You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
The General Annual Cycle of Chlorophyll Standing Crop in Loch Creran
Paul Tett and Andrew Wallis
Journal of Ecology
Vol. 66, No. 1 (Mar., 1978), pp. 227-239
Published by: British Ecological Society
Stable URL: http://www.jstor.org/stable/2259190
Page Count: 13
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
(1) This paper introduces an investigation of the factors controlling phytoplankton growth in Creran, a typical sea-loch on the west coast of Scotland. (2) The hydrography of the loch is summarized. Salinity, irradiance and photosynthesis profiles suggest that the lower limits of the reduced-salinity surface layer and of the euphotic zone can conveniently be taken to coincide at a depth of 8 m. (3) The general annual cycle of phytoplankton standing crop in the loch is shown by a combined plot of 908 chlorophyll a measurements made between 1970 and 1976 in the 1-8 m depth zone. Limits that theoretically include 95% of the data are superimposed on this plot, and show that a number of features recur regularly from year to year. (4) These recurring features are: a winter low (< 0.5 mg chl. m-3); a spring increase, with chlorophyll reaching 1 mg m-3 at some time between 17 February and 12 March, and attaining 12-37 mg chl. m-3 between 13 March and 11 April; a biomass of 1-7 mg chl. m-3 from June until mid-September; no definite autumn bloom; and a reduction of chlorophyll levels to below 1 mg m-3 by 26 November. (5) The importance of salinity layering in the control of the phytoplankton cycle is briefly discussed. The spring increase in Creran starts at about the same time as in other sea-lochs and fjords, and thus 1 or 2 months earlier than in similar seas where the stability of the water column is controlled by temperature. (6) The theoretical basis of the 95% limits superimposed on the data plot is discussed in an Appendix. It is suggested that these limits can be used predictively.
Journal of Ecology © 1978 British Ecological Society