Seagrass Restoration and Monitoring
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,
and scuba diving.
( bubbling )
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,
( sound of an engine faltering )
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.
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 www.nps.gov/bisc 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.