REU 2013 Incubation Project Katie Husk Advisor: Dr. Diane McKnight The Effects of Nutrient Deposition on Alpine Lakes Presentation: Katie Husk Diane McKnight, Katherina Hell, Rylee Archuleta 2013 Environmental REU

Outline Introduction Site Description Project Overview Methods Project Shortcomings Results Future Considerations

Background Alpine lakes are important indicators of climate change ▫Harsh conditions ▫Small changes in atmospheric composition result in drastic changes in algae types/quantities ▫Ice out timing/lake temperature ▫Nutrient deposition from snowmelt

Green Lake 4 Alpine lake- el 11,700ft Oligotrophic Part of Boulder Watershed 4 mi East of Continental Divide West of large metropolitan area– Denver, Fort Collins, Colorado Springs Part of NWT-LTER since 1951 Studied by INSTAAR since 2000

Regular Sampling- Every Week by INSTAAR Samples ▫DOC ▫DOM ▫Nutrients ▫Phytoplankton ▫Chlorophyll a Measurements ▫pH ▫Conductivity ▫Light ▫DO ▫Temperature ▫Secchi Depth Locations ▫Inlet of Lake ▫Outlet of Lake ▫Surface ▫3m ▫9m

My Project Incubate phosphorus enriched carboys at 2m to test the effects of nutrient deposition on alpine lakes Hypothesis: Increased phosphorus deposition will accelerate the growth of algae, which will in turn affect the composition of the lake by adjusting the levels of DO, DOC, DOM pH, etc. as well as contribute to increased nitrogen uptake.

Why This Experiment? Phytoplankton are phosphorus limited rather than nitrogen limited (Gardner et al., 2008.) Phosphorus deposition is linked to pollutants such as aerosols and other anthropogenic sources GL4 not directly influenced by anthropogenic activities Nutrient deposition could affect quality of water from watershed ▫DOM-Alkalinity, Taste, Odor, Smell, Bi-products ▫pH ▫Lake eutrophication Could affect how water must be treated in the future

Incubation Methods Construct Raft Make NaH 2 PO 4 Solution ▫0.1g/250mL Spike carboys ▫2 Controls ▫2 1.5umol/L (9mL solution) ▫2 3 umol/L (18mL solution) ▫2 5 umol/L (30mL solution) Sample each carboy Hang carboys on raft to incubate Sample each carboy when return to lake

Samples Taken ▫Chlorophyll a ▫Phytoplankton ▫DOC ▫Nutrients ▫DOM ▫pH ▫Conductivity ▫Temperature ▫DO ▫Light

Filtering and Processing Methods Filtered and refrigerated at INSTAAR upon return Chlorophyll-a processed by Kathi Nutrients processed by Kiowa Lab Phytoplankton processed using FlowCam DOC using fluorometer (3-D Fluorescence Spectroscopy and UV-VIS Scan)

Where It All Went Wrong Very late Ice-Out ▫Could not begin until late July Weather ▫Battling the current ▫Had to leave due to lightning ▫Less sun got to incubation Buoys and buoyant carboys ▫Couldn’t get to sink so attached rocks ▫Too much weight for buoys, entire raft sank ▫Only retrieved one 5 umol/L and one 3 umol/L on return trip, from 4.9 meters

Temperature Profile in GL4

pH Profile in GL4

DO Profile in GL4

Fluorescence Index

Phytoplankton (Incomplete) Before IncubationAfter Incubation About 10 slides/ 5mL Mostly phytoplankton colonies About 1300 slides/ 5mL Diverse species ▫Phytoplankton ▫Diatoms ▫Cilliates ▫Etc…

Conclusions Increase in phosphorus  ▫Increase in phytoplankton growth  ▫Increase in phytoplankton respiration  ▫Increase in pH ▫Increase in autochtonous DOM ▫Eutrophication of lake Implications ▫Economic- Water treatment infrastructure ▫Environmental- Lake eutrophication

What Is Still Missing? For next incubation ▫Incubate in better weather ▫Phosphorus quantity specific results ▫Repeated results? For my return to Boulder ▫Increased Nitrogen uptake? ▫Specific changes in algal species

In the future… In the Future… Smaller Carboys Handles for the carboys More buoys

Acknowledgements Advisor: Diane McKnight Supervisor: Katherina Hell Grad Student Mentor: Rylee Archuleta Pack Mules: Chris Jaros, Rob Spencer, Katie Li, and William McKnight Driver: Nel Raft Design/McGuckins runner: Steven Crisp