Seagrass Systems under Nutrient Loads and Grazing Marjolijn Christianen, 1th October 2007, NIOO Promoters:  Prof. Dr. P. H...
Importance of Seagrass
Increased Nutrient and Sediment loads
 
Berau delta:  and <ul><li>1.2 million hectare MPA (2005) </li></ul><ul><li>Zoning plan  </li></ul><ul><li>Initiated by loc...
Turtle Conservation <ul><li>Largest nesting + feeding ground </li></ul><ul><li>10-20% of population remained </li></ul><ul...
Pilot Study 2003 EKP <ul><li>With increasing river influence: </li></ul><ul><li>Seagrass cover   ,  </li></ul><ul><li>Num...
Hypothesis <ul><li>Shifts between different states </li></ul>
Hypothesis (2) <ul><li>Direct  toxicity of nitrogen  to seagrass occurs at environmentally relevant concentrations in trop...
Method <ul><li>Test the validity of the general hypotheses in: </li></ul><ul><li>Field  experiments: sites representing 4 ...
Method (2) <ul><li>Provoke shifts  </li></ul><ul><li>Nutrients (N, P) </li></ul><ul><li>Shade  </li></ul><ul><li>Compare g...
Results <ul><li>Used to validate hypotheses </li></ul><ul><li>Provide thresholds for shifts, which can be used for: </li><...
Vragen? Questions?
Seagrass Condition Berau Delta  (2000)
Seagrass species Thalassia hemprichii Halodule uninervis Cymodocea rotundata © Arie Vonk 2004
 
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Seagrass under nutrient load and grazing

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A brief presentation for master students in Biology

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  • Today it is the first day for me to work on my Phd project. My project is about seagrass, in particular how tropical seagrass manages itselves under nutrient and sediment loads and grazing. With this presentation I want to give insight in the problems that seagrass is coping with in the Berau delta, Kalimantan, Indonesia, the actions that are undertaken by NGO’s (non-govermental organisations) and how my project is fitting into the whole.
  • Seagrass under nutrient load and grazing

    1. 1. Seagrass Systems under Nutrient Loads and Grazing Marjolijn Christianen, 1th October 2007, NIOO Promoters: Prof. Dr. P. Herman, Prof. Dr. J.G.M. Roelofs Supervisors: Dr. M.M. Van Katwijk, Dr. T.J. Bouma, Dr. L.P.M. Lamers Counterparts: Dr. S. Wouthuyzen, Dr. M. Hutomo
    2. 2. Importance of Seagrass
    3. 3. Increased Nutrient and Sediment loads
    4. 5. Berau delta: and <ul><li>1.2 million hectare MPA (2005) </li></ul><ul><li>Zoning plan </li></ul><ul><li>Initiated by local people, bottom-up </li></ul><ul><li>Enhancing managing capacity of local government and communities </li></ul><ul><li>Enforcing existing Indonesian laws </li></ul><ul><li>Raising awareness. </li></ul>
    5. 6. Turtle Conservation <ul><li>Largest nesting + feeding ground </li></ul><ul><li>10-20% of population remained </li></ul><ul><li>Threats: </li></ul><ul><li>Turtle egg and meat intake </li></ul><ul><li>Caught during fishing </li></ul><ul><li>Diseases </li></ul><ul><li>Habitat loss (seagrass beds, nesting beaches) </li></ul>(c) WWF Indonesia
    6. 7. Pilot Study 2003 EKP <ul><li>With increasing river influence: </li></ul><ul><li>Seagrass cover  , </li></ul><ul><li>Number of seagrass species  , </li></ul><ul><li>Species composition changed; </li></ul><ul><li>Nitrogen content of above ground seagrass tissues  </li></ul>These variables are therefore potential indicators for river influence.
    7. 8. Hypothesis <ul><li>Shifts between different states </li></ul>
    8. 9. Hypothesis (2) <ul><li>Direct toxicity of nitrogen to seagrass occurs at environmentally relevant concentrations in tropical seagrass beds; a positive feedback increases vulnerability to nitrogen loads, </li></ul><ul><li>Strong grazing may protect seagrass meadows from overgrowth by epiphytes, increasing critical loads, </li></ul><ul><li>Under increased organic loading of the sediment, iron deficiency may push the system in a state of increased sulphate reduction , a positive feedback may arise through sulphide toxicity effects and decreased aeration of the rhizosphere. </li></ul>
    9. 10. Method <ul><li>Test the validity of the general hypotheses in: </li></ul><ul><li>Field experiments: sites representing 4 states </li></ul><ul><li>Mesocosm experiments </li></ul>
    10. 11. Method (2) <ul><li>Provoke shifts </li></ul><ul><li>Nutrients (N, P) </li></ul><ul><li>Shade </li></ul><ul><li>Compare grazed - non-grazed </li></ul><ul><li>Primary production seagrass </li></ul><ul><li>Biomass epiphytes and macro algae </li></ul><ul><li>Tissue contents (plant stress) </li></ul><ul><li>Morphology </li></ul>
    11. 12. Results <ul><li>Used to validate hypotheses </li></ul><ul><li>Provide thresholds for shifts, which can be used for: </li></ul><ul><ul><li>Modeling </li></ul></ul><ul><ul><li>Management </li></ul></ul><ul><ul><li>Assessment of restoration possibilities in disturbed areas </li></ul></ul>
    12. 13. Vragen? Questions?
    13. 14. Seagrass Condition Berau Delta (2000)
    14. 15. Seagrass species Thalassia hemprichii Halodule uninervis Cymodocea rotundata © Arie Vonk 2004

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