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Oyster Reef Mapping at North Fork St. Lucie River Aquatic Preserve Quick Topics

Like seagrass, oyster reefs were first documented in the St. Lucie River (SLR) in the 1940s. GIS data layers have been created for the following years: 1940-1960, 1960-1980, 1990-1996, 1997 and 2003. The 2003 data shows 31 acres of oyster material (dead and alive) within the preserve. Researchers mapped three oyster reefs within the SLR in winter 2005-2006. Recent mapping efforts show that despite availability of potentially suitable substrate, oyster reefs are declining within the SLR. Researchers suspect that these differences result from extended exposure to reduced salinity due to freshwater discharges from Lake Okeechobee and the surrounding watershed. Oysters in the SLR are the least healthy of those sampled in Lake Worth Lagoon, the Loxahatchee River, SLR, and Sebastian River. The smaller size and density of the SLR oysters suggests a younger population (possibly due to recent disturbance) than those in Lake Worth Lagoon and the Loxahatchee River.

Monitoring efforts by Florida Fish & Wildlife Conservation Commission (FWC) began in January 2005 and are expected to continue until 2010. FWC monitors four aspects of oyster ecology:

  • Spatial and size distribution patterns of adult oysters.
  • Distribution and frequency patterns of oyster diseases.
  • Reproduction and recruitment.
  • Juvenile oyster growth and survival in coastal areas subject to freshwater discharge from canals.

FWC monitoring sites are located in:

  • Biscayne Bay.
  • Lake Worth Lagoon.
  • Loxahatchee River.
  • SLR.
  • Sebastian River.
  • Mosquito Lagoon.

The last two sites are not connected to the canal system and are monitored by FWC for comparison purposes.

The Florida Oceanographic Society (FOS) established an oyster reef restoration program in 2006 that involves placement of juvenile oysters on existing natural reefs and seeding of newly created recycled oyster shell reefs. A monitoring component has been established by FOS to document restoration success. FOS measures:

Oyster rake

Biologists use an oyster rake to monitor density of oysters.

  • Growth and mortality of cage-raised juveniles prior to release onto existing oyster reefs.
  • Density and growth on augmented oyster reefs (both natural reefs and recycled-oyster shell reefs).

Monitoring by FOS staff is expected to continue throughout 2009.

 

 

 

 

 

 

 

 

Last updated: September 24, 2010

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