Past Migration, Pleistocene Ice Ages Still Impact Size and Structure of Modern Eelgrass Communities

by Kristen Goodhue

Deep evolution casts a longer shadow than previously thought, scientists report in a new paper published Aug. 1 in the Proceedings of the National Academy of Sciences. Smithsonian scientists and colleagues looked at eelgrass communities—the foundation of many coastal marine food webs along the north Atlantic and Pacific coasts—and discovered their ancient genetic history can play a stronger role than the present-day environment in determining their size, structure and who lives in them. And this could have implications for how well eelgrasses adapt to threats like climate change.

About a half-million years ago, when the world was warmer, some eelgrasses made the difficult journey from their homes in the Pacific to the Atlantic. Not all the plants were hardy enough to make the journey across the Arctic. For those that succeeded, a series of ice ages during the Pleistocene Epoch further affected how far they could spread. Those millennia-old struggles left lasting signatures in their DNA. Even today, eelgrass populations in the Atlantic are far less genetically diverse than those in the Pacific. 

Still, in the classic “nature versus nurture” debate, scientists were stunned to discover that genetic legacy sometimes does more to shape modern eelgrass communities than the current environment.

The Smithsonian’s Oldest In-Place Building Opens to Visitors for the First Time

by Kristen Goodhue

This summer, a new history exhibit opens in the brick house at the entrance of the Smithsonian Environmental Research Center (SERC): the Woodlawn History Center. Built in 1735, Woodlawn is the oldest Smithsonian building still in its original location. Visitors will hear stories from generations who lived and worked on the land, and see how their lives wove into the American tapestry.

For nearly two centuries, Woodlawn served as the plantation home of the Sellman family. Coming to America in indentured servitude, the Sellmans left a double-sided legacy as soldiers, innovators and slaveowners. Their descendants, who spread across the country, fought on both sides of the Civil War.

Marine Predation Intensifies in Warmer Waters; Could Reshape Ocean Communities as Climate Changes

by Kristen Goodhue

_{Triggerfish and pufferfish consume marine invertebrates on a panel exposed to predators in Panama City. Scientists deployed this panel during a previous experiment using similar communities to the ones in the current study. (Credit: Edited by Michele Repetto. Footage from Freestone et al. 2021 Archives)}

A hotter ocean is a hungrier ocean—at least as far as fish predators are concerned. In a new field study published online June 9 in Science, Smithsonian scientists discovered predator impacts in the Atlantic and Pacific peak at higher temperatures. The effects cascade down to transform other life in the ocean, potentially disrupting balances that have existed for millennia.

“It’s taken thousands of years to get to this state, and then suddenly we’re ramping up the temperature at a much higher rate,” said Gail Ashton, lead author of the report and marine biologist with the Smithsonian Environmental Research Center (SERC). “And we don’t really know the implications of that temperature increase.”

Beneficial Effects of Rising CO₂ for Plants Disappear Under Flooding, 33-Year Field Experiment Reveals

by Kristen Goodhue

Wetlands across the globe are in danger of drowning from rising seas. But for decades, scientists held out hope that another aspect of climate change—rising carbon dioxide (CO₂)—could trigger extra plant growth, enabling coastal wetlands to grow fast enough to outpace sea-level rise. That helpful side effect is disappearing, they discovered in a new study published May 18.

Rainforest Trees May Be Dying Twice as Quickly Since the 1980s as a Hotter, Thirstier Atmosphere Dries Them Out

by David Bauman and Kristen Goodhue

Tropical trees in Australia’s rainforests have been dying at double the previous rate since the 1980s, potentially because of climate change, according to an international study published May 18 in the journal Nature. Researchers found the death rates of tropical trees have doubled in the past 35 years as global warming increases the drying power of the atmosphere.

Intact tropical rainforests are major stores of carbon, absorbing around 12% of human-caused carbon dioxide emissions. But their deterioration reduces biomass and carbon storage, making it increasingly difficult to keep global peak temperatures well below the target 2 degrees Celsius required by the Paris Agreement.

“It was a shock to detect such a marked increase in tree mortality, let alone a trend consistent across the diversity of species and sites we studied,” said lead author David Bauman, a tropical forest ecologist at the Smithsonian Environmental Research Center (SERC) and the University of Oxford. “A sustained doubling of mortality risk would imply the carbon stored in trees returns twice as fast to the atmosphere.”

A pattern that existed since the age of dinosaurs is now disappearing—with profound implications for ecosystems

by Christian Elliott, Northwestern University

Sitting on couches at an Airbnb in Montreal for the 2018 Marine World Conference, Jon Lefcheck, the Coordinating Scientist for the MarineGEO program at the Smithsonian Environmental Research Center, and his colleagues started tossing around the sort of questions scientists do in their free time. Questions like, is there a general pattern between what animals eat and how big they are?

Four years later, that conversation has culminated in a new study in Nature Ecology & Evolution, with the most comprehensive analysis yet of the relationship between vertebrate animals’ body sizes and their places on the food chain. The study reaches across taxonomic groups, ecosystems and 150 million years of evolutionary history. Humans, they found, are starting to disrupt a longstanding balance.

by Deva Holliman

To celebrate Arbor Day this month, we’re taking a closer look at forest research with Shelley Bennett, head technician of SERC’s Ecosystem Conservation Lab. Much of the lab’s efforts focus on immediate threats, like invasive species and rising temperatures. However, a new project seeks to uncover what happens when a forest functions normally—including the insects and microbes that feast on its leaves. Learn more in this Q&A. Edited for brevity and clarity.

Q: To start off, could you talk about the project you’re working on?

Shelley: Sure! I’m working on a project [regarding] the interactions between insects, microbes, and trees in the chronosequence forest plot here at SERC. We’re looking at different age stands of beech, sweetgum and tulip poplar trees….Younger stands tend to have more tulip poplar and sweetgum, whereas older stands start to have beech trees. We’re looking at seedlings, saplings and mature trees of the three species and assessing leaf damage by herbivores and microbes.….We’re also sampling the insect community in a subset of the plots and looking at how the interactions between insects and trees change as forests naturally age.

by Caitlyn Dittmeier, Smithsonian Working Land and Seascapes intern

At 6 a.m., bird songs chime a new day of field work for Amy Hruska, a postdoc with the Smithsonian Environmental Research Center (SERC) and Chesapeake Working Land and Seascapes ecologist. Recording the species for every tweet and chirp she hears for 20 minutes is hard work. But Hruska is more concerned about a looming silence. Since 1970, 1 billion birds have disappeared from North American forests, leading scientists like Hruska to study the effects of habitat loss on local populations.

Forests once covered 95% of the Chesapeake Bay landscape. But after centuries of intensive farming and development, approximately half of that forest has been cleared. The remaining forest exists in insular patches, bordered by croplands, roads and cities. Scientists understand that fragmentation threatens native wildlife, but they know far less about its impacts over a long period of time.

Curious to know more, Hruska launched a new project investigating how changing land use has transformed the Bay landscape over the past 40 years. To do so, she’s revisiting the same forest patches that SERC researchers studied decades ago.

by Kristen Goodhue

California is no stranger to extreme events. Record-breaking wildfires or heat waves make headlines nearly every year. But in the winter of 2017, another type of extreme devastated underwater life: A series of “Pineapple Express” storms from Hawai’i created extreme rainfall not seen since the state began keeping records in 1895.

“Several atmospheric rivers came and dumped water on the Bay area,” said Chela Zabin, a marine biologist at the San Francisco branch of the Smithsonian Environmental Research Center (SERC) and lead author of a new study on climate extremes.

“For Northern California, 2017 was the wettest winter on record,” said Andy Chang, a SERC biologist and coauthor. “Given our changing climate, record-breaking, once-in-a-lifetime wet years like 2017 are now projected to occur much more often.”

The downpours wreaked havoc on an oyster and eelgrass restoration site that Zabin, Chang and a team of ecologists had been working on since 2012, as part of the San Francisco Bay Living Shorelines Project. The water’s saltiness plummeted to five parts per thousand—a level Olympia oysters can withstand for days, but not months. When the team checked the restoration later in the spring and summer, not a single oyster had survived. However, all was not lost. The following fall, oysters began growing there again naturally. New oyster larvae had drifted into the barren restoration, likely from more central parts of the bay that were not as affected by the extreme rainfall.

How the appearance of a nonnative shrimp in the Chesapeake unearthed a 160-year-old naming mystery

by Kristen Goodhue

It seemed like such an innocent catch: two peppermint shrimp, netted in the lower Chesapeake Bay during the 2013 Blue Crab Winter Dredge Survey. But their discovery would send Smithsonian biologist Rob Aguilar spiraling down a rabbit hole of century-old field notes, museum fires and World War II bombings. In a new study, Aguilar and SERC’s Fisheries Conservation Lab finally unraveled a taxonomic knot over a century in the making.