Seagrasses | Ecology In Action

Summary

Seagrass 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.