Study Aims to Understand Invasive Algae's Success in New England Waters

May 14th, 2018 @

Peredo and Cardon working in the MRC. Credit: Tom Kleindinst

One of the world’s most successful marine invasive species — the red alga Gracilaria vermiculophylla — is expanding its range. While originally found in the Northwest Pacific Ocean, it has found its way around the world, including into the Atlantic, and is creeping northward around the coasts of Cape Cod. As it moves along this path, it is edging into the range of its native, common relative Gracilaria tikvahiae. Both species are currently found in Waquoit Bay, Falmouth.

This could mean bad news for some flora and fauna indigenous to the Cape Cod area. The invasive species can reduce eelgrass bed productivity and can change the communities of invertebrates in coastal zones important for fisheries. The native and invasive Gracilaria species share many characteristics given their common genetic background, but clearly there is something about the invasive species that makes it a superior competitor.

MBL research Scientist Elena Lopez Peredo is working to understand what it is about the invasive that makes it robust in local waters. She has established experimental tanks at the Marine Resources Center (MRC) at MBL, and is studying locally-gathered algae as well as representatives of the native and invasive species isolated by Dr. Charles Yarish at University of Conneticut.

Red algae naturally look red because they have pigments that strongly absorb green light and use it to grow. This means an important part of the MRC experimental set-up is providing a light spectrum to match the red, green, and blue wavelengths found in natural sunlight. Bright lights donated by Noribachi, Inc. (Harbor City, CA) have that full wavelength spectrum and are tailored to the needs of this experiment.

Several researchers have suggested that the invasive Gracilaria is better at preventing the establishment of colonies of disease-causing and/or fouling microscopic organisms on its surfaces. (This community is called the microbiome.) If that is true, how does the control system work? Depending on the kinds of organisms that get established on algal surfaces, microbiomes can actually be good for algal growth or they can be bad. Understanding what controls the formation of the microbiome and its activities is important for understanding the ecology of algae in natural coastal ecosystems and important for aquaculture of marine algae.

There could be some industrial applications to this research, as well.  Gracilaria species are also used to produce agar, antifouling and antimicrobial compounds, so understanding how these red algae encourage the “right” microbiome and discourage the “wrong” organisms is potentially very useful.

By Zoe Cardon, MBL Senior Scientist; Originally posted in The Well.

MBL Scientists Describe Major Differences Between Related Desert and Aquatic Algae

April 10th, 2018 @

Staying alive in the desert is no simple matter for green algae whose evolutionary ancestors lived in the ocean. How can some algal species survive extreme drought, while others desiccate and die? Understanding this difference can provide important information on requirements for drought tolerance that it may be possible to apply to larger plants as the climate changes.

Researchers have described a new genetic model to study exactly this question in a paper published in Journal of Cell Science. In a group of five closely related species of green algae called Scenedesmaceae, three that have adapted to life in desert crust can withstand multiple rounds of desiccation, whereas their two aquatic cousins perish after drying out once. The paper also details major reproductive differences between the two groups.

“How can that be?” asks MBL Senior Scientist Zoe Cardon. “What in the genetic makeup of these species is making such a difference for both their form and their function?”

Cardon brought these microbes into her lab at the MBL, and she and Research Scientist Elena Lopez Peredo either dried them out rapidly, using airflow through a chemical hood, or more gradually at the bench. They then observed the effect of desiccation on each species. They saw that after the aquatic microbes had dried, no amount of water could revive them. The desert microbes, however, showed evidence of active photosynthesis after multiple rounds of desiccation and rehydration.

“As they dry out, you can see the photosynthesis just shutting down,” says Cardon. “You add a little more water and then, poof! It’s off to the races again.”

Read the full article by Stephanie M. McPherson here>>

Team Discovers a Significant Role for Nitrate in the Arctic Landscape

March 26th, 2018 @

Nitrogen, an essential plant nutrient, is most readily absorbed by plants in its ammonium and nitrate forms. Because of the very low nitrate levels found in arctic tundra soil, scientists had assumed that plants in this biome do not use nitrate. But a new study co-authored by four Marine Biological Laboratory (MBL) Ecosystems Center scientists challenges this notion. The study has important implications for predicting which arctic plant species will dominate as the climate warms, as well as how much carbon tundra ecosystems can store.

The study, published in Proceedings of the National Academy of Sciences, found that plants in northern Alaska’s tussock tundra took up nitrate at comparable rates to vegetation in nitrate-rich ecosystems. Nitrate contributed about one-third of the nitrogen the tundra plants used. Some of the species studied, such as Polygonum bistorta, a pink flowering plant, took up nitrate at even higher rates than species found in low-latitude, high-nitrate environments.

The findings are important in the context of human-caused climate change, which is expected to increase nitrogen, and potentially nitrate, levels in tundra soil. As the climate warms, the microbial processes that generate nitrate could speed up. In addition, permafrost — a layer of soil below the surface that remains frozen throughout the year — could thaw, adding additional nitrogen to the ecosystem. Some of this nitrogen could be converted to nitrate.

The tussock tundra covers a large part of northern Alaska and is currently composed of sedges, herbaceous ground cover, and woody shrubs (about a third coverage for each). The landscape’s productivity is limited by nitrogen availability. If released from this limitation, woody shrub species, such as birch and willow, could become more dominant and shade out other plants as the climate warms. The discovery that nitrate is an important nitrogen source for tundra plants will need to be factored into future projections of species composition.

“As the nutrients start cycling faster and the vegetation starts growing faster, that should stimulate all the vegetation on the tundra. After a while, the woody species should be able to overtop the ones that don’t have stems, that can’t stand up that high. So you tend to lose the sedges and the mosses and the lichens,” explained study co-author Ed Rastetter, a senior scientist at the MBL Ecosystems Center and principal investigator for the National Science Foundation’s Arctic Long-Term Ecological Research site at Toolik Lake, Alaska, where part of the research was conducted.

Continue article >>

Zoe Cardon is Elected Fellow of the Ecological Society of America

March 1st, 2018 @

MBL Senior Scientist Zoe G. Cardon has been elected a life Fellow of the Ecological Society of America (ESA), the pre-eminent professional society for ecologists.

Fellows are members of the ESA who are honored for “outstanding contributions to a wide range of fields served by ESA, including … those that advance or apply ecological knowledge in academics, government, non-profit organizations, and the broader society.”

Cardon, who joined the faculty of the MBL’s Ecosystems Center in 2008, focuses her research on dynamic interactions among plants, microbes, and soils, especially in the rhizosphere [the soil volume surrounding plant roots]. Because the function of this below-ground system is difficult to observe without digging it up, Cardon and colleagues have developed innovative approaches to study rhizosphere processes using stable isotopes, genetically engineered microbiosensors, mathematical modeling, and subterranean imaging.

Read the full article here.

MBL Researchers Contribute to Children's Book on Impacts of Fertilizers and Pesticides

January 25th, 2018 @

Jane Tucker, senior research assistant in the MBL Ecosystems Center, co-wrote this new book for children that explains why treating your lawn and garden with fertilizers and pesticides can harm local waterways and wildlife. The book reinforces a long-standing research focus at the Plum Island Ecosystems Long-Term Ecological Research (PIE-LTER) site in northeastern Massachusetts, which is directed by MBL Senior Scientist Anne Giblin as part of the National Science Foundation’s LTER network.


Framework for Reducing Nitrogen Pollution on College Campuses Receives National Award

November 16th, 2017 @

The Marine Biological Laboratory (MBL) and six partners have received an award for developing “The Nitrogen Footprint Tool Network,” a program for assessing and reducing the amount of nitrogen pollution produced on college and research campuses. The partners received the  “Campus Sustainability Research” award last month from the Association for the Advancement of Sustainability in Higher Education (AASHE).

The award recognizes the collaborative effort of the seven academic institutions to measure, compare, and analyze options for reducing their nitrogen footprints. The group published its research results in April 2017 in a special issue of Sustainability: The Journal of Record.

Among the collaborators are principal investigator James Galloway, a MBL Trustee and the Sidman P. Poole Professor of Environmental Sciences at the University of Virginia; and Elizabeth de la Reguera, formerly a research assistant in the MBL Ecosystems Center and now a graduate student at University of Maryland.


The seven institutions in the Sustainability issue, along with 13 others, are members of the Nitrogen Footprint Tool Network, which was coordinated at University of Virginia by lead author Elizabeth Castner, now a graduate student at University of California, Davis.

“Scientists at the MBL Ecosystems Center have been documenting the detrimental impacts of excess nitrogen on coastal ecosystems for many decades,” says Ecosystems Center Director Anne Giblin. ”We have also been studying nitrogen removal strategies and ecosystem restoration techniques that can be used to mitigate some of the harmful impacts of nitrogen on coastal systems. However, this project is the first time we have worked on ways to eliminate the problem at its source, which is by far the most effective and least expensive solution.”

According to the study, nitrogen footprints for the seven institutions ranged from 7.5 metric tons of nitrogen (MT N) at the MBL to 444 MT N at the University of Virginia. The nitrogen footprints correlated strongly with institutional population, but there was a wide range of per capita footprints, from 7 kg nitrogen to 27 kg nitrogen per full-time equivalent person. Factors that contributed to differences in per capita nitrogen footprints included the proportion of an institution’s population living on campus with full or partial meal plans, dietary choices, energy sources and engagement in research that is nitrogen intensive.

Upstream food production was the largest source of nitrogen pollution for five of the institutions, contributing 50 percent of the footprint on average, followed by utilities, which contribute 33 percent on average.

The largest sector of the MBL’s nitrogen footprint is food production, at 55 percent of total. Utilities is the second-largest sector, at 22 percent of total. Scenarios that were analyzed for reducing MBL’s nitrogen footprint included composting 75 percent of food waste, which would reduce the footprint by 0.1 metric tons nitrogen, and adopting energy efficiency strategies.

The institutions reporting in the Sustainability special issue include the MBL, Brown University, Colorado State University, Dickinson College, Eastern Mennonite University, University of New Hampshire, and University of Virginia.

The Nitrogen Footprint Tool Network’s efforts are sponsored by the Environmental Protection Agency’s Sustainable and Healthy Communities Research Program through a cooperative agreement with the University of Virginia. Started in 2014, the network’s agreement runs through 2019.

by Diana Kenney
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Team Explores Salt Marsh Restoration to Offset Global Warming

November 8th, 2017 @

Salt marshes have been flooded by inland freshwater along nearly a third of the U.S. Atlantic coast, due to diversions by dams, dikes, and other human constructs. This hurts more than the natural biodiversity of a saltwater system. As salt marshes freshen, they emit more and more methane—a powerful greenhouse gas.

“A molecule of methane is 30 times more potent as a greenhouse gas than a molecule of carbon dioxide,” says Jim Tang, an associate scientist in the MBL Ecosystems Center.

Tang and his colleagues at the Bringing Wetlands to Market (BWM) project are laying out a framework for returning salt marshes to their natural salinity by removing various tidal restrictions. In a recently published study, they modeled the rate of methane emissions from freshened marshes and suggested mitigations to the problem.

by Stephanie M. McPherson


Measuring the Risky Feedback Between Soil Carbon and Global Warming

November 7th, 2017 @

A radio interview with MBL Distinguished Scientist Jerry Melillo about his 26-year soil warming experiment at Harvard Forest, the results of which were recently reported in the journal Science.

More from The Well

Despite Crabs, Rising Sea Levels, and Man, the Great Marsh Can be Protected to Shield Coastal Communities

October 24th, 2017 @

by John Muldoon.

Poor old Ipswich. It’s at the mouth of a river, where it gets the last leftover water that 330,000 people have already drawn from. “We suffer the consequences of every decision that made upstream,” said Wayne Castonguay, director of the Ipswich River Watershed Association. Yet the town is right beside the ocean, which means it’s the first to feel the impact of rising sea levels.

But, like other communities between Cape Ann and southern New Hampshire, Ipswich has the Great Marsh for protection. While the marsh is beset by man, green crabs, ocean acidification, and rising sea levels, all is not lost, a symposium was told at the weekend.

Hosted by the Ascension Church in Ipswich as part of its 150th anniversary celebrations, the event was attended by over 160 people who came to hear about challenges faced by the river, marsh, clams, Crane Beach, and green crabs.


One of Oldest Climate Change Experiments Leads to Troubling Conclusion | Washington Post

October 6th, 2017 @

One of the regular complaints of climate change doubters and skeptics is that scientific projections of a dire future are too heavily based on computer simulations, or models, which — they say — rest on a variety of questionable assumptions.

But a major climate change study published Thursday relied not on models but experimental data — a 26-year record of observations, no less — to reach a conclusion perhaps just as worrying. The research, tracking the emissions of carbon from artificially heated plots of a forest in Massachusetts, reinforces fears about the possibility of a climate change “feedback” involving the planet’s soils, one that could pile on top of and substantially worsen the ongoing warming trend triggered by the burning of fossil fuels.

“The study is one of the longest if not the longest climate change ecosystem experiment, beyond the one we are running in our own planet,” said Pep Canadell, an expert on the Earth’s carbon cycle at the Commonwealth Scientific and Industrial Research Organization in Australia. He was not part of the research.

by Chris Mooney

Read more …

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