"As
human populations grew and settled along the coast, they altered
seagrass ecosystems by clearing the land for lumber and agriculture, and
by overgrazing. Increased soil erosion was carried to the sea creating
murky ocean waters that reduced sunlight. Sewage runoff and agricultural
fertilizers added nutrients that promoted plankton blooms,
which also reduced sunlight. With less light, there is less
photosynthesis to generate oxygen. Without enough oxygen, toxic sulfides
can invade and kill the seagrass.
The good news is such lost seagrass
ecosystems are not happening everywhere, and many unaffected regions
support prosperous seagrass ecosystems. It is not a global crisis.
... Seagrass meadows with improved water quality are
thriving and people are now managing sediment runoff better and
developing waste-water treatment to reduce nutrient pollution.
... Seagrass feeds
ancient (but currently threatened) animals like green turtles, manatees
and dugongs, sea urchins, parrot fish and geese. Seagrass supports major
fisheries of pollock and cod and they’re home to seahorses. The
ecosystem serves as a nursery ground for hundreds of species of juvenile
fish. Seagrass supports clams, scallops, shrimp and spiny lobsters.
... The good news is
most of the human factors that have reduced seagrass meadows can be and
are being remedied. Furthermore, rising levels of carbon dioxide will
benefit their growth and recovery."
" ... Since 1999, over 70 million
seeds of a marine angiosperm, eelgrass (Zostera marina), have
been broadcast into mid-western Atlantic coastal lagoons, leading to
recovery of 3612 ha of seagrass.
Well-developed meadows now foster
productive and diverse animal communities, sequester substantial stocks
of carbon and nitrogen, and have prompted a parallel restoration for bay
scallops (Argopecten irradians).
... The
degradation of coastal habitats worldwide through anthropogenic
influences has resulted in the loss of critical services that underpin
the welfare of all Earth’s inhabitants.
The growing desire to protect and restore these services have led to
the development of habitat restoration strategies to reverse the
downward trend,
including notable successes such as seagrasses in Tampa Bay, salt
marshes in San Francisco Bay, and oysters in the Chesapeake Bay. Many of these successes are achieved through passive measures (such as nutrient reductions in Tampa Bay),
although there are increasing efforts to actively transplant
foundational species to restore habitats, such as oysters and seagrasses.
Unfortunately, many other efforts are not successful and therefore go
unreported. Despite setbacks, recent syntheses suggest that some
optimism is warranted, as restorations with sustained long-term and
cooperative efforts on the scale of one to two decades can yield
successful recovery."
