Brown-MBL student Shelby Hayhoe-Riskin’s work on phosphorous uptake and release in soils and associated environmental impacts in the three largest soybean growing regions of the world will be published in an upcoming issue of Bioscience. Brown-MBL joint faculty Stephen Porder and Chris Neill are co-authors on the paper as are Meagan Schipanski of Pennsylvania State University and Elena Bennett of McGill University. Science Daily reported on the research on December 17th. Read more…
Brown-MBL Student Research on Phosphorous Budgets in Soybean Agriculture in Bioscience and Science Daily
On December 5, 2012, Brown-MBL Graduate Student, Anupriya Dutta, successfully defended her PhD dissertation, ‘Recognizing microRNAs (miRNAs) in Microinvertebrates and Confirming their Absence.’
Bdelloid rotifers are aquatic microinvertebrates that have several outstanding qualities among metazoans. They make up the only ancient asexual animal lineage. Bdelloid rotifers are also incredibly robust to DNA damage, which is a necessary adaptation for life in desiccation-prone environments. During desiccation, they are capable of incorporating foreign DNA into their genome. An investigation of a class of noncoding small RNAs, called microRNAs (miRNAs), reveals that the unique characteristics of bdelloid rotifers are reflected in their miRNA repertoire. miRNAs are involved in post-transcriptional gene regulation and have been implicated in numerous cellular processes. Some miRNAs are believed to be indispensable due to their integration into many gene regulatory networks. For this reason, many miRNAs are easy to identify across diverse animal phyla. However, the conserved miRNA repertoire of bdelloid rotifers is exceptional in this regard. The surprising miRNA repertoire of bdelloid rotifers not only provides important clues to understanding the asexual evolution of bdelloid rotifers, but also reveals new insights into miRNA evolution in animals.
Speaking to a live audience in Providence and over videolink to Woods Hole, Susanna Theroux defended her dissertation on November 28th, 2012. Theroux described her doctoral research that was completed in collaboration between the labs of Dr. Yongsong Huang at Brown University’s Department of Geological Sciences and Dr. Linda Amaral-Zettler at the MBL’s Bay Paul Center.
Theroux’s research focused on haptophyte algae that produce organic biomarkers used for paleoclimate reconstruction. Specifically, she identified novel species of haptophyte algae in lake environments that were responsible for producing alkenone lipids that record the temperature of the lake water going back through time. By combining field studies in Greenland and North Dakota, culture studies and DNA sequencing in Woods Hole and organic analyses in Providence, the project was able to identify novel species of algae and their individual lipid signatures. This research also provided new insights into haptophyte bloom dynamics in lake environments and will impact how future geologic records of haptophyte biomarkers are interpreted. This research was supported by grants to Huang and Amaral-Zettler from the National Science Foundation and the Brown SEED fund and an American Association of University Women fellowship to Theroux.
In January, Theroux will be starting a postdoctoral fellowship at the Department of Energy’s Joint Genome Institute.
Catherine Luria is finishing her second year in the Brown-MBL Graduate Program, advised by Hugh Ducklow (Ecosystems Center, MBL) and Jeremy Rich (Dept. of Ecology and Evolutionary Biology, Brown University). She recently returned from her first field season on the Antarctic Peninsula, where she participated in the Palmer Station Long Term Ecological Research (LTER) Project.
The peninsular region is one of the most rapidly warming regions on earth, with a 4-6°C increase in midwinter temperatures over the last 50 years and a 40% decline in winter sea ice extent. These changes are having profound impacts on all levels of the ecosystem, from marine diatoms to Adelie penguins.
Catherine is examining not only how microbial communities in this region change across study sites, seasons, and years, but also what factors drive microbial seasonal succession against a backdrop of rapid climate change. She is particularly interested in the effects of annual sea ice advance and retreat on microbial communities. As sea ice forms during the austral fall, bacteria and phytoplankton are entrained in the ice and often persist through the winter. In the spring, the sea ice melts releasing organic matter as well as bacteria and phytoplankton. This water column “seeding” may have dramatic impacts on microbial community composition within the water column and trigger phytoplankton blooms that help support this productive ecosystem. Although previous studies have examined the effects of sea ice extent and duration on primary production, zooplankton, and seabirds, little is known about the impact of sea ice advance and retreat on microbes and how microbes will respond to climate-driven declines in sea ice extent and duration. Catherine is exploring this question through a combination of environmental sampling and incubation experiments. She is excited to return to the Antarctic in September 2012 for further research.
by Catherine Luria, May 2012
Brown-MBL PhD student Xi Yang and colleagues recently reported in the Journal of Geophysical Research that the New England spring, as measured by plant phenological changes, arrives as much as a week earlier today than it did fifty years ago. Yang and his colleagues at the MBL Ecosystems Center, Brown University’s Department of Geological Sciences, and the University of Minnesota’s Department of Soil, Water Climate used remotely-sensed phenology and metereological data to assess the accuracy of three different species-level budburst phenology models and one senescence model, and then used the best of the budburst models, the Spring Warming Model, and the Delpierre Senescence Model, to reconstruct plant phenology in New England between 1960 and 2010. They determined that New England has experienced a statistically significant advance in the start of season between 1960 and 2010, averaging 0.143 days per year or a more than seven day advance over the 50 year period studied. In addition to showing a significant change in start of season over recent decades, the researchers also demonstrated that phenology models can be useful for both reconstructing and predicting plant phenological changes at the regional level over time.
June 5, 2012
Our IGERT and PIRE graduate training grants are in full swing. These programs, in reverse ecology and African agriculture, cut across multiple departments at Brown and the Bay Paul and Ecosystems Centers at MBL. The IGERT project addresses the question at the boundary of genomics and ecosystem science—how does the make-up of microbial communities influence key ecosystem processes such as sediment recycling of mineral nitrogen cycling or the production of methane. The PIRE tries to evaluate how a rapid increase in the amount of fertilizer in African agriculture can help farmers but at the same time lead to environmental problems. Four Brown-MBL IGERT and PIRE students are now developing doctoral research projects advised by combinations of Brown and MBL scientists.
The Partnership now hosts 20 PhD students. They continue to do innovative and exciting science. Shelby Hayhoe-Riskin was the latest to defend her dissertation, on May 30. Shelby compared multiple small watersheds in forest and in soybean fields to understand how the expansion of soybean agriculture in the Amazon is affecting both the amount of water that runs off into streams and the export of soil nutrients in streamwater.
The Partnership also involves a growing number of undergraduates. A record ten Brown undergraduate students are working in MBL laboratories and on MBL projects this summer, including two Beckman Foundation scholars. The Partnership also helps to support two post-doctoral scholars who work on joint Brown-MBL research projects in microbial ecology and tropical biogeochemistry and a third will arrive at the end of the summer. MBL and Brown faculty collaborated to teach eight new courses since 2010.
The common denominator in all of this work is that the collaboration across MBL and Brown, in teaching and research, allows scientists to tackle problems in innovative ways and to break new scientific ground that would not be possible at one institution alone.
Managing the biosphere and safeguarding human health in the face of accelerating environmental change will take new ways of thinking about problems across disciplines, new analytical tools brought to bear on big questions, and new ways of collaborating across the US and across the nations of the world. Partnership students and research projects are rising to those challenges.
Christopher Neill, Director
Brown MBL Partnership
May 30, 2012
Deep soils that strongly bind phosphorus fertilizer buffer streamwater against changes to dissolved nutrient concentrations across wide areas of the Amazon rainforest that have been recently converted to intensive soybean agriculture, Brown-MBL student Shelby Riskin showed in new research. Riskin, who defended her PhD dissertation on May 30, spent the last five years comparing soils and waters in small forest and soybean watersheds in the Brazilian state of Mato Grosso, where the area of soybean farms has exploded since the early 2000s.
One of Riskin’s main findings is that the flow of water out of small streams in soybean fields increases four-fold because of the loss of evapotranspiration through the leaves of the original forest trees. But that change was not accompanied by increased “flashiness,” or flows of streamwater during storms. That’s because even under intensive cropping, the high permeability of soils allows water to infiltrate directly to groundwater without running overland. So even though more water reaches streams, it arrives in a very even flow controlled by release from groundwater. Because soils over the majority of the new soybean farming region are very deep as well as highly permeable, this allows water to contact soils along very long pathways that further buffer streamwater against changes in dissolved nutrients. “Soils play a critical role in regulating the way that intensive farming systems affect surface waters,” Riskin said, “and those effects may not follow the same patterns that we observe in intensively-farmed areas of temperate regions.”
Riskin analyzed the potential role of soils in controlling both the need for fertilizer and impacts to surface waters in the world’s three largest intensive soybean farming systems in Brazil, Iowa and Argentina. Compared with Iowa and Argentina, the large amounts of phosphorus fertilizer used to overcome the low native fertility of Brazilian Amazon rainforest soils are less likely to move to stream and cause nutrient overenrichment and algae blooms that compromise water quality because the Amazon soils bind phosphorus so tightly and permeable soils resist erosion. But the flip side to all that phosphorus retention is that Amazon soybeans will need high rates of fertilization for many years into the future because soils bind phosphorus so tightly it becomes relatively unavailable to the soybean crop. As crop agriculture on cleared rainforest soils expands around the world on high phosphorus-binding soils, the global demand for phosphorus fertilizer is likely to soar. Because relatively few countries control the vast majority of mineable phosphorus fertilizer is mined in relatively few countries (Morocco, China and Algeria have the world’s largest reserves).
Riskin worked at Tanguro Ranch, a 200,000-acre soybean farm in the headwater region of the Xingu River watershed in central Brazil. She was advised by Chris Neill at MBL and Stephen Porder at Brown. Her work was supported by grants from the National Science Foundation and the Mellon Foundation, a Watson Fellowship from MBL and a Cogut Fellowship from the Center for Latin American and Caribbean Studies at Brown.
Several Brown-MBL Graduate Students received prestigious fellowships in Spring 2012.
Lindsay Brin, a fourth year graduate student advised by Anne Giblin at MBL and Jeremy Rich at Brown, received the Watson Fellowship in Environmental Sciences. Lindsay studies how temperature and organic matter availability affect the balance of nitrogen that is removed from or recycled within coastal ecosystems.
Chelsea Nagy, a second year graduate student advised by Chris Neill at MBL and Stephen Porder at Brown, received a three year EPA Star (Science to Achieve Results) Research Award. Chelsea studies how land-use changes impact forest health in the Amazon soybean-growing region of Brazil.
Victor Schmidt, a first year graduate student advised by Kate Smith at Brown and Linda Amaral Zettler at MBL,received the Crane Family Global Infectious Disease Fellowship. Victor studies how microbial community shifts can influence disease development, pathogen transmission, and human and ecosystem health.
A Brown-MBL course, “Statistical Analysis and Graphics with R”, was offered at MBL in Woods Hole January 7-22, 2013 with Dr. Erika Sudderth of Brown University. The primary aim of this course was to learn methods in R for data manipulation, analysis, and graphical presentation. 20 students attend the intensive 12 day course.