Sustaining Food Webs within the Coorong - CLLAMM technical briefing
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CLLAMMecology
Sustaining food webs within the Coorong
Justin Brookes
Water Research Centre, University of Adelaide
CLLAMMecology Research Cluster partners:
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• CLLAMM Ecology Trophodynamics theme
investigated ecological processes
– Primary productivity
– Nutrient dynamics
– Energy flow through foodwebs
• Focus on food webs and interactions between
species
CLLAMMecology Research Cluster partners:
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Food webs
Food webs connect populations
Food webs describe energy and nutrient
flow through ecosystems and so connect
trophic levels at the scale of the landscape
Redundancy in the food webs increases
ecosystem resilience
CLLAMMecology Research Cluster partners:
9. Moving down into the Northern lagoon –
salinity increases
Australian Pelican
Mulloway
Black bream Fairy Tern
Juv.
crabs
Flounder Sandy sprat Galaxias Gobies Mullet Hardyhead Congolli Crabs
?
Everything &
Anything
Predatory worms Predator larvae
Ficopomatus Capitella Other Worms Arthritica Amphipods Gastropods Insect larvae Juv. small fish
Sharp-tailedSandpiper Red-necked Stint Chestnut teal
Detritus Ruppia megacarp Epiphytes Macroalgae Microalgae
10. TODAY: Jack Point Salinity: 100+ ppt
Australian Pelican
Mulloway
Black bream Fairy Tern
Flounder Sandy sprat Galaxias Gobies Mullet Hardyhead Congolli Crabs
Predatory worms Predatory larvae
Ficopomatus Capitella Other Worms Arthritic Amphipods Brine shrimp Gastropods Insect larvae Juv. small fish
Sharp-tailed Sandpiper Red-necked Stint Chestnut teal
Detritus Ruppia tuberosa Epiphytes Macroalgae Microalgae
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• Who eats who in the Coorong?
• What are the important connections?
• Do we see a simplification of the food web as
salinity increases?
CLLAMMecology Research Cluster partners:
12. Methods
• Sampling
– Field campaign to measure tissue of species at
different sites in the Coorong
• Food web investigation starting at first order
consumers and not including birds
• Carbon isotope signature
– You are what you eat
• Nitrogen isotope signature
– Enriched with trophic level
13.
14.
15. Stable isotope food web Mundoo Channel
16
Ficopomatus
4. Salinator
14 Notospisula
Capitella
Sipunculoid
12 Mytilis
Amphipoda
3. Melita
10 Juv crabs
Crab tissue
2A.
δ N (‰)
Phyllodoce
8 Nephtys
15
Macrobranchium
Mullet S
6 Mullet M
Mullet L
Flounder S
4 Flounder L
Mulloway S
Mulloway M
2 Mulloway L
Congolli S
Congolli L
0 Hardyhead S
-20 -19 -18 -17 -16 -15 -14 -13 -12 -11 -10 -9 -8 Tamar goby S
13 Bream S
δ C (‰ )
16. Application of food web studies
• Diet change of 16
Ficopomatus
mulloway
4 Salinator
14 Notospisula
. Capitella
Sipunculoid
12 Mytilis
• Prey on Crabs
Amphipoda
10
3 Melita
Juv crabs
. Crab tissue
δ N (‰)
2A Phyllodoce
when larger
8 Nephtys
.
15
Macrobranchium
Mullet S
6 Mullet M
Mullet L
• Variety of food
Flounder S
4 Flounder L
Mulloway S
Mulloway M
2
sources necessary
Mulloway L
Congolli S
Congolli L
0 Hardyhead S
-20 -19 -18 -17 -16 -15 -14 -13 -12 -11 -10 -9 -8 Tamar goby S
to support top of 13 Bream S
δ C (‰ )
food chain
17. Food webs in the Coorong
Murray Mouth North Lagoon
(35 g/L)
5 Pelican Point Long Point Noonameena
(45 g/L) (88 g/L) (93 g/L)
Small mulloway
Large bream
Large mulloway
4
Large mulloway
Trophic Level
Large bream
Large flounder
Large mullet
Hardyhead Hardyhead
Congolli Congolli Congolli
Hardyhead
Small flounder Large flounder Hardyhead
Small flounder
3 Large mullet
Small bream Crabs Small flounder
Predatory polychaetes
Predatory polychaetes
Crabs Crabs
Polychaetes Amphipods Polychaetes Amphipods Chironomids Parartemia
2 Molluscs Others Molluscs Others
Polychaetes
Capitella
18. So how do we get redundancy in foodwebs?
• Large fish are feeding down a trophic level as
food sources become scarcer with salinity
• The salinity gradient hosts different
communities
• We need to maintain these communities but
they are currently contracted into the North
lagoon
• Reinstating freshwater flows will maintain
salinity below the tolerance threshold
19. Salinity tolerance
Salinity g/L
0 30 60 90 120 150 180
Phytoplankton
Macrophytes
Ruppia tuberosa
Ruppia megacarpa
Infauna
Capitella polychaete
Chironomidae
Bivalves
Paragrapsus crab
Other polychaetes
Fish
Smallmouth Hardyhead
Congoli
Yellow-eyed Mullet
Tammar River Goby
Mulloway
Black Bream
Birds
Shorebirds
Piscivorous Birds
Waterfowl (ducks, swans)
Ecosystem States
‘Estuarine Fish'
‘Fish and Shorebirds’
‘Ruppia and Waterfowl’
Extreme salinities – no organisms
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• Foodweb studies enable identification of the
interaction between species
• Knowing who eats who provides knowledge
on key ecosystem components that need to
be maintained
• Freshwater flows are required to expand the
area where there are viable foodwebs
CLLAMMecology Research Cluster partners: