The effect of interactions between iron and three different DOMs on the coastal phytoplankton community in a marine mesocosm.
| Project acronym: | HyIII-NTNU-3 |
| Name of Group Leader: | Dr. Bizsel Nihayet, Dokuz Eylul University.Institute of Marine Sciences and Technology, Izmir, Turkey. nihayet.bizsel@deu.edu.tr Dr. Selin Sayin, The University of Mustafa Kemal, Faculty of Fisheries, Serinyol-Hatay, Turkey. ssayin@mku.edu.tr |
| User-Project Title: | The effect of interactions between iron and three different DOMs on the coastal phytoplankton community in a marine mesocosm. |
| Facility: | Research Vessel |
| Proceedings TA Project: | Response of phytoplankton community in trondheim fjord to various ironorganic matter combinations in the mesocosm experiment |
| Data Management Report: | Data Management Reports Page You will need to login to view this page |
Summary:
The main goal of the experiment is to determine the response of coastal phytoplankton to changes in the iron bioavailability when coastal iron reacts with different DOMs. For this purpose, a mesocosm experiment was performed by enriching experimental subsets with iron and three different types of the DOMs in order to manipulate the chemistry of iron and its bioavailability.
The experiment was conducted by culturing a natural phytoplankton assemblage sampled from Trondheim Fjord by the R/V Gunnerus. A medium with natural P:N:Si:Fe level (control) and in mediums enriched with P:N:Si to avoid nutrient limitation, but with or without additions of Fe or DOMs were the experimental subsets. In order to assess the effect of DOMs on the marine phytoplankton community, the following DOMs were used:
- Riverine humic acids, (NOM+Humic acid).
- Hexadentate siderephore, (Siderephore Desferroxiamine).
- Bidentate siderophore (such as L-lysine Hydroxamic acid), (SiderephoreLysine).
Chelex-100 labile Fe and Fe(II) (the most bioavailable Fe form) were measured during the experiment. The variation of Chl a and in vivo fluorescence in different subsets showed that Siderephore Desferroxiamine with Fe or without Fe have a strict differences when it was compared the other treatments. All three Fe forms were made non-bioavailable by Siderephore Desferroxiamine. On the other hand, SiderephoreLysine did not affect the bioavailability of Fe. Presence of NOM+humic acid + Fe resulted the highest phytoplankton biomass and growth rate with maximum Chl a values. Whether or not, there is an effect of various DOM+Fe complexation on the species distribution in the Trondheim fjord water will be clarified after completion of HPLC analysis and phytoplankton countings. During the 10 days experiment (06/08/08-15/08/07), temperature and daily averaged light intensity were also measured and they decreased from 16.5 to 13°C and from 1.41E+20 to 8.30E+18, respectively. Phytoplankton counting has still been continued. HPLC and POC analysis have not been completed yet.