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Marine Ecology Progress Series

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MEPS 452:27-43 (2012)  -  DOI:

Simulating larval Antarctic krill growth and condition factor during fall and winter in response to environmental variability

Alexander T. Lowe1,4,*, Robin M. Ross1, Langdon B. Quetin1, Maria Vernet2, Christian H. Fritsen3

1Marine Science Institute, University of California Santa Barbara, Santa Barbara, California 93106-6150, USA
2Integrative Oceanography Division, Scripps Institution of Oceanography, La Jolla, California 92093-0218, USA
3Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, Nevada 89512, USA
4Present address: Friday Harbor Laboratories, University of Washington, Friday Harbor, Washington 98250, USA

ABSTRACT: The first winter in the life cycle of Antarctic krill Euphausia superba is a critical period in which larval survival and recruitment to the adult population are highly sensitive to environmental conditions, yet little is known about larval physiological dynamics during this period. An individual-based model was developed to investigate patterns of larval krill growth and condition factor in response to environmental variability during fall and winter, west of the Antarctic Peninsula. Field and experimental observations from Southern Ocean Global Ocean Ecosystems Dynamics cruises in 2001 and 2002 and the Palmer Long-Term Ecological Research program were used to parameterize the model. Growth was modeled by partitioning total body carbon between length and condition factor. Total body carbon was simulated with empirical temperature-dependent rates of ingestion of phytoplankton and respiration, and ingestion of algae grown on a surface to simulate sea ice algae. Light-driven diel vertical migration modulated ingestion of phytoplankton and sea ice algae as a function of latitude, season and sea ice cover. Simulations highlighted 3 environmental processes that controlled food availability, and consequently, physiological condition of krill: the fall phytoplankton decline, sea ice advance and development of sea ice microbial communities, and the late winter increase in sea ice microbial community biomass. Fall phytoplankton dynamics were identified as a major driver of the physiological condition of larval krill throughout this critical period. The model presents a mechanism that links larval krill survival and recruitment to fall and winter variability in phytoplankton and sea ice dynamics along the western Antarctic Peninsula.

KEY WORDS: Euphausia superba · Larval Antarctic krill · Condition factor · Growth · Individual-based model · Fall and winter · Critical period

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Cite this article as: Lowe AT, Ross RM, Quetin LB, Vernet M, Fritsen CH (2012) Simulating larval Antarctic krill growth and condition factor during fall and winter in response to environmental variability. Mar Ecol Prog Ser 452:27-43.

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