Shellfish Culture and Particulate Matter Production and Cycling

1. Shellfish Culture and Particulate Matter Production and Cycling P.A.G. BarnesEcological Interactions Research Program Centre for Shellfish ResearchMalaspina University-College Particulate Deposition Rates, Sediment Geochemistry and Benthic Faunal Communities Associated with a Deep-water, Suspended Pacific Oyster Farm in BC

2. Cultured bivalves filter feed on naturally occurring phytoplankton • Fine suspended material is packaged into larger feces and • pseudofeces (biodeposits) • Potential benthic impacts: • increased aerobic microbial activity • low → no oxygen • increased anaerobic microbial activity • negative oxidation-reduction potential & increased sulphide accumulation • decreased species diversity

3. the size and nature of the farm • - culture species, stocking density, overall • production, biomass • site characteristics • - hydrography, bathymetry, primary productivity • fouling communities on the raft structures • mortality and fall-off of cultured bivalves and • fouling organisms Seasonal variation in some of these factors may be reflected in seasonal variation in biodeposition

4. Shellfish Culture and Particulate Matter Production and Cycling BC Aquaculture Research & Development Committee (BCARDC) • Objectives: • 1. to quantify particulate matter (feces, pseudofeces) • and sloughed material produced at deep-water, suspended • Pacific oyster (Crassostrea gigas) raft culture sites in BC; • to quantify particulate material arriving on the seafloor per • unit time (deposition rate) below the C. gigas rafts, • adjacent to the farms, and at reference stations; • to measure water currents and water column variables • which may affect biodeposit production rates and • deposition rates at C. gigas study sites;

5. Shellfish Culture and Particulate Matter Production and Cycling • Objectives: • 4. to investigate the effects of deposition from C. gigas farms • on sediment physical and geochemical parameters; • 5. to investigate the effects of deposition from C. gigas farms • on benthic faunal communities during a period of maximum productivity.

6. Village Bay, Quadra Island

7. Field work • July 2003 to Aug. 2004 • sampling every 3 months • Oyster density • 183 oysters ∙m-3 Schematic – B. Kingzett

8. ← ← ← ← ←

9. Shellfish Culture and Particulate Matter Production and Cycling – Particulate Biodeposition Figure 59 a-e. Total organic carbon deposition rates (g·m-2·d-1) (mean +/- SD) (shallow and deep) for all Village Bay stations, all dates.

10. Shellfish Culture and Particulate Matter Production and Cycling – Sediment Geochemistry Village Bay Figure 66 a-d. Village Bay sediment percent total organic matter (without woodfibre) (mean +/-SD) for all stations, all dates.

11. Shellfish Culture and Particulate Matter Production and Cycling – Sediment Geochemistry Village Bay Figure 67 a-d. Village Bay sediment redox (mV) (mean +/- SD) for all stations, all dates.

12. Shellfish Culture and Particulate Matter Production and Cycling – Sediment Geochemistry Village Bay Figure 68 a-d. Village Bay sediment free sulphide (µM) (mean +/- SD) for all stations, all dates.

13. Shellfish Culture and Particulate Matter Production and Cycling – Benthic Infauna Swartz Dominance Index (SDI) measures the number of species that comprise ~75% of the sample. A high SDI value indicates that abundance is spread relatively evenly over a variety of species. A low SDI indicates that a few taxa dominate the community.

14. Shellfish Culture and Particulate Matter Production and Cycling Summary of Major Results – Village Bay • Deposition rates • significantly higher at the raft station (S3) than reference • stations on most dates • Sediment geochemical characteristics • %TOM at S3 was significantly different (but not always • higher) compared to %TOM at RS1 or RS2 • redox values at S3 were not significantly different from • those at RS1 or RS2 • free sulphides at S3 were significantly higher than • those at RS1 or RS2 in July 2003

15. Shellfish Culture and Particulate Matter Production and Cycling Summary of Major Results – Village Bay • Sediment infaunal invertebrate communities • no indication of infaunal impoverishment at raft • station • infaunal community at the raft station was distinct • from those at other stations (hard substrate fauna, • differences in dominant bivalves and polychaetes)

16. Acknowledgements: Funding: BC Aquaculture Research and Development Committee Advanced Systems Institute (BCIC) NSERC Canada Research Chair Assistance: Julia Rendall, Bee Islets Co-op Brian Stevenson, Viking Bay Ventures BCSGA CSR – D. Tillapaugh, S. Switzer,W. Friesen, A.Perkovich,S.Williams, K. Hunter, N. Plamondon, D.Dalziel, D. Paltzat MU-C Department of Fisheries and Aquaculture - Gord Edmondson, Jenny Dawson-Coates Kingzett Professional Services BCMAFF - Dr. Bill Heath DFO - Institute of Ocean Sciences

17. Shellfish Culture and Particulate Matter Production and Cycling – Benthic Infauna VB-S1 VB-S2 VB-S4 VB-RS1 VB-RS2 VB-S5 VB-S3 ^Parvilucina tenuisculpta ^Acila castrensis ^Axinopsida serricata ^ ^ ^ * ^ * ^ Acila castrensis Axinopsida serricata Rochefortia tumida, Tectura persona & hard subtrate fauna Figure 72. Village Bay July 2003 - SIGTREE analysis for faunal abundance data dendogram (replicates averaged for each station). (<0.025)