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GLIN==> Seminar - Nutrient- vs. Energy-Limitation in the Sea



Seminar Announcement
NOAA/GLERL-CILER Joint Seminar Series

Title
NUTRIENT- vs. ENERGY-STUDIES IN THE SEA: THE RED SEA AND ANTARCTIC
OCEAN AS EXTREME CASE STUDIES

By

Dr. Max M. Tilzer
Faculty of Biology,
University of Constance,
Konstanz, Germany

Date & Time
Friday, February 23
10:30 a.m.

Location:
Main Conference Room (105)
NOAA  Great Lakes Environmental Research Lab
2205 Commonwealth Blvd.
Ann Arbor, MI

Contact:
Dr. John Robbins
NOAA/GLERL
734-741-2283

Abstract - The Law of the Minimum states that the resource in shortest
supply controls biological productivity. In general, nutrient supply
restricts the accumulation of biomass (yield limitation) whereas
energy supply controls the velocity of growth (rate limitation).  In
most marine systems energy supply is ample during summer, allowing the
complete exhaustion of the least available nutrient, most frequently
nitrogen, whereas during winter, deep mixing recharges the euphotic
zone with nutrients which, however, cannot be fully utilized due to
shortage of radiant energy.

The Gulf of Aqaba at the Northern end of the Red Sea can serve as an
example for a purely nutrient-controlled system. During most years,
radiant energy supply is sufficient for the complete exhaustion of
nitrate within the mixed layer, even in winter.  Because winter mixing
depths vary between years, phytoplankton development and productivity
exhibit pronounced inter-annual variations.

For years it has been hypothesized that energy supply in the Southern
Ocean is insufficient to allow the complete depletion of nutrients for
the build-up of phytoplankton biomass throughout the year
(HNLC-Region). However, since the Equatorial Pacific and the Central
North Pacific are also HNLC-Regions, low energy supply cannot serve as
the only explanation for this pattern. Iron fertilization experiments
in the Equatorial Pacific and, more recently, in the Southern Ocean
suggest that also in the Southern Ocean, iron limitation might act at
least as an additional mechanism controlling the primary production
process.


--
Posted by

David F. Reid, Ph.D.
National Oceanic & Atmospheric Administration (NOAA)
Great Lakes Environmental Research Lab (GLERL)
2205 Commonwealth Blvd.
Ann Arbor, MI  48105-2945
Voice:  734-741-2019
FAX:    734-741-2003
Email:  reid@glerl.noaa.gov

Visit the GLERL Website:

http://www.glerl.noaa.gov



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