The assemblages of these organisms vary from one ecosystem to another because the habitat conditions unique to each type of ecosystem tend to affect species distributions. The species adapted to these particular river conditions are rare or absent in the still waters of lakes and ponds. A lake is a sizable water body surrounded by land and fed by rivers, springs or local precipitation. Florida has over 7,700 lakes with a surface area over 10 acres or more. For more information, go to the Special Feature on lakes.
Ponds are smaller bodies of still water located in natural hollows.
Ponds are found in most regions and may exist either seasonally or persist from year to year. Rivers and streams are bodies of fresh, flowing water. The water runs permanently or seasonally within a natural channel into another body of water such as a lake, sea or ocean. Rivers and streams are generally more oxygenated than lakes or ponds, and they tend to contain organisms adapted to the swiftly moving waters. The tidal areas where salt water and fresh water meet are called estuaries .