From enormous tides to millions of shells, here are 6 unique beaches for your summer road trip

Hannah Power, University of Newcastle

As lockdowns ease and we head into summer, many Australians have started thinking about their beach holiday. For most people, a beach involves sun, sand, salt, and waves. A beach is a beach – right?

For coastal scientists and engineers, it’s a little different. We wonder how these beaches are made and why they are so different.

Australia has over 35,000 kilometres of coastline to explore, and our beaches can differ radically. In Australia’s south, where tides are smaller and waves bigger, we get high energy beaches with lots of surf and sand. The north’s larger tides and smaller waves mean the beaches look quite different – they’re flatter, with big intertidal zones. Some even have mud instead of sand.

To pique your interest, here are six beaches from around the country with special characteristics, all well worth exploring on your summer road trip or beach holiday.

1. Sandy Cape – end of the line for the sand islands

K’gari (Fraser Island), Queensland.

Waves and storms along the east coast, from the New South Wales/Victoria border to K'Gari in Queensland, usually come from the south and southeast. This drives longshore sediment transport, a process where sand is moved up the coast by waves and wave-driven currents.

As the sand moves along the NSW coast and into Queensland, it beach-hops its way north, encountering natural barriers like headlands as well as human barriers such as breakwaters. Sand will often skirt these barriers in pulses, as tends to happen at Byron Bay.

As the coast turns to the west in southeast Queensland, the sand keeps getting pushed north. That’s how Australia got the largest sand islands in the world: Minjerribah (South and North Stradbroke), Mulgumpin (Moreton), Yarun (Bribie), and finally K’gari.

The northernmost point of K’gari, Sandy Point, marks where the sand heads underwater, moving along the continental shelf before dropping off the edge and sliding down the slope into the deep abyssal plains.

If you make it to this beach, you can see sand being swirled away into deeper water – the very end of the above-water part of the cycle.

2. The Funnel – the biggest tides in Australia

Collier Bay, Western Australia

The Kimberley region of Australia is home to the biggest tides in the country. Unfortunately, there aren’t many tide gauges in this area, with over 1,000km between instruments in places. So, to find the beach with the biggest tides, we either have to collect more data or use a computer model.

When we model the tides for every Australian beach, The Funnel in Collier Bay comes out as the beach with the biggest tides. Its range is a whopping 13.5 metres!

Getting to this beach might be tricky as you’ll need to arrive by boat. But it would be worth the trip, as the beach at high tide is composed of cobbles and likely sand and mud at low tide. Watching the tide roar in would be something to see – just watch out for crocs!

3. Goolwa Beach – the high energy beach

South Australia

When rivers as big as the Murray – whose basin covers one-seventh of mainland Australia – meet the ocean, they normally form huge deltas like the Mississippi or the Nile.

But because of Australia’s age, low rainfall and water extraction for agriculture, the Murray-Darling Basin only delivers a relatively small amount of water and sediment to the coast. So instead of a classic river delta at the end of the Murray, unusually, we have a beach system.

Goolwa Beach is part of this system, its fine sands representing the last barrier to the mighty Murray River on its journey to the ocean. The beach is also exposed to the huge waves rolling in from the Southern Ocean. That makes it one of our highest energy beaches – so much so it’s the archetype of the high energy beach type called “dissipative” in our Australian beach classification system.

4. Amity Beach – the beach with sinkholes

Minjerribah, Queensland

The islands of Minjerribah (North Stradbroke) and Mulgumpin (Moreton) form the barrier separating Moreton Bay near Brisbane from the Coral Sea. Between them lies Rainbow Channel through which the tide flows in and out of Moreton Bay.

These fast tidal currents cause large amounts of sand to form shifting sand shoals on both the ocean and bay sides of the channel.

Amity Beach sits on the edge of this channel and the constantly changing dynamics of this system cause “sinkholes” to occur regularly on this beach. Rainbow Beach near K'Gari is better known due to its habit of swallowing cars, but Amity Beach is unique. Why? Because the sinkholes always occur in the same place.

That makes it the only place in the world where scientists and engineers can reliably observe this amazing phenomenon to work out why sinkholes occur and how they work.

5. Shell Beach – walk on millions of shells

Shark Bay, Western Australia

Most of us tend to think of beaches as being made up by sand, but they don’t have to be. Beaches can be made of mud or cobbles or even just shells.

Shell Beach in Shark Bay is a rarity as it’s almost entirely made up of trillions of shells, with the piles up to 10m deep.

These shells all come from one mollusc, the Fragum cockle. The reason there are so many of these shells is because the waters of Shark Bay are saltier than the ocean.

This hypersaline environment makes it hard for most species to survive. That means the Fragum cockle has very few competitors or predators and can proliferate. Just remember to bring some footwear!

6. Bengello Beach – a time capsule made of sand

New South Wales

Coastal scientists and engineers love data about beaches, and especially long-term records of how much sand is on a beach.

Bengello Beach in southern NSW represents the longest record of beach surveys in Australia with measurements every 2-6 weeks since January 1972.

These measurements have captured beach erosion during storms and its subsequent recovery. Data like this underpins models forecasting how our beaches will respond to climate change.

Bengello is also a living snapshot of beach evolution, capturing the way many of Australia’s beaches have changed since sea level stabilised at about today’s level after the last ice age.

If you walk from the road to the beach, you pass over ridges of ancient sand dunes. These formed as the beach slowly built out towards the sea over the last 6,000 years, as waves and currents piled up more and more sand on the beach.

When road-tripping to Australia’s beaches, remember to check local weather and marine forecasts to make sure it’s safe to swim and leave only your footprints behind. And if you make it to any of these beaches, why not share your knowledge about their significance with your travel buddies?

Hannah Power, Associate Professor in Coastal and Marine Science, University of Newcastle

This article is republished from The Conversation under a Creative Commons license. Read the original article.

23 December 2021

Shayne McGregor, Monash University

Severe coastal flooding inundated islands and atolls across the western equatorial Pacific last week, with widespread damage to buildings and food crops in the Federated States of Micronesia, Marshall Islands, Papua New Guinea and Solomon Islands.

On one level, very high tides are normal at this time of year in the western Pacific, and are known as “spring tides”. But why is the damage so bad this time? The primary reason is these nations are enduring a flooding trifecta: a combination of spring tides, climate change and La Niña. La Niña is a natural climate phenomenon over the Pacific Ocean known for bringing wet weather, including in eastern Australia. A less-known impact is that La Niña also raises sea levels in the western tropical Pacific. In a terrifying glimpse of things to come, this current La Niña is raising sea levels by 15-20 centimetres in some western Pacific regions – the same sea level rise projected to occur globally by 2050, regardless of how much we cut global emissions between now and then. So let’s look at this phenomena in more detail, and why we can expect more flooding over the summer.

These spring tides aren’t unusual

Low-lying islands in the Pacific are considered the frontline of climate change, where sea level rise poses an existential threat that could force millions of people to find new homes in the coming decades.

Last week’s tidal floods show what will be the new normal by 2050. In the Marshall Islands, for example, waves were washing over boulder barriers, causing flooding on roads half a metre deep.

This flooding has coincided with the recent spring tides. But while there is year to year variability in the magnitude of these tides that vary from location to location, this year’s spring tides aren’t actually unusually higher than those seen in previous years.

For instance, tidal analysis shows annual maximum sea levels at stations in Lombrom (Manus, Papua New Guinea) and Dekehtik (Pohnpei, Federated States of Micronesia) are roughly 1-3cm higher than last year. Meanwhile, those at Betio (Tarawa, Kiribati) and Uliga (Majuro, Marshall Islands) are roughly 3-6cm lower.

This means the combined impacts of sea level rise from climate change and the ongoing La Niña event are largely responsible for this year’s increased flooding.

A double whammy

The latest assessment report from the Intergovernmental Panel on Climate Change finds global average sea levels rose by about 20cm between 1901 and 2018.

This sea level rise would, of course, lead to more coastal inundation in low-lying regions during spring tides, like those in the western tropical Pacific. However, sea level rise increases at a relatively small rate – around 3 millimetres per year. So while this can create large differences over decades and longer, year to year differences are small.

This means while global mean sea level rise has likely contributed to last week’s floods, there is relatively small differences between this year and the previous few years.

This is where La Niña makes a crucial difference. We know La Nina events impact the climate of nations across the Pacific, bringing an increased chance of high rainfall and tropical cyclone landfall in some locations.

But the easterly trade winds, which blow across the Pacific Ocean from east to west, are stronger in La Niña years. This leads to a larger build up of warm water in the western Pacific.

Warm water is generally thicker than cool water (due to thermal expansion), meaning the high heat in the western equatorial Pacific and Indonesian Seas during La Niña events is often accompanied by higher sea levels.

This year is certainly no different, as can be seen in sea surface height anomaly maps here and here.

From these maps, along with past studies, it’s clear Pacific islands west of the date line (180⁰E) and between Fiji and the Marshall Islands (15⁰N-15⁰S) are those most at risk of high sea levels during La Niña events.

What could the future hold?

We can expect to see more coastal flooding for these western Pacific islands and atolls over the coming summer months. This is because the La Niña-induced sea level rise is normally maintained throughout this period, along with more periods with high spring tides.

Interestingly, the high sea levels related to La Niña events in the northern hemisphere tend to peak in November-December, while they do not peak in the southern hemisphere until the following February-March.

This means many western Pacific locations on both sides of the equator will experience further coastal inundation in the short term. But the severity of these impacts is likely to increase in the southern hemisphere (such as the Solomon islands, Tuvalu and Samoa) and decrease in the northern hemisphere (such as the Marshall Islands and the Federated States of Micronesia).

Looking forward towards 2050, a further 15-25cm of global average sea level rise is expected. La Niña events typically cause sea levels in these regions to rise 10-15cm above average, though some regions can bring sea levels up to 20cm.

Given the projected sea level rise in 2050 is similar to the La Niña-induced rise in the western Pacific, this current event provides an important insight into what will become “normal” inundation during spring tides.

Unfortunately, climate projections show this level of sea level rise by 2050 is all but locked in, largely due to the greenhouse gas emissions we’ve already released.

Beyond 2050, we know sea levels will continue to rise for the next several centuries, and this will largely depend on our future emissions. To give low-lying island nations a fighting chance at surviving the coming floods, all nations (including Australia) must drastically and urgently cut emissions.

Shayne McGregor, Associate Professor, and Associate Investigator for the ARC Centre of Excellence for Climate Extremes, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Dec 16 2021

Daryl McPhee, Bond University

Am I not pretty enough? This article is part of The Conversation’s series introducing you to unloved Australian animals that need our help.

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Australia’s oceans are home to a startling array of biodiversity — whales, dolphins, dugongs and more. But not all components of Aussie marine life are the charismatic sort of animal that can feature in a tourism promotion, documentary, or conservation campaign.

The echiuran, or spoon worm, is one such animal. It is also called the penis worm.

There is no “Save the Echiuran Foundation” and no influencers selling merchandise to help save them. But these phallic invertebrates are certainly worth your time as integral and fascinating members — of Australia’s marine ecosystems.

What makes them so interesting?

Taxonomists have classified echiurans in various different ways over the years, including as their own group of unique animals. Today, they’re considered a group of annelid worms that lost their segmentation. There is uncertainty about the exact number of species, but an estimate is 236.

The largest echiuran species reach over two metres in length! They have a sausage-shaped muscular trunk and an extensible proboscis (or tongue) at their front end. The trunk moves by wave like contractions.

Most echiurans live in marine sand and mud in long, U-shaped burrows, but some species also live between rocks. And they’re widespread, living up to 6,000 metres deep in the ocean all the way to the seashore, worldwide.

For example, one species, Ochetostoma australiense, is a common sight along sandy or muddy shorelines of Queensland and New South Wales, where it sweeps out of its burrow to collect and consume organic matter.

In fact, their feeding activities are something to behold, as they form a star-like pattern on the surface that extends from their burrow opening.

In another species, Bonella viridis, there is a striking difference> between the males and females — the females are large (about 15 centimetres long) and the males are tiny (1-3 millimetres). Most larvae are sexually undifferentiated, and the sex they end up as depends on who’s around. The larvae metamorphose into dwarf males when they’re exposed to females, and into females when there are no other females present.

Males function as little more than a gonad and are reliant on females for all their needs.

Why they’re so important

Echiurans perform a range of important ecological functions in the marine environment. They’re known as “ecosystem engineers” - organisms that directly or indirectly control the availability of resources, such as food and shelter, to other species. They do this mainly by changing the physical characteristics of habitats, for example, by creating and maintaining burrows, which can benefit other species.

Echiurans also have a variety of symbiotic animals, including crustaceans and bivalve molluscs, residing in their burrows. This means both animals have a mutually beneficial relationship. In fact, animals from at least eight different animal groups associate with echiuran burrows or rock-inhabiting echiurans — and this is probably an underestimate.

They’re beneficial for humans, too. Their burrowing and feeding habits aerate and rework sediments. Off the Californian coastline, for example, scientists noted how these activities reduced the impacts of wastewater on the seabed.

And they’re an important part of the such as the houndsharks, and species of commercial significance such as Alaskan plaice. Some mammals feast on them, too, such as the in the Bering Sea, and the southern sea otter. In Queensland they also contribute to the diet of the critically endangered eastern curlew.

And many people eat them in East and Southeast Asia, where they’re chopped up and eaten raw, or used as a fermented product called gaebul-jeot. They (allegedly) taste slightly salty with sweet undertones.

The unloved billions

In Australia there is very little known about the biology and ecological roles of our echiuran fauna. This can also be said of many of Australia’s soft sediment marine invertebrates — the unloved billions.

We simply do not understand the population dynamics of even the large and relatively common echiuran species, and the human processes that threaten them. Given their role as ecosystem engineers, impacts to echiuran populations can flow on to other components of the seabed fauna, imperilling entire ecosystems.

We can, in general terms, predict that populations have suffered from the cumulative effects of urbanisation and coastal development. This includes loss and modification of habitats, and changes to water quality.

Populations may also be harmed by undersea seismic activities used in oil and gas exploration, but this is still poorly understood. Until recently, scientists knew only of the threats seismic activity posed to the hearing of whales and dolphins. It’s becoming clearer they can also affect the planet’s vital invertebrate species.

It is a dilemma for marine conservation when so little is known about a species that impacts cannot be reliably predicted, and where there is little or no impetus to improve this knowledge base.

We cannot simply presume an animal does not play an important role in an ecosystem because it lacks charisma.

In George Orwell’s novel Animal Farm, it was said “All animals are equal but some animals are more equal than others”. This remains abundantly true in terms of how humans view animals. But we must move away from this philosophy if we are to conserve and restore the planet’s fragile ecosystems.

Daryl McPhee, Associate Professor of Environmental Science, Bond University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

August 18 2021

Snorkelers discover rare, giant 400-year-old coral – one of the oldest on the Great Barrier Reef

Adam Smith, James Cook University; Nathan Cook, James Cook University, and Vicki Saylor, Indigenous Knowledge

Snorkellers on the Great Barrier Reef have discovered a huge coral more than 400 years old which is thought to have survived 80 major cyclones, numerous coral bleaching events and centuries of exposure to other threats. We describe the discovery in research published today.

Our team surveyed the hemispherical structure, which comprises small marine animals and calcium carbonate, and found it’s the Great Barrier Reef’s widest coral, and one of the oldest.

It was discovered off the coast of Goolboodi (Orpheus Island), part of Queensland’s Palm Island Group. Traditional custodians of the region, the Manbarra people, have called the structure Muga dhambi, meaning “big coral”.

For now, Muga dhambi is in relatively good health. But climate change, declining water quality and other threats are taking a toll on the Great Barrier Reef. Scientists, Traditional Owners and others must keep a close eye on this remarkable, resilient structure to ensure it is preserved for future generations.

Far older than European settlement

Muga dhambi is located in a relatively remote, rarely visited and highly protected marine area. It was found during citizen science research in March this year, on a reef slope not far from shore.

We conducted a literature review and consulted other scientists to compare the size, age and health of the structure with others in the Great Barrier Reef and internationally.

We measured the structure at 5.3 metres tall and 10.4 metres wide. This makes it 2.4 metres wider than the widest Great Barrier Reef coral previously measured by scientists.

Muga dhambi is of the coral genus Porites and is one of a large group of corals known as “massive Porites”. It’s brown to cream in colour and made of small, stony polyps.

These polyps secrete layers of calcium carbonate beneath their bodies as they grow, forming the foundations upon which reefs are built.

Muga dhambi’s height suggests it is aged between 421 and 438 years old – far pre-dating European exploration and settlement of Australia. We made this calculation based on rock coral growth rates and annual sea surface temperatures.

The Australian Institute of Marine Science has investigated more than 328 colonies of massive Porites corals along the Great Barrier Reef and has aged the oldest at 436 years. The institute has not investigated the age of Muga dhambi, however the structure is probably one of the oldest on the Great Barrier Reef.

Other comparatively large massive Porites have previously been found throughout the Pacific. One exceptionally large colony in American Samoa measured 17m × 12m. Large Porites have also been found near Taiwan and Japan.

Resilient, but under threat

We reviewed environmental events over the past 450 years and found Muga dhambi is unusually resilient. It has survived up to 80 major cyclones, numerous coral bleaching events and centuries of exposure to invasive species, low tides and human activity.

About 70% of Muga dhambi consisted of live coral, but the remaining 30% was dead. This section, at the top of the structure, was covered with green boring sponge, turf algae and green algae.

Coral tissue can die from exposure to sun at low tides or warm water. Dead coral can be quickly colonised by opportunistic, fast growing organisms, as is the case with Muga dhambi.

Green boring sponge invades and excavates corals. The sponge’s advances will likely continue to compromise the structure’s size and health.

We found marine debris at the base of Muga dhambi, comprising rope and three concrete blocks. Such debris is a threat to the marine environment and species such as corals.

We found no evidence of disease or coral bleaching.

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‘Old man’ of the sea

A Traditional Owner from outside the region took part in our citizen science training which included surveys of corals, invertebrates and fish. We also consulted the Manbarra Traditional Owners about and an appropriate cultural name for the structure.

Before recommending Muga dhambi, the names the Traditional Owners considered included:

• Muga (big)
• Wanga (home)
• Muugar (coral reef)
• Dhambi (coral)
• Anki/Gurgu (old)
• Gulula (old man)
• Gurgurbu (old person).

Indigenous languages are an integral part of Indigenous culture, spirituality, and connection to country. Traditional Owners suggested calling the structure Muga dhambi would communicate traditional knowledge, language and culture to other Indigenous people, tourists, scientists and students.

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A wonder for all generations

No database exists for significant corals in Australia or globally. Cataloguing the location of massive and long-lived corals can be benefits.

For example from a scientific perspective, it can allow analyses which can help understand century-scale changes in ocean events and can be used to verify climate models. Social and economic benefits can include diving tourism and citizen science, as well as engaging with Indigenous culture and stewardship.

However, cataloguing the location of massive corals could lead to them being damaged by anchoring, research and pollution from visiting boats.

Looking to the future, there is real concern for all corals in the Great Barrier Reef due to threats such as climate change, declining water quality, overfishing and coastal development. We recommend monitoring of Muga dhambi in case restoration is needed in future.

We hope our research will mean current and future generations care for this wonder of nature, and respect the connections of Manbarra Traditional Owners to their Sea Country.

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Adam Smith, Adjunct Associate Professor, James Cook University; Nathan Cook, Marine Scientist , James Cook University, and Vicki Saylor, Manbarra Traditional Owner, Indigenous Knowledge

August 20 2021

This article is republished from The Conversation under a Creative Commons license.