Heart-less pulses: measuring sponge pumping rates
Strehlow
1Centre
1,2,3
BW ,
Pineda
4,5
MC ,
Clode
1
P,
Kendrick
2,3
GA ,
Renton
2
M,
Webster
4,5
N ,
Duckworth
4,5
A
for Microscopy Characterisation and Analysis, 2School of plant biology & 3Oceans Institute, University of Western Australia, Crawley, WA, Australia; 4Australian
Institute of Marine Science, Townsville, QLD, Australia; 5Western Australian Marine Science Institution, Crawley, WA, Australia
• Water exits through a specialized pore called an osculum
• Sponges pump water through their bodies in order to:
Osculum
Flowmeter
Camera
Capture food
Eliminate waste
Flow
& Exchange gas
10 mm
• Pumping rates are measured using a custom built thermistor
flowmeter with integrated camera to track behaviour
• Cliona orientalis: Indo-Pacific, bioeroding sponge on coral • Measuring sponge pumping rates is like taking a pulse
• Why the oscillation in pumping during the day?
• So, what does a sponge pulse look like?
Pumping rate (mm sec-1)
Pumping rate (mm sec-1)
200
Night
160
120
80
40
R2 = 0.495, P < 0.01
0
0 min
Hours
+ 5 min
5
10
Osculum area (mm2)
15
• Oscula open and close throughout the day
• Osculum closure correlates directly with pumping rate
• C. orientalis pumping patterns for 24 hours starting at
10:50
Osculum
closes
80
60
40
20
1
Hours
2
3
• Pumping rates decrease
• Then, oscula close and pumping ceases
• Pumping restarts when sediment
concentrations drop
120
a
30
a
100
a
80
60
b
40
b
20
Percent mortality
100
• For weeks?
• For days?
Percent of oscula open
Pumping rate (mm sec-1)
• For hours?
Suspended Sediment concentration (NTU)
• What happens when suspended sediment is introduced:
25
20
0 NTU
3 NTU
20 NTU
50 NTU
90 NTU
15
10
5
0
0
0 NTU
3 NTU
20 NTU
50 NTU
90 NTU
• Oscula remain closed and pumping
ceases in the highest treatments
• Closure occurred within hours and
persisted for four weeks
Week 1
Week 2
Week 3
Week 4
• 20% (n=20) mortality occurs in
the highest treatments
• Conclusion: High sediment loads
decrease pumping activity and
cause oscula closure, which
contributes to mortality