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Effects of Drought on Diatom Diversity, Distribution and Population Density

Effects of Drought on Diatom Diversity, Distribution and Population Density. Brennan Davis University of New Mexico. Drought. Seasonal drought is predictable; organisms can adapt. Supra-seasonal drought is unpredictable and unrelenting.

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Effects of Drought on Diatom Diversity, Distribution and Population Density

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  1. Effects of Drought on Diatom Diversity, Distribution and Population Density Brennan Davis University of New Mexico

  2. Drought • Seasonal drought is predictable; organisms can adapt. • Supra-seasonal drought is unpredictable and unrelenting. • Drought can increase ion concentrations in natural waters. Graph: Lake, 2003

  3. Drought in New Mexico • New Mexico is in a period of severe supra-seasonal drought. • On the Sevilleta NWR, three springs have dried completely from 2012 to 2013.

  4. Diatoms • Diatoms are photosynthetic organisms. • They are widespread, prolific and diverse. • Diatoms are good indicator organisms, as they are sensitive to changes in water quality.

  5. Questions • How has diatom diversity changed from 2012? • How has drought affected ion concentrations? • How does water quality and chemistry affect diatom density?

  6. Locations • 1 spring and 10 drinkers on the Sevilleta National Wildlife Refuge.

  7. Water Sampling • Three water samples were collected from each source. • Field instruments were used to collect water quality measurements at the time of sampling.

  8. Different Substrates & Surroundings CHEMISTRY?

  9. Diatom Sampling • Sample twice at each water source. • Sampler choice depends on substrate. • Process samples. • Prepare slides. • Identify diatoms and calculate density.

  10. Vegetation and Scat Transects • 4 transects performed at each water source. • Percent cover of vegetation and scat, as well as rough ID performed. • Gives insight into nutrient inputs and water usage.

  11. Results Ordination of Relative Abundance Final stress: 9.95

  12. Genus Richness

  13. Dominant Taxa Nitzsciaperminuta Planothidiumlanceolatum Achnanthidium spp. Rhopalodiagibba Epithemia spp.

  14. Habitat Quality Water quality measures, such as turbidity and salinity, varied from each water source. Three different substrate types were sampled. Surrounding habitat varied by water source; vegetation and scat levels were inconsistent.

  15. Turbidity and Salinity

  16. Substrate • Three different substrate types were sampled. • Flat steel, sediment and wood substrates were sampled; the substrate differed at each source.

  17. Vegetation and Scat

  18. Chemistry Reminder: drought can increase concentration of ions in water. Ions that facilitate algal growth: Cu, V, and Ni, among others not present in refuge waters.

  19. Copper

  20. Vanadium

  21. Boron

  22. Conclusions • Observed diversity increased from 2012 to 2013. • Differences in experimentation. • Ion concentrations have increased from 2012 to 2013. • Increases in beneficial ions may lead to higher diatom density. • Drought may therefore benefit some diatoms to a point.

  23. Future Directions Sample over time to observe diatom reactions to drought on a temporal scale. Test water chemistry over time to observe changes in ion concentrations. Perform vegetation and scat transects at time of water and diatom sampling. More sampling will also contribute to more robust data.

  24. Acknowledgments Lead P.I.: Dr. Scott Collins Mentor: Dr. Rebecca Bixby Program Manager: Amaris Swann Field Partner: Briana Albini

  25. Questions?

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