MEPS 261:1-19 (2003)  -  doi:10.3354/meps261001

Characteristics, distribution and persistence of thin layers over a 48 hour period

M. A. McManus1,*, A. L. Alldredge2, A. H. Barnard3, E. Boss4, J. F. Case2, T. J. Cowles5, P. L. Donaghay6, L. B. Eisner5, D. J. Gifford6, C. F. Greenlaw7, C. M. Herren8, D. V. Holliday7, D. Johnson9, S. MacIntyre10, D. M. McGehee7, T. R. Osborn11, M. J. Perry12, R. E. Pieper13, J. E. B. Rines6, D. C. Smith6, J. M. Sullivan6, M. K. Talbot14, M. S. Twardowski15, A. Weidemann9, J. R. Zaneveld15

1Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, California 95064, USA
2Biological Sciences, University of California Santa Barbara, Santa Barbara, California 93106, USA
3Bigelow Laboratory for Ocean Sciences, 180 McKown Point Road, West Boothbay Harbor, Maine 04575, USA
4School of Marine Sciences, 5741 Libby Hall, University of Maine, Orono, Maine 04473, USA
5College of Oceanic & Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5503, USA
6Graduate School of Oceanography, University of Rhode Island, South Ferry Road, Narragansett, Rhode Island 02882, USA
7BAE Systems, 4669 Murphy Canyon Road, San Diego, California 92123-4333, USA
8Monterey Bay Aquarium Research Institute, 700 Sandholt Road, Moss Landing, California 95003, USA
9Naval Research Laboratory, Code 7331, Stennis Space Center, Mississippi 39529, USA
10Marine Science Institute, University of California Santa Barbara, Santa Barbara, California 93117-6150, USA
11The Johns Hopkins University, 3400 N Charles Street, Baltimore, Maryland 21218, USA
12Ira C. Darling Marine Center, School of Marine Sciences, University of Maine, Walpole, Maine 04573, USA
13Hancock Institute for Marine Science, University of Southern California, Terminal Island, California 90731, USA
14University of Washington, 1492 NE Boat Street, Seattle, Washington 98195, USA
15Wet Labs Inc., 620 Applegate Street, Philomath, Oregon 97370, USA
*(formerly Dekshenieks) Email:

ABSTRACT: The biological and physical processes contributing to planktonic thin layer dynamics were examined in a multidisciplinary study conducted in East Sound, Washington, USA between June 10 and June 25, 1998. The temporal and spatial scales characteristic of thin layers were determined using a nested sampling strategy utilizing 4 major types of platforms: (1) an array of 3 moored acoustical instrument packages and 2 moored optical instrument packages that recorded distributions and intensities of thin layers; (2) additional stationary instrumentation deployed outside the array comprised of meteorological stations, wave-tide gauges, and thermistor chains; (3) a research vessel anchored 150 m outside the western edge of the array; (4) 2 mobile vessels performing basin-wide surveys to define the spatial extent of thin layers and the physical hydrography of the Sound. We observed numerous occurrences of thin layers that contained locally enhanced concentrations of material; many of the layers persisted for intervals of several hours to a few days. More than one persistent thin layer may be present at any one time, and these spatially distinct thin layers often contain distinct plankton assemblages. The results suggest that the species or populations comprising each distinct thin layer have responded to different sets of biological and/or physical processes. The existence and persistence of planktonic thin layers generates extensive biological heterogeneity in the water column and may be important in maintaining species diversity and overall community structure.


KEY WORDS: Thin layer · Bioacoustics · Optics · Bioluminescence · Marine snow · Bacterial production· Physical oceanographic processes


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