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Marine Botany

Marine Botany. T HE U NIVERSITY. O F Q UEENSLAND. 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. Assessing Ecological Health.

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Marine Botany

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  1. Marine Botany THE UNIVERSITY OF QUEENSLAND Ecological Impact of Nutrients from Shrimp FarmsMark O’Donohue,Adrian Jones, Simon Costanzo,Michele Burford, Pat Glibert,Judy O’Neil, Cindy Heil& William Dennison

  2. Assessing Ecological Health • Ecological health has been variously defined, including: • 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 andc) 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 • Habitat:seagrass depth range, phytoplankton density (Chla) • Anthropogenic Impact: • delta 15N, %N, amino acids, nutrient flux, water quality • Key Processes: • denitrification, sediment N flux, phytoplankton bioassays

  4. Treatment Stimulation Factor Control 1 DIN 6 (NH + NO ) 4 3 PO 1 4 SiO 1 3 All 11 DIBM 1998 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] r2 = 0.68 %P does not correlate with dissolved inorganic [P] r2 = 0.08 *Horrocks et al. 94

  5. 100 80 60 % Uptake of ammonium 40 20 0 0 20 40 60 80 100 % Diatoms 100 80 60 % Uptake of urea 40 20 0 0 20 40 60 80 100 % Dinoflagellates N-Form influences biotic response Planktona • N preference NH4+>Urea>>NO3- • NH4+ Diatoms • Urea Dinoflagellates • NO3- Denitrifying bacteria Macrophyteb • NH4+/Urea/NO3- ratio affects macrophyte amino acid content a Glibert, O’Neil, Heil and O’Donohue b Jones, Horrocks, Udy and Dennison

  6. Feed 2600 Effluent 10400 7000 NH4 15000 5400 Sediment Nitrogen budget (Burford et al. 99) 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 (g/ha/d)

  7. Key features of Shrimp Farm Effluent • Composition • seawater • clay particles • marine phytoplankton • particulate and dissolved nutrients • [NH4+]>[NO3-]>[PO43-] • By comparison, sewage effluent • freshwater • dissolved nutrients • [NO3-]>[NH4+][PO43-]

  8. Implications High [nutrient] particularly [NH4+] • phytoplankton bloom potential Elevated turbidity • potential for nutrient sorption

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

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

  11. StudySite: Moreton Bay (estuary) Moreton Bay

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

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

  14. Phytoplankton bioassays Nutrient response

  15. StudySite: Hinchinbrook Channel (tidal creek) Hinchinbrook Channel

  16. Phytoplankton bioassays - Dry

  17. Phytoplankton bioassay - Dry/Wet

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

  19. Shrimp farm - Conceptual model Low particulate and dissolved N Dissolved N Particulate N Elevated delta15N Elevated [amino acid] • Low delta15N • Low [amino acid] • Low phytoplankton bloom potential Elevated phytoplankton bloom potential

  20. Summary • Coastal ecosystems N limited • 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) • N form can influence physiology and community structure in receiving waters • Ecological health indicators provide direct measures of influence of aquaculture discharge

  21. Implications Recommend • On-farm N removal to reduce downstream impacts • Oxidation of N compounds to reduce potentially toxic dinoflagellates and enhance denitrification • 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 Ecological Health Indicators

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

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