1. Ecological Impact of Nutrients from Shrimp Farms Mark O’Donohue, Adrian Jones, Simon Costanzo, Michele Burford, Pat Glibert, Judy O’Neil, Cindy Heil & William Dennison Marine Botany T HE U NIVERSITY O F Q UEENSLAND

2. Assessing Ecological Health Ecological health has been variously defined, including: Ecological health has been variously defined, including: Ecological health is the maintenance of biodiversity and ecosystem integrity (Draft ANZECC Guidelines) Ecological health is the maintenance of biodiversity and ecosystem integrity (Draft ANZECC Guidelines) Ecological health is represented by a) a lack of ‘distress syndrome’ b) stability over time and c) resilience to change Ecological health is represented by a) a lack of ‘distress syndrome’ b) stability over time and c) resilience to change  These definitions are appropriate for describing the ecological health concept, but do not define ecological health in terms of measurable quantities

3. Measuring Ecological Health Ecological Health Indicators Ecological Health Indicators Habitat: seagrass depth range, phytoplankton density (Chl a ) Habitat: seagrass depth range, phytoplankton density (Chl a ) Anthropogenic Impact: Anthropogenic Impact: delta 15 N, %N, amino acids, nutrient flux, water quality delta 15 N, %N, amino acids, nutrient flux, water quality Key Processes: Key Processes: denitrification, sediment N flux, phytoplankton bioassays denitrification, sediment N flux, phytoplankton bioassays

4. N Limitation in coastal waters Phytoplankton bioassay responses N (not P) additions stimulate phytoplankton biomass Macroalgal tissue nutrient content* %N correlates with dissolved inorganic [N] r 2 = 0.68 %P does not correlate with dissolved inorganic [P] r 2 = 0.08 *Horrocks et al. 94 Treatment Stimulation Factor Control1 DIN (NH 4 + NO 3 ) 6 PO 4 1 SiO 3 1 All11 DIBM 1998

5. N-Form influences biotic response Plankton a N preference NH 4 + >Urea>>NO 3 - NH 4 + Diatoms Urea Dinoflagellates NO 3 - Denitrifying bacteria Macrophyte b NH 4 + /Urea/NO 3 - ratio affects macrophyte amino acid content 0 20 40 60 80100 % Uptake of ammonium 020406080100 % Diatoms 0 20 40 60 80100 % Uptake of urea 020406080100 % Dinoflagellates a Glibert, O’Neil, Heil and O’Donohue b Jones, Horrocks, Udy and Dennison

6. The Problem Small fraction of nutrients added to aquaculture ponds is absorbed by target species Large fraction of nutrients added to aquaculture ponds is exported Nutrient enrichment of receiving waters could have potential deleterious impact on ecological health Nitrogen budget (Burford et al. 99) Sediment NH 4 15000 10400 EffluentFeed2600 7000 5400 (g/ha/d)

7. Key features of Shrimp Farm Effluent Composition Composition seawater seawater clay particles clay particles marine phytoplankton marine phytoplankton particulate and dissolved nutrients particulate and dissolved nutrients [NH 4 + ]>[NO 3 - ]>[PO 4 3- ] [NH 4 + ]>[NO 3 - ]>[PO 4 3- ] By comparison, sewage effluent freshwaterfreshwater dissolved nutrientsdissolved nutrients [NO 3 - ]>[NH 4 + ]  [PO 4 3- ][NO 3 - ]>[NH 4 + ]  [PO 4 3- ]

8. Implications High [nutrient] particularly High [nutrient] particularly [NH 4 + ]  phytoplankton bloom potential Elevated turbidity  potential for nutrient sorption sorption

9. Aims Develop & test ecological health indicators for shrimp farm effluent Develop & test ecological health indicators for shrimp farm effluent Using appropriate indicators, assess influence of shrimp farm effluent on ecological health of receiving waters Using appropriate indicators, assess influence of shrimp farm effluent on ecological health of receiving waters Formulate recommendations for aquaculture effluent management Formulate recommendations for aquaculture effluent management

10. Vegetation Nutrient Content [Amino Acid] [Amino Acid] Delta 15 N Delta 15 N

11. Study Site: Moreton Bay (estuary) Moreton Bay

12. Delta 15 N - mangrove, seagrass and macroalgae (passive indicators)

13. Amino acid concentration and composition - seagrass nmol g fresh -1 Amino Acid Concentration 15 000 10 000 5 000 5 000 Glutamine Other Proline Amino Acid Composition

14. Phytoplankton bioassays Nutrient response

15. Study Site: Hinchinbrook Channel (tidal creek) HinchinbrookChannel

16. Phytoplankton bioassays - Dry

17. Phytoplankton bioassay - Dry/Wet

18. Delta 15 N - Macroalgae (4 day incubation)

19. Shrimp farm - Conceptual model Elevatedphytoplankton bloom potential Dissolved N Particulate N Elevated delta 15 N Elevated [amino acid] Low particulate and dissolved N Low delta 15 N Low delta 15 N Low [amino acid] Low [amino acid] Low phytoplankton bloom potential Low phytoplankton bloom potential

20. Summary Coastal ecosystems N limited Coastal ecosystems N limited Shrimp farms contribute large proportion of feed N to receiving waters Shrimp farms contribute large proportion of feed N to receiving waters Nutrients from aquaculture discharge stimulate phytoplankton blooms (but effluent is not an ‘inoculum’ for receiving waters) Nutrients from aquaculture discharge stimulate phytoplankton blooms (but effluent is not an ‘inoculum’ for receiving waters) N form can influence physiology and community structure in receiving waters N form can influence physiology and community structure in receiving waters Ecological health indicators provide direct measures of influence of aquaculture discharge Ecological health indicators provide direct measures of influence of aquaculture discharge

21. Implications On-farm N removal to reduce downstream impacts On-farm N removal to reduce downstream impacts Oxidation of N compounds to reduce potentially toxic dinoflagellates and enhance denitrification Oxidation of N compounds to reduce potentially toxic dinoflagellates and enhance denitrification Can be used to assess potential influence of discharge on intake waters Can be used to assess potential influence of discharge on intake waters Provide a mechanism for assessing downstream impacts in a growing industry in relation to other N sources Provide a mechanism for assessing downstream impacts in a growing industry in relation to other N sources Recommend Ecological Health Indicators

22. Acknowledgments Cooperative Research Centre for Aquaculture Marine Botany, University of Queensland CSIRO Marine Research Horn Pt Labs, University of Maryland