Author Archives: Marcie Grabowski

New research predicts a doubling of coastal erosion by mid-century

Chronic erosion dominates the sandy beaches of Hawai‘i, causing beach loss as it damages homes, infrastructure and critical habitat.  Researchers have long understood that global sea level rise will affect the rate of coastal erosion.  However, new research from scientists at UH Mānoa and the state Department of Land and Natural Resources brings into clearer focus just how dramatically Hawai‘i’s beaches might change.

For the study, published this week in Natural Hazards, the research team developed a simple model to assess future erosion hazards under higher sea levels – taking into account historical changes of Hawai‘i shorelines and the projected acceleration of sea level rise reported from the Intergovernmental Panel on Climate Change (IPCC).  The results indicate that coastal erosion of Hawai‘i’s beaches may double by mid-century.

Like the majority of Hawaiʻi’s sandy beaches, most shorelines at the 10 study sites on Kauaʻi, Oʻahu and Maui are currently retreating. If these beaches were to follow current trends, an average 20 to 40 feet of shoreline recession would be expected by 2050 and 2100, respectively.

“When we modeled future shoreline change with the increased rates of sea level rise (SLR) projected under the IPCC’s ‘business as usual’ scenario, we found that increased SLR causes an average 16 to 20 feet of additional shoreline retreat by 2050, and an average of nearly 60 feet of additional retreat by 2100,” said Tiffany Anderson, lead author and post-doctoral researcher at the UHM School of Ocean and Earth Science and Technology.

“This means that the average amount of shoreline recession roughly doubles by 2050 with increased SLR, compared to historical extrapolation alone. By 2100, it is nearly 2.5 times the historical extrapolation. Further, our results indicate that approximately 92% and 96% of the shorelines will be retreating by 2050 and 2100, respectively, except at Kailua, Oʻahu, which is projected to begin retreating by mid-century.”

The model accounts for accretion of sand onto beaches and long-term sediment processes in making projections of future shoreline position. As part of ongoing research, the resulting erosion hazard zones are overlain on aerial photos and other geographic layers in a geographic information system to provide a tool for identifying resources, infrastructure and property exposed to future coastal erosion.

“This study demonstrates a methodology that can be used by many shoreline communities to assess their exposure to coastal erosion resulting from the climate crisis,” said Chip Fletcher, Associate Dean at the UHM School of Ocean and Earth Science and Technology and co-author of the paper.

Mapping historical shoreline change provides useful data for assessing exposure to future erosion hazards, even if the rate of sea level rise changes in the future. The predicted increase in erosion will threaten thousands of homes, many miles of roadway and other assets in Hawai‘i.  Globally the asset exposure to erosion is enormous.

“With these new results, government agencies can begin to develop adaptation strategies, including new policies, for safely developing the shoreline,” said Anderson.

To further improve the estimates of climate impacts, the next step for the team of researchers will be to combine the new model with assessments of increased flooding by waves.

The research was sponsored by the Hawaiʻi Department of Land and Natural Resources, and the U.S. Geological Survey Pacific Islands Climate Science Center.

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Tiffany R. Anderson, Charles H. Fletcher, Matthew M. Barbee, L. Neil Frazer & Bradley M. Romine (2015). Doubling of coastal erosion under rising sea level by mid-century in Hawai‘i. Natural Hazards doi:10.1007/s11069-015-1698-6

— UH News story

MBARI image of free-drifting ESP system

New research finds oceanic microbes behave in synchrony across ocean basins

Researchers from UH Mānoa and colleagues found that microbial communities in different regions of the Pacific Ocean displayed strikingly similar daily rhythms in their metabolism despite inhabiting extremely different habitats – the nutrient-rich waters off California and the nutrient-poor waters north of Hawai‘i. Furthermore, in each location, the dominant photoautotrophs – light-loving bacteria that need solar energy to help them photosynthesize food from inorganic substances – appear to initiate a cascade effect wherein the other major groups of microbes perform their metabolic activities in a coordinated and predictable way.

As expected, different photoautotrophs dominated the coastal versus open ocean. In contrast, many other heterotrophic bacterial groups were common to both habitats. For the study published this week in the Proceedings of the National Academy of Sciences, the researchers monitored when, throughout the day, these microbes turn on and turn off genes that regulate key metabolic processes (referred to as “transcriptional patterns”). The bacterial groups common to both ecosystems displayed the same transcriptional patterns and daily rhythms  – as if each group is performing its prescribed role at a precise time each and every day, even though these communities are separated by thousands of miles.

“Our work suggests that these microbial communities broadly behave in a similar manner across entire ocean basins and that specific biological interactions between these groups are widespread in nature,” said Frank Aylward, post-doctoral scholar at the Center for Microbial Oceanography: Research and Education (C-MORE) at UHM and lead author of the study.

The investigation used a robotic sampler, the Environmental Sample Processor (ESP), recently developed by co-author Chris Scholin and his colleagues at the Monterey Bay Aquarium Research Institute (MBARI). Riding the same ocean currents as the microbes it follows, the ESP is uniquely equipped to harvest those microbes every few hours, so that researchers can measure exactly when different genes are turned on or off for many different species simultaneously.  Using modern “next generation” genomic technologies Aylward and colleagues were then able to evaluate the daily gene expression cycles in microbial communities in the wild.

Generally microbes from coastal (California coast) and open-ocean (North Pacific Subtropical Gyre) waters have been thought of as completely distinct communities that are shaped by very different environmental conditions. Waters near Hawaii experience high levels of sunlight and warm temperatures year round, for example, while coastal California waters are colder and undergo marked seasonal transitions.

“Surprisingly, however,” said Aylward, “our work shows that these extremely different ecosystems exhibit very similar diel cycles, driven largely by sunlight and interspecies microbial interactions. This suggests that different microbial communities across the Pacific Ocean, and likely waters across the entire planet, behave in much more orderly ways than has previously been supposed.”

“There is a lot more order out there in the ocean than we had previously thought, on vast spatial scales,” remarked Edward DeLong, UHM professor of oceanography and senior author of the paper. “Each day, as sunlight hits the water, a very highly orchestrated cascade of species-specific activities takes place, with each microbe chiming in at a very precise time, each and every day.  This sort of predictable pattern may allow us to better predict the specific timing of matter and energy transformations that are catalyzed by microbes on a daily basis.”

Because of the large volumes of carbon dioxide sequestered by microbes in the oceans, this work has important implications for understanding the factors that shape large-scale carbon cycling in the biosphere. Because interactions between microbial groups appeared to be conserved between environments, this work also has implications for understanding fundamental patterns of how the activities of microscopic life give rise to ecosystem-level phenomena at much larger scales.

Along with their collaborators in the newly established, UH-based initiative called the Simons Collaboration on Ocean Processes and Ecology (SCOPE), the team hopes to achieve finer resolution sampling in space and time using improved robotic sampling devices currently being designed at MBARI.  This will help identify more precisely how microbes are interacting with each other in seawater and how they respond to environmental stimulus.

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Frank O. Aylward, John M. Eppley, Jason M. Smith, Francisco P. Chavez, Christopher A. Scholin, and Edward F. DeLong (2015). Microbial community transcriptional networks are conserved in three domains at ocean basin scales, Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1502883112
http://www.pnas.org/content/early/2015/03/05/1502883112.abstract

— UH News story

Emerald Bay photo by Michael originally posted to Flickr

Lake Tahoe research provides new insights on global change

A recently published study on how natural and man-made sources of nitrogen are recycled through the Lake Tahoe ecosystem provides new information on how global change may affect the iconic blue lake.

“High-elevation lakes, such as Lake Tahoe, are sentinels of climate change,” said Lihini Aluwihare, associate professor of geosciences at Scripps Institution of Oceanography (SIO) at UC San Diego and co-author of the study. “Small changes in the lake’s chemistry can have big impacts on the entire ecosystem.”

Lake Tahoe’s nitrogen concentration is one of several factors that helps maintain its crystal clear waters. To keep Tahoe blue in the future, the researchers say it’s important to keep a close eye on the nitrogen balance in the ecosystem over time.

“The things we do, as humans, affect change in nature.  We know the Lake’s foodweb is changing due to warming and nitrogen inputs. Our marine and aquatic ecosystems across the globe face many of the same environmental stressors. What we’ve learned about how aquatic foodwebs recycle nitrogen in Lake Tahoe may be applicable to the clear waters near Hawai‘i,” said Stuart Goldberg, lead author of the study and post-doctoral researcher at the Center for Microbial Oceanography: Research and Education at the University of Hawai‘i at Mānoa (Goldberg was a post-doctoral researcher at Scripps Oceanography during this research).

The study, published in Nature Communications, tracked nitrogen, including that produced from the burning of fossil fuels, in the Lake Tahoe ecosystem. Nitrogen can affect both the productivity of lake foodwebs and the composition of the microbes that support nutrition for those food webs.

A main goal of the study was to understand how the nutrient is being cycled through the microbial food web. Goldberg compares the foodweb to a cafeteria that sends out a variety of different dining options that support the community as a whole. Nutrients like nitrogen, phosphorus and carbon come in, and the foodweb changes them into different types of nitrogen, phosphorus and carbon – proteins, sugars, and fats, for example. Some types are easier to eat than others, and are reused or eaten almost instantly. Other types, like the proteins isolated for this study, aren’t easily consumed and accumulate in the Lake.

Using radiocarbon isotope techniques, the researchers dated the molecular components of these proteins and discovered that some nitrogen was preserved in proteins and unavailable for biological consumption for 100 to 200 years.

“It is unusual for organic nitrogen to be sitting around for long periods of time in an ecosystem,” said Aluwihare. “This changes our view of how quickly nutrients are recycled in high-elevation lake ecosystems.”

The findings of this study suggest that something is preventing the efficient recycling of nitrogen in these ecosystems, and one possibility may be phosphorus limitation of the recycling bacteria (bacteria need both nitrogen and phosphorus to live).

The Lake Tahoe ecosystem is experiencing rapid change due to regional warming and shifts in precipitation patterns, as well as increased atmospheric nitrogen deposition, which has begun to alter the nutrient balance in the lake.

“This investigation has found that dissolved organic matter can store nitrogen in lake systems,” said Lina Patino, program director for the Earth Sciences Postdoctoral Fellowship Program at the National Science Foundation, which funded the research.  “This result is important because to understand the environmental health of lakes, we need to know the sources of the nutrients and where they are stored.”

Goldberg and colleagues are planning to submit a grant this summer to further understand how the Lake’s foodweb processes nutrients like nitrogen and phosphorus.

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The study’s co-authors include: Goldberg, presently at the University of Hawai‘i (at Scripps Oceanography at the time of the study); Aluwihare and Ian Ball at Scripps Oceanography; Brant Allen and Geoffrey Schladow at UC Davis; Andre Simpson, Hussain Masoom and Ronald Soong of the University of Toronto; and Heather Graven of Imperial College in London.

Higher resolution images are available upon request.

For more information, visit: http://cmore.soest.hawaii.edu/

— UH News story

Hawaiʻi groundwater and geothermal data compiled for first time

The Hawai‘i Institute for Geophysics and Planetology (HIGP) at UH Mānoa recently launched a website, the Hawai‘i Groundwater and Geothermal Resources Center (HGGRC), and, in doing so, introduced an abundance of new data related to these natural resources.

Two HIGP researchers, Drs. Nicole Lautze and Donald Thomas, led the creation of this resource center to organize and publicly disseminate data on Hawai‘i’s groundwater and geothermal resources from private and public agencies and organizations.

“Our goal is to educate individuals and facilitate responsible management of these resources into the future,” said Lautze, HIGP assistant researcher.

“Creating this open data set is an important first step in revitalizing our understanding of Hawai‘i’s water resources, as new and enhanced geophysical methods today promise to update the foundations of our current knowledge, which has been based upon 80-year-old technology and studies,” added Dr. Rhett Butler, who serves as director of HIGP.

In the past, several disconnected repositories existed for groundwater- or geothermal-relevant documents in Hawai‘i. Lautze and Thomas noticed significant public interest in several projects, and realized the need to centralize these datasets along with historical photographs, slides and newspaper articles.

For example, now available through the HGGRC, the Geothermal Collection contains more than 1,000 geothermal-relevant documents. Hosted by the University of Hawai‘i repositories ScholarSpace and eVols, this collection has had approximately 100,000 document downloads since its creation three years ago.

In addition, daily updates will be available from HGGRC when the Humu‘ula Groundwater Research project commences drilling of a second 2 km deep hole in the saddle region of the island of Hawaiʻi. The second drilling effort will enhance understanding of the groundwater resources available there.

The Hawai‘i State Water Wells database shows data for the water wells in Hawai‘i (e.g. name, location, type, and depth) via an interactive map, with downloadable water well files. Previously, the only way to view this information was through physical files in a Hawai‘i State Department of Land and Natural Resources (DLNR) office.  Roy Hardy, Acting Deputy Director of DLNR’s Commission on Water Resource Management, emphasized that they are “thankful that the historical paper copies of data and information have now been digitized.”

As part of the Department of Energy “Play Fairway” project, researchers at the HGGRC continue to compile all data relevant to geothermal across the entire state of Hawai‘i into a probability map, which will indicate the likelihood of encountering a subsurface resource. This will provide the first updated resource assessment since the late 1970s, which found a potential resource on all islands.

While recognizing that discussions about developing groundwater and geothermal resources can be contentious, Lautze emphasized that the goal of HGGRC is information gathering.  “In bringing together this wealth of information, we hope to facilitate innovative research on Hawai‘i’s groundwater and renewable energy resources,” she said. “Ideally, with sound knowledge in hand, scientists, resource managers, potential developers, policymakers, and the public will have the necessary information to protect and optimally utilize Hawai‘i’s natural resources and to plan for a sustainable future.”

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Photos of drill cores available for download:
https://plus.google.com/u/0/photos/117276985112773993644/albums/5883513041783123537/5883513092917061602?pid=5883513092917061602&oid=117276985112773993644

— UH News story

Tsunami model image.

Cooperative Institute for Marine and Atmospheric Research (CIMAR)

CIMAR was established to pursue the common research interests of NOAA and University of Hawai‘i in oceanic, atmospheric, and geophysical research. Major areas of research in CIMAR include ecosystem forecasting, ecosystem monitoring, ecosystem-based management, protection and restoration of resources, equatorial oceanography, climate research and impacts, tropical meteorology, and tsunami and other long-period ocean waves.

Heavy rainfall events becoming more frequent on Big Island, finds new study from UHM

A recent study by University of Hawai‘i – Mānoa (UHM) researchers determined that heavy rainfall events have become more frequent over the last 50 years on Hawai‘i Island. For instance, a rare storm with daily precipitation of nearly 12 inches, occurring once every 20 years by 1960, has become a rather common storm event on the Big Island of Hawai‘i – returning every 3-5 years by 2009.

In a paper published in the International Journal of Climatology, Ying Chen, UHM graduate student at the time of the study, and Dr. Pao-Shin Chu, professor of atmospheric sciences at UHM and Head of the Hawai‘i State Climate Office, analyzed extreme precipitation events and the frequency with which they occur on three islands in Hawai‘i – Oahu, Maui and Hawai‘i Island.

While heavy rainfall events have become more frequent over the last 50 years on the easternmost island in Hawai‘i, the opposite behavior is observed for Oahu and Maui to the west. There, rainfall extremes have become less frequent in the last five decades. This study, therefore, also reveals a regional – that is, east to west – difference in how precipitation patterns are responding to a changing climate.

“In the past, the frequency of heavy rainfall events was assumed to be fairly constant. However, because climate is changing, the assumption of stable precipitation climatology is questionable and needs to be reconsidered,” said Chu.

“Changes in the frequency of heavy rain events have repercussions on ecological systems, property, transportation, flood hazards, and engineering design – including sewage systems, reservoirs and buildings.”

This study also provides clues about why and how the frequency of precipitation extremes has changed. Chu and Chen found a greater number of extreme rain events during La Nina years and the opposite during El Nino years.

In this study, the number of rain gauges used was limited – the researchers used information from 24 weather stations on the three islands.  For future work, Chu hopes analyzing data from additional stations will provide a more detailed assessment of changing rain patterns across the Hawaiian Islands.

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Ying Ruan Chen and Pao-Shin Chu (2014) Trends in precipitation extremes and return levels in the Hawaiian Islands under a changing climate. International Journal of Climatology, 34, 3913-3925, DOI: 10.1002/joc.3950.

— UH News story

New species discovered beneath ocean crust

Two miles below the surface of the ocean, researchers from the University of Hawai‘i – Mānoa (UHM) and colleagues discovered new microbes that “breathe” sulfate — that is, gain energy by reacting sulfate with organic (carbon-containing) compounds.

The microbes, which have yet to be classified and named, exist in massive undersea aquifers — networks of channels in porous rock beneath the ocean where water continually churns. About one-third of the Earth’s biomass is thought to exist in this largely uncharted environment.

Using DNA sequencing, a team of UHM researchers has spent the last few years accumulating strong evidence that this area of the deep subsurface harbors unique microorganisms. It’s a massive biome dominated by microbes that scientists know very little about.

“That’s what makes this recent work exciting – while we suspected it in the past, we now have DNA sequence data linking sulfate reduction to some of these new and novel microorganisms,” said Michael Rappé, associate researcher at the Hawai‘i Institute of Marine Biology (HIMB). Rappé, along with Alberto Robado (lead author; now at University of Southern California) and others, published a paper on the new findings this month in the open-access journal Frontiers in Microbiology.

Sulfate is a compound of sulfur and oxygen that occurs naturally in seawater. It is used commercially in a range of applications — from car batteries to bath salts — and can be aerosolized by the burning of fossil fuels, increasing the acidity of the atmosphere.

Microbes that reduce sulfate are thought to be some of the oldest types of organisms on Earth and have previously been found in marshes and hydrothermal vents. Microbes beneath the ocean’s crust, however, are incredibly tricky to sample.

Researchers took samples from the Juan de Fuca Ridge off the coast of Washington state, where previous teams had drilled into the ocean floor by lowering a drill through two miles of ocean and boring through several hundred feet of ocean sediment and into the rock where the aquifer flows. The holes were then fitted with Circulation Obviation Retrofit Kit observatories, or CORKs, which provide a seal at the seafloor, like a cork in a bottle or a wellhead, allowing scientists to deploy instruments and sampling devices to a borehole in order to collect deep subsurface crustal fluids, while keeping ocean water out.

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“This study would not have been possible without the many years of effort by our late colleague here in Hawai‘i, Jim Cowen, who spearheaded the design of CORKs to be more friendly for fluid sampling, and designed new sampling equipment capable of traveling two miles or more to the bottom of the ocean, pumping up crustal fluids from deep below the seafloor, and bringing those samples back to the ship without contaminating any of it with sediments or seawater. It took tremendous vision and dedication by Jim for us to now be able to routinely achieve this feat and perform experiments such as those described in our current study,” said Rappé.

Like the microbes on the forest floor that break down leaf litter and dead organisms, the microbes in the ocean also break down organic — that is, carbon-based — material like dead fish and algae. Unlike their counterparts, however, the microbes beneath the ocean crust often lack the oxygen that is used on land to effect the necessary chemical reaction.

Instead, these microbes can use sulfate to break down carbon from decaying biological material that sinks to the sea bottom and makes its way into the crustal aquifer, producing carbon dioxide.

Learning how these new microbes function will be important to getting a more accurate, quantified understanding of the overall global carbon cycle — a natural cycling of carbon through the environment in which it is consumed by plants, exhaled by animals and enters the ocean via the atmosphere. This cycle is currently being disrupted by man-made carbon dioxide emissions.

“This is very exciting work that links rates of microbial activity to novel groups of microorganisms,” said study co-author Sean Jungbluth, postdoctoral scholar at the UHM Department of Oceanography and HIMB, “particularly because we are combining cutting edge molecular biology techniques with samples collected from a part of our planet that is less accessible than outer space.”

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The full study can be found online here: http://journal.frontiersin.org/Journal/10.3389/fmicb.2014.00748/full

— UH News story

ASLO honors Hilary G. Close with the 2015 Raymond L. Lindeman Award

The Association for the Sciences of Limnology and Oceanography (ASLO) honored Dr. Hilary Close, UHM Geology and Geophysics assistant researcher, with this year’s the 2015 Lindeman Award in recognition of exceptional paper, “Export of submicron particulate organic matter to mesopelagic depth in an oligotrophic gyre,” published in Proceedings of the National Academy of Sciences in 2013. The Raymond L. Lindeman Award honors a scientist of 35 years of age or less for an outstanding peer-reviewed, English-language paper in the aquatic sciences.

Based on her work in the North Pacific subtropical gyre, Dr. Close’s paper makes important and novel insights into the export of submicron particulate organic matter (POM) into the deep ocean, and has revealed for the first time the necessity of a pathway for this transfer. These findings provide a fundamentally different mechanism of export than previously appreciated, and suggest that the dynamics of picoplankton-derived POM may be of great importance for the marine carbon cycle. Observations and conclusions from this study are likely to have significant implications for the responsiveness of the global carbon cycle to climate change, especially as the ecosystems dominated by picoplankton are expected to expand with warming ocean temperatures.

“Hilary is a terrific scientist and fast becoming an intellectual leader in our efforts to understand how the vast pool of organic carbon and nitrogen affects the ecology and chemistry of global oceans,” said Peter Leavitt, who chaired the ASLO Award Committee. “As shown by her paper, Hilary will be an integral member of the chemical oceanography community for many years to come.”

Dr. Close received her doctoral degree from Harvard University. In 2012, she was named a SOEST Young Investigator and NOAA Climate and Global Change Postdoctoral Fellow at the University of Hawaii, where she worked in the stable isotope lab of Brian Popp. Dr. Close continues to study the cycling, export, and food web linkages of particulate organic matter in the upper- and mid- water column at Station ALOHA and other open-ocean sites.

Read the ASLO press release.