| Summary: | Samples were collected between 03/26/2018 and 04/27/2018 around the northern tip of the Antarctic Peninsula (63° 0' 1.843'' S, 60° 0' 16.901''W) onboard the RV Polarstern during the PS112 campaign in order to identify the elemental composition and stoichiometry of the Antarctic krill (Euphausia superba) and salps (Salpa thompsoni). The sampling stations were situated in the survey grid of the Antarctic Marine Living Resources Program (AMLR). At the time of sampling, the study area was ice free and ambient Chl a levels were comparable to previous studies in this time frame (e.g. Schofield et al., 2017). The phytoplankton community was dominated by dinoflagellates, diatoms and prymnesiophytes, which is typical for autumn (March–May) around the NAP (Pauli et al., 2021). Krill and salps were sampled by using the 1.8 m² Isaacs-Kidd Midwater Trawl Net (IKMT) equipped with a 505 μm mesh which is suitable to collect both salps and krill in good condition. The net was towed obliquely to 170 m, or 20 m from the bottom, at a speed of 2 kts. From these tows, we collected 162 adult krill and 121 blastozooid salp individuals on board which were analyzed for their elemental content. Krill and salp individuals were staged and measured on board before further processing. For size measurements of S. thompsoni, we used the oral atrial length in mm. Total length in mm of Antarctic krill was measured from the anterior margin of the eye to the tip of the telson, excluding the terminal spine. Prior to the elemental analysis, the digestive system of krill and salps was removed to avoid contamination of the tissue elemental composition by the elemental signature of the gut content. Salp individuals were immediately dissected on board after size measurements and frozen at -20 °C. Krill individuals were frozen on board and dissected later in the lab. Frozen krill and salp individuals were individually ground prior to the analyses using a pebble mill and homogenized with distilled water. Homogenization enabled us to take sub-samples of ...
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