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Posted by Alex Harper on 18:49:46 11/30/11
In Reply to: Re: Eider sighting? posted by Carlos Sanchez
Unfortunately for Floridian's on the Gulf, the continental shelf is much wider on the Gulf side than on the Atlantic.
It appears to be at least 150 miles to the continental slope and rise from several points on the Peninsula. I'd imagine pelagic species are more concentrated there. This is not to say there aren't pelagics off of the Gulf closer to Florida, but without any mechanism for upwelling, they are in very low concentrations.
Optimal areas for pelagic birds in the Gulf, or anywhere in Florida, are relatively nonexistent. Simply put, the high water temperature can't contain enough dissolved oxygen to support massive amounts of phytoplankton, and in turn support the organisms that most pelagic birds feed on. The dissolved oxygen and nutrients are present in deeper layers offshore, but suppressed by a deep thermocline. At that depth, light penetration is a limiting factor for phytoplankton abundancy. It all leads back to the missing mechanism.
Offshore North Carolina is one of the best locations for pelagic birding in the North Atlantic. This is because of the proximity to the continental slope, but also because two major water masses are converging and mixing: the cold Labrador Current and the warm Gulf Stream.
Alex
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