direct vs. indirect impacts of salinity on oyster (crassostrea virginica) health and abundance...
TRANSCRIPT
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
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 2005 Mar 2005 May 2005 Jul 2005 Sep 2005 Nov 2005 Jan 2006 Mar 2006 May 2006 Jul 2006 Sep 2006 Nov 2006
Salinity
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
DateJan 2005 Mar 2005 May 2005 Jul 2005 Sep 2005 Nov 2005 Jan 2006 Mar 2006 May 2006 Jul 2006 Sep 2006 Nov 2006
Mean Spat/Shell
0
5
10
15
20
Salinity
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
Mean SH (mm)0
20
40
60
80
100
ML SL-N SL-C SL-S
Salinity0
10
20
30
40
50
ML SL-N SL-C SL-S
Mean LiveOysters/m
2
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
DateJan 2005 Mar 2005 May 2005 Jul 2005 Sep 2005 Nov 2005 Jan 2006 Mar 2006 May 2006 Jul 2006 Sep 2006 Nov 2006
0
20
40
60
80
100
Infection Intensity
0
1
2
3
4
5
Percent Infected and Salinity
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?