Aquatic Sciences Meeting, Albuquerque 2001

SS16 Iron Bioavailability and Limitation to Primary Production (Disciplinary Connections)

Date: Monday, February 12, 2001, Time: 3:45:00 PM

Location: Mesilla

Bucciarelli, E, , LEMAR UMR CNRS 6539-IUEM,, Plouzané, France, Eva.Bucciarelli@univ-brest.fr

Blain, S, , LEMAR UMR CNRS 6539-IUEM,, Plouzané, France, Stephane.Blain@univ-brest.fr

Tréguer, P, , LEMAR UMR CNRS 6539-IUEM,, Plouzané, France, Paul.Treguer@univ-brest.fr

EFFECTS OF IRON-STRESS ON THREE SPECIES OF DIATOMS

The diatoms are one of the phytoplankton groups which responses dramatically in iron fertilisation. In addition, iron-stress may regulate the ratio of the silicic acid/nitrate uptake rates. The understanding of their responses to iron-stress has further implications for the estimate of the efficiency of the oceanic CO2 pump in major regions of the world ocean (i.e. HNLC system) as well as in paleoproductivity reconstruction. Culture laboratory experiments were conducted with two coastal diatoms : Thalassiosira pseudonana (centric diatom), Cylindrotheca fusiformis (pennate diatom) and an oceanic diatom, Thalassiosira oceanica (centric diatom) using the iron buffered medium AQUIL. Cultures were performed as triplicates with total iron concentrations in the medium ranging from 5 nM (iron stressed cell used as a control) to 500 nM (iron saturated medium).The ligth : dark cycle was 14h : 10h and the temperature maintained at 20°C. These cultures were filtered in the exponential phase. Specific growth rate, cellular volume, biogenic silica, particulate organic C and N, 32Si and 14C uptake rates (short-term incubations of 4 hours) were measured. The whole dataset is here discussed.

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Aquatic Sciences Meeting, Albuquerque 2001

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