Post on 02-Apr-2015
Diel Behaviour and Distributions of the Monocle Bream
(Scolopsis bilineatus)
Nemipterids- the forgotten fishes
Diel feeding patterns: Stomach Volumes
Change in feeding strategy over life cycle- diurnal nocturnal feeding
Orpheus Island (n=99)
One Tree Island (n=113)
Dawn Mid-day Dusk
0.00
0.25
0.50
0.75
1.00
Dawn Mid-day Dusk
Sto
ma
ch
Vo
lum
e (
ml)
Dawn Mid-day Dusk
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Dawn Mid-day Dusk
Me
an
Sto
ma
ch V
olu
me
Juveniles (<120mm)
Small Adults (120-160mm)
Large Adults (160-200mm)
Using Observations
0 50 100 150 2000
10
20
30
40
50
60
70
0 50 100 150 2000
10
20
30
40
50
60
70
Num
ber
of
Bite
s pe
r 10
min
utes
Total Length (mm)
Orpheus Island One Tree Island
Diel Feeding Patterns: Daytime Feeding rates
Observations: feeding rate in daytime
r= -0.826 r= -0.697
Diurnal/ Nocturnal Distributions
REEF CREST
Patch reef
10m5m
SAND SAND
15m
30m MethodsCreated a fine scale map of reef section
Surveyed• 3x during the day • 3x at night
HypothesisDistributions and habitat use may differ between day and night
Diurnal/ Nocturnal Distributions
DAY (n=15)
REEF CREST
Patch reef
10m5m
SAND SAND
15m
30m
Data pooled for n=3 nights
Diurnal/ Nocturnal Distributions
DAY (n=15)
NIGHT (n=13)
REEF CREST
Patch reef
10m5m
SAND SAND
15m
30mAdults moved away from reef and onto sand at night.
Implications
Size matters!• Diel feeding patterns differed with age and growth
• A demographic perspective is essential
Shelter sites are important• Adult fish dependent on shelter microhabitats (with site fidelity)
Diurnal/nocturnal distributions differed• Highlights importance of nocturnal surveys
• Nocturnal fishes likely to be overlooked/underestimated historically
Nocturnal feeders form important trophic links• Abundant nocturnal feeders such as Scolopsis bilineatus may play
important roles in energy and nutrient cycling