www.ucd.ie/marbee      The impacts of non-indigenous         oysters on biodiversity and             ecosystem functioning...
Potential impacts of invasive species                        Invasive                        species                      ...
Physical structure of oysters Hard substratum  new habitat for colonisationComplex shell structure  biodiversity
Biological activities of oysters  OM loading                                                                N2 or N2O     ...
Environmental context                       Impacts                         of                       Oysters              ...
My objectives  1. Characterise potential impacts of Pacific oysters      on:  (a) Biodiversity  (b) Ecosystem functioning ...
Experiments Objectives have been addressed using field  experiments: • Expt. 1: Biodiversity and the establishment of a   ...
Experiment 1 • Effects of oysters on boulder-field communities   especially the honeycomb worm, Sabellaria   alveolata
Experiment 1 • Increasing cover of alive and dead oysters were   added onto boulders
Reduction of S. alveolata with oysters on boulders                                      400                               ...
Impacts on biodiversity in boulder-fields                    15                         Alive oysters                   De...
Key impacts on boulder-field biota • The honeycomb worm, Sabellaria alveolata was   negatively impacted by oysters.    – N...
Experiment 2 • Effects of oysters were also assessed in mud-   flat and mussel beds habitats
Measures of biodiversity• Epifauna• Infauna
Measures of ecosystem functioning Functional measures: • Porewater nutrient profiles    – Sediment – water interface flux ...
Impacts on biodiversity at L. Swilly                    21                         Mussel-beds                  Mud-flatsN...
Consistent facilitation of a an invasivebarnacle, macroalgae and a key grazer in all habitats                             ...
Impacts on pore-water ammonium fluxes                            1.2                                  Mussel-beds         ...
Impacts on community respiration                                150                                      Mussel-beds      ...
Summary of impacts  • Biodiversity generally increased.    – but in some cases peaked or declined at greater cover    – Se...
Conclusions • Alteration of nutrient cycling and decomposition   rates may lead to nutrient retention and changes   in pri...
AcknowledgementsHELP and ADVICE• Ciarán McGonigle, Loughs Agency• Carlos Rocha, TCD• Bas Boots, UCD                       ...
Any questions?
Impacts on microbial activity • Oxic sediment                                 440   TPF (ug-1 d-1 dry sediment)           ...
Impacts on microbial community structure• Ammonia oxidising microbes in oxic sediment
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The impacts of non-indigenous oysters on ecosystems functioning - Dannielle Green

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  • looking for potential impacts of the species whose spread she investigated and whose biology and importance she has already introduced. You can also explain that you varied the density to enable better predictions of how oysters could affect ecosystems at different stages of invasion (and in different places).
  • P<0.05 for cover. Density of Sab decreases with increasing cover of oysters.
  • Some impacts were context dependent, differing w.r.t. habitat and cover of oysters.Density of infaunal polychaetes was reduced at the greatest cover of oysters in mussel beds.Fucus vesiculosus, Littorina littorea and Elminius modestus were consistently facilitated by oysters.Biodiversity was reduced by dense populations of oysters in mussel-beds.Changes to biodiversity can alter ecosystem functioning.
  • The impacts of non-indigenous oysters on ecosystems functioning - Dannielle Green

    1. 1. www.ucd.ie/marbee The impacts of non-indigenous oysters on biodiversity and ecosystem functioning Dannielle GreenSupervisor: Tasman Crowe (UCD)Collaborators: Carlos Rocha (TCD), Bas Boots (UCD)
    2. 2. Potential impacts of invasive species Invasive species Ecosystem Biodiversity functioning Ecosystem services
    3. 3. Physical structure of oysters Hard substratum  new habitat for colonisationComplex shell structure  biodiversity
    4. 4. Biological activities of oysters OM loading N2 or N2O Filtering Phytoplankton Biodeposits Oxic Mineralisation Nitrification sediment CO2 NH4+  NO-2  NO-3 Organic Matter Anoxic CH4 Denitrification sediment NO-3  NO-2  N2 Buried N and C
    5. 5. Environmental context Impacts of Oysters Sediment Rocky shores shores Ecosystem Biodiversity functioning Ecosystem services
    6. 6. My objectives 1. Characterise potential impacts of Pacific oysters on: (a) Biodiversity (b) Ecosystem functioning 2. Test whether impacts vary under different environmental contexts and at different oyster abundances
    7. 7. Experiments Objectives have been addressed using field experiments: • Expt. 1: Biodiversity and the establishment of a protected biogenic habitat in boulder-fields. • Expt. 2: Biodiversity and ecosystem functioning of mud-flat and mussel bed habitats. • Expt. 3: Microbial diversity and functioning in mud-flat habitats.
    8. 8. Experiment 1 • Effects of oysters on boulder-field communities especially the honeycomb worm, Sabellaria alveolata
    9. 9. Experiment 1 • Increasing cover of alive and dead oysters were added onto boulders
    10. 10. Reduction of S. alveolata with oysters on boulders 400 Alive oysters Dead oystersNumber of S. alveolata tubes per m2 300 200 100 0 0 5 50 100 0 5 50 100 Oyster cover (%)
    11. 11. Impacts on biodiversity in boulder-fields 15 Alive oysters Dead oystersNumber of species 10 5 0 0 5 50 100 0 5 50 100 Oyster cover (%)
    12. 12. Key impacts on boulder-field biota • The honeycomb worm, Sabellaria alveolata was negatively impacted by oysters. – Not due to competition for space • Biodiversity was enhanced at the lowest cover of living oysters but peaked at greater cover. • Fucus vesiculosus and Littorina littorea were facilitated by oysters and may have indirectly reduced S. alveolata establishment. • Effects were due to both the physical structure and the biological activities of oysters.
    13. 13. Experiment 2 • Effects of oysters were also assessed in mud- flat and mussel beds habitats
    14. 14. Measures of biodiversity• Epifauna• Infauna
    15. 15. Measures of ecosystem functioning Functional measures: • Porewater nutrient profiles – Sediment – water interface flux – Nutrient turnover rates • Gas – Flux rates of CO2, CH4 and N2O
    16. 16. Impacts on biodiversity at L. Swilly 21 Mussel-beds Mud-flatsNumber of species 14 7 0 0 5 50 100 0 5 50 100 Oyster cover (%)
    17. 17. Consistent facilitation of a an invasivebarnacle, macroalgae and a key grazer in all habitats 45 30 Number of individuals 15 0 0 5 50 100 Oyster cover (%)
    18. 18. Impacts on pore-water ammonium fluxes 1.2 Mussel-beds Mud-flatsAmmonium (mmol-1 m-2 d-1) Similar result for silicate 0.8 0.4 0 0 5 50 100 0 5 50 100 Oyster cover (%)
    19. 19. Impacts on community respiration 150 Mussel-beds Mud-flatsCarbon dioxide (mg-1 m-2 h-1) 100 50 0 0 5 50 100 0 5 50 100 Oyster cover (%)
    20. 20. Summary of impacts • Biodiversity generally increased. – but in some cases peaked or declined at greater cover – Several taxa were consistently facilitated in all habitats • Physical structure decreased establishment of a protected biogenic habitat. • Pore-water nutrient fluxes were altered. • Community respiration increased with the greatest cover of oysters. – Likely due to microbial activity (Expt. 3)
    21. 21. Conclusions • Alteration of nutrient cycling and decomposition rates may lead to nutrient retention and changes in primary productivity. • These changes may have consequences for ecosystem services, e.g. reduced carrying capacity for aquaculture. • Some impacts were context dependent. • Further research is needed to accurately scale these impacts up and predict their effects on ecosystems.
    22. 22. AcknowledgementsHELP and ADVICE• Ciarán McGonigle, Loughs Agency• Carlos Rocha, TCD• Bas Boots, UCD www.ucd.ie/marbeeFIELD and LAB WORK• Bas Boots, Mark Browne, Amy Haughton, Robert Fitzpatrick, Laila Higgins, Erin Gleeson, Kelly Dunagan, Eoin O’Gorman, Juan Severino, Julien Chopelet, Myriam Callier, Paul Brooks, Angela Gallagher, Jesko Zimmermann, David Blockley, Ciarán McGonigle & colleagues, Francis O’BeirnFUNDING AGENCIES and SIMBIOSYS coordinators• Environmental Protection Agency, NDP, SSTI, IRCSET & IRCHSS (via UCD Graduate Research Education Programme in Sustainable Development)• Jane Stout , Jens Dauber and David Bourke TCD
    23. 23. Any questions?
    24. 24. Impacts on microbial activity • Oxic sediment 440 TPF (ug-1 d-1 dry sediment) 330 220 110 0 O L M H Cover of oysters
    25. 25. Impacts on microbial community structure• Ammonia oxidising microbes in oxic sediment

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