Effects of N:P:Si ratios and zooplankton grazing on phytoplankton communities in the northern Adriatic Sea. III. Zooplankton populations and grazing

Abstract

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 18:67-75 (1999) - doi:10.3354/ame018067 Effects of N:P:Si ratios and zooplankton grazing on phytoplankton communities in the northern Adriatic Sea. III. Zooplankton populations and grazing Jefferson T. Turner1,*, Patricia A. Tester2, Jean A. Lincoln1, Per Carlsson3, Edna Granéli3 1Biology Department, University of Massachusetts Dartmouth, North Dartmouth, Massachusetts 02747, USA 2National Marine Fisheries Service, NOAA, Southeast Fisheries Science Center Beaufort Laboratory, Beaufort, North Carolina 28516, USA 3University of Kalmar, Deptartment of Marine Sciences, POB 905, S-391 29 Kalmar, Sweden *E-mail: jturner@umassd.edu ABSTRACT: As part of mesocosm experiments to study effects of nutrients and zooplankton grazing on phytoplankton communities from the northern Adriatic Sea, we monitored metazoan zooplankton fluctuations in enclosures and performed grazing experiments in May and June of 1993. An effort was made to increase zooplankton abundances up to 10 times above normal levels in May, whereas in June, we attempted to initially exclude zooplankters >100 μm in size. Neither manipulation mattered since, in both cases, a cohort of copepodites rapidly developed from eggs and nauplii added during initial filling of enclosures. Declines in abundances of nauplii, with concurrent increases in copepodites, during both experiments likely resulted from a combination of nauplii molting into copepodites, and possibly cannibalism of nauplii by copepodites and adults. In May copepodites were almost exclusively Acartia clausi, whereas in June, both A. clausi and particularly Oithona similis copepodites increased in enclosures after 6 to 7 d. Grazing rates by A. clausi adults and copepodites were low in both months (0.01 to 0.35 ml copepod-1 h-1 in May, and <0.21 ml copepod-1 h-1 in June). Zooplankton community grazing had minimal impact, in that phytoplankton growth continued unabated until nutrients were exhausted. KEY WORDS: Zooplankton · Grazing · Adriatic Sea · Copepod Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 18, No. 1. Publication date: July 16, 1999 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 1999 Inter-Research.