Seagrass restoration speeds recovery of ecosystem services

Date:
October 7, 2020
Source:
Virginia Institute of Marine Science
Summary:
The reintroduction of seagrass into Virginia's coastal bays is
one of the great success stories in marine restoration. Now, a
long-term monitoring study shows this success extends far beyond
a single plant species, rippling out to engender substantial
increases in fish and invertebrate abundance, water clarity,
and the trapping of pollution-causing carbon and nitrogen.



FULL STORY ==========================================================================
The reintroduction of seagrass into Virginia's coastal bays is one of the
great success stories in marine restoration. Over the past two decades, scientists and volunteers have broadcast more than 70 million eelgrass
seeds within 4 previously barren seaside lagoons, spurring a natural
expansion that has so far grown to almost 9,000 acres -- the single
largest eelgrass habitat between North Carolina and Long Island Sound.


==========================================================================
Now, a long-term monitoring study shows this success extends far beyond
a single species, rippling out to engender substantial increases in
fish and invertebrate abundance, water clarity, and the trapping of pollution-causing carbon and nitrogen.

Published in the October 7th issue of Science Advances, the study was
led by Dr. Robert "JJ" Orth of the Virginia Institute of Marine Science,
along with VIMS colleagues Mark Luckenbach, Ken Moore, Richard Snyder,
and David Wilcox.

Joining them are Jonathan Lefcheck of the Smithsonian's Environmental
Research Center; Karen McGlathery, Lillian Aoki, and Matthew Oreska of
the University of Virginia; and Bo Lusk of The Nature Conservancy.

"Human activities are degrading coastal habitats worldwide," says
Orth. "Our study serves as a blueprint for restoring and maintaining
healthy ecosystems to safeguard multiple benefits as we move into an
uncertain future." Orth and his co-authors stress that several of
the restoration benefits - - including removal of the greenhouse gas
carbon dioxide via burial of carbon in seafloor sediments -- were not
even considered as management goals when the project began. These novel benefits provide additional impetus for future habitat restoration.

"Seagrasses play an important role in removing carbon dioxide from
the atmosphere and sequestering it out of circulation for decades to millennia," says McGlathery. "This is the first study to show how habitat restoration can make this happen and help combat climate change."
"A major challenge to restoration is determining what constitutes
success," adds Orth.



========================================================================== "Traditional metrics have focused on habitat attributes such as plant
biomass, coverage, or density. But the ultimate motivation is often not
to restore the habitat itself, but the services it provides, benefits
such as enhanced water quality, fisheries production, and now, carbon
storage. As regulatory agencies worldwide seek to conserve and recover ecosystem services, our study shows that marine restorations are possible
on scales that contribute directly to human well-being." Reasons for disappearance and recovery Eelgrass flourished in the seaside bays of Virginia's Eastern Shore until the 1930s, when a wasting disease and
intense hurricane wiped them out. The research team lays out several
reasons for the success of the subsequent restoration effort.

First is that natural recovery was precluded not by degraded environmental conditions but a lack of seeds. With no mature, seed-producing plants
available within these isolated coastal lagoons, they remained almost completely unvegetated for more than half a century. In 1999, when Orth's
team began planting seeds and shoots collected elsewhere, conditions
were ripe for recovery. A corollary, says Orth, is that in areas like Chesapeake Bay where turbidity, nutrient pollution, and warming continue
to challenge eelgrass health, "we must identify the stressors that led
to the problem in the first place, and then mitigate or compensate for
those before restoration efforts begin." Second is the relatively large
size of the seeded plots and the high seeding density. Field monitoring
shows these factors helped jumpstart a positive feedback loop in which
eelgrass patches grew sufficiently robust to dampen waves and stabilize seafloor sediments, clearing the water enough for sunlight to reach the
plants for continued growth and natural seed production.



==========================================================================
A third factor is the long-term commitment to the team's annual seeding
and monitoring efforts, supported by funding from NOAA, the Army Corps
of Engineers, Virginia Coastal Zone Management Program, Virginia Marine Resources Commission's Recreational Fishing License Fund, National
Science Foundation, Keith Campbell Foundation for the Environment,
and other public and private funders.

In the 21 years since 1999, scientists and volunteers have spent more
than 3,500 hours gathering an estimated 10 million seeds from the coastal
bays. They have planted these, plus more than 60 million seeds collected
from harvested shoots, into 536 restoration plots covering roughly 500
acres. Continued seeding has helped the nascent eelgrass meadows survive
the natural ups and downs experienced by any coastal ecosystem.

Lusk says, "The Eastern Shore community has provided a willing partner to
this restoration, as we all rely on the surrounding waters as part of our economy and culture. Working side-by-side with hundreds of volunteers collecting seeds for this project is a highlight of each spring."
A fourth factor is the project's location within the 40,000-acre Virginia
Coast Reserve. Managed by The Nature Conservancy, the reserve has been
under intensive study since 1987 as a Long Term Ecological Research (LTER)
site administered by the University of Virginia. "The reserve protects one
of the last stretches of coastal wilderness along the U.S. East Coast,"
says Lusk. "As a result, water quality there remains exemplary, enabling
the success of eelgrass restoration." Overall, says Orth, the team's
success "required a strong understanding of the causes of decline,
repeated assessment of best restoration practices, and a sustained
commitment to long-term monitoring and research." Bay scallops When
eelgrasses disappeared from the coastal bays in the 1930s, so too did
numerous marine organisms and seabirds that had relied on them for food
and nursery habitat. One notable loss was the bay scallop -- which until
that time had supported a significant commercial fishery.

In 2008, several authors of the current study decided to build on their
success with eelgrass restoration by launching a program to restore
the tasty bivalves as well. They have planted young scallops from North Carolina into Virginia's coastal bays each year since then.

Dr. Dick Snyder, director of VIMS' Eastern Shore Lab in Wachapreague,
reports that bay scallop populations have so far only returned to a
fraction of their estimated historical values. He says "Our results to
date suggest that further intervention may be needed to fully restore this species, including greater seagrass area and broader genetic diversity
of the broodstock." One bright sign is the discovery of bay scallops
in clam aquaculture beds more than 20 miles from where they are set out
in spawning cages, suggesting natural dispersal of larvae via currents.

Dr. Mark Luckenbach, associate director of Research and Advisory Services
at VIMS, says "A harvestable bay scallop population may be one of the
ultimate measures of the overall success of our restoration effort, as
has been the case for wolves in Yellowstone." Luckenbach was director
of VIMS' Eastern Shore Lab in Wachapreague when the scallop restoration
project began.

The authors caution that any eventual scallop harvest would need to be carefully managed to sustain the restored population.


========================================================================== Story Source: Materials provided by
Virginia_Institute_of_Marine_Science. Original written by David
Malmquist. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Robert J. Orth, Jonathan S. Lefcheck, Karen S. McGlathery,
Lillian Aoki,
Mark W. Luckenbach, Kenneth A. Moore, Matthew P. J. Oreska, Richard
Snyder, David J. Wilcox, Bo Lusk. Restoration of seagrass habitat
leads to rapid recovery of coastal ecosystem services. Science
Advances, 2020; 6 (41): eabc6434 DOI: 10.1126/sciadv.abc6434 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201007154308.htm

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