Water quality improving but Cockburn Sound still impacted by pollution legacy

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Water quality in Cockburn Sound has been steadily improving for decades but seagrass and some fish stocks are still struggling to recover from the days of unrestricted pollution discharge, according to marine scientist Dr Fiona Webster.

Dr Webster, who works at the Department of Water and Environmental Regulation assessing marine proposals, was speaking to students about the impacts of marine pollutants as part of WAMSI’s Thinking Blue education outreach program.

The program features lectures by some of the state’s top marine scientists, including from WAMSI’s partner organisations.

Dr Webster told the students that in the 1970s there were concerns about the environmental impact of industry discharging pollutants such as nutrients and heavy metals straight into Cockburn Sound.

“Around 80 percent of seagrass was lost and there were concerns people couldn’t swim or couldn’t fish and many were worried,” Dr Webster said.

“Whilst the extent of environmental deterioration sounds extreme, you have to remember that the Environmental Protection Act didn’t exist until 1986,” she said.

To protect Cockburn Sound, the State Government introduced two key initiatives; firstly direct discharges were banned and secondly the State Environment Policy for Cockburn Sound was developed.

Dr Webster said that while parts of Cockburn Sound will remain industrialised, the State Environment Policy ensured environmental, social and cultural values were protected and the water was safe to swim in and fish were safe to eat.

“Monitoring has shown the water quality has been improving since then and most areas now have good water quality,” Dr Webster said. “But seagrass is not recovering so well.”

“Part of that could be the organic nutrient load in the sediment.”

“Some fish stocks are also still depressed including the garfish and blue swimmer crabs.”

Whilst water quality in Cockburn is looking good, there are always new and emerging contaminants to watch out for such as PFAS (a key constituent in fire fighting foam) and microplastics.

Dr Webster told the students there was good work going on to support the environment including the replenishment of fish stocks and the Seeds for Snapper program. This involved volunteers collecting seagrass seeds and dropping them in areas needing regeneration.

Early inspiration

One of the aims of Thinking Blue is to inspire students to study marine science.

Dr Webster told the students, until her dad gave her a pair of goggles when she was six years old, she’d been nervous of seaweed.

“When I had my goggles on, suddenly I could see fish and bubbles and kelp.”

She later studied science and did a PhD after completing researching at Ningaloo Reef.

She told the students her career had ‘meandered’ from measuring crayfish on commercial vessels at the Abrolhos Islands to spending 18 months on a yacht off Madagascar to working with an Australian aid organisation in Tonga.

It’s a career journey that certainly inspires.

You can watch Dr Fiona Webster’s lecture here.

Marine interdependence – From turtle hunting crabs to tongue eating louse

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A camera focused on a Ningaloo Reef beach captures life and death in a marine ecosystem in its rawest form: Ghost crabs scramble to catch freshly hatched loggerhead sea turtles before sea gulls swoop in to snap up others as they stagger towards the shoreline.

Once in the water, there are new predators for the few that make it that far, but also organisms for them to eat and fuel their growth.

The footage, shot by recent PhD graduate Casper Avenent, was played to students as part of a WAMSI Thinking Blue lecture on the ‘Interdependence of organisms in marine ecosystems’ by Professor Glenn Hyndes from Edith Cowan University.

“As for the golden ghost crabs, they are possibly eaten by rays and dingoes but we don’t know”.

The scene on a small part of one Australian beach represents a much bigger ecological story.

“On this one beach at Ningaloo, there are different species of ghost crabs with very different diets,” Professor Hyndes said.

“We have found from gut analysis, the horned eyed ghost crabs feed a lot on insects and the golden ghost crabs will feed on carrion including dead rats, birds, fish, as well as turtle eggs and hatchlings.”

Professor Hyndes’ talk incorporated the many ways various species of plants and animals are interdependent and along with the video from the Exmouth area, he used an example of life along the south coast of Western Australia.

“There is algae, consumed by abalone and sea urchins, which are eaten by animals such as western blue groper. Bronze whaler sharks are consuming fish.”

One theme of Professor Hyndes’ talk was ‘Habitat Matters’.

Certain jellyfish provided shelter for juvenile fish and seagrass also played a vital role in a number of ways including giving a habitat for fish.

“The different seagrass species will be important for different fish species. For instance, the sea trumpeter fish prefer the canopy formation of the Amphibolis griffithii seagrass and blow fish are more likely to swim among the more sparce Posidonia coriacea.

Another example of interdependence was the anemone fish which can have sea louse feeding on its tongue and the inside of its mouth.

“This has a negative impact on the fish but there are cleaner wrasse fish that feed on the louse” Professor Glenn Hyndes said.

Professor Hyndes’ talk, including his slides and video footage from Ningaloo, can be found here on the WAMSI YouTube page.

Snapper research helping to evaluate hatchery release programs

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Researchers are working on non-lethal ways of evaluating the success of programs that release hatchery-reared snapper fingerlings into Cockburn Sound.

The WAMSI Westport Marine Science Program project, led by the Department of Primary Industries and Regional Development, involves analysing photographs of hatchery snapper to ultimately determine any physical differences with wild snapper.

DPIRD’s Dr David Fairclough, who is working on the WAMSI Westport Marine Science Program project, said the release of hatchery – reared juvenile snapper was perceived as a positive way of improving wild stocks but it was not always clear whether the fish thrived or how long they survived.

“Such information is crucial to assess how hatchery-reared fish may contribute to stocks,” Dr Fairclough said.

The project also involves research scientists from Murdoch University and Flinders University.

“For the research, photographs of the hatchery-reared snapper are imported into a computer program that allows 16 physical features on the fish to be assigned and the distances between them measured,” Murdoch University’s Dr James Tweedley said.

The same process will be conducted on juvenile snapper collected from Cockburn Sound but these fish will also be dissected and have their otoliths – a bone in their ear – removed to determine whether they were grown in the hatchery.  A non-toxic substance is used to stain the otoliths of live hatchery snapper before their release, allowing them to be identified later in biological samples.

“If significant differences end up being detected then, in future, citizen scientists or recreational fishers could become involved in monitoring released snapper by providing photos of their catches for analysis,” Dr Tweedley said.

The project is also investigating whether snapper from inside Cockburn Sound are genetically different than snapper in the open ocean outside the Sound. In addition, it will test if hatchery-reared juveniles contain the same levels of genetic diversity and are as well adapted as those found in the wild population in Cockburn Sound.

“The role of Cockburn Sound as a spawning and nursery area for snapper is well recognised. However, the level of contribution made by those fish to the population and associated fishery along the lower west coast is not fully understood,” Dr Fairclough said.

“Information from this project will help with future identification of where hatchery-reared fish move to, either in Cockburn Sound or along the west coast,” Dr Fairclough said.

Fish frames donated by fishers to DPIRD as part of their ‘Send Us Your Skeletons’ citizen science project, would give researchers an understanding of where hatchery-reared fish move by removing their otoliths to see if they are stained.

 

Huge state delivers vast array of marine ecosystems

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From mud skippers in Kimberley mangroves to orcas in south coast canyons and bizarre looking sea pigs in the deep ocean, Western Australia with its 12,500 kilometre coastline, boasts a vast array of ecosystems, according to marine scientist Dr Tom Holmes.

“In fact, if you include the islands, WA’s coastline is closer to 20,000km which is equivalent to almost half the circumference of the earth,” Dr Holmes said.

In a recorded talk to students, as part of the Western Australian Marine Science Institution’s Thinking Blue series, he discussed WA’s coral reefs, estuaries, mangroves and deep-sea ecosystems.

“There are more than 3,000 species of fish in Western Australia and there are a large number of animal and plants that are not found anywhere else in the world,” Dr Holmes said.

Thinking Blue is WAMSI’s school outreach program which allows students to hear from the state’s top marine scientists on a range of topics.  It’s run with passionate educator and marine scientist John Ryan, who is a teacher at Sacred Heart College in Sorrento.

Dr Holmes, the Marine Science Program Leader at the Department of Biodiversity, Conservation and Attractions, was the first speaker in the latest series of talks and told the students the state they lived in boasted eight of Australia’s 15 biodiversity hotspots.

He explained that mangroves, which are predominantly in the north of the state, supported a lot of life including molluscs, birds and mud skippers. Roots from the plants emerged from the sediment trapping organic matter and allowing the plant to breathe.

“Around Roebuck Bay near Broome scientists have found mangroves are an important area for juvenile green turtles and the area is like a nursery or creche for the animals.”

“There are 13 species of mangroves in the Kimberley and six or seven in the Pilbara.”

Speaking about estuaries, Dr Holmes said they contained a ‘mix of fresh and saltwater species’. One of these was the sawfish, which was a threatened species.

Dr Holmes shared photographs of life in the depths of the Indian Ocean including the sea pig, which is a pink coloured sea cucumber with modified legs and face tentacles.

“It’s a complete alien world at those depths where animals have adapted to live where the environment is cold, with high pressure, low oxygen and low light,” Dr Holmes said.

His talk also covered Western Australia’s spectacular coral reefs, of which Ningaloo is the most famous. He also explained that the biggest individual plant in the world was in WA, a seagrass in the sheltered embayments of Shark Bay.

“This plant has cloned itself over an enormous scale and is now 180km long.”

Dr Holmes finished his lecture, which will be shared with other schools and on the WAMSI website, by taking questions including one from a student about how they could find work in marine science.

He explained he grew up three hours from Queensland’s spectacular coast and learned to dive by retrieving golf balls. Once he had the chance to dive in the ocean, he was hooked on marine life and went on to study marine science.

He said it was a competitive area and it helped to get higher education qualifications.

“But there are many other jobs in this area that don’t require a doctorate including in policy and out in the field as a ranger.

“Get experience where you can, perhaps work towards a skipper’s ticket. It all helps.”

Check out Dr Tom Holmes’ Thinking Blue talk here: