Weekly round-up: June 20

Eurasian jays were responsible for the spreading of acorns in areas of regenerated woodland

Rewilding is an often controversial topic among British farmers, landowners and conservationists, but while the debate continues, Eurasian jays, thrushes, mice and squirrels have been busy regenerating woodland themselves.

A study of two abandoned fields in Cambridgeshire revealed rapid growth of woodland over 24 and 59 years, with the presence of seed-caching and berry-eating species essential for the distribution of shrub and tree seeds across the area, a phenomenon known as “passive rewilding”.

The younger area, a former grassland known as “New Wilderness”, had flourished into a rich shrubland, with 132 trees per hectare. The “Old Wilderness”, a former arable field abandoned in 1961, had grown into a mature woodland with 390 trees per hectare.

In both areas, more than half of the trees are oaks – jays are most likely responsible for the transporting and burying of acorns in the area, followed by squirrels. 

Lead-author Dr Richard Broughton of the UK Centre for Ecology and Hydrology said: “Biodiversity-rich woodland that is resilient to drought and reduces disease risk can be created without any input from us. Our study provides essential evidence that passive rewilding has the potential to expand native woodland habitat at no cost and within relatively short timescales. 

“Natural colonisation could play a significant role in helping to meet the UK’s ambitious targets for woodland creation, as well as nature recovery and net zero greenhouse gas emissions by 2050. It is an effective option for expanding woodland in many places without the costs of planting, the disease risk of transporting nursery-grown saplings, or using plastic tree tubes that are unsightly and pollute the environment.”
Publication PLoS One

Bycatch is a global risk to dolphins and other marine mammals

Dolphins and porpoises are most at risk of bycatch in low- and middle-income regions around the tropics and sub-tropics, according to a new study.

Bycatch – the accidental death of individuals in fishing nets intended for other species – is a major threat to marine life across the globe.

A team from Newcastle University assessed the risks to all 72 species of toothed whale species posed by small-scale fisheries and found the highest risks to cetaceans in the Central Indo-Pacific, Temperate Northern Pacific, Temperate South America and the Western Indo-Pacific.

“Small-scale fisheries are a particular threat to species found in coastal shallow waters where dolphin and porpoise distribution overlaps with gillnet use,” said co-author Professor Per Berggren. “Our results suggest that some of the most at-risk species are the four species of humpback dolphins, Irrawaddy dolphin, Australian snubfin dolphin, Franciscana dolphin, Guiana dolphin, Indo-Pacific finless porpoise, and the likely soon to be extinct vaquita.”

However, the authors also note the results highlight a “wicked problem”. The fisheries involved are vital for the food provision and economic security of many of the communities in the high-risk regions, so conservation methods that do not impact on fishers’ ability to work must be implemented.

Co-author Dr Andrew Temple added: “Managers of these fisheries have to carefully balance the actions required to save these species against the risks that these actions might result in unintentional harm to fishing communities that rely on the oceans for their livelihoods. Solving this “wicked problem” is made even more challenging because funds available to fisheries managers are generally more limited in these high-risk regions, making effective fisheries management extremely difficult.”
Publication Fish and Fisheries

Herring gull eggs have been found to contain up to six different phthalates

A cocktail of chemicals used in plastic production have been found in herring gull eggs from across Cornwall.

In a joint study by Exeter University and the University of Queensland, researchers looked for the presence of phthalates – chemicals used to keep plastics flexible – and found up to six different types in newly-laid eggs.

Phthalates are known to be pro-oxidants, which can damage cells through oxidative stress. Eggs naturally contain vitamin E to help protect chicks from the phenomenon during development and hatching, but those containing a higher concentration of phthalates showed lower levels of vitamin E.

Contaminated eggs also showed higher levels of damage to the lipids needed to nourish embryos during development. 

“Research on the impact of plastic on animals has largely focussed on entanglement and ingestion of plastic fragments,” said co-author Professor Blount, from Exeter University. “Far less is known about the impacts of plastic additives on the body. By testing eggs, our study gives us a snapshot of the mother’s health – and it appears phthalate contamination could be associated with increased oxidative stress, and mothers transfer this cost to their offspring via the egg. 

“More research is now needed to discover how developing offspring are affected by being exposed to phthalates before they have even emerged as a hatchling.”
Publication Marine Pollution Bulletin

A new conservation partnership is bidding to tackle the world’s biodiversity crisis by harnessing the latest DNA technology to map the range and distribution of fish, amphibians, birds and land mammals in the world’s major freshwater ecosystems.

The International Union for the Conservation of Nature has teamed up with NatureMetrics to launch the eBioAtlas programme, a global central database built using measures of environmental DNA – eDNA – taken from water samples in biodiverse but at-risk regions such the Amazon, Ganges, Mekong Delta and Niger Delta.

eDNA is extracted from all the signs of life left behind by individuals, such as skin cells, saliva, faeces and mucus. Using kits from NatureMetrics which require only a small filter to extract traces of DNA, more than 1,000 locals from the areas in focus will be trained to carry out sampling. It is expected that over the first three years around 30,000 samples will be collected and tested. 

The team hopes that a clearer picture of the range of species within each area will help raise conservation funding, while a better understanding of each ecosystem is essential for more targeted and measurable action in combating biodiversity loss.

“eDNA is a game changer because it allows surveys to be done much faster and it has the potential to pick up much more information than through conventional sampling,” said Will Darwall, head of IUCN’s Freshwater Biodiversity Unit. 

“A third of the world’s freshwater fish are threatened. If nothing changes in the way we manage freshwater environments these species are headed for extinction. We need a full-scale bio-blitz using eDNA to rapidly get new and updated information about where freshwater fish live all over the world so we can bring it into the mainstream of conservation and environmental management and policy efforts.”
Source IUCN/NatureMetrics

The coconut rhinoceros beetle (Arian Suresh)

A tropical crop-destroying beetle thought to have been controlled by the introduction of a virus is surging through Pacific islands and edging towards Australia.

The coconut rhinoceros beetle, native to south-east Asia, feeds on coconut palms, banana plants, sugarcane, pineapples and date palms, often killing the entire tree. In the 1970s, populations were limited by the introduction of a virus from Malaysia, but in recent years the beetle has been unencumbered by the disease and spread across Fiji, New Caledonia, Papua New Guinea, Samoa, Solomon Islands, Tonga, Vanuatu and the Philippines in three waves, causing agricultural and economic damage.

“The coconut rhinoceros beetle remains a serious threat to livelihoods across Pacific islands, where the coconut tree remains their ‘tree of life’, providing essential resources like food, copra, building materials and coastal protection for five million vulnerable people,” said University of Queensland researcher Dr Kayvan Etebari. “If they spread to Australia, garden palms would be at risk, along with the country’s emerging date industry, coconuts, oil palms, and many other palms, both wild in the forests and ornamental.”

“It’s imperative that Australian scientists help our neighbouring countries in the Pacific to tackle their emerging pests and diseases. Everything we’re finding in the Pacific islands may later be critical to managing the beetle here in Australia.”
Source University of Queensland

Pelicans are a familiar sight along the California coast (Shauna Fletcher)

A spate of attacks over eight months in the Los Angeles area has left more than 30 brown pelicans mutilated. Twenty two of the birds suffered compound fractures to their wings, meaning the bone breaks through the skin. Only ten individuals have survived.

In a statement, the Huntington Beach Wetlands and Wildlife Care Center, which treated the birds, said: “Someone is intentionally breaking brown pelicans’ wings. Over 32 brown pelicans have been mutilated between San Clemente and Huntington Beach. We need your help to find whomever is performing this atrocious act.”

Dr Elizabeth Wood, an orthopaedic surgeon at the centre, added: “These are very serious injuries that require emergency surgeries and long term care.”

Brown pelicans, a familiar sight in California, were almost driven to extinction in the middle of last century due to pollutants, including DDT. There are now thought to be more than 70,000 nesting pairs in the state.
Source Huntington Beach Wetlands and Wildlife Care Center

Read The whale sentinel: two decades of watching humpback numbers boom 

Watch Tuesday is World Rainforest Day – learn more about these amazing ecosystems with Rainforests 101 from National Geographic

%d bloggers like this: