Research Highlights

A new study led by the University of Hawai‘i at Mānoa’s Hawai‘i Institute of Marine Biology (HIMB) revealed that diversity in Hawaiian corals is likely driven by co-evolution between the coral host, the algal symbiont, and the microbial community.

As coral reef ecosystems have rapidly collapsed around the globe over the past few decades, there is widespread concern that corals might not be able to adapt to changing climate conditions, and much of the biodiversity in these ecosystems could be lost before it is studied and understood. Coral reefs are among the most highly biodiverse ecosystems on earth, yet it is not clear what drives speciation and diversification in the ocean, where there are few physical barriers that could separate populations.

The team of researchers used massive amounts of metagenomic sequencing data to try to understand what may be some of the major drivers of adaptation and variation in corals.

“Corals have incredible variation with such a wide range of shapes, sizes, and colors that it’s really hard for even the best trained experts to be able to sort out different species,” said Zac Forsman, lead author of the study and HIMB assistant researcher. “On top of that, some corals lose their algal symbionts, turning stark white or ‘bleached’ and die during marine heatwaves, while a similar looking coral right next to it seems fine. We wanted to try to better understand what might be driving some of this incredible variation that you see on a typical coral reef.”

Read the full story from University of Hawai’i here.

New University of Montana research suggests recurring continent-spanning drought patterns set the tempo for forest recovery from wildfire.

A study published Nov. 9 in the Proceedings of the National Academy of Sciences shows that forest recovery from fire follows a drought seesaw, called a climate dipole, that alternates between the Northwest and the Southwest every few years.

The researchers examined the relationship between this drought seesaw and post-fire regeneration of ponderosa pine across the Interior West of the U.S. They found that severe droughts under climate change are making it increasingly difficult for tree seedlings to regenerate after fire.

"Managers and scientists are increasingly concerned that western forests won't be able to recover from wildfire under hotter and drier conditions," said Caitlin Littlefield, the study's lead author. "Forest recovery hinges on the success of tree seedlings, which are particularly vulnerable to drought. We wanted to explore how patterns in drought variability across the western U.S. affect post-fire tree regeneration to better understand where and when we can predict robust recovery—or lack thereof."

The authors used annual ponderosa pine regeneration data from a previous UM study led by Kimberley Davis, as well as U.S. Forest Service inventory data. They examined the relationship between ponderosa pine regeneration and the dynamics of the dipole.

Read the full story from Phys.org here.

Researchers from around the world, including the University of Montana, have long observed the movements and behavior of animals in the Arctic, but have had difficulty discovering and accessing data. To solve the problem, an international team led by Sarah Davidson, data curator at the Max Planck Institute of Animal Behavior in Radolfzell, Germany, and Gil Bohrer, professor at Ohio State University, established the global data archive for studies of animal migration in the Arctic and sub-Arctic. It currently contains over 200 projects and movement data of more than 8,000 marine and terrestrial animals from 1991 to the present.

The archive, hosted on the Max Planck Institute’s Movebank platform and funded by NASA, helps scientists share their knowledge and collaborate on questions on how animals are responding to a changing Arctic – particularly important because the Arctic region extends around the world. Researchers from more 100 universities, government agencies and conservation groups across 17 countries are involved in the archive.

UM contributors include Professor Mark Hebblewhite, graduate student Stephen Lewis and former postdoctoral researcher Eliezer Gurarie. Their research is part of Hebblewhite’s funded NASA Arctic Boreal Vulnerability Experiment project that studies the effects of rapid climate change on wildlife in the Arctic, with a focus on caribou.

“UM has a long history, pioneered by researcher Steve Running, of understanding consequences of climate change to ecosystems, and this work builds on this important legacy in a region of the world undergoing some of the fastest rates of climate change, fires and impacts on people and nature,” said Hebblewhite, who studies ungulate habitat ecology.

Three recent studies from the archive reveal large-scale patterns in the behaviors of golden eagles, bears, caribou, moose and wolves in the region and illustrate how the archive can be used to recognize larger ecosystem changes. The results were published Nov. 6 in an article in Science, one of world’s premier scientific journals.

Read the full story from University of Montana here.

Fair-weather fliers may be braving stormy weather when love is on the line and on the clock, says new research from the University of Nebraska–Lincoln. Of the billions of birds that migrate annually, punching tickets for the tropics in the fall and northerly latitudes in the spring, the majority take to the skies only after the horizon has consumed the last slice of sun. And with good reason. At night, the flocking migrants often contend with less turbulence and fewer predators. But their nocturnal flight schedules can’t put them beyond the reach of another potential peril: thunderstorms.

Nebraska’s Matthew Van Den Broeke can spot the signatures of those migrating flocks on meteorological radar “pretty much every night” in the spring and fall, he said. A few years ago, the associate professor of Earth and atmospheric sciences realized that a recent advance in radar technology was offering an opportunity to meld his lifelong love of weather with his interest in ecology.

With help from graduate student Timothy Gunkel, Van Den Broeke set out to study how nocturnally migrating birds in eastern Nebraska, southern Indiana and eastern Iowa responded to isolated thunderstorms between 2013 and 2019.

More than 70% of the time in Nebraska and Indiana, meteorological radar revealed that the density of migrating birds was substantially lower in a thunderstorm’s wake — the stretch that the storm had just passed through. Van Den Broeke said the finding suggests that migrating birds in those areas may be going to the ground, or at least under the meteorological radar, to avoid danger when storms are overhead.

When the researchers compared the effect by season, though, they discovered a potentially telling difference: The reduction in density was measurably greater in the fall than the spring.

Read the full story from University of Nebraska-Lincoln here.

University of Arkansas researchers have established a link between climate patterns in the Amazon and large parts of North and South America using their newly developed tree-ring chronology from the Amazon River basin.

The discovery helps researchers better understand large-scale climate extremes and the impact of the El Niño phenomenon.

Tree growth is a well-established climate proxy. By comparing growth rings in Cedrela odorata trees found in the Rio Paru watershed of the eastern Amazon River with hundreds of similar chronologies in North and South America, scientists have shown an inverse relationship in tree growth, and therefore precipitation patterns, between the areas. Drought in the Amazon is correlated with wetness in the southwestern United States, Mexico and Patagonia, and vice versa.

The process is driven by the El Niño phenomenon, which influences surface-level winds along the equator, researchers said. El Niño is the name given to a large-scale irregularly occurring climate pattern associated with unusually warm water in the Pacific Ocean.

“The new Cedrela chronologies from the Amazon, when compared with the hundreds of tree-ring chronologies in temperate North and South America, document this Pan American resonance of climate and ecosystem extremes in the centuries before widespread deforestation or human-caused climate change,” said Dave Stahle, Distinguished Professor of geosciences and first author of a study documenting the findings in the journal Environmental Research Letters.

Read the full story from University of Arkansas here.

As boreal forest wildfires increase in severity and frequency, new patterns of post-fire recovery are emerging. Research led by Jill Johnstone and colleagues at the U.S. National Science Foundation-supported Bonanza Creek Long-term Ecological Research site found that recent wildfires led to changes in tree species dominance that are persisting through post-fire succession in Alaska's boreal forests.

Boreal black spruce forests have historically been sustained by past fire cycles, but early recovery trends from more recent fires suggest that these forests may shift to deciduous or mixed tree species.

Because Alaskan black spruce forests interact with climate in several ways, shifts in tree species could have local and global implications, including changes to carbon and nutrient cycling, fire behavior, permafrost stability, and net ecosystem carbon balance, and thus have the potential to either warm or cool the atmosphere. However, to accurately model the direction and magnitude of the effect of future shifts on climate, scientists need better predictions of where these changes will occur.

To assess whether initial conditions can be used to predict long-term trajectories and to better understand the drivers behind change, Johnstone tracked post-fire succession across 89 boreal forest sites for a span of 13 years following a widespread fire season in interior Alaska.

Recovery patterns observed two years after fires were the strongest predictors of canopy dominance 13 years later. Fire severity interacted with environmental conditions and allowed deciduous tree seedlings, such as aspen and birch, to successfully establish and outgrow black spruce seedlings.

The researchers published their results in Ecosphere.

Read the full story from Phys.org here.

Microplastic fiber pollution in the ocean impacts larval lobsters at each stage of their development, according to new research. A study published in the Marine Pollution Bulletin reports that the fibers affect the animals' feeding and respiration, and they could even prevent some larvae from reaching adulthood.

"In today's ocean, organisms are exposed to so many environmental factors that affect how many make it to the next stage of life," said Paty Matrai, a study author and senior research scientist at Bigelow Laboratory for Ocean Sciences. "Lobsters play a fundamental role in the Gulf of Maine ecosystem as well as the state's economy, and it is important that we understand how pollutants impact their development."

Young lobsters grow to adulthood through four distinct developmental stages, and the researchers found that the physiology of each stage determined how the animals interacted with plastic fibers. The youngest lobsters didn't consume them - but they were plagued by fibers accumulating under the shells that protect their gills. In experiments where the larvae were exposed to high levels of fibers, the youngest larvae were the least likely to survive.

More mobile and agile, the older lobster larvae did not accumulate fibers under their shells - but they did ingest the particles and keep them in their digestive systems. This could be problematic for lobster larvae coming of age in the ocean. Fresh plastics often leach chemicals, and their surfaces can foster potentially toxic sea life.

Read the full story from EurekAlert! here.

Modern humans arrived in the westernmost part of Europe 41,000 – 38,000 years ago, about 5,000 years earlier than previously known, according to Jonathan Haws, Ph.D., professor and chair of the Department of Anthropology at the University of Louisville, and an international team of researchers. The team has revealed the discovery of stone tools used by modern humans dated to the earlier time period in a report published this week in the journal Proceedings of the National Academy of Sciences.

The tools, discovered in a cave named Lapa do Picareiro, located near the Atlantic coast of central Portugal, link the site with similar finds from across Eurasia to the Russian plain. The discovery supports a rapid westward dispersal of modern humans across Eurasia within a few thousand years of their first appearance in southeastern Europe. The tools document the presence of modern humans in westernmost Europe at a time when Neanderthals previously were thought to be present in the region. The finding has important ramifications for understanding the possible interaction between the two human groups and the ultimate disappearance of the Neanderthals.

“The question whether the last surviving Neanderthals in Europe have been replaced or assimilated by incoming modern humans is a long-standing, unsolved issue in paleoanthropology,” said Lukas Friedl, an anthropologist at the University of West Bohemia in Pilsen, Czech Republic, and project co-leader. “The early dates for Aurignacian stone tools at Picareiro likely rule out the possibility that modern humans arrived into the land long devoid of Neanderthals, and that by itself is exciting.”

Read the full story from University of Louisville here.

Scientists have linked sea urchins, otters and climate change to the destruction of reefs in the Aleutian Islands in a new study published in Science. Uncontrolled by sea otters, their natural predator, sea urchins are devouring the massive limestone reefs surrounding the Aleutian Islands — a process exacerbated by climate-driven changes in the marine environment, according to the study.

Brenda Konar, a University of Alaska Fairbanks professor at the College of Fisheries and Ocean Sciences and a co-author of the study, began diving in the Aleutians in the 1990s, just as the Aleutian sea otter population began to crash from killer whale predation. With otters gone, the urchin population boomed both in body size and density. They began eating more kelp, which grows on the reefs.

“In the past, there would be huge, vast kelp forests that went on for miles,” Konar said. “Now there are carpets of sea urchins everywhere — some places easily have 400 urchins per square meter. Kelp forests are essentially gone in the central and western Aleutians.” The Aleutian reefs and their kelp beds serve as nursery grounds for cod and other fish. The 1,200-mile archipelago helps support the annual multibillion-dollar Bristol Bay and Bering Sea fisheries.

Read the full story form University of Alaska Fairbanks here.

University of Montana scientists examined where high-severity wildfires – combined with hot, dry conditions following fire – are likely to cause shifts from ponderosa pine and Douglas-fir forests to different types of vegetation across the species’ range from Montana to New Mexico. They predict 16% of ponderosa pine and 10% of Douglas-fir forests in the Rocky Mountains could be lost by roughly 2050 due to the combination of high-severity fire and climate change. Their new study, “Fire-catalyzed Vegetation Shifts in Ponderosa Pine and Douglas-fir Forests of the Western United States,” was published Sept. 18 in the academic journal Environmental Research Letters.

“Forests in the West are increasingly affected by wildfire and climate change, and there is concern that this combination may lead to the loss of forests,” said Kimberley Davis, a research scientist in UM’s W.A. Franke College of Forestry and Conservation and the study’s lead author. “Forests may not return after wildfires if two things occur. First, there needs to be a high severity fire that kills adult trees. Second, there needs to be a failure of tree regeneration following the fire.”

If this combination occurs, and trees don’t regenerate, land cover will shift from ponderosa pine and Douglas-fir forests to shrubland, grassland or other forest types. To predict where such shifts are most likely, the authors compared projections of areas most likely to burn at high severity with projections of where the climate may be too hot and dry for trees to regenerate after fires.

“We know that ponderosa pine and Douglas-fir regeneration after wildfires is sensitive to seasonal climate conditions and that conditions are already too hot and dry for regeneration at some of our study sites,” Davis said. “We did not know how widespread these limiting climate conditions were and how that may change in the future.”

The researchers found that the area that can support tree regeneration has declined significantly since the 1980s, and they expect that trend to continue in the near-term future.

Read the full story from University of Montana here.