Factors influencing the distribution and abundance of Daphnia middendorffiana in alpine lakes of the Canadian Rockies. Presented by Janet Fischer at the "Perth II: Global Change and the World's Mountains" conference in Perth, Scotland in September 2010.

1. Factors influencing the distribution and abundance of Daphnia
middendorffiana in alpine lakes of the Canadian Rockies
J.M. Fischer, M.H. Olson, J.C. Everhart, K.C. Rose, C.E.
Williamson, and R. D. Vinebrooke

2. Daphnia middendorffiana in fishless lakes
of the Canadian Rocky Mountains
• co-dominant crustacean species in fishless,
alpine lakes
• affected by temperature and DOM (which are
responding to climate change)

3. Daphnia
HNAN,
Ciliates
Phytoplankton
Bacterial Production
PNAN
CDOM

4. UV
Daphnia
UV screen
HNAN,
Ciliates
Phytoplankton
Bacterial Production
PNAN
CDOM

5. I. Spatial distribution
II.Temporal Dynamics
III.Short-term experiment
IV. Implications

6. I. Spatial Distribution
Survey of 9 deep, fishless,
alpine lakes in Yoho and Banff
National Parks
http://www.pc.gc.ca/eng/docs/v-g/dpp-mpb/sec4/dpp-mpb4d.aspx

7. I. Spatial Distribution
p=0.04
Survey of 9 deep, fishless,
alpine lakes in Yoho and Banff
National Parks
p=0.11 p=0.74

8. II. Temporal Dynamics
Pipit Lake, Banff National Park

9. II. Temporal Dynamics
Pipit Lake, Banff National Park
No significant
correlation with DOC or
chlorophyll

10. III. Short term experiment to explore mechanisms
2 Incubation Sites
Hungabee Oesa
• Contains Daphnia • Daphnia absent/rare
• Warmer, Higher DOM • Colder, Lower DOM
3 Water Sources
Hungabee water, Oesa water, DOM-amended Oesa water

11. 2x3 Factorial Design crossing Incubation Site and Water Source
5 replicates per treatment
11 day incubation at 0.5 m
Measured juvenile growth rate of Daphnia, a metric highly correlated
with population growth rate (Lampert and Trubetskovia 1996)

13. Incubation site

14. Incubation site
Incubation site p<0.001

15. Incubation site
Incubation site p<0.001
Water source p=0.005
Incubation x water ns

16. Incubation site
Incubation site p<0.001
Water source p=0.005
Incubation x water ns

17. Distribution and abundance of Daphnia middendorffiana in
alpine lakes of the Canadian Rockies
I. Spatial survey
• positive effect of DOC
II. Temporal dynamics in Pipit Lake
• positive effect of temperature
III. Short-term experiment
• Effect of incubation site (Temperature and/or UVR)
• Effect of water source
• Not a simple effect of cDOM

18. Climate-driven variation in temperature, precipitation,
treeline, hydrology
Key physical/chemical variables in lakes such as
water temperature, DOC, nutrients, water transparency
Daphnia presence/absence, abundance, and juvenile growth
Daphnia = a powerful
indicator of biotic
consequences of
climate change in
alpine lakes