HOW ARE TIDAL FLATS
WHY ARE TIDAL FLATS VALUABLE?
primary function of tidal flats is the conversion of plant biomass (usually
in the form of detritus) to animal biomass
that can be used by organisms at higher trophic
levels. The presence
of tidal flats in the mosaic of the coastal
environment is very important to shorebirds and wading birds.
For migrating and wintering shorebirds, the tidal flats of the
Laguna Madre represent the largest continuous expanse of suitable habitat
between northern breeding grounds and more distant wintering grounds in
South America. Most shorebird mortality is thought to be due to a lack of
resources in wintering and migratory staging areas. The invertebrates of the flats provide an abundant food source
for shorebirds. Alternate
feeding sites are available on nearby beaches for shorebirds when flats
are completely flooded. Adjacent
upland and transitional habitats provide areas for nesting and roosting.
Tidal flats are also a source of “new” nitrogen to the ecosystem
since the blue-green algae that comprise the algal mat convert atmospheric
nitrogen into nitrogen that can be used by other plants and much of what
is converted leaks from the flat into surrounding shallow water.
ARE TIDAL FLATS THREATENED?
primary threat to tidal flats is a lack of understanding about their importance.
To most people “wetlands” means marshes not tidal flats.
Most people understand why marshes need to be preserved but are
not easily convinced that tidal flats deserve the same consideration.
Although the plight of the Piping
Plover has helped improve the status of tidal flats, the lack of a
readily understood component like cordgrass as a focal point means that
the value of tidal flats remains difficult to convey to people outside
the circle of scientists and resource agencies involved in their management.
Birders aside, most people just don’t understand why they should
care and this poses a distinct challenge in the conservation and protection
of tidal flats as important natural coastal habitats.
flats in Laguna Madre are the most important habitat for wintering
shorebirds at the northernmost extent of most species’ wintering range. The tidal flats in Laguna Madre are being impacted by a
variety of natural and human disturbances, some of which are serious and
long-lasting. Over the last
40 years there have been dramatic reductions in the extent of tidal flats,
largely due to global sea-level rises.
This means that remaining flats may be essential to shorebirds in
general and critical to populations of some species, like Piping Plover. Reduction of serious, long-lasting human disturbances like
commercial or residential development is necessary to ensure the integrity
of this vital habitat.