Sean P. Powers, Kevan Gregalis and Kenneth L. Heck, Jr. University of South Alabama & the Dauphin Island Sea Lab the Dauphin Island Sea Lab RESTORATION

Sean P. Powers, Kevan Gregalis Sean P. Powers, Kevan Gregalis and Kenneth L. Heck, Jr.and Kenneth L. Heck, Jr.

University of South Alabama &University of South Alabama & the Dauphin Island Sea Labthe Dauphin Island Sea Lab

RESTORATION OF OYSTER REEFS IN COASTAL ALABAMA

Fisheries Habitat Fisheries Habitat ProgramProgram

Alabama Oyster Habitat (1972)Alabama Oyster Habitat (1972)

Live oyster reef

Buried oyster shell deposits


Alabama Oyster FisheryAlabama Oyster Fishery(Source: NMFS)(Source: NMFS)

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Landings (kg meat)

Frederic (3)

Opal (3)& Erin (2)

Camille (5)

Ethel (3) Elena (3)

50 yr averag

e


USA OYSTER REEF PROGRAMUSA OYSTER REEF PROGRAMto develop the scientific understanding to develop the scientific understanding necessary to direct oyster restoration necessary to direct oyster restoration and enhancement in Alabama coastal and enhancement in Alabama coastal waters.waters.

to assist in the development of a long-to assist in the development of a long-term strategy for sustained productivity term strategy for sustained productivity of Alabama’s oyster resources and the of Alabama’s oyster resources and the associated ecological benefits that associated ecological benefits that accrue from healthy oyster-based accrue from healthy oyster-based habitat.habitat.

to provide this information to state and to provide this information to state and federal management agencies, the federal management agencies, the fishing industry and the general public fishing industry and the general public through outreach activities. through outreach activities.


Restoration ChallengesRestoration Challenges

Larval recruitmentLarval recruitment

Hypoxic and anoxic bottom watersHypoxic and anoxic bottom waters

PredationPredation

New State Regulations (Dredging)New State Regulations (Dredging)


Oyster RecruitmentOyster Recruitment

Survey 18 sites Survey 18 sites throughout Mobile Bay throughout Mobile Bay every three weeks for every three weeks for oyster settlement.oyster settlement.

Jan 2006 – Dec 2007Jan 2006 – Dec 2007

Synoptic measurements Synoptic measurements of larval supplyof larval supply


Spat Recruitment MethodsSpat Recruitment Methods


Fisheries Habitat Fisheries Habitat

ProgramProgram

Hoese 1972, Spat surveyHoese 1972, Spat survey20 0 10 0 10 5

2

1

# spat m-2 d-1

(Hoese et al. 1972) Fisheries Habitat Fisheries Habitat

ProgramProgram

HypoxiaHypoxia

Based on studies by May, Schroeder, Saoud, and WallaceFisheries Habitat Fisheries Habitat

ProgramProgram

Predation: Oyster Drills


PredationPredation


Cedar Point Reef Shellbank Reef

Sand Reef

1 HR

2 HR

3 LR4 LR

8 LR 7 LR

5 HR 6 HR

1 LR7 LR

8 LR

6 LR4 HR

5 HR

2 HR

3 HR

5 LR 6 HR

7 LR8 HR

4 LR

3 LR1 HR

2 HRCedar Point Reef Shellbank Reef

Sand Reef

1 HR

2 HR

3 LR4 LR

8 LR 7 LR

5 HR 6 HR

1 LR7 LR

8 LR

6 LR4 HR

5 HR

2 HR

3 HR

5 LR 6 HR

7 LR8 HR

4 LR

3 LR1 HR

2 HR


Reef ElevationReef Elevation

u

High Relief (1.0

m)

Low Relief

(0.1 m)

2.5 m

1 m

2 m

Anoxic

Hypoxic

Normoxic

Mobile Bay Results: June 2006 Mobile Bay Results: June 2006

Cedar Point Reef Area H

Sand Reef Area A

Shellbank Reef Area

Mobile Bay


Sand Reef Area A

Shellbank Reef Area

Mobile Bay

0

20

40

60

80

100

120

140

# L

ive

Oys

ters

/ m

2

Cedar Point Reef Sand Reef Shellbank Reef0

20

40

60

80

100

120

140

# L

ive

Oys

ters

/ m

2

0

20

40

60

80

100

120

140

160

# L

ive

Spa

t / m

2

Cedar Point Reef Sand Reef Shellbank ReefSite

0

20

40

60

80

100

120

140

160

# L

ive

Spa

t / m

2

0

10

20

30

40

50

60

70

# D

ead

Spat

/ m

2


0

10

20

30

40

50

60

70

2


High vs. Low reliefHigh vs. Low relief

Cedar Point Reef Shellbank Reef

Sand Reef

1 HR

2 HR

3 LR4 LR

8 LR 7 LR

5 HR 6 HR

1 LR7 LR

8 LR

6 LR4 HR

5 HR

2 HR

3 HR

5 LR 6 HR

7 LR8 HR

4 LR

3 LR1 HR

2 HRCedar Point Reef Shellbank Reef

Sand Reef

1 HR

2 HR

3 LR4 LR

8 LR 7 LR

5 HR 6 HR

1 LR7 LR

8 LR

6 LR4 HR

5 HR

2 HR

3 HR

5 LR 6 HR

7 LR8 HR

4 LR

3 LR1 HR

2 HR

0

20

40

60

80

100

120

2Low High

Reef Height

0

20

40

60

80

100

120

# L

ive

Spa

t / m

2Low High

Reef Height

No effect of vertical relief on average size or total oysters


Oyster Mortality AssaysOyster Mortality Assays


Sand Reef Area A

Shellbank Reef Area

Mobile Bay


Sand Reef Area A

Shellbank Reef Area

Mobile Bay

0.002

.004

.006

.008

.01.012.014.016.018

Oys

ter

Mor

tali

ty R

ate


HighLow

0.002

.004

.006

.008

.01.012.014.016.018

Oys

ter

Mor

tali

ty R

ate


High reliefLow relief

A

B

C*


Restoration Challenges: Mobile BayRestoration Challenges: Mobile Bay• Dissolved Oxygen

• Larval supply

20 0 10 0 10 5

2

1

# spat m-2 d-1

(Hoese et al. 1972)

• Predation


ConclusionsConclusionsPersistence of structure following three major Persistence of structure following three major hurricanes.hurricanes.Greater vertical relief of reefs can enhance Greater vertical relief of reefs can enhance recruitment.recruitment.Cost: Benefit ratio falls short of the 10:1 Cost: Benefit ratio falls short of the 10:1 necessary to justify high relief reefs from a necessary to justify high relief reefs from a fisheries perspective. fisheries perspective. Because reefs are colonized by other sessile Because reefs are colonized by other sessile invertebrates, low oyster density does not invertebrates, low oyster density does not mean in absence of ecological function.mean in absence of ecological function.


New StrategiesNew Strategies

Expand areal coverage of low relief reefs Expand areal coverage of low relief reefs at Cedar Point and Sand Reefat Cedar Point and Sand Reef

D.O. studies at white house reefD.O. studies at white house reef

Seed oyster reefs at Shellbank with Seed oyster reefs at Shellbank with Hatchery seed and establish spawning Hatchery seed and establish spawning sanctuarysanctuary


Spawner sanctuary in Bon SecorSpawner sanctuary in Bon Secor

Results of the Park and Kim biophysical transport model indicating concentrations of dye released at Shellbank (upper panel) after 6 days and Fish River Reef after 10 days. Release location is indicated by the red star. Fisheries Habitat Fisheries Habitat

ProgramProgram

Documents

Sean P. Powers, Kevan Gregalis and Kenneth L. Heck, Jr. University of South Alabama & the Dauphin Island Sea Lab the Dauphin Island Sea Lab RESTORATION