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| Titel |
Light availability in the coastal ocean: impact on the distribution of benthic photosynthetic organisms and their contribution to primary production |
| VerfasserIn |
J.-P. Gattuso, B. Gentili, C. M. Duarte, J. A. Kleypas, J. J. Middelburg, D. Antoine |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 3, no. 4 ; Nr. 3, no. 4 (2006-11-06), S.489-513 |
| Datensatznummer |
250001161
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| Publikation (Nr.) |
 copernicus.org/bg-3-489-2006.pdf |
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| Zusammenfassung |
One of the major features of the coastal zone is that part of its sea floor
receives a significant amount of sunlight and can therefore sustain benthic
primary production by seagrasses, macroalgae, microphytobenthos and corals.
However, the contribution of benthic communities to the primary production of
the global coastal ocean is not known, partly because the surface area where
benthic primary production can proceed is poorly quantified. Here, we use a
new analysis of satellite (SeaWiFS) data collected between 1998 and 2003 to
estimate, for the first time at a nearly global scale, the irradiance
reaching the bottom of the coastal ocean. The following cumulative functions
provide the percentage of the surface (S) of the coastal zone receiving an
irradiance greater than Ez (in mol photons m−2 d−1):
SNon-polar = 29.61 − 17.92 log10(Ez) + 0.72 log102(Ez) + 0.90 log103(Ez)
SArctic = 15.99 − 13.56 log10(Ez) + 1.49 log102(Ez) + 0.70 log103(Ez)
Data on the constraint of light availability on the major benthic primary
producers and net community production are reviewed. Some photosynthetic
organisms can grow deeper than the nominal bottom limit of the coastal ocean
(200 m). The minimum irradiance required varies from 0.4 to 5.1 mol photons
m−2 d−1 depending on the group considered. The daily compensation
irradiance of benthic communities ranges from 0.24 to 4.4 mol photons
m−2 d−1. Data on benthic irradiance and light requirements are
combined to estimate the surface area of the coastal ocean where (1) light
does not limit the distribution of primary producers and (2) net community
production (NCP, the balance between gross primary production and community
respiration) is positive. Positive benthic NCP can occur over 33% of the
global shelf area. The limitations of this approach, related to the spatial
resolution of the satellite data, the parameterization used to convert
reflectance data to irradiance, the lack of global information on the benthic
nepheloid layer, and the relatively limited biological information available,
are discussed. |
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