A new paper now extends the estimate of Arctic sea ice volume back more than a century, to 1901. To do so it used both modern-day computer simulations and historic observations, some written by hand in the early 1900s aboard precursors to today’s U.S. Coast Guard ships.

“This extends the record of sea ice thickness variability from 40 years to 110 years, which allows us to put more recent variability and ice loss in perspective,” said Axel Schweiger, a sea ice scientist at the UW’s Applied Physics Laboratory and first author of the study published in the August issue of the Journal of Climate.

“The volume of sea ice in the Arctic Ocean today and the current rate of loss are unprecedented in the 110-year record,” he added.

PIOMAS provides a daily reconstruction of what’s happening to the total volume of sea ice across the Arctic Ocean. It combines weather records and satellite images of ice coverage to compute ice volume. It then verifies its results against any existing thickness observations. For years after 1950, that might be fixed instruments, direct measurements or submarines that cruise below the ice.

During the early 20th century, the rare direct observations of sea ice were done by U.S. Revenue cutters, the precursor to the Coast Guard, and Navy ships that have cruised through the Arctic each year since 1879. In the Old Weather project, the UW, the National Oceanic and Atmospheric Administration and the National Archives have been working with citizen scientists to transcribe the weather entries in digitized historic U.S. ships’ logbooks to recover unique climate records for science. The new study is the first to use the logbooks’ observations of sea ice.

“In the logbooks, officers always describe the operating conditions that they were in, providing hourly observations of the sea ice at that time and place,” said co-author Kevin Wood, a researcher at the Joint Institute for the Study of the Atmosphere and Ocean. If the ship was in open water, the logbook might read “steaming full ahead” or “underway.” When the ship encountered ice, officers might write “steering various courses and speeds” meaning the ship was sailing through a field of ice floes. When they found themselves trapped in the ice pack, the log might read “beset.”

These logbooks until recently could only be viewed at the National Archives in Washington, D.C., but through digital imaging and transcription by Old Weather citizen-scientists these rare observations of weather and sea ice conditions in the Arctic in the late 1800s and early 1900s have been made available to scientists and the public.

“These are unique historic observations that can help us to understand the rapid changes that are taking place in the Arctic today,” Wood said.

Wood leads the U.S. portion of the Old Weather project, which originated in 2010 in the U.K. The weather observations from historic logbooks transcribed by Old Weather citizen scientists have already been added to international databases of climate data and were used in the model of the atmosphere that produced the new results.

Officers recorded the ship’s position at noon each day using a sextant. They would also note when they passed recognizable features, allowing researchers today to fully reconstruct the ship’s route to locate it in space and time.

While the historic sea ice observations have not yet been incorporated directly into the ice model, spot checks between the model and the early observations confirm the validity of the tool.

“This is independent verification that the model is doing the right thing,” Schweiger said.

The new, longer record provides more context for big storms or other unusual events and a new way to study the Arctic Ocean sea ice system.

“The observations that we have for sea ice thickness and variability are so limited,” Schweiger said. “I think people will start analyzing this record. There’s a host of questions that people can ask to help understand Arctic sea ice and predict is future.”

The PIOMAS tool is widely used by scientists to monitor the current state of Arctic sea ice. The area of Arctic sea ice over the month of June 2019, and the PIOMAS-calculated volume, were the second-lowest for that time of year since the satellite record began.

The lowest-ever recorded Arctic sea ice area and volume occurred in September 2012. And while Schweiger believes the long-term trend will be downward, he’s not placing bets on this year setting a new record.

“The state of the sea ice right now is set up for new lows, but whether it will happen or not depends on the weather over the next two months,” Schweiger said.

The other co-author is Jinlun Zhang at the UW Applied Physics Laboratory. The research was funded by the National Science Foundation, NASA, and the North Pacific Research Board.

Freshwater megafauna include all freshwater animals that weigh 30 kilograms or more, such as species of river dolphins, beavers, crocodiles, giant turtles and sturgeons. The scientists compiled available time series data for 126 freshwater megafauna species worldwide, as well as the historical and contemporary geographic distribution data of 44 species in Europe and the USA.

“The results are alarming and confirm the fears of scientists involved in studying and protecting freshwater biodiversity,” says Sonja Jähnig, senior author of the study and expert for global change effects on river ecosystems at IGB. From 1970 to 2012, global populations of freshwater megafauna declined by 88 percent, most notably in the Indomalaya (by 99 percent) and Palearctic (by 97 percent) realms — the former covering South and Southeast Asia and southern China, and the latter covering Europe, North Africa and most of Asia. Large fish species such as sturgeons, salmonids and giant catfishes are particularly threatened: with a 94 percent decline, followed by reptiles with 72 percent.

Two main threats: overexploitation and loss of free-flowing rivers

Overexploitation is the primary threat to freshwater megafauna as they are often targeted for meat, skin and eggs. “Furthermore, the decline of large fish species is also attributed to the loss of free-flowing rivers as access to spawning and feeding grounds are often blocked by dams. Although the world’s large rivers have already been highly fragmented, another 3700 large dams are planned or under construction — this will exacerbate the river fragmentation even further. More than 800 of these planned dams are located in diversity hotspots of freshwater megafauna, including Amazon, Congo, Mekong and Ganges river basins,” says Fengzhi He, first author of the study and expert for diversity patterns and conservation of freshwater megafauna at IGB.

Successful conservation: sturgeons, beavers and the Irrawaddy river dolphin

Thanks to targeted conservation actions, populations of 13 megafauna species including the green sturgeon (Acipenser medirostris) and the American beaver (Castor canadensis) have been stable or even increasing in the USA. In Asia, the population of the Irrawaddy river dolphin (Orcaella brevirostris) in the Mekong basin has increased for the first time in twenty years. In Europe, efficient and large-scale conservation strategies seem to be more difficult to implement, arguably due to politic boarders and differences in environmental awareness among countries. Nevertheless, the Eurasian beaver (Castor fiber), for example, has now been reintroduced to many regions where it was extirpated. In Germany, IGB is working with international partners to reintroduce the two formerly native sturgeon species European sturgeon (Acipenser sturio) and Atlantic sturgeon (Acipenser oxyrinchus) to European waters.

Room for improvement: monitoring and conservation of freshwater biodiversity

Despite that freshwater megafauna are highly threatened, current conservation actions are inadequate for many species. “According to the International Union for Conservation of Nature’s Red List of Threatened Species, over half of all assessed freshwater megafauna species are considered as threatened with extinction. Nonetheless, they receive less research and conservation attention than megafauna in terrestrial or marine ecosystems,” reminds Jähnig. The now quantified global decline of freshwater megafauna highlights the urgent need for conservation actions for freshwater biodiversity. It is important to improve the monitoring of population trends and distributions of freshwater species in regions such as Southeast Asia, Africa and South America. After all, changes in abundance and distribution are better indicators of the condition of ecosystems and their living organisms than the extinction of species.

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In a study examining pests of tobacco plants and opportunistic insects that eat the pests, researchers show that sticky glandular trichomes on tobacco leaves trap insects that aren’t adapted to interacting with perilous plant surfaces. The trapped insects perish and then become food for the spined stilt bug (Jalysus wickhami) — a small but long-legged insect predator that has a beneficial relationship with tobacco plants.

Tobacco plants provide a trapped-insect buffet that spined stilt bugs are more than happy to feast upon, which helps protect the plant from pest infestation and damage. Better still, the spined stilt bug — which uses its long legs as leverage to navigate across the sticky parts of tobacco leaves to reach its bug banquet — isn’t harmful to tobacco plants, researchers say, although it drinks some sap from tobacco plants to stay hydrated between pest meals.

“A sticky plant isn’t a dead end for all insects; some actually prefer sticky plants and take advantage of the difficult plant surface,” said Peter Nelson, an NC State Ph.D. graduate and lead author of a paper describing the study.

“By taking a closer look at how insects interact with plants, we might be able to take advantage of unique interactions for pest management,” Nelson added. “Our review of the literature found that over 25 economically important plants have sticky surfaces that trap insects and might benefit from the same type of interaction with predatory arthropods.”

“This is a mutualistic relationship previously unrecognized on domesticated tobacco plants,” said Clyde Sorenson, Alumni Association Distinguished Undergraduate Professor of Entomology at NC State and corresponding author of the paper. “The academic literature shows a number of wild flowers with similar symbiotic relationships with predators to reduce damage to the plant, but tobacco is the first economically important plant to show this mutualistic relationship.”

In the study, the abundance of spined stilt bugs grew when researchers added dead fruit flies (Drosophila melanogaster) to the leaves of tobacco plants in greenhouse and field settings. Increased leaf yield — the primary economic consideration for tobacco farmers — and less damage to tobacco plant structures resulted when additional fruit flies were added to leaves.

The study also showed that insecticide use did not affect pest entrapment by sticky glandular trichomes. Plants treated with imidacloprid, a common tobacco insecticide, had fewer spined stilt bugs than untreated plants, but that did not significantly affect pest densities or plant health.

Surprisingly, the study showed that densities of pests like the tobacco budworm on tobacco leaves did not decrease, even though more spined stilt bugs were present.

“We’re not completely sure about why this counterintuitive finding occurred, although one hypothesis is that the increased number of predator stilt bugs may trigger a behavioral response in the tobacco budworm and other pests to feed less on tobacco plants,” Sorenson said.

Sorenson said the results could lead to further improvement or manipulation of glandular trichomes.

“We don’t expect farmers to throw dead fruit flies on 40 acres of a tobacco crop, but recognizing the effects of beneficial insects and how these mutually beneficial relationships work is important,” he said. “Plus, these types of effects may occur in other economically important crops with glandular trichomes, like tomatoes.”

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