Field observations on the ontogeny of schooling of Euphausia superba furciliae and its relationship to ice in Antarctic waters.

• Published in: Limnology and Oceanography
• Main Authors: Hamner, W. M., Hamner, P. P., Obst, B. S., Carleton, J. H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1989
• Subjects: Aquatic Science; Oceanography; Antarctic; Gerlache; Gerlache Strait; Antarc*; Antarctica; Euphausia superba; ice algae
• Online Access: http://dx.doi.org/10.4319/lo.1989.34.2.0451; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.4319%2Flo.1989.34.2.0451; https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1989.34.2.0451

We investigated the ontogeny of behavior during the transition in Euphausia superba from dispersed solitary larvae to clumped swarms and schools of furciliae. We directly observed behavior of krill larvae in the Gerlache Strait, Antarctica, with open‐ocean SCUBA techniques. In the absence of ice, isolated furciliae occurred at the surface at a density of 0.003 m −3 . In the presence of ice, density of isolates was 10 2 times higher and density of furciliae in schools was 10 9 times higher than in open water. Larvae first exhibited schooling behavior at furcilia IV–V(body length 1 cm). Furcilia V larvae segregated by size in immediately adjacent schools, with highly significant differences in body lengths of as little as 0.5 mm. Late stage furciliae moved the thoracic basket in the same way that adults filter phytoplankton, and furciliae fed like adults on epontic ice algae. For larval krill in the Gerlache Strait, ice provided concentrated algal food and protection from predators and facilitated aggregation and formation of swarms of nonpolarized individuals and of small, ice‐oriented schools that contained 10 2 −10 4 individuals per school.