Tessa M. Hill, Ph.D.

Students

Ongoing Research

Bamboo corals as records of climate change in the ocean's interior

Left: Pieces of a bamboo coral skeleton, showing calcite sections with organic nodes. Scale bar is 5cm.

This research utilizes bamboo corals, which reside at intermediate depths (250 to 2500m) along the California margin as records of the temperature, geochemistry, and ventilation history of north Pacific intermediate waters. This research project is in collaboration with H. Spero (UC Davis) and investigators at the Monterey Bay Aquarium Research Institute (MBARI).
Above: Cross-sectional view of calcite skeleton of bamboo coral, showing radial growth bands.

Bamboo corals have a skeleton that is composed of both calcite sections and organic nodes. Bamboo corals produce visible alternating bands in their calcium carbonate skeleton.  The frequency of the banding is hypothesized to be annual or sub-annual (Roark et al., 2005).  Bamboo corals can live for hundred of years, preserving a high-resolution record of environmental conditions at intermediate depths. Despite the geographic extent and importance of these corals as part of the deep-sea ecosystem, very little is understood about their biology, geochemistry, and biogeography.

For more information, please visit the website of our recent MBARI/NOAA cruise,

Recent abstracts from this research:

This project is supported by the National Science Foundation and NOAA’s Undersea Research Program.

Please learn more about the deep sea corals in our collection and our ongoing research by visiting the Deep Sea Coral page: CURRENTLY IN DEVELOPMENT

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Past and present pH variability: Impacts on larval invertebrates


Bodega Ocean Acidification Research: Experimental setup for culturing organisms in controlled CO2 and pH environments. Pictured: Dr. Eric Sanford, Annaliese Hettinger (Ph.D student) and Jennifer Hoey (REU student)
Climate change impacts due to the release of anthropogenic carbon dioxide (CO2), including ocean and climate warming and changes in the hydrological cycle, have received intense international attention from scientists and policy-makers for several decades (IPCC, 2007 and references therein). As anthropogenic CO2 is added to the atmosphere, a portion of the CO2 is absorbed by the ocean, and this process leads to a decline in ocean pH.  However, the potential consequences of ocean acidification have only recently received increased attention (Caldeira and Wickett, 2003; Feely et al., 2005; Orr, et al., 2005), despite predictions that reductions in ocean pH are likely to accelerate in the future. Improving our understanding the impact of changes in ocean pH on the carbonate saturation state of seawater and on marine organisms and ecosystems is increasingly urgent as many of them form shells or internal skeletons made of calcium carbonate.

Our interdisciplinary research group (Gaylord, Sanford, Hill and Russell) aims to investigate the impacts of ocean acidification on coastal California environments. A fundamental question in understanding the response of organisms to shifts in pH includes investigating both natural and anthropogenic variability in the pH and carbonate system.  To that end, our research project includes:

  • Culturing of key species in the laboratory under reduced pH conditions
  • Monitoring modern pH variability on the Northern California coast using pH sensors and oceanographic transects
  • Reconstructing past pH variability utilizing geochemical proxies for pH in marine carbonates

This project is supported by the National Science Foundation and UC MRPI program.

For more information, please visit the Bodega Ocean Acidification Research (BOAR) webpage, and view the following conference abstracts:

Records of anthropogenic environmental change from coastal environments

Only limited data exist as a basis to understand the potential consequences of ocean acidification on organisms and ecosystems in temperate coastal environments. This research proposes to addresses a critical step towards understanding the influence of changes in pH on coastal environments by quantifying the natural and anthropogenic variability in ocean pH and constraining the components that contribute to change in pH of coastal California waters, including upwelling, coastal runoff, and atmospheric CO2 flux. This is a collaborative project with Ann Russell (UC Davis), Adina Paytan (UC Santa Cruz), Dorothy Pak & James Kennett (UC Santa Barbara).

The California coast resides in a critical region for natural pH variability. This is due to the influence of a strong but variable upwelling system that brings nutrient-rich, low-pH water to the surface. Furthermore, changes in terrestrial runoff can significantly alter coastal ocean and estuarine pH, through direct influence on the natural buffering capacity of seawater. Thus it is important to determine the natural variability of pH over longer timescales (hundreds to thousands of years) to provide historic perspective on the ongoing and expected future changes resulting from increased anthropogenic CO2 inputs, and to determine the critical threshold at which organisms may be negatively affected. This research is expected to provide an important integrated paleoceanographic and modern perspective on the response of nearshore ecosystems to natural and anthropogenic environmental variability.

We are engaged in an integrative study of the recent geologic history (Holocene; past 11,000 years to present) of upwelling, hydrology and pH change on the California margin, via high-resolution sedimentary records at three coastal California sites. This project has three major objectives:

  • Constrain the history of natural and anthropogenic variability in pH along the California margin;
  • Understand the relative roles of atmospheric CO2, upwelling and freshwater runoff in controlling surface water pH, and
  • Quantify past and predict future biological response to pH changes via indicators such as species shifts and organic matter input to coastal sediment

This project is supported by the UC Marine Council Coastal Environmental Quality Initiative.

Please view these recent abstracts from this project:

Causes and consequences of the Storegga submarine landslide: Was methane hydrate involved?

Location of Storegga slide

The Storegga slide (offshore Norway) is the largest known submarine slide on a continental margin, affecting an area of ~95,000 km 2 and associated with tsunami deposits in Scotland, Norway, and Iceland (Haflidason et al., 2005; Bondevik et al., 2005). The Storegga landslide occurred in the early Holocene (~8.1 ka) and is hypothesized to be associated with the disturbance of gas hydrates on the Norwegian continental margin during deglacial warming and sea level rise. I am investigating the sedimentary history of the Storegga landslide and associated implications for gas hydrate stability, with collaborators C. Paull (MBARI), B. Ussler (MBARI) and S. Holbrook (U Wyoming).

Analyses of benthic foraminiferal assemblages from the Storegga slide, on board the R/V Knorr, September 2004.

 

This project is supported by the American Chemical Society Petroleum Research Fund.

For more information on this project, please check these recent abstracts:

 

 

 

 

 

 

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