1. Title slide Wayne Wurtsbaugh & Michelle Baker Utah State University
TOPO-MORPHOMETRIC ANALYSIS OF
LAKE-STREAM INTERACTIONS
IN ALPINE WATERSHEDS
Title slide
Wayne Wurtsbaugh & Michelle Baker
Utah State University

2. Stream Ecologists are from Saturn…
Limnologists are from Mercury
Noted
Stream Ecologist
Normal Lake
Limnologist
With limited exceptions stream ecologists and lake limnologists don’t talk to each other, despite the fact that the flowing and lacustrine ecosystems are often closely linked in time and space.

3. Landscape Approaches to Limnology
Recent Advances
Landscape Approaches to Limnology
Kratz et al. 1991, 1997
Soranno et al. 1999
Hershey et al. 1999
Riera et al. 2000 }
Lake placement
in the watershed
Baron and Campbell 1997
Hillbricht-Ilkowska 1999
Kling et al
Chemical interactions across stream-lake landscapes {
Richardson & Mackay 1991
Insect communities & processes at lake outlets
Fisher (1997)
Wiens (2002)
Landscape ecology
of streams

4. An important question: How do complex patterns of lakes and streams influence ecosystem function?
Boulder Chain Lakes Watershed, White Cloud Mountains, Idaho A B E C D

5. Study site
Sawtooth
Mountains, ID
Boise
Logan

6. Glaciated watershed map
Glaciated Salmon River Watersheds
1 to 25 lakes
Mean inter-lake
distance = 2.8 km
Glaciated watershed map
Sawtooth
Mountains, ID

7. Methods: Morphometric Estimates
Lake Volumes
Stream Areas, Depths & Volumes
Stream Order
Width (m)
Depth (m)

8. PHYSICAL COMPARISONS OF WATERSHEDS WITH AND WITHOUT MAJOR LAKES
Watershed Volumes Residence Time
(1000 m3) @ mean discharge (days)
Stream Lakes % lake
“Lakeless” (N. Alturas) %
Yellow Belly %

9. PHYSICAL COMPARISONS OF WATERSHEDS WITH AND WITHOUT MAJOR LAKES
Radiation / airshed Watershed Interaction Interaction Strength Strength
Area (ha) Perimeter (km)
Watershed
Streams Lakes % Stream Lakes %
Lake Lake
“Lakeless” % % (N.Alturas)
Yellow Belly % %
PHYSICAL COMPARISONS OF WATERSHEDS WITH AND WITHOUT MAJOR LAKES

10. Significance: (1) How do lakes influence watershed temperatures?
Yellow Belly L.
Stanley
Lake X
Thermistors
Yellow Belly
watershed
Stanley Creek
watershed
Brian Heiland, UC Davis

11. Effect of Lakes on Watershed Temperatures Data of Brian Heiland (UCD) 2000
Yellow Belly Watershed
Stanley Watershed

12. So What? Trout growth: 6°  12°C, +370% (Elliott 1994)
Adams et al Ecosystems

13. Yellow Belly Creek Watershed
(2) Lakes are dissolved nutrient traps whereas streams are “sources” of dissolved nutrients 16
2.5
2.0 12
Temp
1.5
Temperature (°C)
NO3 (µM) ± S.E. 8
1.0 4
NO3
0.5
Yellow Belly Creek Watershed
Lake
Lake
Lake 2 4 6 8 10 12
Distance from inflow of headwater lake (km)
Yellow Belly Watershed

14. (3) When present, lakes dominate aquatic primary production
This figure must have
an error in it--check
Areal production
Watershed
production
- Lake -
-Stream
“Lakeless”
Stream productivity: Minshall et al. 1992
Lake productivity: Wurtsbaugh (unpublished)

15. Lake seston is removed relatively slowly
(4) A large proportion of streams in these watersheds are under the influence of seston exported from lakes
Lake seston is removed relatively slowly
At 0.35 m3 s-1, Maciolek & Tunzi 1968

16. Watersheds with more lakes have had higher TN at terminal end
The influence of lakes
2003 Baseflow
Watersheds with more lakes have had higher TN at terminal end

17. Summary
When lakes are present in watersheds, they dominate water area & volume of the channalized flow, and thus interactions with radiation & gas exchange. The large volumes greatly increase water & nutrient residence times.
Streams dominate perimeters & thus interaction with the terrestrial watershed
Many ecological functions are dependent on lake-stream interactions
The spatial patterning of streams and lakes is thus a crucial factor influencing watershed function

18. Closing photo