Title Interannual and spatial variability in light attenuation; evidence from three decades of growth in the Arctic kelp, Laminaria solidungula
Author Dunton, K.H.; Schonberg, S.V.; Funk, D.W.
Author Affil Dunton, K.H., University of Texas Marine Science Institute, Port Aransas, TX. Other: LGL Alaska Research Associates
Source p.271-284, ; Smithsonian at the poles, Washington, DC, May 3-4, 2007, edited by I. Krupnik, M.A. Lang and S.E. Miller. Publisher: Smithsonian Institution Scholarly Press, Washington, DC, United States. ISBN: 978-0-9788460-1-50-9788460-1- X
Publication Date 2009
Notes In English. 28 refs. CRREL Acc. No: 63004406
Index Terms attenuation; chlorophylls; ecology; ocean environments; photosynthesis; plant ecology; Arctic Ocean--Beaufort Sea; Arctic Ocean; Beaufort Sea; chlorophyll; International Polar Year 2007-08; IPY 2007-08 Research Publications; marine environment; organic compounds; photochemistry; pigments; Plantae; productivity; seasonal variations; spatial variations
Abstract We examined long-term variations in kelp growth in coincidence with recent (2004- 2006) measurements of underwater photosynthetically active radiation (PAR), light attenuation coefficients, chlorophyll concentrations, and total suspended solids (TSS) to determine the impact of sediment resuspension on the productivity of an isolated kelp bed community on the Alaskan Beaufort Sea coast. Attenuation coefficients exhibited distinct geographical patterns and interannual variations between 2004 and 2006 that were correlated with temporal and geographical patterns in TSS (range 3.5-23.8 mg L-1). The low chlorophyll levels (3.0 g L-1) in all three years were unlikely to have contributed significantly to periods of low summer water transparency. Blade elongation rates in the arctic kelp, Laminaria solidungula, are excellent integrators of water transparency since their annual growth is completely dependent on PAR received during the summer open-water period. We noted that blade growth at all sites steadily increased between 2004 and 2006, reflective of increased underwater PAR in each successive year. Mean blade growth at all sites was clearly lowest in 2003 (8 cm) compared to 2006 (18-47 cm). We attribute the low growth in 2003 to reported intense storm activity that likely produced extremely turbid water conditions that resulted in low levels of ambient light. Examination of a 30- year record of annual growth at two sites revealed other periods of low annual growth that were likely related to summers characterized by exceptional strong storm activity. Although kelp growth is expected to be higher at shallower sites, the reverse occurs, since sediment re-suspension is greatest at shallower water depths. The exceptionally low growth of kelp in 2003 indicates that these plants are living near their physiological light limits, but represent excellent indicators of interannual changes in water transparency that result from variations in local climatology.
URL http://hdl.handle.net/10088/6804
Publication Type monograph
Record ID 292163