What whales and dolphins can tell us about the health of our oceans

Dolphins contribute important knowledge about ocean health.
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Stephanie Plön, Nelson Mandela University

From the poles to the equator, marine mammals such as seals, dolphins and whales, play an important role in global ecosystems as apex predators, ecosystem engineers and even organic ocean fertilisers. The ocean off the coast of South Africa is home to a high diversity of these mammals and is recognised as a global marine biodiversity hotspot.

Marine mammals are often referred to as “sentinels” of ocean health. Numerous studies have explored the effects of both noise and chemical pollution, habitat degradation, changes in climate and food webs on these marine apex predators. Yet the interplay of these factors isn’t well understood.

Our research on the unfortunate dolphins incidentally caught in shark nets off South Africa’s KwaZulu-Natal coast has helped fill in some of the gaps. By assessing the health of these dolphins we have provided valuable baseline information on conditions affecting coastal dolphin populations in South Africa. This is the first systematic health assessment in incidentally caught dolphins in the Southern Hemisphere.

But to gain a fuller picture of the health of marine mammals in these waters I am now combining this contemporary field research with historical data, like the collection at the Port Elizabeth Museum Bayworld.

The combination of data on diet, reproduction, population structure and health helps us gain a better understanding of the pressures and changes these apex predator populations face. And it helps us understand it in relation to global change, including both climate change and pressures brought about by human behaviour.

My research sheds light on multiple factors: pollutant levels, parasites, and availability of prey, all have an impact on individuals as well as populations.

Understanding the health of these animals also gives us insight into the state of the world’s oceans. This is relevant because oceans affect the entire ecosystem including food security, climate and people’s health. This degree of connectedness is highlighted by recent discoveries about how whales act as ecosystem engineers.

The accumulation of this knowledge is important because the planet’s oceans aren’t being protected. Recent popular documentaries such as “Sonic Sea” and “Plastic Ocean” have highlighted their exploitation and pollution.

What’s missing

Without baseline knowledge it’s challenging to establish the potential effects that new anthropogenic developments (those caused by human behaviour) have on local whale and dolphin populations.

For example, we know that whales are sensitive to shipping noise, so what potential impact could a new deep water port have on mothers and their calves? Could it drive them away from these nursery areas, or could it lead to an increased risk of whales and ships colliding? To answer this and monitor the change that a new port brings with it, we are investigating the soundscape of two bays in the Eastern Cape (one with a new port, one without) in parallel with baleen whale mother-calf behaviour.

Another example is understanding how changes in the Sardine run over the past 15 years have affected the diets of these mammals. The Sardine run is an annual phenomenon when large shoals of Sardine migrate northwards along the coast into KwaZulu-Natal waters to spawn. Using long-term data and samples from the Port Elizabeth Museum research collection, we have been able to establish that over the the past 20 or so years the main predator in the Sardine run – the long-beaked common dolphin – has shifted its diet to mackerel. Although such changes in diet can have potential impacts on the health of the dolphins, parallel investigations on the trophic level these animals feed at (using isotope data from teeth) and the body condition of the dolphins (using long-term data on blubber thickness), indicated no adverse effects to the dolphins.

Our analysis highlights how marine mammals may be used as indicators of environmental change and why research is important.

Finding answers to intricate questions on environmental change is not always easy. But a better understanding and knowledge of the environment these animals live in has to be incorporated into studies contributing to their conservation and management. Such studies are becoming increasingly relevant as they highlight the fast degradation of the marine environment.

For example, a recent study identified antibiotic resistant bacteria in both sea water samples and exhaled breath samples from killer whales. This suggests that the marine environment has been contaminated with human waste which in turn has significant medical implications for humans.

Gaining such information is particularly important given the rapid changes taking place in the oceans, such as those on South Africa’s southern and eastern coastline. This includes increasing coastal development, new deep water ports being built or expanded, and parts of the deep sea being explored for oil and gas.

To assess these changes and what they mean for the environment, baseline studies need to be carried out so that potential effects can be assessed. Whales and dolphins are increasingly being recognised as indicators of ocean health in this endeavour.

And a continuation of the research we did on dolphins caught in nets will help document the cyclic changes that can be seen as normal variation in a population. This could prove important for assessing future catastrophic events, such as the Deep Horizon oil spill.

What next

The oceans absorb over 25% of the world’s carbon pollution as well as heat generated by global warming. They also produce at least 50% of the planet’s oxygen, and are home to 80% of all life on earth. Yet only 5% of this vital component of our planet has been explored.

Research on whales and dolphins contributes important knowledge about ocean health. Historical data increasingly provides a guideline to teasing out natural variations in populations and assessing the contribution that multiple factors have on these animals. In time, this will ensure that policy makers are being given sound scientific information. It will also provide us with a good barometer of the overall health of our oceans.

Stephanie Plön, Researcher, Earth Stewardship Science Research Institute, Nelson Mandela University

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

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What if Antarctica’s dormant, ice-covered volcanoes wake up?

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John Smellie, University of Leicester

Antarctica is a vast icy wasteland covered by the world’s largest ice sheet. This ice sheet contains about 90% of fresh water on the planet. It acts as a massive heat sink and its meltwater drives the world’s oceanic circulation. Its existence is therefore a fundamental part of Earth’s climate.

Less well known is that Antarctica is also host to several active volcanoes, part of a huge “volcanic province” which extends for thousands of kilometres along the western edge of the continent. Although the volcanic province has been known and studied for decades, about 100 “new” volcanoes were recently discovered beneath the ice by scientists who used satellite data and ice-penetrating radar to search for hidden peaks.

Some of the volcanoes known about before the latest discovery.
antarcticglaciers.org, Author provided

These sub-ice volcanoes may be dormant. But what would happen if Antarctica’s volcanoes awoke?

We can get some idea by looking to the past. One of Antarctica’s volcanoes, Mount Takahe, is found close to the remote centre of the West Antarctic Ice Sheet. In a new study, scientists implicate Takahe in a series of eruptions rich in ozone-consuming halogens that occurred about 18,000 years ago. These eruptions, they claim, triggered an ancient ozone hole, warmed the southern hemisphere which caused glaciers to melt, and helped bring the last ice age to a close.

Mt Takahe grew over hundreds of thousands of years and its 8km-wide caldera now towers above the ice sheet.
NASA / Jim Yungel, CC BY-SA

This sort of environmental impact is unusual. For it to happen again would require a series of eruptions, similarly enriched in halogens, from one or more volcanoes that are currently exposed above the ice. Such a scenario is unlikely although, as the Takahe study shows, not impossible. More likely is that one or more of the many subglacial volcanoes, some of which are known to be active, will erupt at some unknown time in the future.

Eruptions below the ice

Because of the enormous thickness of overlying ice, it is unlikely that volcanic gases would make it into the atmosphere. So an eruption wouldn’t have an impact like that postulated for Takahe. However, the volcanoes would melt huge caverns in the base of the ice and create enormous quantities of meltwater. Because the West Antarctic Ice Sheet is wet rather than frozen to its bed – imagine an ice cube on a kitchen work top – the meltwater would act as a lubricant and could cause the overlying ice to slip and move more rapidly. These volcanoes can also stabilise the ice, however, as they give it something to grip onto – imagine that same ice cube snagging onto a lump-shaped object.

In any case, the volume of water that would be generated by even a large volcano is a pinprick compared with the volume of overlying ice. So a single eruption won’t have much effect on the ice flow. What would make a big difference, is if several volcanoes erupt close to or beneath any of West Antarctica’s prominent “ice streams”.

A velocity map of Antarctic ice streams as they move toward the ocean.
NASA/JPL, CC BY-SA

Ice streams are rivers of ice that flow much faster than their surroundings. They are the zones along which most of the ice in Antarctica is delivered to the ocean, and therefore fluctuations in their speed can affect the sea level. If the additional “lubricant” provided by multiple volcanic eruptions was channelled beneath ice streams, the subsequent rapid flow may dump unusual amounts of West Antarctica’s thick interior ice into the ocean, causing sea levels to rise.

Under-ice volcanoes are probably what triggered rapid flow of ancient ice streams into the vast Ross Ice Shelf, Antarctica’s largest ice shelf. Something similar might have occurred about 2,000 years ago with a small volcano in the Hudson Mountains that lie underneath the West Antarctica Ice Sheet – if it erupted again today it could cause the nearby Pine Island Glacier to speed up.

The volcano–ice melt feedback loop

Most dramatically of all, a large series of eruptions could destabilise many more subglacial volcanoes. As volcanoes cool and crystallise, their magma chambers become pressurised and all that prevents the volcanic gases from escaping violently in an eruption is the weight of overlying rock or, in this case, several kilometres of ice. As that ice becomes much thinner, the pressure reduction may trigger eruptions. More eruptions and ice melting would mean even more meltwater being channelled under the ice streams.

Mt Erebus is one of Antarctica’s most active volcanoes. The rocks in the foreground are the remnants of several younger subglacial volcanoes.
antarcticglaciers.org, Author provided

Potentially a runaway effect may take place, with the thinning ice triggering more and more eruptions. Something similar occurred in Iceland, which saw an increase in volcanic eruptions when glaciers began to recede at the end of the last ice age.

So it seems the greatest threat from Antarctica’s many volcanoes will be if several erupt within a few decades of each other. If those volcanoes have already grown above the ice and their gases were rich in halogens then enhanced warming and rapid deglaciation may result. But eruptions probably need to take place repeatedly over many tens to hundreds of years to have a climatic impact.

More likely is the generation of large quantities of meltwater during subglacial eruptions that might lubricate West Antarctica’s ice streams. The eruption of even a single volcano situated strategically close to any of Antarctica’s ice streams can cause significant amounts of ice to be swept into the sea. However, the resulting thinning of the inland ice is also likely to trigger further subglacial eruptions generating meltwater over a wider area and potentially causing a runaway effect on ice flow.

John Smellie, Professor of Volcanology, University of Leicester

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

Money can’t buy me love, but you can put a price on a tree

Mountain ash in the Victorian Central Highlands.
Takver/Flickr, CC BY-SA

Heather Keith, Australian National University; David Lindenmayer, Australian National University, and Michael Vardon, Australian National University

What is something worth? How do you put a dollar value on something like a river, a forest or a reef? When one report announces that the Great Barrier Reef is worth A$56 billion, and another that it’s effectively priceless, what does it mean and can they be reconciled?

This contrast points to fundamentally different notions of value. Environmental accounting is a way of recognising and comparing multiple sources of value, in order to better weigh competing priorities in resource management.

In practice it is sometimes crude, but it’s been standardised internationally and its scope is expanding to include social, cultural, and intrinsic benefits.

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Read more: What’s the economic value of the Great Barrier Reef? It’s priceless

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Using environmental accounting we’ve investigated the tall, wet forests of Victoria’s Central Highlands to weigh the competing economic cases for continuing native timber harvesting and creating a Great Forest National Park. But first we’ll explain a little more about environmental accounting, and how we put a price on trees.

What we count

Essentially, environmental accounting involves identifying the contributions of the environment to the economy, summarised as gross domestic product (GDP). In Australia, the Australian Bureau of Statistics standardises the data and reporting of these contributions in the System of National Accounts. The Bureau also produces environmental accounts that extend the range of information presented – e.g. water and energy use and greenhouse gas emissions.

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Read more: Why we need environmental accounts alongside national accounts

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But there are other things of value, like positive environmental and social outcomes, worth incorporating into calculations. Ecosystem accounting gives researchers a framework for doing this, extending the accounting to look at the value of different “ecosystem services” – the contributions of ecosystems to our wellbeing – and not just goods and services captured in our national accounts or environmental accounts.

For example, businesses and homes pay a price for water delivery, but the supplier doesn’t pay for the water that entered the dam. That water is an ecosystem service created by forests and the atmosphere. By assessing costs in the water supply industry, we can estimate the value of the ecosystem service of water provisioning.

The value of Victoria’s Central Highlands

Victoria’s Central Highlands are contested ground. Claims and counter-claims abound between the proponents of native timber production and those who are concerned about the impacts of logging on water supply, climate abatement and threatened species.

Our research has, for the first time, directly compared the economic and environmental values of this ecosystem. It shows that creating a Great Forest National Park is clearly better value.

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Read more: Why Victoria needs a Giant Forest National Park

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With any change in land management, there will be gains and losses for different people and groups. Assessing these trade-offs is complex, made even more so by patchy and inconsistent data.

Through careful accounting, we synthesised the available data and calculated the annual contributions of industries to GDP. In 2013-14, the latest year for which all financial data were available, these came to A$310 million for water supply, A$312 million for agriculture, A$260 million for tourism and potentially A$49 million for carbon storage. (There is no current market for carbon stored in native forests in Australia – more on that in a minute.)

All of this far exceeds the A$12 million from native timber production. Although timber production is a traditional industry, its contribution to the regional economy is now comparatively small.

The GDP contribution in millions of dollars by primary industries in 2013-14.
Author provided

The industries that use ecosystem services are classified as primary production – agriculture, forestry and water supply. This classification is comprehensive (it covers all economic activities) and mutually exclusive (there is no overlap of categories). Downstream uses of the products from agriculture, forestry and water supply are an important consideration for the industries as a whole, but are included in manufacturing industries and not in ecosystem accounts.

Older forests are more valuable

Native timber production involves clearfell harvesting (removing the majority of trees at the site) and slash burning (using high-intensity fire to burn logging residue and provide an ash bed for regeneration). Regenerating forests are younger, with all trees the same age, and have lower species diversity.

This means these young forests contribute less to biodiversity, carbon storage, water supply and recreation. Therefore harvesting native timber requires a trade-off between these conflicting activities.

Trade-offs between industries in their use of ecosystem services can be complementary (green) or conflicting (red).
Author provided

But more than 60% of the native timber harvested in the Central Highlands is used for pulp. This can be substituted by production from plantations that are more efficient and increased use of recycled paper. Both softwood and hardwood plantations can provide substitute sawlogs.

If we phased out native forest harvesting, increases in the value of water supply and carbon storage would offset the loss of A$12 million per year contributed by the industry. (It would also most likely increase profits for the tourism and plantation timber sectors.)

Older trees use less water than young regrowth, and allowing native forests to age would increase the supply of water to Melbourne’s main reservoirs by an estimated 10.5 gigalitres per year. That’s worth A$8 million per year. Security of water supply for the increasing population of Melbourne is an ever-present concern, particularly with projected decreases in rainfall and streamflow.

Older forests also store more carbon than younger regrowth forests. The federal government’s Emission Reduction Fund does not recognise native forest management as an eligible activity for carbon trading, but if this changed the forest could earn carbon credits worth A$13 million per year. This would provide an ongoing and low-cost source of carbon abatement, which could be used to meet Australia’s emissions reduction targets, while the Victorian government could use the money gained to support an industry transition.

Of course, economic benefit is only one way of looking at land. We know that the Central Highlands is home to unique flora and fauna that cannot be replaced (much of which is increasingly under threat). But careful environmental accounting can help explicitly define the various trade-offs of different activities.

It’s particularly important when legacy industries – like native timber harvesting – are no longer environmentally or economically viable. The accounting reveals the current mix of benefits and costs, allowing management of this area to be reconsidered.

Heather Keith, Research Fellow in Ecology, Australian National University; David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National University, and Michael Vardon, Visiting Fellow at the Fenner School, Australian National University

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