REU 2013 Incubation ProjectKatie HuskAdvisor: Dr. Diane McKnight

The Effects of Nutrient Deposition on Alpine Lakes

Presentation: Katie Husk

Diane McKnight, Katherina Hell, Rylee Archuleta2013 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 NaH2PO4 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

5 6 7 8 9 10 110.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

18-Jul 25-Jul

30-Jul

Temperature (°C)

Dis

tanc

e B

elow

Sur

face

(m

)

2m Cntrl A

Cntrl B

1.5A 1.5B 3A 3B 5A 5B 9.0

9.5

10.0

10.5

11.0

11.5

12.0t0

t5

Tem

pera

ture

(C)

pH Profile in GL4

5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.000

2

4

6

8

10

12

18-Jul

25-Jul

30-Jul

pH

Dis

tanc

e B

elow

Sur

face

(m

)

2m

Cntrl A

Cntrl B

1.5

A 1.5

B 3A

3B

5A

5B

5.00

5.50

6.00

6.50

7.00

7.50

8.00

8.50

9.00

9.50

t0

t5

pH

DO Profile in GL45 5.5 6 6.5 7 7.5 8

0

2

4

6

8

10

12

14

18-Jul 25-Jul

30-Jul

DO (mg/L)

Dep

th B

elow

Sur

face

(m

)

2m

Cntrl A

Cntrl B

1.5

A 1.5

B 3A

3B

5A

5B

4

4.5

5

5.5

6

6.5

7

7.5 t0

t5

DO

(m

g/L)

Fluorescence Index

2m Cntrl A Cntrl B 1.5A 1.5B 3A 3B 5A 5B1.30

1.35

1.40

1.45

1.50

1.55

t0

t5

Fluo

resc

ence

Ind

ex

Phytoplankton (Incomplete)Before Incubation After 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