A guide for planners and managers - IUCN

200 MARINE AND COASTAL
PROTECTED AREAS
Box II-1. Types of Critical Habitats
Sea grass, kelp, and algal beds are sources of primary productivity and detritus
production. These are important feeding grounds for certain fishes and waterfowl and
nurseries for shrimp and fishes.
Mud and sand flats are the habitats of bivalves and the feeding grounds of shrimp
and crabs. They are particularly important to over-wintering waders and shorebirds, the
substrate for nitrogen-fixing blue-green algae, and a storage unit for important dissolved
substances.
Salinas (barren salt flats) may be important in flood control and, in some areas,
harboring valuable species, such as the brine shrimp (Artemia).
Creeks and Meanders are the critical habitat of many species, and during certain
seasons may be replete with juvenile shrimp and fishes. They are a source of algal and
phytoplankton productivity and serve as the course of tidal and freshwater supplies and
the routes of access to different parts of the wetlands complex for aquatic organisms.
Oyster reefs are valuable in their own right for the harvest of their biomass and
for providing a special habitat.
Coral reefs are connected to estuaries/lagoons in many ways: e.g., as the spawning
places of fishes that seek refuge as juveniles in the mangroves.
Reed beds (Phragmites) at stream or river mouths and deltas are important silt traps
that help control the turbidity of waters flowing into the estuary, and they may also be
important factors in flood control. They also provide nesting habitats for a variety of birds.
Sand dunes, barrier islands, and beaches are dynamic habitats. They are sensitive
to overuse and prone to erosion, which alters natural cycles of accretion and erosion of
sand supplies along the seashore. This may result in the sea breaching the coastal
barrier and flooding wetlands with salt water, the smothering of wetland habitats by windblown
sand, and the choking of lagoon and estuary mouths by increased longshore drift
of sand. These beaches and barrier islands often provide valuable nesting habitat for sea
turtles (e.g., Tortuguero National Park in Costa Rica)
Alluvial bars are unstable dynamic habitats formed of water-borne silt. When
disturbed, they are prone to resuspending fine alluvial particles that cloud the water,
reducing phytoplankton, sea grass, and algal productivity.
Mangroves have multiple roles, including shoreline stabilization, trapping riverborne
silt, detritus production, and providing nursery habitats for fishes and shrimp and
safe roosting and nesting sites for birds.
estuary by air to locate and map critical habitats like wetlands. If recent aerial
photography (or satellite imagery in the case of very large areas) can be used, it should
be spot checked (“ground truthed”) by walking or boat surveys. It is convenient to
use computers for storage, retrieval, and display of data; for example through
Geographic Information Systems (GIS) as discussed in Section I-5.1.