A multiple biomarker approach to tracking the fate of an ice algal bloom to the sea floor |
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Authors: | Nathalie Morata Michel Poulin Paul E Renaud |
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Institution: | (1) Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, CT 06340, USA;(2) Present address: Department of Arctic and Marine Biology, University of Troms?, 9037 Troms?, Norway;(3) Research Division, Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, ON, K1P 6P4, Canada;(4) Akvaplan-niva, Polar Environmental Centre, 9296 Troms?, Norway |
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Abstract: | In ice-covered Arctic seas, the ice algal production can be the main input of organic matter to the ecosystem. Pelagic–benthic
coupling is thought to be particularly tight in those areas. The increase in ice algal production in Franklin Bay from January/February
to April/May 2004 paralleled an increase in benthic oxygen demand. However, sedimentary chlorophyll a, which is usually an indicator of “fresh” organic matter inputs to the sea floor, did not increase. Consequently, it was
asked what was the fate of the ice algal phytodetritus arriving at the sea floor? To answer this question, photosynthetic
pigments from the sea ice, water column particulate organic matter, and sediment, as well as diatom frustules in the sediment,
were studied from January to May 2004. The number of ice diatom cells in the sediment showed an increase in April/May, confirming
higher inputs of fresh ice algae to the sediment. Changes in sedimentary pigment profiles in the first 10 cm suggested an
increase in bioturbation due to enhanced benthic activities. Finally, the decrease in the ratio of chlorophyll a to phaeophorbide a implied an increase in macrobenthic activity. Benthic macrofauna consumed some of the deposited material and mixed some within
the top five cm of sediment. The response of sedimentary pigments to an ice algal input can be studied at different levels
and it is only the combination of these studies that will allow an understanding of the overall fate of phytodetritus in the
benthic compartment. |
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