Life in the High Marsh

Published: Thursday, November 7, 2013 at 11:16 AM.

Other plants often found on or near salt barrens are saltwort (Batis maritima), and sea purslane (Sesuvium portulacastrum). Saltwort may cover the ground almost exclusively in very saline areas, and can be found in profusion on some of the low islands in St. Joseph Bay. It flowers from spring to late fall and produces a berry. Sea purslane, like glasswort, is edible. The pinks and purples of sea purslane flowers add color to the browns and greens of marshes.

Along the inland fringe of the salt marsh occur species of plants associated with coastlines but growing in areas that are flooded only during the extreme storm surges. This group includes sea myrtle (Baccharis halimifolia), marsh elder (Iva frutescens), seaside goldenrod (Solidago sempervirens) and Christmas berry (Lycium carolinianum), as well as various willows and sumac. It is the cottony flowers of sea myrtle and the small blossoms of marsh elder that attract and feed so many migrating butterflies each fall. Both can be seen on US 98 just east of town and along the edge of the marsh. If you see a bush covered in butterflies during this time of year, it is likely either sea myrtle or marsh elder. Christmas berry brightens the high marsh with bluish flowers and bright red fruit. Blending into upland hammocks is the beautiful and poisonous coral bean (Erythrina herbacea). In the spring, the bright red blossoms of this plant are conspicuous along the marsh edge, as well as, along the roads along St. Joseph Bay. Coastal Indians once made beads from its poisonous red and black seeds, and it is these red seeds that are visible now.

Relatively few animals can endure the extremes of the upper marsh. The clapper rail both feeds and nests in the upper marsh. The diamondback terrapin, the only turtle in the world that lives in brackish and saltwater marshes, hibernates in the marsh muds, but lays its eggs in the sandy areas above the high tide mark. The rough green snake and the salt marsh snake (Nerodia clarkii) live in this zone. Rarely seen, the salt marsh snake is strictly nocturnal. Besides rails, marsh wrens and seaside sparrows are some of the birds that inhabit this zone. Scott’s seaside sparrow (Ammodramus maritimus peninsulae) is the race found locally and is picky in terms of habitat. It is a salt marsh obligate.

Besides resident populations of fiddler crabs, rails, wrens, and terrapins, the marsh vegetation supports many migrants. Raccoons, opossums, deer and mice visit the upper marsh for food.

Considerable research has been conducted on the regularly flooded low marshes, where nutrients and metabolic wastes can be exchanged on each high tide. Only spring tides, storm tides, and wind-driven tides ever cover the upper marshes, where nutrient exchanges are less well understood. Yet, the high marsh plants function as a buffer between polluted water run-off from land and the highly productive lower marsh. Construction set-backs are necessary to protect this critical transition zone, which is not only an important wildlife habitat but a protective buffer for the regularly flooded salt marsh.

Tom Baird has been a fisheries biologist, high school and community college teacher (oceanography and microbiology), director of a science and environmental center, teacher of science and principal in Pinellas County as well as an educational consultant. He retired from the Florida Department of Education and he and his wife divide their time between Tallahassee and Cape San Blas.

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