Macroalgae in the coastal bays

January 6, 2003

by Steve Doctor. Doctor is a DNR finfish biologist who works in the coastal bays.

There is a quiet invasion underway in Maryland's coastal bays. Although the names sound like something out of a science fiction movie- ulva, enteromorpa, ceramium, and polysiphonia- it is not aliens, but green, brown, and red macroalgae that are blanketing the coastal bays.

Macroalgae are the same as the slimy green stuff you looked at under a microscope in freshman biology or the green scum covering a pond in summer, but they also come in a vast array of shapes, colors and sizes. Ulva, a green algae, comes in large two-cells thick sheets larger than a dinner plate, and gracilaria, a red algae, looks like a plastic aquarium plant that is fleshy and translucent.

These algae are not new to the area and are common in coastal areas all around the world, but recently local scientists have noticed an increase in these algae in the Maryland, Virginia, and Delaware coastal bays. Algae, like seagrass, is a natural component of the coastal bays. In 1966 scientists from the Virginia Institute of Marine Science did a survey of the Ocean City Inlet and found 34 different algae on the north jetty of the harbor entrance. Algae can grow anywhere they can find sufficient nutrients in the water and they have access to sunlight. They also have some positive benefits as they provide structure and primary production for the estuary system.

By harnessing the energy for the sun and producing plant matter, macroalgae provide food for small aquatic animals. Fish have greater feeding success in vegetated areas than in non-vegetated areas. Macroalgal habitats have been found to play an important role in successful recruitment of juvenile tautog, a structure-loving fish which can reach up to 10 pounds.

However what concerns scientists is that large quantities of algae are smothering sea grasses and producing oxygen deficiencies when they die off. Surveys done by the monitoring division of DNR have documented that mats of algae are flourishing in the recently recovering grass beds and those algae are competing with the grasses. The Maryland Coastal Bays Finish Investigation survey, which has been sampling the Maryland Coastal Bays at the same sites for the past 29 years, now has to move some of the sites because the macroalgae is so dense that they cannot sample there anymore. The macroalgae invasion has raised concerns that valuable juvenile summer flounder seagrass habitat is being lost.

It is concerns like these which recently led a group of local scientist to undertake a comprehensive survey of the macroalgae distribution in all of Maryland's coastal bays, and Virginia's Chincoteage Bay. Using time and equipment borrowed from an interdisciplinary group of state and federal projects, seven teams spent this spring pulling a small basket-sized dredge at 800 sites around the bays. The samples were inspected for types and quantities of macroalgae, and the data will now be analyzed giving us the first comprehensive picture of total algae biomass in these bays.

It is the hope of those involved that this data will be a big step in tracking the long-term abundance of these algae and in learning about the value of the macroalgae and its impact on our coastal bays.

To supplement the work, the Coastal Bays Program awarded the University of Maryland Center for Environmental Science $25,000 last month to study the environmental parameters associated with certain kinds of macroalgae blooms. The researchers will measure the mixture of temperature, light and nutrient loading that fuel the growth of the free-flowing plants.

The work will help give scientists management options to slow the growth of the algae which threatens to dominate parts of the coastal bays.

Part of the National Estuary Program, the Maryland Coastal Bays Program is a cooperative effort between Worcester County, Berlin, and Ocean City which have come together to produce the first ever management plan for their bays. Home    |    About Us    |    Contact Us    |    Site Directory Copyright 2003 - Maryland Coastal Bays Program Questions? Email: mcbp@mdcoastalbays.org