Juvenile coho salmon "dine and dash" to exploit thermal heterogeneity in streams

Transcription

1 Juvenile coho salmon "dine and dash" to exploit thermal heterogeneity in streams Jonny Armstrong PhD Candidate, School of Aquatic and Fishery Sciences University of Washington

2 Bristol Bay, Alaska

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4 Rapid advancements in the ability to quantify habitat heterogeneity

5 How do organisms interact with habitat heterogeneity? What about us?

6 Pulsed salmon subsidies

7 Sockeye subsidies: ephemeral pulse of high quality, vulnerable food Pulsed timing taxes processing The red wave systems

8 Fish require warmer temperatures to capitalize on resource pulses Joules/day Feeding capacity (Cmax) Net Profits: Cmax-Respiration Temperature (C)

9 The red wave How does thermal heterogeneity mediate the ability of coho salmon to exploit sockeye salmon eggs?

10 Wood River system streams: >10 C range in summer water temperature Armstrong et al Ecology P. Lisi in prep Wood River System

11 m upstream Headwaters of Bear Creek: low velocity, minimal shading = warm water, Beaver meadow complexes

12 m upstream 9C 3C Upwelling groundwater produces longitudinal variaeon in water temperature

13 m upstream: cold water and extensive off- channel habitat: groundwater seeps preclude any downstream warming

14 Temperature Distance upstream (m)

15 Sockeye per 200m Temperature Distance upstream (m) 7 6 5

16 Sockeye per 200m Temperature Distance upstream (m) 7 6 5

17 The spatial distribution of sockeye eggs in coho diets % ind s with egg in diet egg.prop Total # fish captured total "pink" pink Distance dist Upstream

18 The spatial distribution of sockeye eggs in coho diets % ind s with egg in diet egg.prop Total # fish captured total "pink" pink Distance dist Upstream

19 The spatial distribution of sockeye eggs in coho diets % ind s with egg in diet egg.prop Total # fish captured total "pink" pink Distance dist Upstream

20 The spatial distribution of sockeye eggs in coho diets % ind s with egg in diet egg.prop Movers? Total # fish captured total "pink" pink Distance dist Upstream

21 2008: Deploy PIT tag Antenna Arrays m: cold w/ sockeye m and up: warm w/o sockeye m: cold w/o sockeye

22 Feeding forays into the cold downstream region Age-1 coho salmon-- 24-July: 85 mm 7.1 g 21-Aug: 108 mm 17.6 g

23 Region 2 to Region 1 Frequency Start feeding foray 6:00pm 12:00am 6:00am 12:00pm Frequency Region 1 to Region 2 End Feeding Foray 6:00pm 12:00am 6:00am 12:00pm

24 Fish reside in warm water for 1-4 d between feeding forays Frequency Hours between downstream feeding foray

25 Fish reside in warm water for 1-4 d between feeding forays Why the long pause? Frequency Hours between downstream feeding foray

26 Shouldn t fish be done digeseng eggs aker 24 hours? Digestion of sockeye fry (1-2) Ration = 1-3 % body mass Ruggerone 1988

27 In situ measures of gastric evacuation: Fish can consume up to 17% of body mass in single meal Mass spec. stomach contents warm10c cold 6C post-feeding Time after feeding (h) Huge stomach capacity + slow processing of lipids explains long digestive pauses in Bear Creek coho

28 0.04 Diel Movers Stay Downstream Stay Upstream Unclassified Movers Natural Log of Growth Natural Log of Fish Mass

29 Successful coho don t compromise Habitat coupling: Combine favorable elements of different locations Predator physiology makes this possible: big stomachs for moving food from one habitat patch to another Food Abundance Gorge cold Digest warm Temperature

30 Diel movement: ubiquitous in lakes and oceans

31 What about fish behavior in streams? We need a better understanding of how fish behavior integrates across spatial and temporal variation in stream habitats

32 Why should we care about whether lotic organisms exploit habitat heterogeneity in their daily behavior? Lotic systems are some of the most threatened worldwide Understanding how fish exploit heterogeneity will help us restore it

33 Acknowledgements Adviser: Daniel Schindler Collaborators: Casey Ruff, Kale Bentley, Gabriel Brooks, Christian Torgersen Funding: NSF, Moore Foundation, SAFS