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The feeding ecology and physiology of vagrant Chaetodon species on temperate
New South Wales reefs
Marcus A Gregson
Dept Environmental Sciences
Institute for Water and Environmental Resource Management
University of Technology, Sydney
Supervisors:
Professor David J Booth (UTS)
Dr Morgan S Pratchett (James Cook University)
Introduction
•East Australian Current
•Vagrant Species
CSIRO Images
Heath Folpp, NSW Fisheries
Feeding Interactions
Morphological Factors Environmental Factors
•Body size and energy needs
•Digestive/ buccal system
•Presence of suitable prey
•Environmental conditions
Prey Intake
Growth and Condition
Adapted from Drickamer et al 2002
•Competitors
•Predators
Social Factors
Current Study
Latitudinal differences in feeding ecology of juvenile Chaetodons
H0i: Chaetodon diet does not differ between tropical and temperate regions
H0j: Difference in diet does not affect Chaetodon growth or condition
Study Species
www.daveharasti.comRandall JE, www.fishbase.org
Chaetodon auriga Chaetodon flavirostris
Family: Chaetodontidae
Methods
Locations
•Sydney (3 sites)
•One Tree Island (3 sites)
Melbourne
Canberra
SYDNEYNewcastle
Brisbane
ONE TREE ISLANDRockhampton
Townsville
Cairns
Hobart
MethodsH0i: Chaetodon diet does not differ between tropical
and temperate regions• Food Intake: Bite Rate• Potential Prey: Grazing Surface• Actual Diet: Gut Content Analyses
H0j: Difference in diet does not affect Chaetodon growth or condition• Body Condition: Fulton’s Condition k
H0i: Chaetodon diet does not differ between tropical and temperate regions
Bite Rate
0
2
4
6
8
10
12
14
16
18
20
22
Sydney One Tree Island
Mea
n B
ite R
ate
(5 m
in)
C. auriga
C. flavirostrisn=42 n=16n=27 n=10
Factor p
Location 0.293
Species 0.829
Location*Species 0.547
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Pro
po
rtio
n o
f T
ota
l B
ites
0
0.1
0.2
0.3
0.4
0.5
0.6
Bare EncrustingCoralline
Sediment MacroAlgae
Amphiroaanceps
Othercoralline
Turf algae
Pro
port
ion
of T
otal
Bite
s
C. flavirostris
Sydney
C. auriga
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Pro
po
rtio
n o
f T
ota
l B
ites
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Scleractinia CoralRubble
Sediment Rhodolith MacroAlgae
Pro
po
rtio
n o
f T
ota
l B
ites
One Tree Island
C. auriga
C. flavirostris 0
0.1
0.2
0.3
0.4
0.5
0.6
Bare EncrustingCoralline
Sediment MacroAlgae
Amphiroaanceps
Othercoralline
Turf algae
Pro
po
rtio
n o
f T
ota
l Bit
es
Prey Items Found in the Field
1 mm 1 mm
1 mm1 mm 1 mm
Gut Content Analyses: Chaetodon aurigaMean Volume at Sydney and One Tree Island
Sydney
Coral
Unidentif ied
Crustacea
Polychaete
Polychaete Setae
One Tree Island
Sydney Ranking Index
(occurrence X volume) (Harmelin-Vivien & Bouchon-Navaro 1983)
Coral 0
Unidentified 316
Crustacea 160
Polychaete 9221
Polychaete Setae 13
1 mm
n=9
n=11
H0i: Chaetodon diet does not differ between tropical and temperate regions
Gut Fullness: Chaetodon auriga
t = 3.04, df=11, p= 0.011
0
2
4
6
8
10
12
14
16
One Tree Island Sydney
Mea
n G
ut
Fu
lln
ess
Ind
ex
(100
0*[G
CW
/(W
T-G
CW
)])
n=9n=11
t= -3.04, df= 12, p= 0.005
H0j: Difference in diet does not affect Chaetodon growth or condition
Fulton’s Condition k: C. auriga• k= 105*[w/l3]
t=1.77, df=13, p=0.359
2.5
2.55
2.6
2.65
2.7
2.75
2.8
2.85
2.9
2.95
3
Sydney One Tree Island
Me
an
Fu
lto
n's
Co
nd
itio
n k
n=9 n=13
t= 0.369, df=13, p=0.36
Summary and Future Research•Food Intake: Bite rate does not differ between Sydney
and One Tree Island-Gut fullness of Chaetodon auriga in Sydney suggests there is ample food available
•Potential Prey: Chaetodon species at both Sydney and One Tree Island exploit habitats of high
macroinvertebrate diversity and abundance•Diet: Sydney Chaetodon auriga appear to eat a much
higher volume of polychaetes than those at One Tree Island
•Body Condition: Despite this variation in diet, no difference in body condition
Acknowledgements• Research was supported by an ARC Discovery Grant
(DP0560005- D Booth) “The mechanisms of settlement success in coral reef fishes”
• Matt and Ali at One Tree Island Research Station
• Pat Hutchings at Australian Museum for polychaete ID assistance