One-year seasonal survey of the chlorophyll photodegradation process in the northwestern Mediterranean Sea - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Deep Sea Research Part II: Topical Studies in Oceanography Année : 2002

One-year seasonal survey of the chlorophyll photodegradation process in the northwestern Mediterranean Sea

Philippe Cuny
Jc Marty
  • Fonction : Auteur
  • PersonId : 861906
  • IdRef : 153584017
J Chiaverini
  • Fonction : Auteur
I Vescovali
  • Fonction : Auteur
D Raphel
  • Fonction : Auteur
Jf Rontani

Résumé

Particulate samples from the water column were collected monthly from depths of 5-150 m, between May 1996 and March 1997, in the northwestern Mediterranean Sea (Ligurian Sea) as part of the DYFAMED project within the French JGOFS program. These samples were analyzed by gas chromatography-electron impact mass spectrometry for their phytol and 3-methylidene-3,7,11-trimethylhexadecan-1,2-diol (phytyldiol) content. The corresponding Chlorophyll Phytyl side chain Photodegradation Index, molar ratio of phytyldiol to phytol, was calculated and the mean amount of chlorophyll photodegraded within the euphotic zone estimated. Seasonal differences in the chlorophyll photodegradation process appear in the one-year study. The chlorophyll appeared more photodegraded in the surface water (generally more than 40% photodegraded at 5-10m) than at the deep chlorophyll maximum (DCM) (40-50m) observed in the summer stratified waters (about 20% photodegraded). This difference was attributed to the healthy state of the phytoplankton community (coincidence with the highest primary production levels) and to the lower intensity of irradiance at the DCM level. On the other hand, the bulk of the detrital chlorophyll (chlorophyll associated with phytodetritus, phaeopigments) undergoes photodegradation before it sinks out of the photic zone. However, in January (winter mixed water) the pigments exported towards the sea floor were less photodegraded. This is thought to result from a shorter period of residence of the pigments in the photic zone due to vertical convection and grazing activity of macrozooplankton (salps), which are producers of rapid sinking fecal pellets. (C) 2002 Elsevier Science Ltd. All rights reserved.

Domaines

Océanographie

Dates et versions

hal-03483013 , version 1 (16-12-2021)

Identifiants

Citer

Philippe Cuny, Jc Marty, J Chiaverini, I Vescovali, D Raphel, et al.. One-year seasonal survey of the chlorophyll photodegradation process in the northwestern Mediterranean Sea. Deep Sea Research Part II: Topical Studies in Oceanography, 2002, 49 (11), pp.1987-2005. ⟨10.1016/S0967-0645(02)00023-1⟩. ⟨hal-03483013⟩
19 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More