Seagrasses | Ecology In Action
Summary
TLDRSeagrass meadows, underwater ecosystems rich in biodiversity, play a crucial role in marine life support, water filtration, and carbon sequestration. They act as nurseries for fish and help in coastal protection. Despite their importance, seagrasses face threats from pollution and destructive fishing practices. Urgent conservation and restoration efforts are needed to preserve these vital ecosystems.
Takeaways
- 🌿 Seagrasses are marine plants that form dense underwater meadows, providing one of the most productive and valuable ecosystems on Earth.
- 🌱 They have a long evolutionary history, descending from flowering land plants that returned to water over 75 million years ago.
- 🌊 Seagrass meadows thrive in shallow coastal waters with the right combination of water quality, light, and depth.
- 🐢 They support a diverse range of marine life, including endangered species like seahorses, turtles, sharks, and stingrays.
- 🌱 Seagrass meadows act as natural filters, enhancing water quality by stabilizing heavy metals and pollutants, and absorbing bacteria and excess nutrients.
- 💨 They produce vast quantities of oxygen through photosynthesis, enriching the water column and sediment for the species that live there.
- 🐟 They serve as important nurseries for coral reef animals and commercially valuable fish species, including the second most important catch fish, Alaska pollock.
- 🌳 Seagrasses contribute significantly to 'blue carbon', removing carbon dioxide from the atmosphere and storing it in marine sediments.
- 🌍 Seagrass prairies account for over 10% of the ocean's total carbon absorption per hectare, holding twice as much carbon as rainforests.
- 🌊 They are ecosystem engineers that alter the landscape, slowing water currents, building up the seafloor, and protecting coastal settlements from storm surges.
- ⚠️ Seagrasses are under threat from fishing practices, pollution, and coastal development, with an area the size of two football fields lost every hour.
Q & A
What are seagrasses and where do they typically form?
-Seagrasses are marine plants that form dense underwater meadows, typically found in shallow coastal waters on continental shelves.
How long have seagrasses been evolving?
-Seagrasses have a long evolutionary history, descending from flowering land plants that returned to the water over 75 million years ago.
How many species of seagrasses are there and what are the four main lineages?
-There are 60 species of seagrasses spread across four main lineages, although the specific lineages are not named in the script.
What kind of marine life depends on seagrass meadows for their habitat?
-Seagrass meadows support a diverse range of marine life including marine reptiles, mammals, invertebrates, endangered species such as seahorses, green turtles, sharks, and stingrays.
How do seagrasses contribute to water quality?
-Seagrasses enhance water quality by stabilizing heavy metals and pollutants, absorbing bacteria, and excess nutrients.
What is the role of seagrass meadows in oxygen production?
-As they photosynthesize, seagrasses produce vast quantities of oxygen, enriching the water column and the sediment for the species that dwell there.
How do seagrass meadows support fisheries and coral reefs?
-Seagrass meadows serve as important nurseries for coral reef animals and commercially valuable fish species, including the world's second most important catch fish, the Alaska pollock.
What is blue carbon and how does it relate to seagrasses?
-Blue carbon refers to the carbon dioxide removed from the atmosphere by marine ecosystems. Seagrass prairies, despite covering only 0.1 percent of the ocean floor area, account for over 10 percent of the ocean's total carbon absorption per hectare.
How much carbon do seagrasses bury each year?
-Seagrasses bury 27 million tons of carbon each year.
What benefits do seagrasses provide in terms of coastal protection?
-Seagrasses act as ecosystem engineers, altering the landscape to slow down water currents, building up the seafloor, and forming shallow offshore banks that shield coastal settlements from storm surges and high waves.
What are the main threats to seagrass meadows?
-The main threats to seagrass meadows include fishing practices that uproot the grasses, pollution from land and coastal development, nutrient runoff that fuels algal blooms blocking sunlight, and overfishing of top predators.
How much seagrass meadow area is lost each hour and what is being done to restore it?
-An area the size of two football fields of seagrass meadows is lost each hour. Efforts to restore them include replanting using cuttings from donor meadows in artificial sandbags, and researchers are developing new planting methods and seed banks.
Outlines
🌿 Seagrass Ecosystems: Nature's Carbon Sinks
Seagrasses are marine plants that form dense underwater meadows, which are incredibly productive and valuable ecosystems. They have a long evolutionary history, descending from land plants that returned to water over 75 million years ago. These grasses thrive in shallow coastal waters where they provide a perfect habitat for a diverse range of marine life, including endangered species. Seagrass meadows offer a multitude of ecosystem services, such as supporting marine herbivores, enhancing water quality by stabilizing heavy metals and pollutants, and producing oxygen. They also serve as important nurseries for coral reef animals and commercially valuable fish species. Seagrasses are particularly notable for their role in carbon sequestration, known as 'blue carbon'. Despite covering only 0.1% of the ocean floor, they account for over 10% of the ocean's carbon absorption per hectare, storing twice as much carbon as rainforests. They bury 27 million tons of carbon annually, locking it away under the sediment through their root systems. However, seagrass meadows are under threat from fishing practices, pollution, and coastal development, leading to a loss of these vital ecosystems.
🌊 The Plight of Seagrass Meadows
Seagrass meadows are facing significant threats in the 21st century, including damage from fishing practices and pollution. The pollution, particularly from land and coastal development runoff, introduces nutrients like nitrogen and phosphorus into the seas, which are toxic to the grasses and lead to algal blooms that block sunlight, halting photosynthesis and causing the ecosystem to collapse. Overfishing of top predators also disrupts the balance, as it reduces the control of grazing species that help maintain the health of the prairies. Despite efforts to regrow seagrass meadows using cuttings and artificial methods, restoration is challenging, expensive, and labor-intensive. It is clear that the focus should be on protecting existing seagrass prairies, as they are crucial tools in combating global climate change. The loss of seagrass meadows could have severe consequences for both the marine ecosystem and global food security.
Mindmap
Keywords
💡Seagrasses
💡Ecosystem Services
💡Blue Carbon
💡Nurseries
💡Coral Reefs
💡Food Security
💡Ecosystem Engineers
💡Carbon Sequestration
💡Pollution
💡Overfishing
💡Restoration
Highlights
Seagrasses form dense underwater meadows that are highly productive and valuable ecosystems.
They have a long evolutionary history, descending from flowering land plants over 75 million years ago.
Seagrass meadows are found in shallow coastal waters on continental shelves.
There are 60 species of seagrass spread across four main lineages.
Seagrass meadows support a diverse range of marine herbivores.
Endangered species like seahorses, green turtles, sharks, and stingrays inhabit these ecosystems.
Seagrass meadows act as a natural filter, enhancing water quality by stabilizing pollutants.
They produce vast quantities of oxygen, enriching the water column and sediment.
Seagrass meadows are important nurseries for coral reef animals and commercially valuable fish species.
Seagrass savannas support both coral reefs and global food security.
Seagrasses are a significant source of 'blue carbon', removing CO2 from the atmosphere.
Seagrass prairies account for over 10% of the ocean's total carbon absorption per hectare.
They bury 27 million tons of carbon each year.
Seagrass meadows store nearly 20 billion tons of organic carbon globally.
Seagrasses are ecosystem engineers, altering the landscape around them.
They slow down water currents, building up the seafloor and forming shallow offshore banks.
Seagrasses protect coastal settlements from storm surges and high waves.
Pollution and runoff from coastal development pose the greatest threat to seagrass meadows.
Seagrass restoration is expensive and labor-intensive, making protection of existing meadows a priority.
Seagrass prairies are crucial tools to combat global climate change and must be protected.
Transcripts
hey
[Music]
seagrasses are marine plants that form
dense underwater meadows which are among
the most productive and valuable
ecosystems on earth these grasses have a
long evolutionary history they descend
from flowering land plants which
returned to the water over 75 million
years ago
their meadows form in shallow coastal
waters on continental shelves
they are a diverse group with 60 species
spread across four main lineages but
only the coasts provide their specific
habitat needs a perfect combination of
water quality light availability and
shallow depth the sheer range of
ecosystem services that these grasslands
provide is immense
they support an entire guild of marine
herbivores from marine reptiles to
mammals to invertebrates all graze the
submarine meadows
and endangered species such as seahorses
green turtles sharks and stingrays all
call this habitat home
and the huge prairies act as a natural
filter enhancing water quality by
stabilizing heavy metals and pollutants
absorbing bacteria and excess nutrient
and because sea grass is
photosynthesized they produce vast
quantities of oxygen enriching the water
column and the sediment for the myriad
species which dwell there these
underwater grasslands are important
nurseries for coral reef animals and for
commercially valuable fish species half
of all global fisheries exploit species
whose young grow in the sea grass
meadows including the world's second
most important catch fish the alaska
pollock the seagrass savannas support
both coral reefs and global food
security
if we lose them we stand to lose both
the reefs
and the fisheries too
[Music]
but perhaps the greatest asset that
seagrasses provide concerns blue carbon
blue carbon is the name for all the
carbon dioxide removed from the
atmosphere by marine ecosystems they may
cover only 0.1 percent of the ocean
floors area but seagrass prairies
account for over 10 percent of the
ocean's total carbon absorption per
hectare they hold twice as much carbon
as rainforests
burying 27 million tons of carbon each
year
this incredible process has its roots in
roots
unlike seaweeds sea grasses have roots
and rhizome systems which absorb carbon
and lock it away under the sediment
and because they grow using
photosynthesis
they use the sun's energy to convert the
carbon dioxide and water
into carbohydrates and oxygen
unlike carbon stored in forest soils on
land which can be released by forest
fires or deforestation
marine sediments are anoxic with low
microbial activity
meaning organic carbon can be
continually stored away for thousands
upon thousands of years
globally the seagrass meadows are
estimated to store nearly 20 billion
tons of organic carbon
but these vast underwater prairies can
have profound short-term benefits as
well for both people and the natural
world
seagrasses are ecosystem engineers
because they alter the landscape around
them their rising leaves slow down water
currents
causing them to drop their sediment
building up the seafloor
and forming shallow offshore banks of
sea grass and sediment
these shield coastal settlements from
storm surges and high waves and protect
valuable ecosystems like mangroves and
salt marshes
their underground network of routes
stabilizes these banks
reducing coastal erosion as well
seagrasses have thrived for millions of
years but in the 21st century these
delicate underwater grasslands are under
threat
fishing with dredges and beam trollers
uproots and destroys the meadows but
it's pollution from the land and runoff
from coastal development which poses the
greatest danger nutrients like nitrogen
and phosphorus run off into the seas
they're toxic to the grasses and they
fuel the growth of algae blocking out
the sunlight and halting the
photosynthesis needed for growth
as the grasses decay the algae bloom and
the ecosystem collapses a cascading
shift from seagrass to algal dominance
and overfishing of top predators like
sharks reduces the control of grazing
species which strip the fragile prairies
bear it's thought that today there are
between 300 to 600 000 kilometers
squared of seagrass meadows across the
world
but each hour an area the size of two
football fields is lost the damage must
be halted before it's too late seagrass
prairies can be regrown using cuttings
from donor meadows planted in sunken
artificial sandbags and researchers and
marine biologists are experimenting with
new planting methods and developing seed
banks for some species but restoration
is expensive and labor intensive and to
so far produce poor outcomes it is clear
that with the current understanding and
technology our ability to regenerate
seagrass meadows will always fall short
of the sea grasses natural ability to
spread and therefore our foremost
priority must be the protection of
existing seagrass prairies these rich
fragile ecosystems could be one of our
greatest tools to combat global climate
change
and they must be protected
at all costs
[Music]
wow
[Music]
you
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