Approximately 0.8 ha of the study site are occupied by

 an open pond and its border of vegetation. The pond is in

 the deepest portion of a depression in the marsh

 approximately 4 ha in extent; but, except for the pond and

 its border, the depression cannot be distinguished from the

 rest of the marsh by vegetational features visible on

 aerial photographs. The pond is bordered on two sides by

 islands of higher ground supporting tropical hardwood

 trees. The rest of its margin is contiguous with the

 marsh.

 The pond is connected to the marsh during the wet

 season, when the whole area is covered by a sheet of water.

 During the dry season the pond shrinks to less than 0.2 ha.

 Because this pond is in a depression in the center of a

 slough, under most circumstances it would contain water

 throughout the year and thereby act as a holding area for

 aquatic life during the dry season and a center for its

 redispersal at the beginning of the wet season. A shallow

 well and deisel pump operated by owners of range cattle in

 the area assure that the pond never dries. The pond has a

 sand bottom covered with a layer of flocculent material,

 which increases in thickness during the dry season, giving

 the pond its name, "Mud Lake."

 The pond's eulittoral zone is covered by a mixture of

marsh temperate species dominated by pickerel weed

(Pontederia lanceolata), maidencane (Panicum hemitomom),

and water hyssop (Baco a sp.). A solid stand of Sesbania