2003-2013, Research Assistant, British Antarctic Survey, Cambridge, UK

2014, Visiting scientist, University of Plymouth, UK

2015-2017, Plankton Analyst, Sir Alister Hardy Foundation for Ocean Science, Plymouth, UK

since 2018, Research Assistant, University of Plymouth, UK

Professional membership

Challenger Society

Staff serving as external examiners

2014, Mette Dalgaard Agersted, Technical University of Denmark, PhD thesis: 'Functional biology and ecological role of krill in Northern Marine Ecosystems'

2018, Fokje Schaafsma, Wageningen University, The Netherlands, PhD thesis: 'Life in the polar oceans: the role of sea ice in the biology and ecology of marine species'

Research interests

My main research interest is zooplankton feeding. Feeding is a key process at the organism level as it dictates growth rates, reproduction and survival. It is also key to the functioning of ecosystems, shaping foodweb relationships and biogeochemical cycles. Therefore, some of my studies are centred around the diet and feeding behaviour of individual zooplankton species - e.g. copepods of the Baltic Sea (Schmidt et al. 1997, 1998), Northern krill (Schmidt 2010) or Antarctic krill (Schmidt et al. 2014, Schmidt & Atkinson 2016), while others touch topics of biological oceanography such as harmful algal blooms (Schmidt et. al. 2002, Koski et al. 2002), carbon export via zooplankton fecal pellets (Atkinson et al. 2012, Schmidt et al. 2012) and the marine iron cycle (Schmidt et al. 2011, 2016). I have also tested the scope and limitations of various biomarkers in feeding studies – i.e. bulk- and compound specific stable isotopes (Schmidt et al. 2003, 2004, 2006), fatty acids (Schmidt et al. 2006, 2012, 2014) and highly-branched isoprenoids (Schmidt et al. 2018). Most recently, I have focussed on the mutual interactions between nutrients and phytoplankton in temperate shelf seas. This study has shown that in warm and dry summers, enduring water column stratification and low river flow can lead to severe nutrient shortage in surface waters of shelf- and coastal regions. These conditions favour picocyanobacteria (Synechococcus) over pico- and nanoeukaryotes, due to their efficient light harvesting at low irradiance and high affinity to iron. Over the last 20 years, we see a shift in the phytoplankton community structure towards these smaller forms of lower nutritional value which has led to a strong decline in copepod abundances with potentially adverse effects for fish stocks (Schmidt et al. submitted). The co-operation with biogeochemists and physical oceanographers has helped me to understand the suite of processes that can affect phytoplankton blooms, bringing the role of zooplankton grazing and fertilisation into perspective. Working at the interface of different disciplines – biogeochemistry, oceanography, physiology and ecology – is what I find challenging and most rewarding. 

Research degrees awarded to supervised students

2001, Nicola Plathner, University of Rostock, Master thesis: An experimental study on stable carbon and nitrogen isotope fractionationby Meganyctiphanes norvegica – the influence of food source, assimilation efficiency, growth rate and turnover. Degree: 'cum laude'

2002, Christina Augustin, University of Rostock, Master thesis: Salinity tolerance of the copepod Pseudocalanus spp. in the North Sea and in the Baltic Sea. Degree: 'cum laude'


Grants & contracts

1994-1997, Research Assistant, Project: 'Exchange and transformation processes in the Pomeranian Bay' (German Federal Ministry of Research & Technology, PI: B. v. Bodungen)

1999-2002, named Research Assistant, Project: 'Seasonal feeding strategies of Euphausia superba - Antarctic krill' (German Federal Ministry of Research & Technology, PI: U. Bathmann)

1999, 3 months research visit to Tvaerminne/ Finland (Nessling Foundation Finland)

2000, 2 months research visit to Kristineberg/ Sweden (Large Scale Facility Program at Kristineberg Marine Research Station)

2003-2005, Post-doctoral Research Fellow, Project: 'How omnivorous is Antarctic krill ...' (German Science Foundation)

2005-2009, named Research Assistant, Project: 'The quantitative importance of copepods in the diet of Antarctic krill ...' (Ant. Funding Initiative, PI: D. Pond)

2010-2013, named Research Assistant, Project: 'The role of krill grazing in Southern Ocean nutrient cycles' (AFI, PI: A. Atkinson, Co-PI: E. Achterberg)

2018, Research Assistant, Project: 'Integration of iron biogeochemistry into ERSEM' (NERC, PI: S. Ussher)

since 2019, named Research Assistant, Project: 'Quantifying the contribution of sympagic versus pelagic diatoms to Arctic food webs ...' (NERC, PI: A. Atkinson, Co-PI: S. Belt)

Reports & invited lectures


Cavan EL, Belcher A, Atkinson A, Hill SL, Kawaguchi S, McCormack S, Meyer B, Nicol S, Ratnarajah L, Schmidt K, Steinberg DK, Tarling GA, Boyd PW (2019) The importance of Antarctic krill in biogeochemical cycles. Nature Communications (revised)

Atkinson A, Hill SL, Pakhomov EA, Siegel V, Reiss CS, Loeb VJ, Steinberg DK, Schmidt K, Tarling GA, Gerrish L, Sailley SF (2019) Krill (Euphausia superba) distribution contracts southward during rapid regional warming. Nature Climate Change 9, 142-147. https://doi.org/10.1038/s41558-018-0370-z

Schlosser C, Schmidt K, Aquilina A, Homoky WB, Castrillejo M, Mills RA, Patey M, Fielding S, Atkinson A, Achterberg EP(2018) Mechanisms of dissolved and labile particulate iron supply to shelf waters and phytoplankton blooms of South Georgia, Southern Ocean. Biogeosciences 15, 4973-4993, doi.org/10.5194/bg-15-4973-2018

Schmidt K, Brown TA, Belt ST, Ireland L, Taylor K, Thorpe SE, Ward P, Atkinson A (2018) Do pelagic grazers benefit from sea ice? Insights from the Antarctic sea ice proxy IPSO25. Biogeosciences 15, 1987-2006, doi.org/10.5194/bg-15-1987-2018

Atkinson A, Hill SL, Pakhomov EA, Siegel V, Anadon R, Chiba S, Daly KL, Downie R, Fretwell P, Gerrish L, Hosie GW, Jessopp MJ, Kawaguchi S, Krafft BA, Loeb V, Nishikawa J, Peat HJ, Reiss C, Ross RM, Quetin LB, Schmidt K, Steinberg DK, Subramaniam RC, Tarling GA, Ward P (2017): KRILLBASE: a circumpolar database of Antarctic krill and salp numerical densities, 1926–2016. Earth System Science Data. doi:10.5194/essd-2016-52

Schmidt K, Schlosser C, Atkinson A, Fielding S, Venables HJ, Waluda CM, Achterberg EP (2016) Zooplankton gut passage mobilizes lithogenic iron for ocean productivity. Current Biology 26: 2667-2673, http://dx.doi.org/10.1016/j.cub2016.07.058

Atkinson A, Hill SL, Barange M, Pakhomov EA, Raubenheimer D, Schmidt K, Simpson SJ, Reiss C (2014): Sardine cycles, krill declines, and locust plagues: revisiting ‘wasp-waist’ food webs. TREE. doi.org/10.1016/j.tree.2014.03.011

Schmidt K, Atkinson A, Pond DW, Ireland LC (2014): Feeding and overwintering of Antarctic krill across its major habitats: The role of sea ice cover, water depth, and phytoplankton abundance. Limnol Oceanogr. 59:17-36

Flores H, Atkinson A, Kawaguchi S, Krafft BA, Milinevsky G, Nicol S, Reiss C, Tarling GA, Werner R, Bravo Rebolledo E, Cirelli V, Cuzin-Roudy J, Fielding S, Groeneveld JJ, Haraldsson M, Lombana A, Marschoff E, Meyer B, Pakhomov EA, Rombolá E, Schmidt K, Siegel V, Teschke M, Tonkes H, Toullec JY, Trathan PN, Tremblay N, Van de Putte AP, van Franeker JA, Werner T (2012) Impact of climate change on Antarctic krill. Mar Ecol Prog Ser 458, 1-19.

Schmidt K, Atkinson A, Venables HJ, Pond DW (2012): Early spawning of Antarctic krill in the Scotia Sea is fuelled by „superfluous“ feeding on non-ice associated phytoplankton blooms. Deep-Sea Res II 59-60: 159-172

Atkinson A, Schmidt K, Fielding S, Kawaguchi S, Geissler PA (2012): Variable food absorption by Antarctic krill: Relationship between diet, egestion rate and the composition and sinking rates of their fecal pellets. Deep-Sea Res II 59-60: 147-158

Ward P, Atkinson A, Venables HJ, Tarling GA, Whitehouse MJ, Fielding S, Collins MA, Korb R, Black A, Stowasser G, Schmidt K, Thorpe SE, Enderlein P (2012) Food web structure and bioregions in the Scotia Sea: A seasonal synthesis. Deep-Sea Res II 59-60: 253-266

Pond DW, Tarling GA, Schmidt K, Everson I (2012): Diet and growth rates of Meganyctiphanes norvegica in autumn. Mar Biol Res 8: 615-623

Schmidt K, Atkinson A, Steigenberger S, Fielding S, Lindsay MCM, Pond DW, Tarling GA, Klevjer TA, Allen C, Nicol S, Achterberg EP (2011): Seabed foraging by Antarctic krill: Implications for stock assessment, bentho-pelagic coupling, and the vertical transfer of iron. Limnol Oceanogr. 56: 1411-1428

Meyer B, Fuentes V, Guerra C, Schmidt K, Atkinson A, Spahic S, Cisewski B, Freier U, Olariaga A, Bathmann U (2009) Physiology, growth, and development of larval krill Euphausia superba in autumn and winter in the Lazarev Sea, Antarctica. Limnol Oceanogr. 54: 1595-1614

Atkinson, A, Siegel V, Pakhomov EA, Rothery P, Loeb V, Ross RM, Quetin LB, Schmidt K, Fretwell P, Murphy EJ, Tarling GA, Fleming AH (2008) Oceanic circumpolar habitats of Antarctic krill. Mar Ecol Prog Ser 362:1-23

Schmidt K, Atkinson A, Petzke KJ, Voss M, Pond DW (2006): Protozoan as a food source for Antarctic krill, Euphausia superba - complementary insights from stomach content, fatty acids and stable isotopes. Limnol Oceanogr. 51: 2409-2427

Schmidt K, Tarling G, Plathner N, Atkinson A (2004): Moult cycle related changes in feeding rates of larval krill Meganyctiphanes norvegica and Thysanoessa spp. MEPS 281:131-143

Schmidt K, McClelland JW, Mente E, Montoya JP, Atkinson A, Voss M (2004): Trophic level interpretation based on δ15N values: the implications of tissue-specific fractionation and amino acid composition. Mar Ecol Prog Ser 266: 43-58

Stübing D, Hagen W, Schmidt K (2003) On the use of lipid biomarkers in marine food web analyses: An experimental case study on the Antarctic krill, Euphausia superba. Limnol Oceanogr 48: 1685-1700

Schmidt K, Atkinson A, McClelland JW, Montoya J, Stübing D, Voss M (2003): Trophic relationships among Southern Ocean copepods and krill: Some uses and limitations of a stable isotope approach. Limnol Oceanogr 48: 277-289

Atkinson A, Meyer B, Stübing D, Hagen W, Schmidt K, Bathmann U (2002): Feeding and energy budget of Antarctic krill Euphausia superba at the onset of winter. II. Juveniles and adults. Limnol Oceanogr 47: 953-966

Schmidt K, Koski M, Engström J, Atkinson A (2002): Development of Baltic Sea zooplankton in the presence of a toxic cyanobacterium: a mesocosm approach.J Plankton Res 24:979-992

Koski M, Schmidt K, Engström-Öst J, Viitasalo M, Jónasdóttir SH, Repka S, Sivonen K (2002): Calanoid copepods feed and produce eggs in the presence of toxic cyanobacteria Nodularia spumigen. Limnol Oceanogr 47: 878-885

Engström-Öst J, Koski M, Schmidt K, Viitasalo M, Jónasdóttir SH, Repka S, Kokkonen M (2002): Effects of toxic cyanobacteria on a plankton assemblage: community development during decay of Nodularia spumigena. Mar Ecol Prog Ser 232: 1-14

Schmidt K, Kähler P, Bodungen B (1998): Copepod egg production rates in the Pomeranian Bay (Southern Baltic Sea) as a function of phytoplankton abundance and taxonomic composition. Mar Ecol Prog Ser 174:183-195

Schmidt K, Jónasdóttir SH (1997): Nutritional quality of two cyanobacteria: How rich is poor food? Mar Ecol Prog Ser 151: 1-10


Schmidt K, Atkinson A (2016) Feeding and food pocessing in Antarctic krill (Euphausia superba Dana) in: Siegel V (ed) ‚Biology and Ecology of Antarctic Krill‘ in Advances in Polar Biology. Springer, Dordrecht. DOI: 10.1007/978-3-319-29279-3_5

Schmidt K, (2010) Food and feeding in Northern krill (Meganyctiphanes norvegica SARS). Adv Mar Biol 57:121-171 

Other academic activities

Media outreach