DOI: 10.5061/dryad.cvdncjtg0
title: Data from: The production of ‘food boluses’ by Antarctic krill and implications for organic matter transport

description: Antarctic krill (Euphausia superba) are a key species in the marine
 Antarctic ecosystem. Food boluses, a byproduct of feeding where krill form
 a compact food mass within their feeding basket, were formed and rejected
 under laboratory conditions. We explored the mechanism used to form these
 boluses by examining krill feeding behaviour and observed two distinct
 scenarios that can lead to the formation of boluses: 1) when
 concentrations of food items are too high for krill to filter feed
 efficiently; 2) when either biological or foreign particles are caught in
 the feeding basket and unable to be processed by the krill. We measured
 the frequency of rejection of the boluses, along with their composition,
 sinking rates, and carbon and nitrogen contents. For cell concentrations
 over 108 cells L-1, the frequency of rejection ranged from 2.6 to 17
 boluses per hour. Bolus sinking velocities averaged 367 m d-1, with carbon
 and nitrogen contents averaging 24.1 µg C mm-3 and 2.3 µg N mm-3,
 respectively. Our findings suggest krill may display this behaviour in
 situ, and, if so, this behaviour may also occur in other krill species
 with similar feeding behaviour.
description: # Data from: The production of ‘food boluses’ by Antarctic krill and
 implications for organic matter transport Dataset DOI:
 [10.5061/dryad.cvdncjtg0](10.5061/dryad.cvdncjtg0) ## Description of the
 data and file structure This dataset was collected to investigate how
 Antarctic krill (*Euphausia superba*) form and reject food boluses under
 varying phytoplankton concentrations, and to quantify the physical and
 elemental characteristics of these boluses. Experiments were conducted in
 temperature-controlled laboratory conditions using captive krill fed
 different microalgal diets. Measurements include the size, sinking
 velocity, carbon and nitrogen content, and production/rejection rates at
 different food concentrations of both boluses and faecal pellets. ###
 Files and variables #### File: Bolus_krill_data.xlsx **Tab 1_Bolus**
 **Description:** Measurements of individual food boluses formed by
 Antarctic krill under laboratory conditions. ##### Variables * Diet- Genus
 of microalgae fed to krill (e.g., *Geminigera*)  * Diameter_mm- Measured
 bolus diameter (mm) * Volume_mm3- Calculated volume assuming ellipsoid
 shape (mm³) * SV- Sinking velocity * SV_mday-Sinking speed of bolus
 (metres per day) **Tab 2_FP** **Description:** Measurements of faecal
 pellets formed by Antarctic krill under laboratory conditions. #####
 Variables * Diet- Genus of microalgae fed to krill (e.g., *Geminigera*)  *
 Length_mm- Measured length of faecal pellet (mm) * Volume_mm3- Calculated
 volume assuming cylindrical shape (mm³) * SV- Sinking velocity *
 SV_mday-Sinking speed of bolus (metres per day) **Tab 3_CN**
 **Description:**\ Elemental composition of krill boluses, faecal pellets,
 and phytoplankton cultures. **Variables:** * Sample_ID- Type of material
 analysed (e.g., Bolus, Pellet, Phytoplankton and diet) * N \[µg\]-
 Nitrogen content (micrograms) * C \[µg\]- Carbon content (micrograms) * H
 \[µg\]- Hydrogen content (micrograms) * C:N- Carbon to nitrogen ratio
 **Tab 4\_5\_hours** ### **4. Bolus_Production_Rates** **Description:**
 Bolus production and rejection rates over a 5-hour feeding period at
 different phytoplankton concentrations. **Variables:** * Diet-
 Phytoplankton species provided * Concentration of cells- Cell density of
 phytoplankton added (cells per litre) * Bolus_number- Number of food
 boluses produced during the 5-hour period * FP_number- Number of faecal
 pellets produced during the same trial ## Code/software Excel