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

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Juveniles (<120mm)

Small Adults (120-160mm)

Large Adults (160-200mm)

Using Observations

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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