Nekton Utilization of Constructed Intertidal Oyster Reefs and ...
An Assessment of Habitat Value of Constructed Intertidal Oyster Reefs and Oyster Aquaculture Systems in Delaware Bay, USA Jaclyn Taylor and David Bushek Rutgers University Haskin Shellfish Research Laboratory, Port Norris, NJ 08349
Oyster Reef Ecology Oysters build reefs ¾
create a unique habitat z increase biodiversity z nursery grounds z refuge from predation z foraging sites
Intertidal Oyster Reefs in Delaware Bay
Why Don’t Intertidal Oyster Reefs Persist in Delaware Bay?
Preliminary Study Summer 2006 ¾
Three shellbag reefs • 1-layer (Reef 1) • 2-layer (Reef 2) • 3-layer (Reef 3)
¾
Monitored oyster recruitment & mortality
¾
Examined reef persistence thru winter
Summer 2006 Oyster Recruitment
Over-Winter Survival 2007 5000
Oysters m
-2
4000 3000
* - High mortality on Reef 1 due to sedimentation - Reef height necessary for reef persistence
2000 1000 0
Reef 1 Reef 2 Reef 3
What do they attract?
Oyster Aquaculture at Cape Shore ¾
New activity on the tidal flats ¾ Rack and bag system creates structure ¾ Are these structures functionally equivalent to oyster reef habitat?
2007 Habitat Comparisons
• 6 replicate 2-layer shellbag reefs (1.5 m x 3 m) • 6 control sand plots • 6 aquaculture racks Do intertidal reef and aquaculture habitats support increased motile macrofuana diversity, abundance and biomass? Are constructed shellbag reefs and aquaculture racks comparable habitat for motile fauna?
Motile Fauna Trap Sampling Treatments: Reefs Racks Sand
18 eel pots 18 minnow traps 6 crab pots Randomized block design to ensure all sampled simultaneously
39 tides sampled May to October
Oyster Recruitment & Mortality 16 ten-cm2 quadrats per reef
b
ab
b
a
High recruitment Low early mortality
ab
ab
Common Name Grass shrimp Eastern mud snail Longwrist hermit crab Blue crab Sand shrimp American eel Atl horseshoe crab Silver Perch Estuarine mud crab Striped Cusk-eel Atl silverside Flatback mud crab Atl mud crab Smallmouth flounder Striped Bass Atl Croaker Asian shore crab Naked goby Oyster toadfish Pinfish Green crab Summer flounder Black Sea Bass Alewife Bay anchovy Gray snapper Spot Striped killifish Weakfish White Perch
Species Name Palaemonetes pugio Nassarius obsoletus Pagurus longicarpus Callinectes sapidus Crangon septemspinosa Anguilla rostrata Limulus polyphemus Bairdiella chrysoura Rhithropanopeus harrisii Ophidion marginatum Menidia menidia Eurypanopeus depressus Panopeus herbstii Etropus microstomus Morone saxatilis Micropogonias undulatus Hemigrapsus sanguineus Gobiosoma bosc Opsanus tau Lagondon rhomboides Carcinus maenas Paralichthys dentatus Centropristis striata Alosa pseudoharengus Anchoa mitchilli Lutjanus griseus Leiostomus xanthurus Fundulus majalis Cynoscion regalis Morone americana Species Richness
Sand 541 117 235 60 70 2 13 1 3 5 3 3 2 3 1 1 1
17
Reef 1890 869 867 53 30 15 16 2 12 3 6 10 2 1 1 3
Aquaculture 3534 840 658 58 33 42 1 17 4 2 7 1 2
6 2 2 1 1 1
5 1 2 1 1
22
2 2 1 1 1 1 1 25
Species Abundance and Biomass
Species Composition PCA 40
PC1 -35
35
Principal Component 1
6
Sand R² = 0.24 Reef R² = 0.87 Aqua R² = 0.56
30 20 10 0 -10 -20 0
-6 PC2 Sand
Reef
Aquaculture
0.05 Sand
0.1 0.15 0.2 Relative depth (m) Reef Aquaculture
• PCA – 99% of species composition variation • PC1 – 95% • Linear regression with PC1 scores and habitat relative depth
0.25
Common Name Species Name Sand Reef Aquaculture Grass shrimp Palaemonetes pugio 541 1890 3534 Eastern mud snail Nassarius obsoletus 117 869 840 Longwrist hermit crab Pagurus longicarpus 235 867 658 Blue crab Callinectes sapidus 60 53 58 Sand shrimp Crangon septemspinosa 70 30 33 American eel Anguilla rostrata 2 15 42 Atl horseshoe crab Limulus polyphemus 13 16 1 Silver Perch Bairdiella chrysoura 1 2 17 Estuarine mud crab Rhithropanopeus harrisii 3 11 4 Striped Cusk-eel Ophidion marginatum 4 3 2 Atl silverside Menidia menidiaspecies 1 4 6 • Important commercial fishery Flatback mud crab Eurypanopeus depressus 2 4 1 Atl mud crab Panopeus herbstii 2 1 2 • Complex life history Smallmouth flounder Etropus microstomus 3 1 Striped Bass Morone saxatilis 1 1 Asian shore crab Hemigrapsus sanguineus 1 • Yellow-phase eels in estuaries 2-20 years Atl Croaker Micropogonias undulatus 1 Naked goby Gobiosoma bosc 3 3 Oyster toadfish Opsanus tau 2 1 Pinfish Lagondon rhomboides 2 2 Green Carcinus maenas species utilizing1 oyster reefs 1 • Arecrab American eels a resident Black Sea Bass Centropristis striata 1 and aquaculture racks as habitat? Alewife Alosa pseudoharengus 2 Bay anchovy Anchoa mitchilli 2 Spot Leiostomus xanthurus 1 Striped killifish Fundulus majalis 1 Summer flounder Paralichthys dentatus 1 Weakfish Cynoscion regalis 1 White Perch Morone americana 1 Species Richness 17 20 24
• 7 eels recaptured • 1 recaptured 2x • 13% recapture rate • no preference • n = 4 Aquaculture • n = 3 Reef
Total Number of Eels
• 52 eels marked • Aquaculture > Reef > Sand
Abundance
*
40 30 20 10 0 Sand
Reef
Recaptured Eels
3000 Total Biomass (g)
American Eel Mark-Recapture
50
Aquaculture Marked Eels
Biomass
*
2500 2000 1500 1000 500 0 Sand
Reef
Aquaculture
Conclusions ¾
Constructed reefs and aquaculture racks support increased species richness, abundance and biomass compared to sand flats.
¾
Rack and bag oyster culture increased species richness of motile fauna by increasing habitat diversity.
¾
Oyster aquaculture structures are at least functionally equivalent habitat as intertidal oyster reefs.
¾
Species composition is influenced by both habitat type and relative depth.
¾
Mark-recapture results show Anguilla rostrata is a resident reef/rack species.
Acknowledgements Special thanks to: Greg Debrosse Fernando Fuentes Emily Scarpa Iris Burt
Sean Boyd Jeff Pydeski Tom Evans Emma Green-Beach
And to: James Tweed of Atlantic Capes Fisheries for allowing us to sample on their oyster farm. Funding: New Jersey Water Resources Research Institute Graduate Student Grant-in-Aid The Rutgers University Graduate Program in Ecology and Evolution Academic Excellence Fund Rutgers University Research Council Grant Dupont Clear Into the Future Fellowship
Oyster Reef Ecology Oysters build reefs ¾
create a unique habitat z increase biodiversity z nursery grounds z refuge from predation z foraging sites
Intertidal Oyster Reefs in Delaware Bay
Why Don’t Intertidal Oyster Reefs Persist in Delaware Bay?
Preliminary Study Summer 2006 ¾
Three shellbag reefs • 1-layer (Reef 1) • 2-layer (Reef 2) • 3-layer (Reef 3)
¾
Monitored oyster recruitment & mortality
¾
Examined reef persistence thru winter
Summer 2006 Oyster Recruitment
Over-Winter Survival 2007 5000
Oysters m
-2
4000 3000
* - High mortality on Reef 1 due to sedimentation - Reef height necessary for reef persistence
2000 1000 0
Reef 1 Reef 2 Reef 3
What do they attract?
Oyster Aquaculture at Cape Shore ¾
New activity on the tidal flats ¾ Rack and bag system creates structure ¾ Are these structures functionally equivalent to oyster reef habitat?
2007 Habitat Comparisons
• 6 replicate 2-layer shellbag reefs (1.5 m x 3 m) • 6 control sand plots • 6 aquaculture racks Do intertidal reef and aquaculture habitats support increased motile macrofuana diversity, abundance and biomass? Are constructed shellbag reefs and aquaculture racks comparable habitat for motile fauna?
Motile Fauna Trap Sampling Treatments: Reefs Racks Sand
18 eel pots 18 minnow traps 6 crab pots Randomized block design to ensure all sampled simultaneously
39 tides sampled May to October
Oyster Recruitment & Mortality 16 ten-cm2 quadrats per reef
b
ab
b
a
High recruitment Low early mortality
ab
ab
Common Name Grass shrimp Eastern mud snail Longwrist hermit crab Blue crab Sand shrimp American eel Atl horseshoe crab Silver Perch Estuarine mud crab Striped Cusk-eel Atl silverside Flatback mud crab Atl mud crab Smallmouth flounder Striped Bass Atl Croaker Asian shore crab Naked goby Oyster toadfish Pinfish Green crab Summer flounder Black Sea Bass Alewife Bay anchovy Gray snapper Spot Striped killifish Weakfish White Perch
Species Name Palaemonetes pugio Nassarius obsoletus Pagurus longicarpus Callinectes sapidus Crangon septemspinosa Anguilla rostrata Limulus polyphemus Bairdiella chrysoura Rhithropanopeus harrisii Ophidion marginatum Menidia menidia Eurypanopeus depressus Panopeus herbstii Etropus microstomus Morone saxatilis Micropogonias undulatus Hemigrapsus sanguineus Gobiosoma bosc Opsanus tau Lagondon rhomboides Carcinus maenas Paralichthys dentatus Centropristis striata Alosa pseudoharengus Anchoa mitchilli Lutjanus griseus Leiostomus xanthurus Fundulus majalis Cynoscion regalis Morone americana Species Richness
Sand 541 117 235 60 70 2 13 1 3 5 3 3 2 3 1 1 1
17
Reef 1890 869 867 53 30 15 16 2 12 3 6 10 2 1 1 3
Aquaculture 3534 840 658 58 33 42 1 17 4 2 7 1 2
6 2 2 1 1 1
5 1 2 1 1
22
2 2 1 1 1 1 1 25
Species Abundance and Biomass
Species Composition PCA 40
PC1 -35
35
Principal Component 1
6
Sand R² = 0.24 Reef R² = 0.87 Aqua R² = 0.56
30 20 10 0 -10 -20 0
-6 PC2 Sand
Reef
Aquaculture
0.05 Sand
0.1 0.15 0.2 Relative depth (m) Reef Aquaculture
• PCA – 99% of species composition variation • PC1 – 95% • Linear regression with PC1 scores and habitat relative depth
0.25
Common Name Species Name Sand Reef Aquaculture Grass shrimp Palaemonetes pugio 541 1890 3534 Eastern mud snail Nassarius obsoletus 117 869 840 Longwrist hermit crab Pagurus longicarpus 235 867 658 Blue crab Callinectes sapidus 60 53 58 Sand shrimp Crangon septemspinosa 70 30 33 American eel Anguilla rostrata 2 15 42 Atl horseshoe crab Limulus polyphemus 13 16 1 Silver Perch Bairdiella chrysoura 1 2 17 Estuarine mud crab Rhithropanopeus harrisii 3 11 4 Striped Cusk-eel Ophidion marginatum 4 3 2 Atl silverside Menidia menidiaspecies 1 4 6 • Important commercial fishery Flatback mud crab Eurypanopeus depressus 2 4 1 Atl mud crab Panopeus herbstii 2 1 2 • Complex life history Smallmouth flounder Etropus microstomus 3 1 Striped Bass Morone saxatilis 1 1 Asian shore crab Hemigrapsus sanguineus 1 • Yellow-phase eels in estuaries 2-20 years Atl Croaker Micropogonias undulatus 1 Naked goby Gobiosoma bosc 3 3 Oyster toadfish Opsanus tau 2 1 Pinfish Lagondon rhomboides 2 2 Green Carcinus maenas species utilizing1 oyster reefs 1 • Arecrab American eels a resident Black Sea Bass Centropristis striata 1 and aquaculture racks as habitat? Alewife Alosa pseudoharengus 2 Bay anchovy Anchoa mitchilli 2 Spot Leiostomus xanthurus 1 Striped killifish Fundulus majalis 1 Summer flounder Paralichthys dentatus 1 Weakfish Cynoscion regalis 1 White Perch Morone americana 1 Species Richness 17 20 24
• 7 eels recaptured • 1 recaptured 2x • 13% recapture rate • no preference • n = 4 Aquaculture • n = 3 Reef
Total Number of Eels
• 52 eels marked • Aquaculture > Reef > Sand
Abundance
*
40 30 20 10 0 Sand
Reef
Recaptured Eels
3000 Total Biomass (g)
American Eel Mark-Recapture
50
Aquaculture Marked Eels
Biomass
*
2500 2000 1500 1000 500 0 Sand
Reef
Aquaculture
Conclusions ¾
Constructed reefs and aquaculture racks support increased species richness, abundance and biomass compared to sand flats.
¾
Rack and bag oyster culture increased species richness of motile fauna by increasing habitat diversity.
¾
Oyster aquaculture structures are at least functionally equivalent habitat as intertidal oyster reefs.
¾
Species composition is influenced by both habitat type and relative depth.
¾
Mark-recapture results show Anguilla rostrata is a resident reef/rack species.
Acknowledgements Special thanks to: Greg Debrosse Fernando Fuentes Emily Scarpa Iris Burt
Sean Boyd Jeff Pydeski Tom Evans Emma Green-Beach
And to: James Tweed of Atlantic Capes Fisheries for allowing us to sample on their oyster farm. Funding: New Jersey Water Resources Research Institute Graduate Student Grant-in-Aid The Rutgers University Graduate Program in Ecology and Evolution Academic Excellence Fund Rutgers University Research Council Grant Dupont Clear Into the Future Fellowship
