· · ·

Sydney’s coastal ecosystems suffer ‘once-in-a-generation’ mass mortality event, Australia

sydney-mass-mortality-event

Marine ecosystems along a wide stretch of coastline in Sydney, Australia, have been devastated in recent months by a combination of bushfire debris, drought, and severe storms. Researchers for The Abyss Project, a scientific group of divers, described it as potentially the worst "mass mortality event" in decades.

To have a dry spell followed by fires and storms from February onwards was 'a once-in-a-generation event,' said Carl Fallon, co-founder of the 12-year-old project that monitors marine health near the state capital.

From the Hawkesbury River to Botany Bay, the worst affected species range from soldier crabs to urchins, soft sponges, and coral-like bryozoa invertebrates.

Invertebrate species down to as deep as 8 m (26 feet) appear to have been greatly affected by a series of changes in water quality and conditions.

Salinity has increased in shallow estuaries as freshwater inflows dropped with the dry period, then the bushfires brought additional phosphorous and nitrogen, including from fire retardants, which stimulated cyanobacteria growth.

The severe storms gave the final blow for much of the aquatic life, said Fallon. Meanwhile, sea life continues unaffected in areas deeper than 8 m (26 feet) or areas where waters easily mix, like much of Sydney Harbor.

According to Nathalie Simmonds, head of marine science at the project, the loss of foundational species may cause "feedback loops occurring throughout the entire ecosystem." Some species are recovering faster, with possibly long-lasting impacts. 

At sites such as Monterey, highly-varied species previously found attached to nets and other objects submerged had started to be replaced by an unidentified algal species.

"They are all completely gone except for this one algae that has literally covered everything," Fallon stated.

Poor water quality, as well as the coronavirus pandemic restrictions, had limited scientists' ability to study the impact of this event, said Dr. David Booth, a marine ecologist at the University of Technology Sydney.

Booth added that it was very unusual to lose kelp and urchins from many areas, which are usually "two opposing forces". Kelp is typically resilient, while urchins "are pretty good at hunkering down."

Impacts on fish may take time to be evident. Some grazing species, for instance, may fare better than others, depending on the mix of plant species that return.

The Abyss Project's report noted that "climate change will see an increase in the intensity and frequency of extreme weather events," but also mitigate droughts and bushfires.

"Our observational and scientific data will provide a baseline for future researchers to enable these coastal environments to be protected for future generations."

The increasing climate stresses in the future could "just decouple everything" in the marine ecosystems around Sydney and beyond.

Booth suggested that the New South Wales government should revisit plans for a Sydney Marine Park, in wake of the previous marine destruction. The government ditched the plan in September 2018, even before the public consultation period had closed, following complaints.

"It shouldn't have dropped off the agenda," Booth said, adding the originally proposed marine park consisted of 17 sanctuary zones, covering 2.4 percent of waters around the city.

Featured image credit: The Abyss Project/YouTube

If you value what we do here, create your ad-free account and support our journalism.

Share:

Related articles



Your support makes a difference

Dear valued reader,

We hope that our website has been a valuable resource for you.

The reality is that it takes a lot of time, effort, and resources to maintain and grow this website. We rely on the support of readers like you to keep providing high-quality content.

If you have found our website to be helpful, please consider making a contribution to help us continue to bring you the information you need. Your support means the world to us and helps us to keep doing what we love.

Support us by choosing your support level – Silver, Gold or Platinum. Other support options include Patreon pledges and sending us a one-off payment using PayPal.

Thank you for your consideration. Your support is greatly appreciated.

Sincerely,
Teo Blašković

$5 /month

  • Ad-free account
  • Clean user interface and fast browsing
  • Direct communication with us via chat and email
  • Suggest new features, content and applications
  • Early access to new apps and features

$50 /year

$10 /month

  • Ad-free account
  • Clean user interface and fast browsing
  • Direct communication with us via chat and email
  • Suggest new features, content and applications
  • Early access to new apps and features

$100 /year

$25 /month

  • Ad-free account
  • Clean user interface and fast browsing
  • Direct communication with us via chat and email
  • Suggest new features, content and applications
  • Early access to new apps and features

$200 /year

You can also support us on Patreon

support us on patreon

or by sending us a one-off payment using PayPal:


Commenting rules and guidelines

We value the thoughts and opinions of our readers and welcome healthy discussions on our website. In order to maintain a respectful and positive community, we ask that all commenters follow these rules:

  • Treat others with kindness and respect.
  • Stay on topic and contribute to the conversation in a meaningful way.
  • Do not use abusive or hateful language.
  • Do not spam or promote unrelated products or services.
  • Do not post any personal information or content that is illegal, obscene, or otherwise inappropriate.

We reserve the right to remove any comments that violate these rules. By commenting on our website, you agree to abide by these guidelines. Thank you for helping to create a positive and welcoming environment for all.

One Comment

Leave a reply

Your email address will not be published. Required fields are marked *