| Abstract | Introduction | Methods1 | Methods2| Results1 | Results2 | Results3 | Discussion1 | Discussion2 | Discussion3 | Future| Acknowledgments |
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| Determination of Water Depth at the Deep Edge of Seagrass Meadows in Tampa Bay Using GPS Carrier Phase Processing |
| J.O.R. Johansson, K.B. Hennenfent and J.J. Pacowta. (City of Tampa, Bay Study Group) |
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Seagrass Elevations
Deep edge elevations of the measured seagrass meadows ranged from -0.30mMTL for H. wrightii in the upper portion of Hillsborough Bay to -1.96mMTL for S. filiforme in southwestern Middle Tampa Bay. Further, all sites visited in the present study had deep edge elevations shallower than the TBEP seagrass restoration target depth for the respective bay segment.
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| Locations of seagrass elevation survey sites in Tampa Bay. Also shown are major bay segments (HB=Hillsborough Bay; OTB=Old Tampa Bay; MTB=Middle Tampa Bay [including sub-segments]; and LTB=Lower Tampa Bay). |
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The greatest deviation from the target depth was found at the Long Branch and Big Island sites in western Old Tampa Bay, where the deep edges of the H. wrightii meadows were about 1.20m shallower than the -1.9mMTL target depth.. The least deviation was found at three sites: the H. wrightii meadow in the Kitchen in southeastern Hillsborough Bay, the T. testudinum meadow at Bel Mar Shores in eastern Old Tampa Bay, and the S. filiforme meadow at Coquina Key in southwestern Middle Tampa Bay. These three areas had deep edges that were approximately 0.50m shallower than the respective bay segment targets.
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| Results of GPS seagrass elevation measurements conducted for different seagrass species in different sections of Tampa Bay. Elevation expressed as mean tie level (MTL) |
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The greatest deviation from the target depth was found at the Long Branch and Big Island sites in western Old Tampa Bay, where the deep edges of the H. wrightii meadows were about 1.20m shallower than the -1.9mMTL target depth.. The least deviation was found at three sites: the H. wrightii meadow in the Kitchen in southeastern Hillsborough Bay, the T. testudinum meadow at Bel Mar Shores in eastern Old Tampa Bay, and the S. filiforme meadow at Coquina Key in southwestern Middle Tampa Bay. These three areas had deep edges that were approximately 0.50m shallower than the respective bay segment targets.
Additional elevation measurements in Lower Tampa Bay may find deeper seagrass edges than those measured at Port Manatee. Dixon (2000) conducted light requirement studies on T. testudinum sites in Lower Tampa Bay that ranged in depth from -1.98 to -2.37mMTL. These depths, which were estimated from sea surface observations, are approximately 0.3 to 0.6m deeper than the T. testudinum meadows surveyed at Port Manatee.
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