University of California, Riverside

The EDGE Institute



Ongoing Research


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Featured Graduate Researchers

2017 EDGE Award Recipient
Michelle E. Zill, Ph.D. Candidate in Earth Sciences: Bioturbation’s Impact on the Deep-Sea Sediment Record During the Paleocene-Eocene Thermal Maximum

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Our current climate is changing at a rapid pace, and one of the best ways to predict the future is to investigate the past. Current climate models are limited by a lack of the biogeochemical processes that obscure Earth's reaction to such a rapid release of carbon into the atmosphere, and thus fail to predict Earth's current system. As CO2 levels continue to increase in our atmosphere, a major concern is how ocean ecosystems will react to consequential warming. My research analyzes past events to answer this question, and focuses on major climate shifts throughout the Late Paleocene and Early Eocene, including events such as Paleocene-Eocene Thermal Maximum (PETM). I am currently working on a project which compares the biological and chemical responses of the Atlantic and Pacific basins, to quantify one of the great mysteries left in paleoceanography: the amount of carbon released during this extreme event.

2017 EDGE Award Recipient
Marissa Giroux, Ph.D. Candidate in Environmental Science: How climate changes stressors such as increasing salinities and temperature affect smoltification and salmonid survival

marissa_GThe intrusion of saltwater into estuarine and fresh water environments due to rising oceans caused by climate change results in hypersaline waterways, such as in the San FranciscoBay-Delta. The increasing sea surface salinity is also due to a decrease in freshwater input from the drought. Organisms living in the estuaries are exposed to a higher salinity range, and this can cause increased stress. Endangered juvenile salmonid species, Steelhead trout (Oncorhynchus mykiss) and Chinook salmon (Oncorhynchus tshawytscha) inhabit the San Francisco Bay-Delta during the alevin, fry and parr stages and are exposed to the stress of premature hypersaline acclimation. Salmonid species undergo smoltification, the transition of fish from freshwater to saltwater, which involves significant physiological and morphological changes during this life stage. The first aim of my research is to better understand how climate change stressors, such as increasing salinities and temperatures, affect smoltification and salmonid survival.

2017 EDGE Award Recipient
Eleinis Ávila-Lovera, Ph.D. Candidate in Evolution, Ecology & Organismal Biology: Do woody plants with photosynthetic stems respond differently to drought? An ecophysiological evaluation of tropical and subtropical ecosystems

Eleinis_AWoody plants with green photosynthetic stems inhabit all the drylands of the world, including subtropical deserts in North America and tropical dry woodlands. Plants with photosynthetic stems are usually drought deciduous, so having green stems allows them to continue gaining carbon through the dry season of the year. With more frequent, severe and longer droughts, stem photosynthesis along with other drought survival traits seem to be a good strategy for plants to continue physiological activity during drought and ensure survival (Santiago et al. 2016). The main question I address in my dissertation is “do woody plants with photosynthetic stems respond differently to drought?” Plants with green stems are thought to have advantages that allow them to live and persist in the hot and dry ecosystems they inhabit, including 1) extra carbon gain, and 2) high photosynthetic water-use efficiency (WUE). There is a lot of evidence for the first advantage, but for the water-use efficiency hypothesis the data is more scarce. My research focuses on two aspects of this framework: 1) comparing leaves and green stems to see if established relationships among leaf traits hold for stems as well, in which case we can use our knowledge of leaf physiology to better understand stem physiology; and 2) comparing green-stemmed and non-green stemmed plants to find out if the advantages are real.

Leanne Hancock, Ph.D. Candidate in Earth Sciences: Reconstructing Past Marine Environmental Chemistry

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My name is Leanne Hancock, and I am a 5th year Ph.D. student in the Earth Sciences department at UCR. My research is focused on reconstructing past marine environmental chemistry in an attempt to understand and quantify evolutionary drivers and ecological interactions. My work more specifically focuses on marine methane cycling.

Methane is an extremely potent greenhouse gas that has played a major role in much of Earth’s climatic history. Since methane is a gas, it is not readily preserved in the rock record. We are therefore forced to look at other chemical species that interact with methane that do get preserved.

I have quantified the relationships between sulfur and methane in the modern time period as a function of methane fluxes in marine systems in hopes that sulfur compositions of rocks can be used as a proxy for understanding methane’s presence and importance in the past.

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One environment in which methane is very important is in cold seeps. Cold or hydrocarbon seeps are places on the seafloor where methane and other gases are diffusing out of the sediment into seawater. The chemicals in these fluids are capable of sustaining a unique and diverse community of organisms that do not require energy from sunlight to survive. These environments and the organisms that thrive there are thought to have evolved very early in Earth’s history. They are also thought to have been places of refuge for marine organisms during mass extinctions, as they are isolated from surface conditions.

I am interested in understanding the production of the methane and sulfide that these systems require and how the cycling of these components might control the distribution of organisms found at these sites throughout time. 

 

Graduate Student Jon Nye's Research in Patagonia, Argentina

john_nyeAt the intersection between the Atlantic, Pacific and Southern oceans, Tierra del Fuego and the Beagle Channel are physical and biological nexus points that are poised to be highly influenced by climate change. Such changes can alter the function and significance of species within an ecosystem. One way to identify effects of climate and human activity on an ecosystem is by comparing Holocene and historic food webs, by measuring changes in food chain length and fluctuation in species’ niche and population. Graduate student Jonathan Nye aims to address three primary questions: (1) How has the marine ecosystem near Tierra del Fuego  changed  over time, (2) How have  humans  influenced and been  influenced  by  changes  in  this  ecosystem and (3) What are the characteristics and changes in population of Southern Fur seals in the Holocene? Check out his blog.

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