1 / 26

Elon M. Malkin, David H. Hollander, Ernst B. Peebles

Parallel Nitrogen Cycles in Southwest Florida’s Tidal Rivers: Selective Remineralization of Algal Material Supports Fish Biomass. Elon M. Malkin, David H. Hollander, Ernst B. Peebles University of South Florida College of Marine Science. Land Use. Southwest Florida:

mercia
Download Presentation

Elon M. Malkin, David H. Hollander, Ernst B. Peebles

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Parallel Nitrogen Cycles in Southwest Florida’s Tidal Rivers: Selective Remineralization of Algal Material Supports Fish Biomass Elon M. Malkin, David H. Hollander, Ernst B. Peebles University of South Florida College of Marine Science

  2. Land Use Southwest Florida: Land Development & Fisheries • Anthropogenic Land Development: • N Drains into receiving waters • 2. Estuarine Dependent Juvenile Fish: • Occupy Receiving Waters • Positively or negatively influenced by N • 3. Sedimentary N Processing: • N Transformation between land and fish • Study Questions: • What is the source of sedimentary recalcitrant nitrogen? • What is the source of sedimentary labile nitrogen? • Which of these pools are associated with fish production?

  3. Study Sites: 8 Watersheds Feather Sound Alafia River Wildcat Creek Curiosity Creek McMullen Creek Frog Creek Myakka River Peace River

  4. NH4+ NH4+ NH4+ NH4+ NH4+ NH4+ NH4+ NH4+ NH4+ SOM vs. Sedimentary Porewater NH4+ Sediment Porewater NH4+ (SedNH4+) Labile Sediment Nitrogen Pool NH4+ Recalcitrant Sediment Nitrogen Pool Sediment Organic Matter (SOM)

  5. 16 14 12 10 8 6 4 2 0 -2 0 2 4 6 8 10 12 SOM vs. Sedimentary Porewater NH4+ SOM δ15N SOM, ‰ AIR r2= 0.17 δ15N SedNH4+, ‰ AIR

  6. 1 2 3 1 2 3 1 2 3 What is the Source of Recalcitrant SOM? • Approach: δ15N System Averaging to Account for Advection • Sample Collection: (Primary producers, SOM) • Each primary producer δ15N value averaged across sites • Each SOM δ15N value averaged across sites • Mean values of 1oP plotted against mean SOM values Collection Sites 1 average value per 1oP 1 average value for SOM River A 1 average value per 1oP 1 average value for SOM River B 1 average value per 1oP 1 average value for SOM River C

  7. Microalgae is not Recalcitrant N 12 POM BMA r2= 0.45 10 8 r2= 0.33 δ15N, ‰ AIR δ15N Sedimentary Organic Matter, ‰ AIR 6 4 2 0 -2 2 2.5 3 3.5 4 4.5 5

  8. Vascular Plant Detritus is Recalcitrant N 12 Emergent Vegetation Upland Plants 10 8 δ15N, ‰ AIR r2= 0.83 δ15N Sedimentary Organic Matter, ‰ AIR 6 4 r2= 0.91 2 0 -2 2 2.5 3 3.5 4 4.5 5

  9. 1 2 3 1 2 3 1 2 3 What is the Source of Sedimentary Labile NH4+? • Approach: δ15N Site Specific Values to Maximize Data Points • Site Collections (various 1OP, sedimentary NH4+) • Site Specific Values of 1oP plotted vs. sedNH4+ Collection Sites 3 values per 1oP, porewater NH4+, SOM River A 3 values per 1oP, porewater NH4+, SOM River B 3 values per 1oP, porewater NH4+, SOM River C

  10. 16 14 12 10 8 6 4 2 0 -2 0 2 4 6 8 10 12 Upland Plant Detritus is Not Labile N Mangroves Upland Plants δ15N, ‰ AIR δ15N Sedimentary Porewater NH4+, ‰ AIR r2= 0.07 r2= 0.32

  11. 16 14 12 10 8 6 4 2 0 -2 0 2 4 6 8 10 12 BMA is Labile N r2BMA = 0.99 BMA δ15N, ‰ AIR δ15N Sedimentary Porewater NH4+, ‰ AIR

  12. 16 14 12 10 8 6 4 2 0 -2 0 2 4 6 8 10 12 POM is Labile N POM r2BMA = 0.68 δ15N, ‰ AIR δ15N Sedimentary Porewater NH4+, ‰ AIR

  13. Which N Pool Supports Fish Production? Approach: δ13C vs. δ15N plots for all available data: Benthic Microalgae (BMA) Particulate Organic Matter (POM) Fish vs. Upland Plants (UP) Mangroves (MAN) Emergent Vegetation (EM)

  14. Stable Isotopes Link 1oP to Fish 10 9 8 7 6 δ15N ‰ AIR 5 1OC (Benthic inverts) 4 3 2 ΔN=3‰ 3:1 per TL 1 0 1OP ΔC=1‰ -26 -25 -24 -23 -22 δ13C ‰ PDB

  15. Stable Isotopes Link 1oP to Fish 10 9 8 2OC (fish) 7 6 δ15N ‰ AIR 5 ΔN=3‰ 1OC (Benthic inverts) 3:1 per TL 4 3 ΔC=1‰ 2 ΔN=3‰ 3:1 per TL 1 0 1OP ΔC=1‰ -26 -25 -24 -23 -22 δ13C ‰ PDB

  16. What 1oP Support Fish Production? Fish 16 14 12 δ15N, ‰ AIR 10 8 6 4 2 0 δ13C, ‰ PDB -30 -28 -26 -24 -22 -20

  17. Mangroves Do Not Support All Fish Fish MAN 16 14 12 δ15N, ‰ AIR 10 8 6 4 2 0 δ13C, ‰ PDB -30 -28 -26 -24 -22 -20

  18. Emergent Plants Do Not Support All Fish Fish MAN EM 16 14 12 δ15N, ‰ AIR 10 8 6 4 2 0 δ13C, ‰ PDB -30 -28 -26 -24 -22 -20

  19. Fish MAN EM UP Upland Plants Do Not Support All Fish 16 14 12 δ15N, ‰ AIR 10 8 6 4 2 0 δ13C, ‰ PDB -30 -28 -26 -24 -22 -20

  20. Fish MAN EM UP Vascular Plants Do Not Support All Fish 16 14 12 δ15N, ‰ AIR 10 8 6 4 2 0 δ13C, ‰ PDB -30 -28 -26 -24 -22 -20

  21. TB & CH POM Microalgae Supports Fish Production Fish POM BMA 16 14 12 δ15N, ‰ AIR 10 8 6 4 2 0 δ13C, ‰ PDB -30 -28 -26 -24 -22 -20

  22. TB & CH POM Benthic Invertebrates are Intermediates Fish POM BMA INV 16 14 12 δ15N, ‰ AIR 10 8 6 4 2 0 δ13C, ‰ PDB -30 -28 -26 -24 -22 -20

  23. Conclusions: Parallel Nitrogen Cycles

  24. Vascular Plant Cycle: Recalcitrant OM is Buried Vascular Plants Bulk SOM Burial

  25. Microalgal Cycle: Labile OM is Remineralized POM Vascular Plants BMA Labile SOM Bulk SOM SedNH4+ Burial Recycle

  26. Foodwebs Are Associated with Labile Cycle POM Vascular Plants BMA Labile SOM Bulk SOM SedNH4+ Burial Recycle

More Related