Data from: The production of ‘food boluses’ by Antarctic krill and implications for organic matter transport
Data files
Aug 18, 2025 version files 31.76 KB
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Bolus_krill_data.xlsx
29.29 KB
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README.md
2.47 KB
Abstract
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.
Dataset DOI: 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