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The impact of trophic interactions on rates of nitrogen regeneration and grazing in Chesapeake Bay
Author(s) -
Miller Carolyn A.,
Penry Deborah L.,
Glibert Patricia M.
Publication year - 1995
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1995.40.5.1005
Subject(s) - acartia tonsa , copepod , grazing , trophic level , zooplankton , phytoplankton , chesapeake bay , bay , microbial loop , primary producers , environmental science , ecology , biology , oceanography , food web , nutrient , estuary , crustacean , geology
We investigated the effect that zooplankton grazing had on NH 4 + regeneration during August 1991 in the mesohaline Chesapeake Bay, when NH 4 + regeneration was important in supporting phytoplankton production. We measured rates of NH 4 + regeneration and uptake by organisms in <15‐, <63‐, and <202‐ µ m size fractions as a function of the density of the copepod Acartia tonsa, as well as rates of grazing on 5–20‐ µ m particles by microzooplankton and copepods over a 24‐h period. The primary regenerators of NH 4 + were organisms <15 µ m; these organisms were strongly controlled by microzooplankton. Microzooplankton, in turn, were strongly controlled by the copepods. Thus, copepods appeared to affect the primary NH 4 + regenerators indirectly through trophic interactions with microzooplankton, relieving grazing pressure on or stimulating rapid growth of the primary regenerators.