Seagrass Restoration and Monitoring

Biscayne National Park

Open Transcript


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My name is Michelle Tongue.

I am a Biologist working in the Damage Recovery Program

under the Division of Resource Management

at Biscayne National Park.

Today we’ll be talking about seagrass restoration

and monitoring that is done here in the park.

I hope you enjoy the video clip

and at the end be sure to hear

what you can do to help protect our underwater resources.

Biscayne National Park encompasses 173,000 acres of the waters

between Miami and Key Largo.

The park was created in 1968 and includes

mangrove, seagrass, coral reef, and hardwood hammock resources

as well as shipwrecks and other historic sites.

The park is responsible

for preserving and protecting these rich resources

and providing recreational opportunities for the public.

The need for seagrass restoration and monitoring

is tied to the amount of boat traffic in Biscayne National Park.

The park is 95% water, and over the years,

an increasing number of boats are using the park

for all types of recreation,

such as



and scuba diving.

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Increased boat traffic translates

into more boaters running aground

in shallow water and damaging park resources.

Causes for these groundings can vary

from inexperienced captains or engine failure,

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to, loss of visibility in bad weather.

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The Damage Recovery Program is part of the Division

of Resource Management at Biscayne National Park.

When boats run aground

and damage shallow seagrass beds and coral reefs,

we assess that damage

and choose the best options for restoration.

Our goal in restoration is to take actions

so that the resources can recover to pre-injury conditions

as soon as possible.

There are several types of injuries

that can be caused when a boat runs aground in seagrass habitat.

Prop scarring,

blowholes and berms

are most common.

Propeller scars are long trenches in the seagrass bed

made by a boat’s propellers.

Blowholes are deep holes that are formed

when a boat operator attempts

to free the boat using its engines.

The sediment excavated from a blowhole,

or even from a deep propeller scar,

forms piles that are called berms.

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When boats run aground in seagrass habitat,

they often excavate sediment

and leave seagrass roots and rhizomes

exposed in the water column.

Seagrass rhizomes grow horizontally

and need to be surrounded by sediments to grow.

When the rhizomes are exposed at a grounding site,

the plants cannot grow back into the injured area.

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To restore these injuries,

the first thing we do

is place sediment into blowholes

and deep propeller scars to return the seafloor

to its original grade.

This stabilizes the substrate to prevent further erosion,

and prepares the area for colonization by seagrasses.

Sediment for fill, usually fine limestone sand,

is obtained from a local quarry.

This sediment is transported to the restoration site

on a shallow draft barge

and then placed into the injury either in burlap sacks,

or as loose fill using a clamshell bucket.

Coastal sediments in South Florida are nutrient-limited,

which means that certain nutrients important to plant growth

are in low supply.

We try to provide a fertilizer source at our restoration sites

to help the seagrasses recover more quickly.

After filling the injury sites,

bird stakes are placed in the restoration areas

to encourage roosting of waterfowl.

Bird stakes are constructed of PVC support poles

with treated wood blocks attached atop the poles.

While birds are perched on the stakes,

their droppings provide a regular source of natural fertilizer

to the seagrass beds below the stake.

We leave the bird stakes in place for about 18 months,

to allow the nutrients to accumulate in the sediments.

After that time, the bird stakes are removed

and used again at another site.

Sometimes, we transplant seagrasses that have been harvested

from donor areas into the restoration sites.

This helps to stabilize the sediments and more quickly increase

seagrass cover at the restoration site.

Both Individual seagrass plants and seagrass plugs

can be used as transplants.

Individual plants are carefully removed from the sediments,

and then bundled into planting units for transplanting.

Seagrass plugs that are thick enough to contain the rhizome mat

and surrounding sediments are collected

using a hand trowel or coring device.

The harvested plants and plugs are then secured

in the restoration site with a sod staple

to help keep them in place.

Once the sediment levels have been returned

to match the area around the injury

and bird stakes and or transplanted seagrasses

have been installed, it is important to monitor

the success of the restoration.

We monitor our restoration sites regularly

for five years to document the recovery process.

We usually monitor a site twice a year

for the first two years after restoration,

and then annually for years 3, 4 and 5.

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Our definitions of restoration success

are based on project objectives.

For blowholes and deep scars, our objective is to restore

topographic elevation- in other words, to fill the hole.

Success is measured by the stability of the backfilled material.

Over the 5 year monitoring period,

we monitor erosion of the fill

and consider a project successful

if there is less than 10cm loss during that time.

When we place bird stakes and transplant seagrasses

into an injury site,

our objective is to encourage seagrass recruitment

by providing a fertilizer source and

to increase overall seagrass cover.

Success is measured by the survival and expansion of the

transplants, and also by overall increasing seagrass cover.

Seagrass coverage is measured during each monitoring event

using visual assessment methods.

Comparing changes in seagrass coverage within the restored site

with changes in an undisturbed area outside of the injury

allows us to assess seagrass recolonization.

For each of our monitoring events we use a computer program

to give us the location of a specific number of points

within each injury and surrounding reference area.

At each point we place a square quadrat made out of PVC

and measure the abundance of algae, seagrasses, sponges, corals

and any other living organisms within the quadrat area.

Each item is then given a score based on the area

it takes up within the quadrat,

and that number is recorded on the data sheet.

We also collect water temperature and salinity measurements

using a handheld water quality meter

and take photos of the injury

and reference areas at each site.

Once all the data is collected

it gets entered into a database and then analyzed statistically.

The seagrass monitoring data we collect allows us

to track the success of our restoration efforts

and modify our techniques in order to

get the best results from our work.

We use it to plan for future projects

and estimate how long it will take for the injured areas

to recover to the health and productivity levels

that existed before the injury occurred.

We strive to protect and restore damaged seagrass habitat

because it plays a very important role

in the health of our oceans.

Seagrasses serve as a nursery ground

to many commercially important species of fish and crustaceans;

they also stabilize coastal sediments,

and improve water clarity by trapping sediment particles

in the water column.

Seagrass ecosystems are also

extremely important in cycling nutrients,

and in capturing energy from sunlight and transferring it

to other organisms higher up the food chain.

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There are things YOU can do to help protect seagrass habitat.

Know where you are going

before you set out for a trip on your boat!

Use up-to-date nautical charts

to plan where you are going AHEAD OF TIME.

Identify the shallow areas

which you need to be aware of during your trip,

and know when the tides are low

so you don’t get caught in a shallow area

during the low tide.

Make sure you have someone on your boat

to be a look-out for shallow areas,

waterway markers and other vessels.

When you are anchoring,

be sure you place your anchor in an area

that does not have seagrass,

if possible, and when you pull up your anchor,

be careful not to bring up clumps of seagrass and sediment.

Please visit for more information

and for help in planning your visit to Biscayne National Park.

I am Michelle Tongue and I thank you for watching!

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Seagrass Restoration and Monitoring in Biscayne National Park. Hosted by Michelle Tongue.