Water Mass Properties of the Straits of Florida and Related Waters

The hydrography of the Straits of Florida is greatly influenced by a flow of water originating in the Caribbean-Gulf of Mexico region and to a lesser extent by waters of the Western Atlantic. The Caribbean or Yucatan Water, identified by its well-defined salinity maximum, is found along the entire insular margin of the Florida Current. Evaporation and seasonal cooling modify the upper 300 m of the original Yucatan Water, creating new water masses in the northern and western Gulf of Mexico. The Continental Edge Water, a water mass somewhat intermediate between Yucatan and Western Gulf Waters, becomes well-differentiated in the eastern Gulf, being easily identified by temperature-salinity and oxygen-density relationships. The Continental Edge Water is found along the continental margin of the Florida Current throughout the length of the Straits. The influx of Western Atlantic Water is frequently observed in the northern Straits of Florida off Bimini, being detected by its higher oxygen content; it is restricted to a narrow band along the Bahama Banks. The study of oxygen distribution shows that Western Atlantic Water intermixes with the waters flowing out of the Straits of Florida. Present information on dissolved inorganic phosphate is too unreliable to permit a critical study of its distribution. The Straits of Florida are part of an extensive sill preventing interchange of waters from depths greater than about 800 m between the Gulf of Mexico and the Atlantic Ocean. The sill depth of the Straits of Florida and portions of the Blake Plateau is slightly below the average depth of the oxygen minimum and is exactly within the average depth of the dissolved inorganic phosphate maximum.