Research

Despite the biological, biogeochemical, and economic importance of the sea urchin to California’s coastal systems, little is known about the resilience of the urchin industry, and the ecosystem that supports it, in the face of global climate change and ocean acidification (OA). Acidifying ocean water has the potential to harm calcium carbonate structures within the urchin body at crucial life stages, thereby potentially reducing population viability over time. In collaboration with Dr. Steve Schroeter, this project utilizes long-term juvenile urchin datasets to assess how calcification within urchin populations along the California coast may have been impacted by chronic and acute acidification events over the past 25 years, and seeks to understand if analysis of historical data enables us to generate predictive proxies of future climate change impacts on coastal systems.

During December, 2017 a massive wildfire, termed the Thomas Fire, in Ventura and Santa Barbara counties burned over 280,000 acres, prompting severe air quality warnings and initiating a series of debris flow events. During this time, our coastal ecosystem was affected by ash deposition as well as mud input (from both debris flows and intentional dumping). These influences on California coastal marine systems may become more important as the severity and occurrence of fire events in California appears to be increasing. However, the impact of these events on our coastal ecosystem is currently unclear. Thus, our lab is investigating the effects of wildfire ash and mud input on our local marine ecosystem with a focus on phytoplankton physiology and community composition. Seasonal experiments have been conducted with natural SBC phytoplankton communities in incubators providing realistic conditions with constant flowing seawater and natural light at UCSB's marine laboratory to investigate how ash or mud-derived nutrient sources affect phytoplankton communities in different seasons (funded by Coastal Fund, UCSB).

The ocean is a major player in controlling the Earth’s climate and marine microbes are key in this process. The motivation for the work we do is that climate-driven processes such as ocean acidification, warming, and alterations in nutrient availability control the short- and long-term fate of marine phytoplankton. We have recently focused our work on the Santa Barbara Channel through the SBC-LTER and the Plumes & Blooms projects where we conduct monthly sampling for inorganic carbon chemistry and analysis of coccolithophore populations through flow cytometry.

Coccolithophores are important contributors to marine calcium carbonate deposits. Studying coccolithophores is challenging because there is significant variability in physiological properties between and even within strains. We are interested in exploring the species concept elucidating the mechanisms controlling the environmental selection of morphological types within the same species bearing different amounts of calcium carbonate.

A lot of our work has explored genetic and physiological diversity in bioluminescent dinoflagellates and in coccolithophores. More recently, our studies have focused on the coccolithophore species Emiliania huxleyi, because it has extraordinary genetic and functional diversity. We are interested in the mechanisms controlling selection (adaptation) and physiological responses (acclimation) to environmental change. We work in collaboration with Dr Robert Miller to understand the mechanisms controlling phytoplankton diversity in the Santa Barbara Channel.

Lab PI, Debora Iglesias-Rodriguez, and graduate student Tanika Ladd have been working with collaborators at the National Oceanic and Atmospheric Administration (NOAA) to learn more about coccolithophore blooms in the Eastern Bering Sea. During blooms of coccolithophores, these microscopic cells in massive numbers can change the color of the water where even satellites and observers from space can see them! Blooms of coccolithophores in the Eastern Bering Sea usually occur in the late summer/early fall, but some years we see very little of the bright turquoise water indicative of these blooms, while in other years, blooms can cover massive areas of the surface ocean. The causes and consequences of these blooms in the Bering Sea are what we hope to learn more about as we collect samples aboard research cruises and observe these blooms from satellite.

https://curious.kcrw.com/2016/05/a-year-later-what-we-know-about-the-refugio-oil-spill

On May 19th, 2015, an underground pipeline near Refugio State Beach, about 20 miles west of Santa Barbara, CA, leaked between 101,000 to 140,000 gallons of oil with approximately 21,000 gallons entering the ocean (http://www.refugioresponse.com/go/doc/7258/2588430/). Although not a large spill compared to others in the marine environment, this event was the largest accidental release of crude oil into the Santa Barbara Channel (SBC) since the historic 1969 oil well blowout. This spill occurred at a time of high primary production in the SBC where the toxic pennate diatom Pseudo-nitzschia spp. dominated phytoplankton assemblages. Not long after the spill, an unprecedented coccolithophore bloom occurred in the SBC, turning the water a bright turquoise color. These events led to questions about how the Refugio spill impacted these phytoplankton and in general how oil affects phytoplankon physiology and so our lab ran experiments testing how the toxic diatom species, Pseudo-nitzschia australis, and the bloom forming coccolithophore species, Emiliania huxleyi, responded to oil exposure. See the first product of that work published here: https://www.int-res.com/abstracts/meps/v603/p61-78/