Saving the Great Barrier Reef, One Wetland at a Time

ENVIRONMENT

A large-scale conservation project is underway on an Australian cattle ranch. Its aim: to help save the Great Barrier Reef, 12 miles away. (New Scientist)

Why is ag not so sweet for the Great Barrier Reef?

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Discussion Ideas

“The Great Barrier Reef is a World Heritage Site, and one that is known to be in dire trouble,” reports the terrific New Scientist article. What are the leading threats to the Great Barrier Reef? Take a look at this page from the Great Barrier Reef Foundation for some help.
- climate change: Rising water temperatures and associated events have contributed to coral bleaching, extreme weather, and ocean acidification.
  - Learn more about coral bleaching events with our study guide here.
- poor water quality: Nutrient-rich runoff from human activity has contributed to coral “drowning” and outbreaks of crown-of-thorns sea stars, which prey on corals at a rate faster than coral populations can recover.
  - Learn more about runoff and its influence on crown-of-thorns sea star populations with our activity.
- development: Industrial, housing, and agricultural development in coastal areas impact nearshore habitats and contribute to urban runoff, litter, and marine debris.
  - Learn more about the impact of marine debris with our activity.
- fishing: Large-scale commercial fishing is legal in some zones of Great Barrier Reef Marine Park. Illegal and unsustainable extractive activities, however, threaten the food web of the reef, as well as reducing populations of specific species of shellfish, fish, and corals. Some extractive activities, such as dredging, may impact the seafloor itself.
  - Watch our Picture of Practice to see how students understand the consequences of the way we fish our ocean.

Runoff is a key contributor to two major threats to the Great Barrier Reef: poor water quality and development. According to our short reference resource on runoff, “Runoff from human activity comes from two places: point sources and nonpoint sources.” Is the runoff impacting the Great Barrier Reef point-source pollution or nonpoint-source pollution?
- Runoff impacting the Great Barrier Reef is primarily nonpoint-source pollution. Nonpoint source pollution describes water pollution in which runoff is not emptied directly into a waterway. Runoff threatening the Great Barrier Reef may include fertilizers and pesticides associated with agriculture; industrial waste; sewage; litter; car exhaust; and even spilled gasoline from a car. (Impervious surfaces, or surfaces that can’t absorb water—paved surfaces, basically—increase runoff.)

How does the landscape of Mungalla Station, a cattle ranch, influence the habitat of the Great Barrier Reef 20 kilometers (12 miles) away? Read through the New Scientist article for some help.
- At Mungalla Station itself, “overgrazing had caused soil erosion, native vegetation had been cleared, and the wetlands along the coast were choked with invasive weeds. This presented a big threat to the Great Barrier Reef. Sediments, pesticides and fertilisers were leaking into the wetlands and out to sea, poisoning and smothering reef organisms like coral, fish and turtles.”

How are the indigenous Nywaigi Traditional Owners transforming Mungalla Station to mitigate damage to the Great Barrier Reef?
- They kept one section for cattle ranching and are working to restore native habitats to the rest of the property.
- The Nywaigi owners have focused on restoring the Mungalla wetlands. There, nutrient-rich pollutants from runoff stick to native grasses and sedges, and are buried in their hardy root systems. Wetlands are nicknamed the “‘kidneys’ of the Reef, because they help to filter out silt and chemicals before they spill into the ocean.”
  - The primary focus of restoring wetlands is removing invasive weeds—so-called “Weeds of National Significance.”
    - “Fortunately, there was a simple solution: [Nywaigi owners] knocked down an earth wall that had been built in the 1940s to stop the tide from coming in. The introduced species could not handle the saltiness of the incoming seawater and withered en masse.”
  - Restoring native wetland plants helped restore entire wetland ecosystems as well as reduce pollution to the Great Barrier Reef. The brackish plants have attracted primary consumers such as fish and birds, and secondary consumers such as saltwater crocodiles.