Ian A. FlemingDepartment of Ocean Sciences

Memorial University of NewfoundlandSt. John’s, NL

(ifleming@mun.ca)

Role of Habitat Complexity (environmental enrichment) in Salmon Development

Photo by van Ryckevorsel

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Reshaping of Fish

Morphology, physiology, behaviour, life history …

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• But how early does this begin?

Habitat complexity – Early life

Shaping of the phenotype• Morphology• Behaviour• Neural development• Gene expression

Captive - simple

Nature – complex(gravel)

Fitness consequences

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IncubationSimple versus complex (gravel)

• Eggs common pool (85 crosses)• 4,000 eggs per incubation unit

Results – morphology(start of exogenous feeding)

Simple Complex P .

Weight (g) 0.189 < 0.199 < .01*Length (cm) 2.94 ≤ 2.96 = .08Condition -0.012 < 0.016 < .01*(residuals)

Gravel-incubated fish: heavier & higher condition

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Gravel-incubated fish: enhanced feeding & more risk adverse

Results – behaviour(start of exogenous

feeding)

Simple Complex P . Feeding (novel live prey) 74% < 47% = .02*

Simulated PredatorReacted 84% = 90% = .48Sought shelter 59% = 63% = .80 Reemergence (s) 204 < 252 < .01*

Results – brain volume(start of exogenous feeding)

No difference in brain volume

(absolute and size-corrected measures)P .

Whole brain 0.11 - 0.68Telenchepalon 0.68 - 0.73Olfactory bulb 0.76 – 0.83

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Rearing environment affects gene transcription

• degree of response is highly dependent on genetic background

Summary

Incubation environment shapes:• Body morphology (movement, shelter, stress)

• Behaviour (stimulation & complexity)

• Gene expression• BUT not brain volume (cell proliferation,

neuron number, dendrite length )

Do these phenotypic responses translate into performance (growth and survival) in semi-natural

conditions?

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Fitness - Semi-natural streams(start of exogenous feeding)

• 8 replicate streams• 40 simple & 40 complex fish per stream• 42 days

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Results

p = 0.04*

Gro

wth

rate

–le

ngth

(% /

day)

Complex ComplexSimple Simple

Sur

viva

l (#

fish)

48.1% 39.7%

p = 0.03*

Survival Growth

Gravel incubated fish: higher survival & faster growthin semi-natural streams

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Can such effects persist to later life

stages & in nature?

Release experimentSMOLTPRO

0.00%

2.00%

4.00%

6.00%

8.00%

10.00%

12.00%

14.00%

CCC CCS CSC CSS SCC SCS SSC SSS

Overwinter recapture (%)

B B B

P = 0.03

Survival (260 days)

A

A

% re

capt

ured

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

CCC CCS CSC CSS SCC SCS SSC SSS

Mean SGR adjusted for initial size

C

Specific Growth Rate (260 days)S

peci

fic G

row

th R

ate

(% d

ay-1

)

A AAAB

ABCABC

BC

P < 0.01

Conclusions & Implications

• Incubation environment profound effects on phenotype

• Affects subsequent survival and growth (fitness)

• Density however may be more important than structure as fish grow

• Captive rearing environments can be altered to promote phenotypic traits that may be more favourable in nature

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Acknowledgements

Mactaquac Biodiversity Facility staff

Graduate student: John Winkowski Postdoctoral fellow: Melissa Evans

Funding Agencies:

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The collaborators: Jörgen Johnsson & the SMOLTPRO team