Sustaining Food Webs within the Coorong - CLLAMM technical briefing

HEADLINE TO BE PLACED IN THIS SPACE CLLAMMecology Sustaining food webs within the Coorong Justin Brookes Water Research Centre, University of Adelaide CLLAMMecology Research Cluster partners:

HEADLINE TO BE PLACED IN THIS SPACE • 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:

HEADLINE TO BE PLACED IN THIS SPACE 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:

Salinity gradient in the Coorong 2001 250 2002 2003 2004 200 2005 Salinity (PPT TDS) 2006 150 2007 2008 2009 100 50 0 58 52 45 39 29 19 12 8 2 -6 -11 -16 -21 -26 -31 -36 -41 Position along Coorong

Links to food: Black Swan

Links to food: Fairy Tern

The trophic pyramid Tertiary Consumers Secondary consumers Primary consumers Primary Producers

Murray Estuary 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 megacarpa Epiphytes Macroalgae Microalgae

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

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

HEADLINE TO BE PLACED IN THIS SPACE • 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:

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

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 (‰ )

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

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

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

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

HEADLINE TO BE PLACED IN THIS SPACE • 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:

Sustaining Food Webs within the Coorong - CLLAMM technical briefing

by University of Adelaide on Jul 21, 2009

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