Abundance and size measurements of calanoid copepods in the subtropical South Atlantic Ocean during POLARSTERN cruise PS81 (ANT-XXIX/1)

Abundance and community structure of calanoid copepods of one day (stn. 16; bottom depth 5,433 m) and one night station (stn. 15; bottom depth 5,462 m) were analyzed (Fig. 1). Stratified vertical hauls were carried out within 24 h with a HydroBios Multinet Maxi (0.5 m2 net opening, 9 nets, 150 µm mesh size) from 800 m depth to the surface (strata: 800-700-600-500-400-300-200-100-50-0 m). The filtered water volume was measured with a flowmeter attached to the net opening. After retrieval, samples were preserved in a 4% borax-buffered formaldehyde in seawater solution. Calanoid copepods were sorted according to their developmental stages (copepodids C1-3 and C4/5, adult females and males), counted and identified to genus or, if possible, to species level under a dissecting microscope (Leica MZ12). Rare species (<100 individuals per sample) were counted from the entire sample. Total length (TL) of up to 100 calanoid individuals per taxonomic category (i.e. family/genus/species) and stage was measured (~6,600 specimens in total). Dry mass (DM) of calanoids was calculated based on the median TL of each taxonomic category. Individual respiration rates were calculated from individual DM and in situ temperatures, which were then converted to carbon units and used to calculate ingestion and egestion rates.