1 / 19

Carbon Isotope Variations in Aquatic Plants: Applications

Explore the role of δ13C in sea plants and the impact on marine ecosystems, including benthic vs. pelagic productivity and food sources for coastal animals. Understand how changes in δ13C affect phytoplankton growth rates and productivity in the Bering Sea.

omann
Download Presentation

Carbon Isotope Variations in Aquatic Plants: Applications

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. Carbon Isotope Variations in Aquatic Plants: Applications Onshore-Offshore (Benthic vs. Pelagic?) Kelp forest ecology Decreased productivity in the Bering Sea? Phytoplankton 13C from whale baleen and seal teeth?

  2. Compilation of 13Cfor Freshwater Algae Freshwater benthic algae from lakes are more 13C-enriched than benthic algae collected in rivers One possible mechanism: development of a "stagnant boundary layer" in less turbulent waters restricting the rate of CO2 diffusion and requiring use of 13C-enriched of CO2 pool [France, 1995]

  3. Compilation of 13Cfor Marine Algae In coastal marine areas, 13C values of benthic algae are +5‰ higher than average planktonic 13Cvalues Planktonic 13C = -22 ± 4‰ Benthic 13C = -17 ± 3‰ [France, 1995]

  4. Food Sources for Coastal Marine Animals d13C values of consumers can be used to indicate food source Fish: Offshore = primarily planktonic food source Seagrass = some primarily planktonic, some primarily benthic Invertebrates: Offshore = primarily planktonic food source Seagrass = primarily benthic food source [France, 1995]

  5. Foley & Koch (in press)

  6. Highly variable inputs seasonally

  7. Foley & Koch (in prep)

  8. Carbon Isotope Record from Whale Baleen • Baleen plates contain a continuous record of dietary 13C/12C • Arctic bowhead whales - feed on zooplankton - migrate seasonally WINTER SUMMER [Kroopnick, 1985; Ravelo & Andreasen, 2000]

  9. Composite record constructed using presumed winter 13C values (most positive in cycle) from many baleen plates (n = 37) Whale got these values while occupying the Bering Sea "Summer" values not used because of apparent disagreement between different specimens [Schell, 2000]

  10. Interpretation 2.7‰ decline in 13Cphytoplankton from 1966 to 1997 Assumes: 1) constant offsets b/w 13Cbaleen, 13Czoo,and 13Cphyto 2) No change in plankton species composition/ abundance 3) Constant surface 13CDIC 4) Whales spent winter in roughly the same place every year [Schell, 2000]

  11. 2.7‰ decrease in 13Cphytoplankton What does it mean? • Schell [2000] interprets an increase in p related to a decrease in phytoplankton growth rates () • Infers a 30-40% decrease in productivity between 1966 and 1997 in the Bering Sea http://visibleearth.nasa.gov/Regions/Bering_Sea/350.html

  12. [Popp et al., 1998] [Laws et al., 1995]

  13. What about changes in [CO2(aq)] andsurface 13CDIC? p dependent upon: - growth rate - [CO2(aq)] Cullen et al. [2000] suggest that 13Cphyto was decreased over the last 30 yrs due to a combination of: - increase in [CO2(aq)] (resulting in an increase in p) - decrease in 13CDIC Both effects result from increased pCO2 and invasion of anthropogenic CO2 into surface waters [Cullen et al., 2001]

  14. [Zeebe & Wolf-Gladrow, 2001]

  15. Schell Responds No evidence for decrease in 13CDIC or increase in [CO2(aq)] in the north Pacific - Not enough time for atmospheric equilibration in regions of vigorous vertical mixing - Similar decline in 15Nbaleen (however, note low 15N values in the late '40s) [Schell, 2001]

  16. Newsome et al. (2007)

  17. Newsome et al. (2007)

More Related