Calibration procedures and first data set of Southern Ocean chlophyll-a profiles collected by elephant seal equipped with a newly developed CTD-fluorescence tags : Chlorophylla profiles collected by elephant seal in the Southern Indian Ocean : MEMO_Chla

• Main Authors: Guinet, Christophe, Xing, Xiaogang, Monestiez, Pascal, Marchand, Stéphane, Picard, Baptiste, Jaud, Thomas, Authier, Matthieu, Cotté, Cédric, Dragon, Anne Cécile, Diamond, Emily, Antoine, David, Lovell, Philipp, Blain, Stephane, Dortenzio, Fabrizio, Claustre, Hervé
• Format: Article in Journal/Newspaper
• Language: English
• Published: MEMO 2012
• Subjects: Fluorescence profiles; Chlorophyll a profiles; Southern Elephant Seal; Southern Ocean; Indian; Elephant Seal; Elephant Seals; Southern Elephant Seals
• Online Access: https://dx.doi.org/10.7491/memo.1; http://www.cebc.cnrs.fr/ecomm/Fr_ecomm/ecomm_memoOCfd.html

In-situ observation of the marine environment has traditionally relied on ship-based platforms. The obvious consequence is that physical and biogeochemical properties have been dramatically undersampled, especially in the remote Southern Ocean (SO). In this research program, we use an innovative sampling fluorescence approach to quantify phytoplankton concentration at sea. For the first time, a low energy consumption fluorometer was added to Argos CTD- SRDL tags, and these novel instruments were deployed on 27 southern elephant seals between 25/12/2007 and the 4/02/2011. As many as 3388 fluorescence profiles associated with temperature and salinity measurements were thereby collected from a vast sector of the Southern Indian Ocean. This paper address the calibration issue of the fluorometer before being deployed on elephant seals and present the first results obtained for the Indian Sector of the Southern Ocean. This in situ system is implemented in synergy with satellite ocean colour radiometry. Satellite-derived data is limited to the surface layer and is restricted over the SO by extensive cloud cover. However, with the addition of these new tags, we’re able to assess the 3 dimension distribution of phytoplankton concentration by foraging southern elephant seals. This approach reveals that for the Indian sector of the SO, the surface chlorophyll-a (chl-a) concentrations provided by MODIS were underestimated by a factor of the order of 2-3 compared to in situ measurements. The scientific outcomes of this program include an improved understanding of both the present state and variability in ocean biology, and the accompanying biogeochemistry, as well as the delivery of real-time and open-access data to scientists.