On water renewal and salinity variability in the northeast subregion of Florida Bay

• Autores: Thomas N. Lee, Nelson Melo Ginzález, Elizabeth Johns, Christopher Kelble, Ryan H. Smith
• Localización: Bulletin of Marine Science, ISSN 0007-4977, Vol. 82, Nº. 1, 2008, págs. 83-105
• Idioma: inglés
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• Resumen

  • The northeast subregion of Florida Bay receives approximately 75% of the direct freshwater runoff to the bay, most of which is retained within the subregion and has little impact on the dilution of hypersalinity development in adjacent subregions. Using direct measurements of the volume transports through connecting channels and indirectly estimating the total transport to the subregion from mean sea level variability, we show that interior basin water exchanges are weak and controlled by local wind forcing. East-west winds produced seasonally averaged throughflows of 33 and 78 m3s-1 during the El Niño-influenced wet and dry seasons of 2002 and 2003, respectively, and resulted in a one year residence time for the northeast sub-region. The long residence time of the interior waters is due to the confining nature of the shallow banks and mangrove borders that surround the northeast subregion, as well as the lack of significant tidal exchange. Weak interbasin exchange results in the trapping of freshwater discharge from the Everglades within the northeast subregion. Development of hypersalinity within the north-central subregion of the bay has been associated with seagrass die-off and algal blooms that can cause water quality reduction in south Florida's coastal waters, including the Florida Keys reef tract. To reduce the development of hypersalinity within this region of the bay it will be necessary to divert a portion of the Everglades flow away from the northeast basin and into Whipray Basin during the dry season. Seasonal water balance estimates made for the northeast subregion and previous estimates from the north-central region indicate that groundwater inflows to Florida Bay are negligible and probably not a factor in water quality considerations.