The Seaweeds in Maryland

There are more than 7,000 varieties of seaweed in the world's oceans and seas. Many of these varieties grow in the waters off of Maryland's coast. When the New World was being explored, settlers relied on the seaweeds that grew predominantly along the coast as a food source. Today, seaweed is farmed off the coast of Maryland because of its nutritional and medicinal properties. Maryland's seaweed varieties can be divided into six categories, including kelp, bull kelp, brown algae, red algae, sea lettuce and Irish moss.

Kelp

• Giant kelp is a perennial, which grows from a spore and continues to thrive for an average of seven years. Although kelp is more prevalent along the Pacific Coast, it does occur along the coast of Maryland as well. According to the National Marine Sanctuaries, kelp forests grow in clear water with a depth of up to 90 feet. Kelp needs a high level of light penetration to thrive, most commonly occurs in areas with a rocky coastline, and prefers cooler water to warm. Kelp has anchors, called holdfasts, as opposed to a fibrous root system. The holdfasts cling to the surface of rocks to keep the kelp from being washed out to sea. Gas bladders in the kelp's foliage keep the upper part of the plant near the surface of the water for better light absorption and growth.

Bull Kelp

• Bull kelp is an annual, which completes its life cycle in a single growing season. It grows at a rate of approximately 10 inches a day, and reaches a mature stem height of 30 to 60 feet. Bull kelp is significant to the coastal ecosystem because it provides housing for invertebrate sea life, including urchins, crabs and snails. It is farmed and harvested for use in commercial products including medical-grade nutrition supplements and face masks. Bull kelp is golden when seen in the water, but washes ashore and dries to a dull brown color.

Red Algae

• There are between five and six thousand varieties of red algae in the world, some of which grow off the coast of Maryland. Red algae prefer clean-running salt water, in areas where movement is ongoing. The fossil record of these algae can be dated back to at least the Cambrian period of history. Red algae buildup contributes to the construction of limestone reefs at sea.

Brown Algae

• Brown algae is found in shallow waters in subtidal or intertidal zones. They prefer areas of cold water, and are plentiful in the waters off of Maryland. Brown algae have a gold to brown pigment created by the interaction between chlorophyll and other pigments which disguise the green undertones. Brown algae is harvested for use in cosmetics and pharmaceuticals.

Sea Lettuce

• Sea lettuce is a seaweed that grows in sheets rather than long blade-like structures. The leaves have curled edges and closely resemble loose leaf lettuce, for which it has been named. When in the water, sea lettuce appears bright green or red, but when dehydrated it turns black or white. Like kelp, it attaches to rocks along the shoreline by holdfasts, and grows in water up to 75 feet deep, in intertidal areas and marshes. Sea lettuce is very resistant to nutrient pollution, and as a result is considered a signal plant. When it is present in large populations, it is a sign of high levels of pollution in the water.

Irish Moss

• Irish Moss, as is suggested by the name, is most commonly harvested along the shores of Ireland and Wales, but does occur off the Maryland coast as well. Irish Moss is technically a member of the red algae family. The plant is soft, but rich in cartilage, and ranges in color from yellow to deep purple. It is used as a thickening element in gelatin desserts and ice creams because it has a rich and smooth jelly texture when boiled.