Rhythmic oscillations in krill visual sensitivity.

• Main Authors: Jonathan H. Cohen (7958483), Kim S. Last (11581392), Corie L. Charpentier (3200505), Finlo Cottier (749186), Malin Daase (471602), Laura Hobbs (9152223), Geir Johnsen (257802), Jørgen Berge (235355)
• Format: Other Non-Article Part of Journal/Newspaper
• Language: unknown
• Published: 2021
• Subjects: Physiology; Ecology; Inorganic Chemistry; Environmental Sciences not elsewhere classified; Astronomical and Space Sciences not elsewhere classified; Biological Sciences not elsewhere classified; thysanoessa inermis </; therefore question whether; main migratory species; acoustic field observations; 81 ° n; 5 ° n; arctic ocean extends; light measurements demonstrate; characterize light across; weak midday twilight; div >< p; arctic krill (<; arctic polar night; arctic krill; light plays; polar night; zooplankton community; using electroretinogram; traditional definitions; sun ’; subjective night; photophysiological cycles; north pole; midnight sun; maximum extent; lower latitudes; latitudinal gradient; high latitudes; fundamental role; darkest parts; constant darkness; circadian clock; auroral components; although differences; Arctic; Arctic Ocean; North Pole; Arctic krill; Kongsfjord*; Kongsfjorden; Zooplankton; Thysanoessa inermis
• Online Access: https://doi.org/10.1371/journal.pbio.3001413.s002

To test whether Arctic krill ( T . inermis ) showed rhythmic changes in visual sensitivity, and, in turn, warranted further experiments, we collected an individual krill from Kongsfjorden in January, and immediately prepared it for ERG recording. (a) ERG magnitude (red line = 1.75 hours running mean) is plotted in response to a 50-ms flash of 488-nm light at 3.65 × 10 9 photons cm −2 s −1 . Since this animal was in darkness, subjective solar elevation (negative degrees relative to horizon) is plotted for the collection location. Peaks in ERG response magnitude occurred during the time of subjective night. (b) Lomb–Scargle periodogram for ERG data in (a), resulted in a peak period at 20.4 hours. Dashed line represents significance at the ɑ = 0.05 level. For data, see S2 Data . ERG, electroretinogram. (DOCX)