Why we’re watching the giant Australian cuttlefish



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Hello little ones! Juvenile giant Australian cuttlefish developing under rocks in the waters of South Australia.
Fred Bavendam, Author provided

Bronwyn GIllanders, University of Adelaide

Australia is home to the world’s only known site where cuttlefish gather to mate en masse.

From May to August, if you head into the water around Point Lowly, South Australia, it will be a chilly 12℃. But you’ll be able to observe what look like aliens – hundreds, even thousands of tentacled organisms with their unusual distinctive W-shaped eye pupils, and pulsating colours moving across their body.

Intent on mating, the cuttlefish will be totally oblivious to your presence.

Giant Australian cuttlefish can change the colour and texture of their skin.
David Wiltshire, Author provided



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But this population of cuttlefish dropped in abundance from an estimated 150,000 animals in the late 1990s to only 13,492 in 2013.

Although counts in recent years suggest the creatures have recovered, my research aims to determine what sorts of factors influence this very unique cuttlefish population. This may allow us to better manage and protect the species – important not just for science, but also for the local environment and economy.

Rockstars of the sea

Every time I head to the Point Lowly coastline and dive with the giant Australian cuttlefish I’m amazed and excited by their antics.

Giant Australian cuttlefish in an intimate embrace.
Matt McMillan, Author provided

The name “giant” is perhaps a misnomer. Giant Australian cuttlefish only ever reach about one metre in size. Most animals are much smaller, especially in South Australia.

Cephalopods have been described as rockstars of the sea for their “live fast, die young” life history strategy – they grow rapidly, reproduce early and die following reproduction. Giant Australian cuttlefish live for 1-2 years.

Although they are found in waters across southern Australia, giant Australian cuttlefish live in distinct populations that do not interact. We know from genetic studies that those breeding along that small area of Upper Spencer Gulf coastline are restricted to an area north from a line across the gulf from Wallaroo to Arno Bay (around 6,500 km²).

The most northern waters of Upper Spencer Gulf in South Australia host a unique population of giant Australian cuttlefish.
Ellen Rochelmeyer (using Google Maps), CC BY-NC-ND

Outside the breeding season of May to August they are distributed throughout this northern region. Come May they start to move towards a narrow 8km stretch of rocky coastline. At their peak you see literally one cuttlefish per square metre. It’s the sheer numbers that are impressive!

They come solely for one purpose over winter – to find mates to reproduce.

Cuttlefish gather to breed from May-August each year.
Tim Rogers, Author provided

Sudden drop in numbers

Around the late 1990s, the cuttlefish breeding aggregation in the Upper Spencer Gulf began to be targeted by fishers. Since then, a number of restrictions on taking cuttlefish and other cephalopods from these waters have been in place.

Around that time, a program of research through the University of Adelaide and SARDI Aquatic Sciences also began. Estimates of abundance and biomass of the breeding aggregation population suggested around 150,000 cuttlefish bred in the Upper Spencer Gulf. The surveys stopped after a few years.

Numbers of giant Australian cuttlefish in the Upper Spencer Gulf fell dramatically between the late 1990s and 2013.
Matt McMillan, Author provided

Then in 2005 anecdotal reports from SCUBA divers suggested cuttlefish were less abundant. A survey at that time and continual data collected since 2008 confirmed that numbers had dropped. In 2013 less than 15,000 individuals were estimated on the breeding aggregation.

Significant resources were put towards studying the cuttlefish to determine what might be causing such a decline. Changes in water temperature and salinity may be involved.




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We looked at data for other cephalopods over a similar time frame, and found no such decline. In fact, over the last 60 years many different types of cephalopod have been increasing in abundance – it’s not yet clear why.

The low numbers of 2013 seem to be unique to the giant Australian cuttlefish on the Upper Spencer Gulf.

Since this time there has been a recovery in this population, with numbers bouncing back towards their late 1990s levels.

Some giant Australian cuttlefish reach one metre in length – but most are smaller.
Nick Payne, Author provided

How cuttlefish breed

We know that cuttlefish come to this breeding aggregation to mate using a range of amazing strategies and behaviours – for example, small males impersonate females to avoid detection by larger males and gain access “under cover”.




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Because the population on the breeding aggregation is skewed towards males (an average o four to one), females have some choice over who they mate with.

After mating takes place, females deposit eggs on the underside of rocks.

Cuttlefish eggs deposited on the underside of rocks.
Fred Bavendam, Author provided

Cuttlefish eggs take three to five months to develop, hatching from mid-September through to early November. They emerge as miniature adults about the size of your thumbnail.

Baby cuttlefish disperse within the Upper Spencer Gulf with an even sex ratio.

Cuttlefish gather in only a few metres of water in the Upper Spencer Gulf.
Matt McMillan, Author provided

To work out why there was a difference in sex ratio between the broader region (1 male:1 female) and the breeding aggregation (4 males:1 female), we tagged male and female cuttlefish using trackable acoustic markers. We discovered that males spend around four times the length of time on the breeding aggregation compared to females, and that individuals are not present for the whole breeding season.

So the breeding aggregation is likely larger in size than fixed time frame counting estimates allow us to measure.

Positive influence on local economy

Although the apparently low population size in 2013 caused great concern, we are now cautiously optimistic for our giant Australian cuttlefish in Upper Spencer Gulf.

There’s something behind you!
Matt McMillan, Author provided

These creatures attract tourists from around the world, who come and snorkel or SCUBA dive on a unique breeding aggregation. This in turn injects money into the local economy and diversifies business in the region.

The cuttlefish are just one “user” of our shared marine environment along with the other activities and industries of South Australia.


The ConversationThis article is based on a presentation delivered by Bronwyn Gillanders at the South Australian Museum as part of the Sprigg Lecture Series.

Bronwyn GIllanders, Professor , University of Adelaide

This article was originally published on The Conversation. Read the original article.

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Figs, ferns and featherwoods: learn all about Australia’s native trees and plants


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You love Australian plants, I love Australian plants, we all love Australian plants!
Percita/Flickr

Madeleine De Gabriele, The Conversation and Molly Glassey, The Conversation

Sign up to the special Beating Around the Bush newsletter here.


Australia is classified as “megadiverse” meaning it’s a global hotspot for plant and animal diversity, and has vast numbers of unique species found nowhere else on Earth. With this newsletter we want you to be able to wander down the garden path, off the beaten track, and smell the gum leaves. Specifically, what kind of gum leaf? What is it from? Where does it grow?




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We’ll let you know every time a new edition in our Beating Around the Bush series comes out, putting the spotlight on a different native plant every time. We’re on a roughly fortnightly schedule, but like any garden there might be a few surprises along the way. I’ll also be rounding up some of the greatest hits from our archives, and talking about what’s new in the plant world.

This one is for all you floraphiles out there.
Felicity Burke/The Conversation

The ConversationIf someone else in your life might enjoy this mix in their inbox, please let them know about it. And if you have any feedback, feel free to let us know in the comments.

Madeleine De Gabriele, Deputy Editor: Energy + Environment, The Conversation and Molly Glassey, Audience Development Manager, The Conversation

This article was originally published on The Conversation. Read the original article.

Here’s how many times you actually need to reuse your shopping bags



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Jeremy Piehler/Flickr, CC BY-NC

Trevor Thornton, Deakin University

The plastic bag ban by the major supermarkets (and Coles’ pivot away from its ban after backlash, then pivot back to the ban after a backlash to the backlash) has left plenty of people scratching their heads.




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What are the best replacements for single-use plastic bags? Given that reusable bags are much sturdier, how many times must we use them to compensate for their larger environmental impact?

The simple answer is that there is no simple answer. However, a kind of research called “life cycle assessment” can help us work out the impact of common types of reusable bags.

Life cycle assessments

I am not aware of any Australian studies of plastic-bag substitutes. Research conducted overseas can offer a basic guide.

Life cycle assessments consider a wide range of factors, including raw materials, manufacturing, transport, and eventual disposal.

Looking at all of these elements, researchers calculate greenhouse gas emissions, waste disposal, water and energy consumption and a variety of other impacts.

To complicate the decision further, if you choose a plastic bag, is it made from virgin resin or from recycled plastic? Even if the bag is recycled, transport is an issue – where was it made? Printing on the bag also adds to the environmental burden.

Finally, what happens to the bags when they can no longer meet their purpose? Are they recycled, reused as bin liners, or thrown away immediately?




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How many times must a bag be reused?

Once all of this information has been distilled, scientists can usually offer a fairly straightforward guide: the number of times a given bag should be reused when compared to the standard supermarket plastic bag.

A 2018 Danish study, looking at the number of times a bag should be reused before being used as a bin liner and then discarded, found that:

  • polypropylene bags (most of the green reusable bags found at supermarkets) should be used 37 times
  • paper bags should be used 43 times
  • cotton bags should be used 7,100 times.

Another UK study, which only considered the climate change impact, found that to have lower global warming potential than single-use plastic bags:

  • paper bags should be used three times
  • low-density polyethylene bags (the thicker plastic bags commonly used in supermarkets) should be used four times
  • non-woven polypropylene bags should be used 11 times
  • cotton bags should be used 131 times.

Note, however, that if a plastic bag is reused (even as a bin liner) the number of times an alternative needs to be used increases.

It’s worth noting that, according to the 2018 Danish study, using organic cotton has a greater environmental impact than non-organic due to higher production costs. Our assumptions about what is environmentally friendly don’t always stand up to scrutiny.

A 2014 study in the United States found that reusable LDPE and polypropylene bags do have a lower environmental impact than the usual plastic bags found in supermarkets – but only if they are reused enough times. This study found that about 40% of shoppers forgot to bring their reusable bags and therefore end up using the plastic bags. This then adds to the environmental burden of shopping.

One final consideration is how many bags you need. The Danish researchers equalised the volume of the bags so that evaluations were made on the same volume of space (this meant that for some assessments it was necessary to consider the impact of two bags).

As with all matters environmental, it’s essential that we have the right knowledge to make informed decisions. After looking at all this data, here are the things I’d like you to remember:

  1. whatever bag type you use, use it as many times as possible

  2. choose bags made from recyclable materials

  3. avoid bags that have printing or decorations – these alone can add significantly to the environmental burden of the bag

  4. never allow a bag to become litter – recycle, reuse and repurpose your bags.


The Conversation


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Trevor Thornton, Lecturer, School of Life and Environmental Sciences, Deakin University

This article was originally published on The Conversation. Read the original article.

Three reasons why it’s a bad idea to ramp up Adelaide’s desalination plant


Sarah Ann Wheeler, University of Adelaide

Drought-affected farmers in New South Wales have called for South Australia to increase the use of its desalination plant to enable an increase in water allocations for other users along the Murray River.

The farmers’ argument is that if Adelaide in particular draws less water from the river more will be available for agriculture in NSW and Victoria.

The logic may sound appealing, but there are three good reasons why it’s not a good idea. Not only is desalination an incredibly expensive project, there are other strategies – like water pricing – that can more effectively reduce water demand.




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It’s also important to remember that the water flowing to South Australia is not “wasted” if it’s not diverted for industry. Stream flows are vital for keeping many ecosystems alive, and there are already serious concerns about current levels.

Adelaide doesn’t use that much water

First, Adelaide uses a very small amount of water from the River Murray. Over the past two decades, average diversions for metropolitan Adelaide and associated country areas have been just over 100 gigalitres (GL). This represents an average 1.25% of the water diversions in the Murray-Darling Basin.

SA in general (including irrigator use) has used an average 11% of water diversions over the past two decades. NSW has diverted 52% of surface water in the Murray-Darling Basin over the same period. Hence, the reality is that ramping up SA’s desal plant will have very little actual impact on NSW irrigators’ water allocations.

South Australia (the grey line) receives much less water from the Murray River than other states.
MDBA Water Audit Monitoring reports, CC BY

Desalination is expensive

Second, increasing desalination has heavy financial and environmental costs. The financial cost is why the plant has been run at only about 10% capacity (the minimum needed to maintain its working condition).

Previous economic analysis by consultants has suggested the desalination plant should only be used to increase water allocations to SA irrigators when temporary water market prices are above A$510 per megalitre (ML).

Given that temporary water prices are now trading around A$300/ML (albeit increasing due to increased water scarcity), we’re still a long way from a financial argument for turning to the desal plant, let alone considering the cost of its negative environmental impacts.




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Water is always variable

Third, we need to take into account the variable nature of Australia’s irrigation sector.

Farmers in NSW are complaining that they are on zero percentages of water allocations at the start of the water year (August 1). This sounds like a big problem. But it doesn’t mean the farmers will get no water from the river at all.

At the start of the season, water managers allot water in districts to irrigators every two weeks. Depending on the type of water entitlement owned, and given the current state of water conditions (e.g. storage, inflows, rainfall predictions), water managers will allocate a percentage of water to high security entitlements first, then general security, then low security. Only in high rainfall years will the low security group get any water. Most years they get none.

Since water was separated from land in the Murray-Darling Basin, this water is not tied to any particular use. Once allocated, irrigators can use their seasonal water for their crops, store it, sell it on the water market, or even choose to let it flow down the river.

It is not unusual for irrigators with low or general security entitlements to start the water year with low or no water allocated, especially in times of water scarcity. One reason is that these rights are traditionally associated with districts where farmers typically grow annual crops like rice and cotton. They have larger farms and more water rights – but also more flexibility about the amount they plant every year.

Low water allocations at the start of the water year act as a signal to these producers to think carefully about the amount of acreage to plant in the coming months. In addition, many NSW and Victorian farmers have access to carry-over water (unused stored water from the previous year).

The other option is the water market; irrigators can enter the water market to buy water. Current temporary water prices are still historically a lot lower than prices in the Millennium Drought, when temporary prices hit over A$1000/ML in many regions.

Finally, it is important to emphasise that water destined for urban use in SA is not “wasted water” for NSW and Victoria. It is still providing surface-water flows in the basin as it makes it way to SA.

Economic studies show that a healthy and sustainable river is worth millions of dollars in tourism and recreation, plus providing important cultural values, on which many small regional town economies are heavily dependent. And there is ongoing evidence that the Murray-Darling Basin is still far from being sustainable.




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Unfortunately, many of the people who support more sustainable water reallocation for the environment are widely dispersed. They often do not have the lobbying power or the resources to engage successfully in policy debate.

The ConversationOf course, farmers need support. But the calls for more water to be allocated to irrigators will sound loudly as the drought continues, and it’s important to remember that there are other, less costly, options that also protect our environment.

Sarah Ann Wheeler, Professor in Water Economics, University of Adelaide

This article was originally published on The Conversation. Read the original article.

How the Wardian case revolutionised the plant trade – and Australian gardens



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Melburnians admire the first primrose to arrive in the colony, transported by a Wardian case, in Edward Hopley’s A Primrose from England, circa 1855.
Bendigo Art Gallery, Gift of Mr and Mrs Leonard Lansell 1964.

Luke Keogh, Deakin University

The first journey of a Wardian case was an experiment. In 1829, the surgeon and amateur naturalist Nathanial Bagshaw Ward accidentally discovered that plants enclosed in airtight glass cases can survive for long periods without watering. Four years later he decided to test his invention by transporting two of his cases filled with a selection of ferns, mosses and grasses from London to Sydney, the longest sea journey then known.

On November 23 1833, Ward received a letter from Charles Mallard, the ship captain responsible for the two cases, telling him: “your experiment for the preservation of plants alive … has fully succeeded”.

Gleichenia microphylla.
Krzysztof Ziarnek, Kenraiz/Wikimedia Commons, CC BY

The next challenge was the return journey. In February 1834, the cases were replanted with specimens from Australia. Eight months later, when Ward and friend George Loddiges, a well-known nurseryman, went aboard the ship in London they inspected the healthy fronds of a delicate coral fern (Gleichenia microphylla), an Australian plant never before seen in Britain. The experiment was a success.

The Wardian case, as it would become known, revolutionised the movement of live plants around the globe. They were shaped like a miniature greenhouse, made of timber and had glass inserts in the roof. In the cases, plants had a greater chance of survival when in transit.

Wardian cases full of cycads from Rockhampton, Queensland, arrive at the Missouri Botanic Gardens after a long journey via London and New York, c.1920.
Missouri Botanic Gardens.

Often thought of as only a product of the gardening crazes of the Victorian era, the Wardian case was actually a notorious prime mover of plants. Some of the key uses of the case include moving tea from China to India to lay the foundations of the Assam and Darjeeling tea districts; helping move rubber from Brazil and transporting it via London to Asia, which is now the leading producer of the crop; and repeatedly moving bananas over many decades to the Pacific Islands, Central America and the Caribbean.

A tea plantation in India: the cases moved tea from China to India to lay the foundations of the Assam and Darjeeling tea districts.
Wikimedia Commons

The Wardian case resolved a major bottleneck in the transport of live plant species, but it also had major consequences for environmental relationships in the 19th and 20th centuries.

An untold story

Botanists and horticulturalists used this simple box for over a century to carry hundreds of thousands of plants around the globe, whether they were in England or the United States, France or India, Russia or Japan. The Australian story of the Wardian case is an important and untold one.

Wardian cases line the paths at the Adelaide Botanic Gardens.
Adelaide Botanic Gardens.

Each state has an important connection to it. New South Wales received the first plants from Ward himself. The Royal Botanic Gardens, Kew, sent its first Wardian cases, full of fruit trees and ornamental plants, to Western Australia. The Adelaide Botanic Gardens even had a path lined with Wardian cases. Tasmania was vital in the 19th-century fern trade. And Queensland used the Wardian case to transport the cactoblastis moth to help solve the prickly pear infestation.

Victoria’s connection to the case is unsurprisingly one of gardeners and ornamental plants. Today, Victoria is home to Australia’s largest nursery industry, by some reports worth more than $1.6 billion annually and employing more than 11,000 people. The industry today cannot be separated from the long global history of moving beautiful and useful plants to Australia more than a century ago. Two examples illuminate the thriving early trade in Victoria.

Preparing to send live plants in Wardian cases at the Jardin d’Agronomie Tropicale, Paris, c.1910.
Image courtesy Bibliothèque historique du CIRAD.

Published in 1855, Charles Mackay’s widely circulated poem The Primrose was about the landing in Melbourne of a beautiful rare flower and the procession from the docks to an exhibition location in the city. It read, in part:
“She has cross’d the stormy ocean/A pilgrim, to our shore/As fresh as Youth and Beauty/And dear as days of yore.”

By some reports, more than 3,000 people turned out to see the floral traveller. Police were called in to restore order to Melbourne’s streets during the procession. News of the fanfare was carried in major international newspapers including Harper’s Weekly and the Illustrated London News.

The British artist Edward Hopley painted the scene, A Primrose from England (1855), to memorialise both the moment of the plant arriving in Melbourne and, in typical Hopley style, the social milieu of the period.

The technology for moving the plant was not lost on either artist. The primrose that Mackay so eloquently lyricised and Hopley so captivatingly brought to life arrived in Melbourne in a specially designed Wardian case. It would not have arrived without this technology for moving plants. It was not just the primrose. In the decades following 1858, the Wardian case played a major role in shaping the aesthetics and species available in the Victorian landscape.

Melbourne, the Garden Capital of Victoria, Australia, by James Northfield.
State Library Victoria.

In early April 1862, three decades after Ward’s invention, the well-known Victorian nurseryman Thomas Lang delivered a lecture to the Ballarat Horticultural society titled “On Wardian, or Plant Cases”. Lang began by describing his first encounter with the cases in Edinburgh. He went on to detail the many useful plants, such as the giant Californian redwood, that he had introduced with the help of the case. By his own estimate, Lang transported nearly a million plants to Victoria in just one decade in the late 19th century, a staggering number by just one nurseryman.

Californian redwoods in Victoria’s Great Otway National Park.
Shutterstock

Now living in regional Victoria, after many years of travel researching a book on the Wardian case, I often think about Lang and the enthusiasm colonists had for bringing over beautiful plants. Lang proclaimed in his lecture of 1862: “The comfort, the pleasures, the commercial interests, the happiness of mankind are promoted by the use of Wardian cases.”

To move beautiful ornamental plants here was very much part of the home-making process for colonists.

But it was always a trade. While beautiful plants came into Australia, many useful ones went out. Often we forget that the beauty of our gardens is as much about moving plants, as it is about the hard work of tilling the soil.

Next time your hands are covered in soil, it might be good to wonder where that camellia or fuchsia or rose or apple or kiwi fruit or lemon originated – chances are it travelled in a Wardian case.


The ConversationLuke Keogh’s book The Wardian Case will be published next year by the University of Chicago Press. He delivers the Redmond Barry Fellowship Presentation at the University of Melbourne on July 25 2018.

Luke Keogh, Visiting Scholar, Deakin University

This article was originally published on The Conversation. Read the original article.