Phytoplankton spatial distribution patterns along the western Antarctic Peninsula (Southern Ocean)

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 261:21-39 (2003) - doi:10.3354/meps261021 Phytoplankton spatial distribution patterns along the western Antarctic Peninsula (Southern Ocean) Irene A. Garibotti1,*, María Vernet2, Martha E. Ferrario3, Raymond C. Smith4, Robin M. Ross5, Langdon B. Quetin5 1Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, CRICyT, CONICET, CC 330, 5500 Mendoza, Argentina 2Scripps Institute of Oceanography, University of California, San Diego, La Jolla, California 92093-0218, USA 3Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, 1900 La Plata, Argentina 4Institute for Computational Earth System Science and 5Marine Science Institute, University of California, Santa Barbara, California 93106, USA *Email: ireneg@lab.cricyt.edu.ar ABSTRACT: This paper describes spatial distribution patterns of the phytoplankton community (composition, cell abundance and biomass concentration) in relation to local environmental conditions in the Southern Ocean. Sampling was performed during summer 1997 off the coast of the western Antarctic Peninsula between Anvers Island and Marguerite Bay. Phytoplankton was characterized by relatively low biomass throughout most of the study area and was dominated by nanoalgae (<20 µm). Phytoplankton varied along an on-offshore gradient, with decreasing total cell abundance, chlorophyll a (chl a) concentration and carbon biomass toward the open ocean. Chl a concentration showed surface or subsurface maxima in coastal and middle-shelf waters, and deep maxima between ~40 and 100 m in oceanic waters. Across-shelf variability in phytoplankton correlated with vertical stability in the water column, which appears to be the major parameter affecting phytoplankton community structure in the area. We hypothesize that the deep chl a maximum offshore may be associated with iron limitation in near-surface waters and higher iron concentration in Œwinter waters¹ (subsurface remnant of Antarctic Surface Waters). On a smaller spatial scale, a cluster analysis showed great regional variability in phytoplankton assemblages. The area was divided into 4 main regions based on differences in the phytoplankton composition and concentration. Three peaks in phytoplankton abundance were found on a north-to-south gradient in near-shore waters: a Cryptomonas spp. bloom near Anvers Island, a small unidentified phytoflagellate bloom in Grandidier Channel, and a diatom bloom in Marguerite Bay. These assemblages resemble different stages of the phytoplankton seasonal succession, and may be related to the progressive sea-ice retreat, which might have regulated the timing of the onset of the phytoplankton seasonal succession in a north-south gradient. Biological environmental factors, such as seeding of the water column by epontic algae and selective zooplankton herbivory, are hypothesized to affect community composition in coastal regions. We conclude that large-scale variability in phytoplankton community structure is related to water column physical conditions and possibly iron availability, while mesoscale variability, as seen in coastal waters, is more likely due to seasonal succession of different algae groups. KEY WORDS: Western Antarctic Peninsula · Phytoplankton spatial variability · Seasonal progression · Environmental gradients · Palmer LTER Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 261. Online publication date: October 17, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.