Direct vs. indirect impacts of salinity on oyster ( Crassostrea virginica ) health and abundance

Direct vs. indirect impacts of salinity on oyster (Crassostrea virginica)

health and abundance

Melanie L. Parker and William S. ArnoldFWC - Fish & Wildlife Research Institute

100 Eighth Avenue SESt. Petersburg, FL 33701

727-896-8626melanie.parker@myfwc.com

U.S. Army Corps of Engineers, Jacksonville District

Water Flow in Florida

Comprehensive Everglades Restoration Plan (CERP)

• CERP implemented as a means of reinitiating natural freshwater flow to both coasts of south Florida

• Monitoring component of CERP addresses impacts of changed FW flow on the flora and fauna

• Eastern oyster chosen as a target species for CERP

Study Sites

• IMPACTED SITES

St. Lucie Estuary

Loxahatchee River

Lake Worth Lagoon

Biscayne Bay

• CONTROL SITES

Tampa Bay

Mosquito Lagoon

Sebastian River

Mosquito Lagoon

• Pristine environment

• Located within Canaveral National Seashore

• Few anthropogenic or freshwater inputs

Mosquito Lagoon Stations

1

3

2

St. Lucie Estuary

• Urban environment

• Increasing levels of development, industry and agriculture

• Flood control canals and drainage ditches

St. Lucie Estuary

• Exposed to altered patterns of water quantity and quality– excess wet season

flows– insufficient dry

season flows– extreme salinity

fluctuations– High sediment and

pollutant inputs

St. Lucie Stations

North

South

Central

1

1

1

2

2

2

3

3

3

Salinity Patterns Mosquito Lagoon

0

10

20

30

40

50

St. Lucie-North

0

10

20

30

40

50

St. Lucie-South

Date

Jan 2

005

Mar

200

5

May

200

5

Jul 2

005

Sep 2

005

Nov 20

05

Jan 2

006

Mar

200

6

May

200

6

Jul 2

006

Sep 2

006

Nov 20

06

Sal

init

y

0

10

20

30

40

50

St. Lucie-Central

0

10

20

30

40

50

Juvenile Recruitment

• Monthly sampling

• 3 replicate spat arrays at each station

• Count live oysters on underside of each strung shell

Juvenile Recruitment

St. Lucie-South

DateJa

n 200

5

Mar

200

5

May

200

5

Jul 2

005

Sep 2

005

Nov 20

05

Jan 2

006

Mar

200

6

May

200

6

Jul 2

006

Sep 2

006

Nov 20

06

Mea

n S

pat

/Sh

ell

0

5

10

15

20

Sal

init

y

0

10

20

30

40

50

Mosquito Lagoon

0

5

10

15

20

0

10

20

30

40

50

St. Lucie-North

0

5

10

15

20

0

10

20

30

40

50

St. Lucie-Central

0

5

10

15

20

0

10

20

30

40

50

Spat/ShellSalinity

Abundance and Distribution

• Twice per year

• 10 replicate 1-m2 quadrats at each station

• Count total live and dead oysters

• Measure SH of 50 live oysters

Abundance and Distribution

Site

ML SL-N SL-C SL-S

Mea

n S

H (

mm

)

0

20

40

60

80

100

ML SL-N SL-C SL-S

Sal

init

y

0

10

20

30

40

50

ML SL-N SL-C SL-S

Mea

n L

ive

Oys

ters

/m2

0

100

200

300

400

500

Winter 2005Summer 2005Spring 2006Fall 2006

Perkinsus marinus (Dermo)

• Monthly sampling

• Collect and dissect 15 oysters from each site

• Process gill and mantle tissues with RFTM

• Parasite density ranked with Mackin scale

St. Lucie-Central

Date

0

20

40

60

80

100

Infe

ctio

n In

ten

sity

0

1

2

3

4

5

Per

cen

t In

fect

ed a

nd

Sal

init

y

0

10

20

30

40

50

% Infected

Infection IntensitySalinity

Mosquito Lagoon

0

20

40

60

80

100

0

1

2

3

4

5

0

10

20

30

40

50

No oysters collected fromJuly 2005 through April 2006

Perkinsus marinus (Dermo)

Summary

Mosquito Lagoon St. Lucie estuary

Mean Max Min Mean Max Min

Salinity 33.6 42.4 26.1 11.1 29.5 0.20

Mean S.D. % Mean S.D. %

Recruitment 1.35 2.52 0.28 1.10

Density 43.0 53.3 96.2 144.4

Shell Height 53.0 26.3 28.4 8.7

Dermo 0.43 0.71 46 0.05 0.25 9

Conclusions

• The prevalence and intensity of dermo infection is greater at the high salinity Mosquito Lagoon site than at the more variable salinity St. Lucie site

• Nevertheless, oysters in Mosquito Lagoon exhibit higher recruitment rates and less variable adult populations relative to the St. Lucie estuary

• The indirect (negative) effects of salinity appear to exceed the direct effects of dermo on oyster health and abundance in east coast Florida waters

• In FLORIDA SOUTHEAST COAST ESTUARIES,it may be premature to conduct oyster reef rebuilding operations until freshwater entering those estuaries is properly managed

Questions?