Plastic in the ocean kills more threatened albatrosses than we thought


Lauren Roman, Author provided

Richelle Butcher, Massey University; Britta Denise Hardesty, CSIRO, and Lauren Roman, CSIRO

Plastic in the ocean can be deadly for marine wildlife and seabirds around the globe, but our latest study shows single-use plastics are a bigger threat to endangered albatrosses in the southern hemisphere than we previously thought.

You may have heard of the Great Pacific garbage patch in the northern Pacific, but plastic pollution in the southern hemisphere’s oceans has increased by orders of magnitude in recent years.

We examined the causes of death of 107 albatrosses received by wildlife hospitals and pathology services in Australia and New Zealand and found ocean plastic is an underestimated threat.

Plastic drink bottles, disposable utensils and balloons are among the most deadly items.

Albatrosses are some the world’s most imperiled seabirds, with 73% of species threatened with extinction. Most species live in the southern hemisphere.

We estimate plastic ingestion causes up to 17.5% of near-shore albatross deaths in the southern hemisphere and should be considered a substantial threat to albatross populations.




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Magnificent ocean wanderers

Albatrosses spend their entire lives at sea and can live for more than 70 years. They return to land only to reunite with their mate and raise a single chick during the warmer months.

Although the world’s largest flying birds are rarely seen from land, human activities are driving nearly three quarters of albatross species to extinction.

An albatross flying across the ocean.
The great albatrosses are the largest flying birds in the world, circumnavigating the southern oceans in search of food.
Lauren Roman, Author provided

Each year, thousands of albatrosses are caught as unintended bycatch and killed by fishing boats. Introduced rats and mice eat their chicks alive on remote islands and the ocean where they spend their lives is becoming increasingly warmer and filled with plastic.

Young Laysan albatrosses with their bellies full of plastic are not just a tragic tale from the remote northern Pacific. Albatrosses are dying from plastic in the southern oceans, too.

When a Royal albatross recently died in care at Wildbase Hospital after eating a plastic bottle, it was not an isolated incident.

Single-use plastics hit albatrosses close to home

A veterinarian treating a light-mantled albatross
Veterinarian Baukje Lenting treating a light-mantled albatross at The Nest Te Kōhanga at Wellington Zoo.
Wellington Zoo, Author provided

Eighteen of the world’s 22 albatross species live in the southern hemisphere, where plastic is currently considered a lesser threat. But the amount of discarded plastic is increasing every year, mostly leaked from towns and cities and accumulating near the shore.

Single-use items make up most of the trash found on coastlines around the world. Seven of the ten most common items — drink bottles, food wrappers and grocery bags — are made of plastic.

When albatrosses are found struggling near the shore in New Zealand, they are delivered to wildlife hospitals such as Wildbase Hospital and The Nest Te Kōhanga. A recent spate of plastic-linked deaths spurred us to dig a little deeper into the risk of plastic pollution to these magnificent ocean wanderers.

A thousand cuts: plastic and other threats

Of the 107 albatrosses of 12 species we examined, plastic was the cause of death in half of the birds that had ingested it. In the cases we examined, plastic deaths were more common than fisheries-related deaths or oiling.

We compared these cases with data on plastic ingestion and fishery interaction rates from other studies. Based on our findings, we used statistical methods to estimate how many albatrosses were likely to eat plastic and might die from ingesting it, and how these figures compared to other major threats such as fisheries bycatch.

We found that in the near-shore areas of Australia and New Zealand, the ingestion of plastic is likely to cause about 3.4% of albatross deaths. In more polluted near-shore areas, such as those off Brazil, we estimate plastic ingestion causes 17.5% of all albatross deaths.




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Because albatrosses are highly migratory, even those birds that live in less polluted areas are at risk as they wander the global ocean, travelling to polluted waters. Our results suggest the ingestion of plastic is at least of equivalent concern as long-line fishing in near-shore areas.

For threatened and declining albatross species, these rates of additional mortality are a serious concern and could result in further population losses.

Deadly junk food for marine life

Balloon fragments found in the stomach on an endangered albatross
The remains of two balloons in the stomach of an endangered grey-headed albatross.
Lauren Roman, Author provided

Not all types of plastic are equally deadly when eaten. Albatrosses can regurgitate many of the indigestible items they eat.

Soft plastic and rubber items (such as latex balloons), in particular, can be deadly for marine animals because they often become trapped in the gut and cause fatal blockages, leading to a long, slow death by starvation. Plastic is difficult to see with common scanning techniques, and gut blockages often remain undetected.

A plastic bottle found in the stomach of an albatross
A 500ml plastic bottle and balloon fragments were found in the stomach of a southern royal albatross which died in care at Wildbase Hospital.
Stuart Hunter, Author provided

Albatrosses like to eat squid, and inexperienced young birds are especially prone to mistaking balloons and other plastic for food, with potentially lethal consequences.

We recommend that wildlife hospitals, carers and biologists consider gastric obstruction when sick albatrosses are presented. Our publication includes a checklist to help in the detection of gastric blockages.

Global cooperation to reduce leakage of plastic items into the ocean — such as the Basel Convention and the recommendations by the High Level Panel for a Sustainable Ocean Economy — are first steps towards preventing unnecessary deaths of marine animals.




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Stronger adherence to multilateral agreements, such as the Agreement on the Conservation of Albatrosses and Petrels which aims to reduce the impact of activities known to kill albatrosses, would help prevent the decline of breeding populations to unsustainably low levels.

If populations fall to critically endangered levels, intensive remediation including the expansion of chick and nest protection programmes, invasive species eradication and seabird translocations, may be required to prevent species extinction.


We would like to acknowledge our New Zealand and Australian colleagues who contributed to this research project. Veterinarians Baukje Lenting and Phil Kowalski care for injured seabirds and other wildlife at The Nest Te Kōhanga at Wellington Zoo. Veterinarian Megan Jolly cares for injured wildlife at Wildbase Hospital and vet pathologist Stuart Hunter provides a nationwide wildlife pathology service at Wildbase pathology at Massey University. David Stewart conducts threatened species research and monitoring at the Queensland state government’s Department of Environment and Science.The Conversation

Richelle Butcher, Veterinary Resident at Wildbase, Massey University; Britta Denise Hardesty, Principal Research Scientist, Oceans and Atmosphere Flagship, CSIRO, and Lauren Roman, Postdoctoral Researcher, Oceans and Atmosphere, CSIRO

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

We tested tiger snake scales to measure wetland pollution in Perth. The news is worse than expected


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Damian Lettoof, Curtin University; Kai Rankenburg, Curtin University; Monique Gagnon, Curtin University, and Noreen Evans, Curtin University

Australia’s wetlands are home to a huge range of stunning flora and fauna, with large snakes often at the top of the food chain.

Many wetlands are located near urban areas. This makes them particularly susceptible to contamination as stormwater, urban drainage and groundwater can wash metals — such as arsenic, cadmium, lead and mercury — into the delicate ecosystem.

We know many metals can travel up the food chain when they’re present in the environment. So to assess contamination levels, we caught highly venomous tiger snakes across wetlands in Perth, and repurposed laser technology to measure the metals they accumulated.

In our new paper, we show metal contamination in wild wetland tiger snakes is chronic, and highest in human-disturbed wetlands. This suggests all other plants and animals in these wetlands are likely contaminated as well.

34 times more arsenic in wild wetland snakes than captive snakes

Urban growth and landscape modification often introduces metals into the surrounding environment, such as mining, landfill and waste dumps, vehicles and roadworks, and agriculture.

When they reach wetlands, sediments collect and store these metals for hundreds of years. And if a wetland’s natural water levels are lowered, from agricultural draining for example, sediments can become exposed and erode. This releases the metals they’ve been storing into the ecosystem.

A reflective lake, with green vegetation surrounding it
The wetland in Yanchep National Park, Perth, was supposed to be our ‘clean’ comparison site. Its levels of metal contamination was unprecedented.
Shutterstock

This is what we suspect happened in Yanchep National Park’s wetland, which was supposed to be our “clean” comparison site to more urban wetlands. But in a 2020 study looking at sediment contamination, we found this wetland had higher levels of selenium, mercury, chromium and cadmium compared to urban wetlands we tested.

And at Herdsman Lake, our most urban wetland five minutes from the Perth city centre, we found concentrations of arsenic, lead, copper and zinc in sediment up to four times higher than government guidelines.




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In our new study on tiger snake scales, we compared the metal concentrations in wild wetland tiger snakes to the concentrations that naturally occurs in captive-bred tiger snakes, and to the sediment in the previous study.

We found arsenic was 20-34 times higher in wild snakes from Herdsman Lake and Yanchep National Park’s wetland. And snakes from Herdsman Lake had, on average, eight times the amount of uranium in their scales compared to their captive-bred counterparts.

Tiger snake on the ground, near rubbish.
Our research confirmed snake scales are a good indicator of environmental contamination.
Damian Lettoof, Author provided

Tiger snakes usually prey on frogs, so our results suggest frogs at these lakes are equally as contaminated.

We know for many organisms, exposure to a high concentration of metals is fatally toxic. And when contamination is chronic, it can be “neurotoxic”. This can, for example, change an organism’s behaviour so they eat less, or don’t want to breed. It can also interfere with their normal cellular function, compromising immune systems, DNA repair or reproductive processes, to name a few.

Snakes in general appear relatively resistant to the toxic effects of metal contamination, but we’re currently investigating what these levels of contamination are doing to tiger snakes’ health and well-being.

Our method keeps snakes alive

Snakes can be a great indicator of environmental contamination because they generally live for a long time (over 10 years) and don’t travel too far from home. So by measuring metals in older snakes, we can assess the contamination history of the area they were collected from.

Typically, scientists use liver tissue to measure biological contamination since it acts like a filter and retains a substantial amount of the contaminants an animal is exposed to.

But a big problem with testing the liver is the animal usually has to be sacrificed. This is often not possible when studying threatened species, monitoring populations or working with top predators.

Two black swans in a lake, near cut grass
Sediment in Herdsman Lake had four times higher heavy metal levels than what government guidelines allow.
Shutterstock

In more recent years, studies have taken to measuring metals in external “keratin” tissues instead, which include bird feathers, mammal hair and nails, and reptile scales. As it grows, keratin can accumulate metals from inside the body, and scientists can measure this without needing to kill the animal.

Our research used “laser ablation” analysis, which involves firing a focused laser beam at a solid sample to create a small crater or trench. Material is excavated from the crater and sent to a mass spectrometer (analytical machine) where all the elements are measured.

This technology was originally designed for geologists to analyse rocks, but we’re among the first researchers applying it to snake scales.

Laser ablation atomises the keratin of snake scales, and allowed us to accurately measure 19 contaminants from each tiger snake caught over three years around different wetlands.

Wild tiger snake
Snakes generally appear resistant to the toxic effects of heavy metals.
Kristian Bell/Shutterstock

We need to minimise pollution

Our research has confirmed snake scales are a good indicator of environmental contamination, but this is only the first step.

Further research could allow us to better use laser ablation as a cost-effective technology to measure a larger suite of metals in different parts of the ecosystem, such as in different animals at varying levels in the food chain.

This could map how metals move throughout the ecosystem and help determine whether the health of snakes (and other top predators) is actually at risk by these metal levels, or if they just passively record the metal concentrations in their environment.




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It’s difficult to prevent contaminants from washing into urban wetlands, but there are a number of things that can help minimise pollution.

This includes industries developing strict spill management requirements, and local and state governments deploying storm-water filters to catch urban waste. Likewise, thick vegetation buffer zones around the wetlands can filter incoming water.The Conversation

Damian Lettoof, PhD Candidate, Curtin University; Kai Rankenburg, Researcher, Curtin University; Monique Gagnon, Researcher, Curtin University, and Noreen Evans, Professor, Curtin University

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