Maryland’s coastal bays support 115 fish species, more than 400 different types of birds, a variety of wetland plants (2 species of seagrasses), and about 150 species of crabs, shellfish, bugs and worms that live on or in the bays’ sediment.

These plants and animals depend on a clean environment for their survival. Their health and abundance is generally worse in the northern bays (Assawoman and Isle of Wight) and artificial canals, and better in the southern bays (Sinepuxent and Chincoteague).

Fishes

Most fish communities appear in good condition, but there is concern for some species. For example, pollution sensitive species such as flounder are becoming less abundant in the northern bays while pollution tolerant species like mummichogs are becoming more abundant.

Changes in fish populations are early warning signs that the water quality is being affected by human activity. If attention is not paid to these early warning signs, Maryland’s coastal bays may end up like Delaware’s bays which had fish populations similar to Maryland 20 years ago but are now dominated by pollution-tolerant species.

Crabs and Shellfish

Scientists often use bottom dwelling organisms as indicators of the bay’s health. A diverse community suggests a healthy environment, while areas with only a few species are considered degraded. Scientists found the artificial canals and larger tributaries in the coastal bays to be the most degraded. Degraded bottom communities are related to stressed conditions such as low oxygen, harmful levels of chemicals or physical environment. These unhealthy conditions are mostly found in the northern bays.

Some bottom animals are important economically (blue crabs and hard clams) as commercial and recreational species, while others are very important in recycling nutrients in the sediment (clams, worms & other burrowing animals).

Harvests of hard clam have increased over the past 20 years while harvests of oysters have dropped significantly. Increased hard clam harvests most likely reflect changes in harvesting technology more than increases in the clam population. During this century disease, predation, and over-harvesting have impacted the oyster population to the point where there is no commercial oyster fishery remaining in the coastal bays. The Atlantic scallop was once abundant in the bays but was wiped out due to the loss of seagrasses in the 1930s.

Harvests of both hard and soft crabs declined sharply in the 1950s, but gradually increased through the 1970s and 1980s. Fortunately, harvest data suggests that current crab populations are stable. The majority of the area’s crab harvest occurs early in the season since the bays’ shallow waters heat up quickly in the spring. This early harvest brings crabbers to the coastal bays until crabs in the Chesapeake Bay become more abundant. Therefore, the sustainability of the coastal bays’ blue crab industry has state-wide implications.

Seagrasses

Seagrasses are rooted underwater plants that help clean the water and provide shelter to young fish and crabs. Like all plants, seagrasses absorb nutrients and release oxygen through photosynthesis. Seagrasses are also important food sources for ducks and other waterfowl.

Seagrasses, wiped out by an eelgrass blight in the 1930s, have increased in acreage since 1985. Currently, seagrass beds are most abundant in Chincoteague Bay and almost non-existent in the northern bays.

Many factors determine the health of seagrass communities including water quality, sediment type, light availability and density of plants. Physical disruption by boats, seed availability, temperature, rainfall and disease also influence seagrass abundance and distribution. Most seagrasses are found along the eastern side of the coastal bays where the sediments are sandier and more conducive to growth.

Birds

The coastal bays are home to numerous bird species, many of which suffer from habitat loss. This area is critical for many migrating birds including song birds, waterfowl and shore birds because it lies within the Atlantic flyway, one of only four major migratory bird routes in North America. Forests, wetlands and beaches along this coastal corridor are important wintering, staging and breeding habitats for more than 360 bird species.

Colonial nesting birds -- birds that nest together -- have 30 active nesting sites in the coastal bays. These include the northernmost nesting colonies of brown pelicans and royal terns. Nearly one quarter of Maryland’s colonial nesting waterbird population is found in Worcester County.

The bays also provide habitat for approximately 30 species of waterfowl and shorebirds. The number of mallards and wood ducks has increased in recent years. While the number of black ducks, which are more sensitive to disturbance by human activities, declined in the early 1980s, but seem to have stabilized since harvest restrictions were imposed in 1985.

Threaten and Endangered Species

The coastal bays are also home to 108 threatened and endangered plants and animals. Threatened and endangered animals include the piping plover, the royal tern, Wilson’s plover the white tiger beetle and the little white tiger beetle.

Related  Links: Monitoring Data on DNR's website