Ecological considerations for oyster restoration: interactions between oyster larvae and reef-associated fauna Brian B. Barnes*, Mark W. Luckenbach, Peter R. Kingsley-Smith

Commercial oyster landings (millions of pounds) Virginia landings Maryland landings Plight of oysters in Chesapeake Bay Current Crassostrea virginica population levels in Chesapeake Bay are < 1% biomass of those at the start of the last century (Newell, 1988) chesapeakebay.noaa.gov

Shells are limiting to Shells are limiting to epibenthic fauna AND restoration managers Substrate additions are Substrate additions are often done without regard for how substrate colonization affects oysters Epifaunal interactions research is often conducted using artificial substrates Epifaunal interactions research is often conducted using artificial substrates Supplementing shell substrate Shell planting on Rappahannock River

Research Objectives Investigate the effects of single-species epifaunal populations on the recruitment of oyster larvae using natural substrates Investigate the effects of single-species epifaunal populations on the recruitment of oyster larvae using natural substrates Effect of water soluble cues Effect of water soluble cues Effect of clamworms (Neanthes succinea) Effect of clamworms (Neanthes succinea)

Collection sites a Rappahannock River site b Pungoteague Creek site VIMS ESL Images from maps.google.com a b

Experimental treatments Cliona sp. No fouling Balanus improvisus Membranipora tenuis Dead BarnacleBarnacle Mould

ml adult oyster bathwater ~ 75 larvae Combusted very fine sand (63 – 125 μm) Test shell (~3 cm x ~3 cm) Microcosm design – Effect of epifauna 5.7 cm 4.3 cm

Overall layout = x 16

Results – Effect of epifauna on oysters: Settlement rate, Experiment 1 (C. a.) *

Results – Effect of epifauna on oysters: Settlement Rate ExperimentSpecies Low Barnacles Medium Barnacles High Barnacles BryozoansCliona Dead Barnacles Barnacle Moulds 1 C. virginica +++- p = p = C. ariakensis +++ p = C. virginica p = C. ariakensis +-- 4C. virginica --- p = C. virginica p = p < p = C. ariakensis p = p = C. virginica +++ p =

Results – Effect of epifauna on oysters: Mortality ExperimentSpecies Low Barnacles Medium Barnacles High Barnacles BryozoansCliona Dead Barnacles Barnacle Moulds 1 C. virginica ++++ p = C. ariakensis -++ 2C. virginica +++ p = C. ariakensis ++++ p = C. virginica p = C. virginica C. ariakensis C. virginica p = p <

ml adult bathwater ~ 75 larvae Microcosm design – Effect of bathwaters 5.7 cm 4.3 cm

Results – Bathwater experiments * * * * * * * * *

Conclusions No clear differences between C. virginica and No clear differences between C. virginica and C. ariakensis larvae C. ariakensis larvae Balanus improvisus presence likely affects settling oyster larvae Balanus improvisus presence likely affects settling oyster larvae Increased structure likely not important Increased structure likely not important Water soluble cue causes mortality, increased settlement Water soluble cue causes mortality, increased settlement Membranipora tenuis largely inert to mortality and settlement rate of oyster larvae Membranipora tenuis largely inert to mortality and settlement rate of oyster larvae Cliona sp. causes mortality to oyster larvae and deters settlement Cliona sp. causes mortality to oyster larvae and deters settlement

Conclusions (continued) Clamworms (Neanthes succinea) are voracious predators on oyster larvae; their bathwater also causes mortality Clamworms (Neanthes succinea) are voracious predators on oyster larvae; their bathwater also causes mortality Average predation rate = ~11 larvae day -1 worm -1 Average predation rate = ~11 larvae day -1 worm -1 Field population abundance = ~10,000 clamworms m -2 Field population abundance = ~10,000 clamworms m -2 Oyster bathwater causes mortality to conspecifics Oyster bathwater causes mortality to conspecifics Effect significant after 2 days Effect significant after 2 days Reef-associated invertebrates certainly influence settling oyster larvae Reef-associated invertebrates certainly influence settling oyster larvae Effect is not uniform or easily predictable Effect is not uniform or easily predictable Interactions should inform the location and timing of shell planting projects Interactions should inform the location and timing of shell planting projects

Acknowledgements VIMS – Eastern Shore Lab VIMS – Eastern Shore Lab Steph Bonniwell, Lynn Walker, Heather Harwell, Edward Smith, Roshell Brown, Alan Birch, Sean Fate, Reade Bonniwell, Al Curry, Jamie Wheatley, Linda Ward, Summer Aides Steph Bonniwell, Lynn Walker, Heather Harwell, Edward Smith, Roshell Brown, Alan Birch, Sean Fate, Reade Bonniwell, Al Curry, Jamie Wheatley, Linda Ward, Summer Aides VIMS – Gloucester Point VIMS – Gloucester Point Roger Mann, John Brubaker, Missy Southworth, Juli Harding, Roger Mann, John Brubaker, Missy Southworth, Juli Harding, Peter van Veld Peter van Veld UMD – CBL UMD – CBL Mario Tamburri Mario Tamburri Funding Funding Kelley Watson Fellowship, Eastern Shore Lab Research Grants, GSA Mini-Grant, VIMS Assistantship Kelley Watson Fellowship, Eastern Shore Lab Research Grants, GSA Mini-Grant, VIMS Assistantship