CHAPTER IV: WILDLIFE HABITATS FOR MISSISSIPPI’S SGCN,
THREATS AND CONSERVATION ACTIONS^27014.6 Seagrass Beds
Value to SGCN - 25
Rank - 13th of 17 Marine, Estuarine and Estuarine Fringe
DESCRIPTION
Mississippi coastal waters contain three submergent bed types: barrier island seagrass, widgeon grass
and American wildcelery beds. The types can be distinguished by differences in species composition,
habitat requirements and location within the estuary. Barrier island seagrass beds originally contained
three species of seagrasses: shoal, turtle and manatee grasses. Several of these have become very rare or
have disappeared altogether. The beds occur in less turbid, moderately saline habitats of the nearshore
zone north of the barrier islands. Widgeon grass or Ruppia beds occur in shallow and moderately turbid
waters that are lower in salinity. The beds are found in bays, along bayous, on mudflats and
occasionally in barrier island ponds. Their abundance in Mississippi waters has fluctuated dramatically
over time due to damage caused by hurricanes, which eliminated them from many areas. Recently
widgeon grass has returned to many of the areas in which it once existed. American wildcelery or
tapegrass prefers freshwater or oligohaline waters and can be found growing on muddy substrates in the
upper reaches of many estuarine bayous and streams flowing into coastal bays and the Mississippi
Sound. The lower limits of wildcelery are near the mouths of coastal streams. American wildcelery
forms beds of submerged strap- or ribbon-like leaves from several inches to several feet in length.
Wildcelery is occasionally found growing with widgeon grass. Seagrass beds provide habitat for
numerous aquatic species. Productivity of the beds can be continued by maintaining or improving local
water quality and by reducing the mechanical damage to the beds.
Although not technically a seagrass bed, the macroscopic algae bed community is mentioned here to
recognize that it once occurred in Mississippi waters. They still exist in waters off the southern Florida
coast. Macroscopic algae beds were observed near Cat Island but have not been recorded in recent
years. Algae beds are predominantly composed of macrophytic red algae that are attached to benthic
shell material. They grow to a height of about two feet.
LOCATION, SIZE, CONDITION AND CONSERVATION STATUS
NGM
Seagrass beds are found in a variety of shallow subtidal habitats in
bays, bayous and rivers along the coastal mainland and in the
Mississippi Sound. Seagrasses require fairly clear water for sunlight
to penetrate to a depth where the plants are attached and growing. It
is estimated that approximately 2,000 acres of this subtype are
found in the state.
14.6 Seagrass Beds
Range of Seagrass Beds