A guide for planners and managers - IUCN

PART II
Protected Areas for Lagoons and Estuaries
You can enter on the base map—manually or electronically—known critical
habitats of species both inside and outside the estuary, including submerged sea
grass and algal beds, as well as connections to the sea (lagoon mouths, deltaic
channels). Some critical habitats may overlap others, for example the nesting and
roosting sites of shorebirds and seabirds in mangroves may overlap the habitat of
muskrats in marshes (Figure II-21). Designated habitats should include those of
commercial species, showcase species, and endangered species.
Highlight the selected critical habitats
--whether using manual methods of mapping
or GIS—and indicate the recommended
management approach for each on the map.
Be aware that the areas chosen may be
subject to multiple use, not exclusively
assigned to protection, and the recommended
extent of such uses has to be clearly indicated
so that zones can be designated.
You will need to investigate the pattern
of human use and settlement in the estuary
and record significant sources of impacts. In
larger inhabited estuaries where there has
been some use and alteration of wetlands and
other coastal habitats, identify the remaining areas of high conservation value, which
generally will be those in a natural state, removed from human settlements, or
currently managed for recreation, research or education, or as private nature reserves.
Depending on the extent and location of settlement and commercial use, a larger
estuary can be zoned for different MPA management approaches, or as mentioned
above, allotted to CZM protection if there is an effective CZM process for the lagoon
or estuary. In this case, the most valuable and vulnerable critical habitats should be
given the fullest protection that MPAs can afford through zoning or other means.
2.7 Delineating the Zone of Influence
FIGURE II-21.
A muskrat house on a transitional brackish tidal
marsh next to a small creek (Pautuxent River,
Chesapeake Bay, Maryland, U.S.A.).
Water supply is vital to the estuary’s functioning. Sources of water include the
catchment, rivers and streams crossing the watershed, groundwater seepage and
sheet flow (runoff), rainfall, and intrusion of salt water from the sea. These water sources
link estuaries to agricultural and development activities that are tens, even hundreds,
of kilometers away. Disturbance of these sources--including their reduction, diversion,
and pollution—may have disastrous consequences for estuarine ecosystems. Such
distant activities are difficult to monitor, but must be controlled if an estuary and its
valuable components are to survive. When the main catchments that discharge to the
estuary lie close at hand and are not heavily settled, the two may be protected as single
“source-to- sink” units.
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Photo by John Clark.