marine science – Michmutters
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Australia

‘Major barriers’ to restoring Australia’s degraded coastal ecosystems as scientists push for national plan

Squeezed between tropical wetlands and the Great Barrier Reef, the wetlands of Mungalla Station should be a colorful haven teeming with life.

The former pastoral property in north Queensland was, until not long ago, choked with weeds and devoid of fish.

James Cook University’s Center for Tropical Water and Aquatic Ecosystem Research associate professor Nathan Waltham describes efforts to restore it to health as the most rewarding project he has ever worked on.

It involved seven years of exchanging scientific knowledge with the Nywaigi traditional owners.

“It’s been a two-way learning street and seeing country slowly healing and seeing the Indigenous rangers become so inspired, creating jobs for Indigenous youth has just been so rewarding,” Dr Waltham said.

“Unfortunately, it’s very small scale, and we need to now be thinking about this as an example that can be taken to much larger scales.”

Harder than it needs to be

Restoration projects like the one at Mungalla have experienced success around Australia.

But new research led by Megan Saunders, a senior research scientist at the CSIRO’s oceans and atmosphere division, and Dr Waltham reveals there are major barriers to projects going ahead at the scale required to restore the nation’s degraded coasts.

An aerial image of a wetland surrounded by tropical green vegetation.
Mungalla Station is now restored to a coastal wetland.(Supplied)

They found there was insufficient funding to restore many degraded sites and that Australia lacked a consistent approach to mapping and classifying coastal and marine ecosystems.

Processes to engage with traditional owners on restoration projects are often not even executed, they found.

Mungalla’s health has also slightly declined since its restoration project concluded, highlighting the need for ongoing love and care.

Sometimes when restoration projects do receive funding, they are brought unstuck by complex approval processes.

“[It can be] anywhere from 50 per cent, 60 per cent of the allocated funding time just to get the approval and, unfortunately, that is a challenge we have to break down,” Dr Waltham said.

“That has possibly huge implications on projects even starting.”

A portrait image of a smiling woman wearing glasses and a blue top, standing in front of the sea and mountains in the background.
Dr Saunders is the lead author of the research into scaling up coastal and marine restoration work.(ABC Far North: Christopher Testa)

Climate the biggest threat

The main threat to coastal low-lying areas is, unsurprisingly, climate change and its associated threats such as more severe storms.

Scientists this month confirmed frequent El Niño events caused hundreds of kilometers of coastal mangroves in the Gulf of Carpentaria to die.

Dr Saunders, who specializes in coastal and marine restoration, said Australia needed a national plan to restore coastal ecosystems, involving state and local governments, First Nations people, philanthropic groups and the finance sector.

Examples of coastal restoration in environments that have been irreversibly altered include the retrofitting of seawalls in Sydney Harbor to make them a more suitable habitat for marine life to flourish.

Dr Saunders said adopting a road map similar to the one set out in their research paper could make Australia a “world leader” in coastal restoration.

Indigenous Rangers from the Carpentaria Land Council look at dead mangroves
Mangroves along the coast of the Gulf of Carpentaria have died in recent years due to the effects of climate change.(ABC North West Queensland: Lucy Murray)

Meanwhile, she said, across the nation, there was a lot of work to do.

“Oyster reefs in Australia have declined by 92 per cent since the arrival of Europeans and the coastal development activities that have happened,” Dr Saunders said.

“We’ve also lost 95 per cent of Tasmanian kelp beds more recently due to warming water temperatures, so our natural assets, in particular, are in decline due to climate change.”

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Categories
Australia

Feeding coral larvae helps them grow and survive, new research finds

Little is known about the dietary requirements of coral larvae but new Australian research has revealed feeding them can improve their chances of survival.

A study by Southern Cross University PhD candidate Colleen Rodd, published in the journal Frontiers in Marine Science, found giving the larvae supplement nutrients boosts their energy at a critical early stage of development.

Scientists expect the findings will improve the effectiveness of coral restoration projects being done to help degraded systems such as the Great Barrier Reef.

“Our research has shown if you do feed coral, you can drastically increase the number of those larvae that actually turn into corals on a reef, which is actually pretty exciting,” Ms Rodd said.

A shooting task

Adult coral reproduces by releasing gametes into the water, which form into coral larvae.

Those larvae face a “particularly precarious” time in the water before settling on to the reef where they grow complex skeletons.

“The larvae themselves have a finite amount of energy and they use up about 70 per cent of that in the first week of swimming around,” Ms Rodd said.

“From there they can run out of energy and die either before they can transform into a coral or shortly thereafter because transforming from a larvae into a coral is very energetically costly for them.

“Most of those larvae will die if we don’t intervene there.”

She said the feeding allowed the larvae “a little bit of leeway to make it until they turn into a polyp where they can start feeding like adults”.

What do they eat?

The coral larvae in Ms Rodd’s research were fed blended artemia — a crustacean also known as brine shrimp.

The feed contained a mix of nutrients, including proteins, carbohydrates, and fats.

A woman wearing a blue top in a laboratory with equipment set up to feed coral
PhD candidate Colleen Rodd works on the food-reared coral larvae experiment.(Supplied: Southern Cross University)

How exactly the larvae feed remains somewhat of a mystery, however.

“That’s where we’re taking the research next — to figure out the exact mechanisms through which they feed,” Ms Rodd said.

“Coral larvae are very, very, very small — less than a millimeter in length — and it was assumed they can’t feed.

“They have an oral pore, not quite a mouth but nevertheless a way to take in food, but they can also absorb it through their cell wall.”

Coral-rearing cones set up for a feeding experiment at the Australian Institute of Marine Science.
Coral-rearing cones set up for a feeding experiment at the Australian Institute of Marine Science.(Supplied: Southern Cross University)

Implementing the research

Ms Rodd said feeding coral larvae used for restoration projects would be “very cheap to implement”.

Two types of mass-spawning reef-building coral species used in the research were cultured at the Australian Institute of Marine Science’s National Sea Simulator experimental facility near Townsville.

So far though, larvae have not been observed feeding in the wild.

An image showing the extent of growth of coral larvae that have been fed brine shrimp.
An image showing the extent of growth of coral larvae that have been fed brine shrimp.(Supplied: Southern Cross University)

One theory is wild coral larvae obtain their nutrients after unfertilized sperm and eggs break down in the water during spawning.

“It hasn’t been seen because you need a microscope to see it, but we are looking at some research down the line where we explore those kinds of questions,” Ms Rodd said.

“From our understanding of their life cycle, it [was] assumed they can’t feed and that they don’t or that they don’t feed because they can’t.

“This actually changes our understanding of their basic biology, which has some pretty cool implications for restoration work.”

Ms Rodd will present the research this week at the Australian Marine Sciences Association conference in Cairns.

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