Home main Quiz1 SAV Nutrient pollution Quiz2

juniper.gif Welcome again--
So you are curious about these baygrasses,and want to know something about them huh.

You came to the right place.

Table of contents:

Species of SAV
Causes for decline
Facts about SAV
What's being done
          How can you help?

What is SAV?
How is it important
to bay's health?what
do you need to
know about it?
Do you know you too can help restore the bay grasses?

Brief Introduction:

Beneath the waters of the chesapeake bay, long streaming grasses sway with currents.Minnows and juvenile crabs peep from behind the flowing fronds, hiding from larger fish that are hunting for a midday snack. Occasionally, ducks poke their heads through the water’s surface to nibble at the grasses’ tender tips.

These Underwater grasses also called SAV -Submerged Aquatic vegetation is a diverse assembly of rooted macrophytes found in shoal areas of Chesapeake bay, from its mouth to the headwaters of its tributaries.
The underwater vascular plants that make up the submerged aquatic vegetation (SAV) community in Chesapeake Bay are widely regarded as keystone species and primary indicators of water quality conditions in the Bay, and they form an important part of the Chesapeake bay ecosystem.

SAV produces oxygen by   photosynthesis, provides  shelter for many fish and shellfish species.The main requirement for their survival is the quality of water in which they live.

SAV species:

There are approximately about ten species of submerged aquatic vegetation found in Chespeake bay and its tributaries. They can be divided into three categories depending on the salinity tolerance:
  • Species that are tolerant to higher salinities(existing in the lower  reaches of thebay)
               Eg:Zostera marina (eelgrass)
  • Species that are less tolerant of higher salinities(existing in the middle and upper reaches of the bay)
               Eg:Potamogeton pectinatus (sago pondweed),Vallisneria americana  (wild celery) etc.,
  • Species tolerant of wide range of salinities(existing in the bay mouth)
               Eg: Ruppia maritima(widgeon grass).

Decline in SAV:

One of the major threats to the bay ecosystem is the drastic reduction in the SAV beds.

So, what are the factors influencing SAV reduction.The primary reason is----    We! meaning the people. Hard to believe huh!. So anyway what's really happening ?

As we have learned earlier water quality is very important for the growth of bay grasses.Primarily the decline in SAV population is linked to excessive nutrients like nitrogen and phosphorus. Excessive amounts of nutrients are being released into the bay from sewage treatment plants,fertilizers used in the agricultural fields etc.These excessive nutrients trigger algal blooms (meaning rapid growth of algae).These algae clouds the water and reduces the amount of light reaching the SAV. When these algae die, their decomposition by bacteria uses lots of oxygen.


Importance of SAV:

The main importance of SAV lies in it's being one of the primary indicators of bay's health.

          SAV beds are primary nursing grounds for crabs and many species of fish.Provides food and shelter for waterfowl, fish and shellfish.Also SAV beds provides habitat to many aquatic mammals.

          SAV produces oxygen which is very important for the growth of all living organisms.

          SAV acts as filter,traps the sediments.They reduces the wave energy and inturn reduces erosion.

           Decaying SAV proivides food to the microscopic zooplankton, provides shelter to the shedding bluecrabs until their shells has  hardened.Along with the crabs, many fishes like sharks, rays, sea horses, herring and shad etc seek shelter in the sav beds.

           Not only the fishes and shellfish, many invertebrates are dependant on the sav beds in one way or another.For example sponges and sea squirts grow on the grasses, snails and many worms graze over the plants.

           Last but not least, SAV retains nitrogen and phosphorus and helps in removing excess nutrients.

Facts about SAV:

More than 200,000 acres of bay grasses grew along the shoreline of the bay historically. But since 1960's over half of the sav has disppeared from the bay.In 1984 only 38,000 acres of SAV were reported. Current surveys find approximately 60,000 acres of under water grasses in the Bay. This acreage represents a 66% increase over the 1983 low of 38,000 acres. However, this is a mere 10% of the historic potential of 600,000 acres of underwater grasses. Now our goal is that  underwater grasses (submerged aquatic vegetation or SAV) should cover 225,000 acres in the Bay and the tidal portions of its tributaries.

What is that we can do in improving SAV

Reduce the amount of fertilizers applied to yards. Plant vegetation suited to your soil, moisture and climate conditions.
Prevent shoreline erosion by planting shoreline vegetation.
When boating, avoid disturbing SAV beds. Propellors may tear rooted vegetation out of bottom sediments.
Waterfront property owners should avoid using herbicides that may harm delicate SAV plants. Citizens also help track the presence of SAV by participating in a volunteer SAV survey. Everyone who lives, works and plays in the Chesapeake Bay watershed directly affects the water quality through everyday activities.

What was being done for SAV protection:

The U.S. Fish and Wildlife Service, other federal and state agencies, and the Virginia Institute of Marine Science monitor SAV distribution each year. By examining aerial photographs, locations of SAV are mapped for the entire Chesapeake Bay and its tidal tributaries. By monitoring SAV in Chesapeake Bay, biologists can determine which areas need to be protected. By examining historical distribution, areas where SAV once flourished are targeted for restoration.

Water quality is the key to restoring grasses to the bay. Scientists have identified the water quality conditions and requirements necessary for the survival of different SAV species. Managers are using these requirements as the basis of recovery plans for various sections of the bay and its rivers and creeks.The presence or absence of SAV reflects the general water quality of an area.SAV can be used as a barometer to gauge the health of the bay and its tributaries.

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