Into the wild: documenting and predicting the spread of Pacific oysters (Crassostrea         gigas) in Ireland            ...
Influences of aquaculture on ecosystems  • Interactions with wild-fisheries resources     • capture of seed mussels     • ...
Ireland   • One of the three main aquaculture species in Ireland is     the Pacific oyster   • Pacific oysters cultured on...
Pacific oyster                                                 1950`s                                        1960`s       ...
Range of impacts   • Invasive populations in many parts of the world with     significant changes on ecosystems:      • de...
Shift from mussel beds to oyster reefs in the Wadden Sea  Oyster reef   Blue mussel bed
Pacific oyster in  • Thought not to be able to reproduce in Ireland  • Some individuals observed outside aquaculture  • Ex...
Aims • Aim 1 Characterise the distribution and abundance of   Pacific oysters in Ireland – observational approach • Aim 2 ...
Aim 1  • Aim 1: Characterise the distribution and abundance of    Pacific oysters in Ireland    Assess the current range ...
Sampling Design • 2009 sampling programme   undertaken together with Marine   Institute, Lough’s Agency, Queen’s   Univers...
Distribution and abundance• Oysters were found at  18 out of 69 sites visited• Transect results:   • Lough Swilly, rocky s...
Size frequencies               20                        Lough Swilly, rocky shore                                n=182   ...
Environmental factors• Probability of oyster presence was assessed as a function  of variables using logistic regression a...
Aim 2 • Aim 2: Test the influence of relevant factors on survival   and growth of oysters – experimental approach         ...
Aim 2                       10 individuals per tile  1. Macroalgae  2. Predation    No cage      Cage control    Cage     ...
Results - survival                        100                         80         survival (%)                         60  ...
Ballynacourty            Rinville               100               80survival (%)               60               40        ...
Results - growth                        40                                                                *               ...
Results - growth                        40                                 Ballynacourty                        35        ...
Aim 3  • Aim 3: Comparison of genetic structure between feral    and aquaculture oyster populations         Establish whe...
Results      • Evidence for the uncoupling of aquaculture and feral        populations      • Self-recruitment of feral po...
Summary• Pacific oysters are established in Ireland and most likely  self-recruiting• No dense reefs in the intertidal• Se...
Summary • Oyster presence strongly associated with hard   substrata and biogenic reef, long residence times   of embayment...
Summary  • Although feral oysters can be demographically    uncoupled from closest aquaculture, further sampling    of bay...
Thank you for your attention!
AcknowledgementsHELP and ADVICE• Tasman Crowe• Francis O’Beirn• Jon Yearsley• Stefano Mariani and Jens Carlsson• Ciarán Mc...
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Into the wild: documenting and predicting the spread of pacific oysters (Crassotrea gigas) in Ireland- Judith Kochmann

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  • As Tas Crowe said already this morning, aquaculture is important from an economic point of view but can also have significant impacts on ecosystems. I will focus on aquaculture acting as a vector for non-native species which may become invasive.
  • Feral oysters = pacific oysters outside aquaculture
  • Exact number of cohorts or age classes not known but literature comparisons
  • Factors, that explained oyster presences best were:Although macroalgae could not be tested in the model
  • Although not tested in the model due to a negative correlation with hard substrata and bioreef, a negative association with macroalage was revealed in small-scale habitat associations, and less oysters were observed at macroalgae-dominated site, more crabs observed
  • Dramatic effect on small oysters, however, using different locations and different sizes
  • Shown are mean oyster growth
  • Relatively high genetic differentiation (FST) of aquaculture and feral populationslarge number of private alleles in feral populationsignificant larger effective population sizes in feral population
  • Into the wild: documenting and predicting the spread of pacific oysters (Crassotrea gigas) in Ireland- Judith Kochmann

    1. 1. Into the wild: documenting and predicting the spread of Pacific oysters (Crassostrea gigas) in Ireland Judith Kochmann GREP in Sustainable Development, Urban Institute Ireland, UCD Supervisor: Tasman Crowe Collaborators: Francis O’Beirn (MI), Jon Yearsley (UCD), Stefano Mariani (The University of Salford), Jens Carlsson (UCC)
    2. 2. Influences of aquaculture on ecosystems • Interactions with wild-fisheries resources • capture of seed mussels • fish capture for feed production • Physical changes to the habitat • addition of structures • Organic and nutrient enrichment photo: Valdimar Ingi Gunnarsson • Invasive species • Vectors, escapes, facilitation • Interactions with seals and birds • positive and negative
    3. 3. Ireland • One of the three main aquaculture species in Ireland is the Pacific oyster • Pacific oysters cultured on intertidal trestles since early 1970`s • 6-7 k tonnes produced in 2007, valued € 15 million
    4. 4. Pacific oyster 1950`s 1960`s 1920`s• Shell length of 30-40 cm, up to 1 kg live wet weight
    5. 5. Range of impacts • Invasive populations in many parts of the world with significant changes on ecosystems: • decrease carrying capacity, especially of aquaculture bays • native mussels show reduced growth between oysters • act as a vector for other non-native species • Most obvious and significant change is change of habitat structure
    6. 6. Shift from mussel beds to oyster reefs in the Wadden Sea Oyster reef Blue mussel bed
    7. 7. Pacific oyster in • Thought not to be able to reproduce in Ireland • Some individuals observed outside aquaculture • Extent of feral populations not known
    8. 8. Aims • Aim 1 Characterise the distribution and abundance of Pacific oysters in Ireland – observational approach • Aim 2 Test the influence of relevant factors on survival and growth of oysters – experimental approach • Aim 3 Comparison of genetic structure between feral and aquaculture oyster populations - molecular tools
    9. 9. Aim 1 • Aim 1: Characterise the distribution and abundance of Pacific oysters in Ireland  Assess the current range and status of Pacific oysters in Ireland  Identify main factors associated with the presence/absence of oysters – observational approach
    10. 10. Sampling Design • 2009 sampling programme undertaken together with Marine Institute, Lough’s Agency, Queen’s University Belfast, BIM • Repeatable, cost effective protocol developed • Semi-quantitative assessment of abundance and habitat types at all sites (SACFOR, EUNIS framework) • Quantitative transects to assess maximal densities and small-scale habitat associations
    11. 11. Distribution and abundance• Oysters were found at 18 out of 69 sites visited• Transect results: • Lough Swilly, rocky shore: 6.3 ind/m2 • Lough Foyle, mussel bed: 5.4 ind./m2 • Shannon Estuary, rocky shore: 0.7 ind./m2 common frequent occasional rare absent
    12. 12. Size frequencies 20 Lough Swilly, rocky shore n=182 15 Frequency 10 5 0 0 20 40 60 80 100 120 140 oyster length (mm) • Sizes ranged from 25 – 135 mm indicating several recruitment events
    13. 13. Environmental factors• Probability of oyster presence was assessed as a function of variables using logistic regression and stepwise model selection (AIC)• Factors explaining oyster presence best: Aquaculture present but > 500 m; p = 0.035 Hard substrate and biogenic reef; p = 0.002 Shore width > 50 m; p = 0.010 Residence time; p = 0.001
    14. 14. Aim 2 • Aim 2: Test the influence of relevant factors on survival and growth of oysters – experimental approach Macroalgae Predators • Modify flow, affecting • Consume juvenile stages sediment (-) or food (+) • Smother and interfere with filter apparatus Interaction • Macroalgae may increase influence of predation by providing habitat for predators
    15. 15. Aim 2 10 individuals per tile 1. Macroalgae 2. Predation No cage Cage control Cage No cage Cage control Cage Replicated at 2 sites
    16. 16. Results - survival 100 80 survival (%) 60 40 20 0 + - cc + - cc • Strong effect of predation in pilot study July 2010, mean oysters size 16 mm
    17. 17. Ballynacourty Rinville 100 80survival (%) 60 40 20 0 + - cc + - cc + - cc + - cc • effect of predation absent in September 2011, mean oysters size 36 mm
    18. 18. Results - growth 40 * Rinville * 35 * oyster growth (mm) 30 * * 25 20 with macroalgae 15 without macroalgae 10 5 0 7/3/11 9/3/11 11/3/11 1/3/12 3/3/12 5/3/12 • Significant larger growth (*) without macroalgae in Rinville
    19. 19. Results - growth 40 Ballynacourty 35 30 oyster growth (mm) * 25 * 20 15 with macroalgae without macroalgae 10 5 0 7/3/11 9/3/11 11/3/11 1/3/12 3/3/12 5/3/12 • Opposite pattern, but not significant • Condition index May 2012 (DTW*1000/DSW)  no significant effect of macroalgae
    20. 20. Aim 3 • Aim 3: Comparison of genetic structure between feral and aquaculture oyster populations  Establish whether oysters outside aquaculture are forming self-sustaining populations or are the result of repeated spawning from aquaculture vs 1 Bay 2 Populations 3 Size classes 14 Microsatellites
    21. 21. Results • Evidence for the uncoupling of aquaculture and feral populations • Self-recruitment of feral populations likelyGenetic evidence for the uncoupling of local aquaculture activities and a population of an invasive species – a casestudy of Pacific oysters (Crassostrea gigas) by J Kochmann, J Carlsson, T P Crowe, S Mariani (accepted by Journal ofHeredity)
    22. 22. Summary• Pacific oysters are established in Ireland and most likely self-recruiting• No dense reefs in the intertidal• Several cohorts present and new recruits found in 2011• Occurrences known from shallow subtidal native oyster beds (report by Marine Institute and BIM 2011) • 5.64 million feral Pacific oysters estimated for Lough Swilly in intertidal/subtidal habitats
    23. 23. Summary • Oyster presence strongly associated with hard substrata and biogenic reef, long residence times of embayments and large intertidal areas • Macroalgae and predators can influence growth and survival, but effects vary
    24. 24. Summary • Although feral oysters can be demographically uncoupled from closest aquaculture, further sampling of bays without aquaculture is needed to characterise the association of aquaculture more fully • Sampling protocol provides a baseline and repeatable method for future sampling by state agencies • Combination of coordinated sampling, experiments and molecular tools can help to identify factors associated with spread of oysters and inform strategies for adaptation and control
    25. 25. Thank you for your attention!
    26. 26. AcknowledgementsHELP and ADVICE• Tasman Crowe• Francis O’Beirn• Jon Yearsley• Stefano Mariani and Jens Carlsson• Ciarán McGonigle, Loughs Agency• Grainne O’Brien & regional officers, BIM• Heike Büttger, BioConsult, Germany• Claire Guy & Dai Roberts, Queen’s University BelfastFIELD/LAB WORK• Jen Coughlan, Rónán Mag Aoidh, Tomasz Dabrowski, Mike Burrows, Sarah Burke, Paul Brooks, Catherine Butler, Myriam Callier, Mave Cavanagh, Mozart Fazito, Vangelis & Panagiotis Giannakakis, Dannielle Green, Hao Li, Colm Ó Murchú, Silvia Saloni, Peter White, Chloe Kinsella, Caroline Kerrigan, Catherine Collins, Eda Ustaoglu, Susanne Schmidt, Jurate Jaraite, Rebecca Doyle, Bas Boots, Erin, Morteza Matkan, Maria Sala- Bonzano, Carlotta SacchiFUNDING AGENCIES• IRCSET & IRCHSS (via UCD Graduate Research Education Programme in Sustainable Development)• SEED funding, UCD

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