Macroalgae in MD's Coastal Bays

Algae are generally divided into macroscopic (seen by the human eye) and microscopic (phytoplankton).  Macroscopic algae, commonly referred to as macroalgae or seaweeds, are large plant like structures commonly found in coastal waters worldwide.  A total of 24 genera have been found in the Maryland Coastal Bays. 

Macroalgae appear in a variety of colors and forms. They are divided into the three groupings- red, brown and green -based on pigments (e.g. color of the plant).  They can appear as small "fur like clumps," moderate-sized branched specimens, or large leaf-type structures. 

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An excess of macroalgae can be problematic for aquatic life (bay critters can be impaired or killed as a result of decreased oxygen levels when algae die and decompose), boaters (prop fouling), citizens and tourists (odor).  Such excessive levels are categorized as Harmful Algae Blooms. This can particularly be a problem in dead end canals where high nutrient loads and limited flushing make ideal environments for some macroalgae species.

For more information download one of these technical reports:

Red Algae or Rhodophytes

Red algae are the most diverse group of macroalgae inhabiting, both temperate and cold marine waters. Three genera, Ceramium, Agardhiella and Gracilaria, are prominent in the mid-Atlantic. Red algae are often commercially raised and harvested for their agar and carrageenans which are used in the food, cosmetic and medical industry.  These species are common in coastal waters, and have been shown to be beneficial habitat for small fish and invertebrates. Red algae had the greatest richness in the coastal bays with eight genera identified.  Learn more about red algae in the coastal bays.

Green Algae or Chlorophytes

Green seaweeds need plenty of light and are most common at higher intertidal levels or subtidally in shallow water.  Six genera of green algae have been documented in the coastal bays including: Ulva, Chaetomorpha, Enteromorpha, Cladophora, Bryopsis and Codium.  Of these, Ulva spp. was the most prevalent, occurring at 10% of all stations sampled, 13% in the spring, 5% in the summer, 9% in fall and 11% in winter. Ulva spp. was generally distributed through out the bays, however, it was most consistently present in the northern bays and Sinepuxent Bay.  Learn more about green algae in the coastal bays.

Brown Algae or Phaeophytes

Brown algae are usually marine (abundant in cold water) and many species inhabit the intertidal zone.  Brown algae contain the brown pigment fucoxanthin which masks the green chlorophyll pigments.  Algins, which are used to produced rubber and textiles, are a major constituent of all brown algae. Brown algae in the coastal bays were represented by four genera:  Desmarestia, Ectocarpus, Stilophora and Sphaerotrichia.   Learn more about brown algae in the coastal bays.

If you have any questions about Maryland's Coastal Bays, 
please feel free to e-mail, Cathy Wazniak, or call (410) 260-8638.

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