News

On 02 April 2019 we deployed our first prototype oyster biosensors which will measure shell gape at the same time as we are measuring the hydrodynamic and oxygen conditions. The deployment itself required some last minute MacGyvering, but we got it done! The estuary mouth started to close on 12 August 2019 in response to large waves the prior night, and is currently completely closed and filling in with fresher water from upstream. We returned yesterday, 16 April 2019 to swap out the biosensor battery and SD card to capture data over the closure. A first quick look at the first week of data looks good! More information on this project and the undergraduate research here!

Our lab participated in the 2019 San Diego Climate Summit on March 26, 2019. Sarah gave a talk on estuarine response to shoreline change and Angelica and Maddie set up a table and presented our work to interested attendees. We forgot to take photos, but some should be coming soon on the summit website!

A weary set of travelers returned from the Seychelles yesterday. This trip marked the 7th trip our SLOMO group has completed! As usual, we recovered instrumentation and met with local agencies. A departure from usual – some of our longer-term moorings were not-redeployed. However we did still redeploy several instruments around Mahé. Isa is busily plugging away at her ongoing analysis of dynamics around and atop the plateau, while new postdoctoral scholar, Alma is working to write a summary paper of the dynamics atop the plateau.

Graduate student Isabella Arzeno just published the first chapter of her dissertation on examining the dynamics over coral reefs. While prior dynamical studies over coral reefs have predominantly focused on cross‐reef dynamics, this manuscript examines the along-shore dynamics. This is done through using observations of a Hawaiian fringing reef system to quantify the dominant terms in the depth‐averaged alongshore momentum budget as a function of tidal phase. Importantly, while the canonical balance is important, the observations also suggest the importance of advective acceleration at one of the sites – a term often ignored.

With an El Niño watch ongoing this winter, this recent publication with lead author Adam Young looks back at the 2015-2016 El Niño response along the Southern California coastline, particularly focusing on the morphodynamic changes (erosion/accretion) seen along our beaches, estuaries, and cliffs. Key findings are that the coastal change is highly variable spatially with some regions showing erosion, some showing accretion, and the average being moderate erosion. The relatively moderate response is attributed to the wave angle and the coastline shape sheltering Southern California from the largest waves, minimal rainfall, and the fortunate asynchronous timing of the largest waves and largest tides. Investigating how the 2015-2016 El Niño impacts our coastlines gives us an idea of how our coasts may be affected under future climate scenarios where similar storm tracks and wave angles are predicted.

A new paper highlights some results from our CSIDE study was recently released in the Journal of Physical Oceangraphy. “Cross-Shore Deformation of a Surfzone-Released Dye Plume by an Internal Tide on the Inner Shelf” led by graduate student Derek Grimes, describes 2015 observations of the fate of a dye plume released in the surfzone as it was deformed by an internal tide on the inner-shelf. While this paper focuses on the detailed dynamics over just a few hours, it highlights the importance of the timing of transport from the surfzone relative to the solar cycle and the internal tide on the ultimate fate of surfzone-sourced material.

Graduate student Angelica Rodriguez just published her research results in Geophysical Research Letters (with co-authors Giddings and Kumar (UW)) and is highlighted in the Scripps news. The paper, “Impacts of Nearshore Wave‐Current Interaction on Transport and Mixing of Small‐Scale Buoyant Plumes” uses idealized modeling of the interaction between small buoyant plumes (e.g., rivers, creeks, storm drains, etc.) and the surfzone to assess their interaction. Under strong waves and/or small outflows, buoyant outflow plumes were effectively trapped close to the coastline, spreading alongshore instead of cross-shore. This has major implications for transport of pollutants that typically accompany freshwater outflows and can hopefully improve beach water quality sampling and management.

The coupling between plumes and waves has been studied before on large scale plumes, but the interaction between smaller plumes and the surfzone – the region where surface gravity waves break near shore – has been investigated here for the first time. Using an idealized model domain representative of the scales of estuaries and plumes common in Southern California, we coupled a hydrodynamic model (ROMS) with a wave model (SWAN) using the COAWST modeling framework. This modeling framework allowed us to look at wave-current interactions and assess the impact of the surfzone on small buoyant outflows. Importantly, we found that vigorous mixing due to waves in the surfzone vertically mixed the buoyant outflow in the surfzone and wave-driven velocities reduced offshore plume propagation, while enhancing alongshore spreading.

This important question is addressed in a new paper “Expected limits on the ocean acidification buffering potential of a temperate seagrass meadow,” led by David Koweek at the Department of Global Ecology, Carnegie Institution for Science, Stanford. A press-release from the Carnegie Institution and a blog post by David Koweek do an excellent job summarizing the paper in detail.

This paper is the culmination of an interdisciplinary collaboration amongst seagrass ecologists, chemists, climate scientists, and physicists to address the buffering potential of seagrass meadows against ocean acidification, a critical topic as we face a changing climate. We employed a numerical box model coupled with hydrodynamics and a complex bio-geochemical seagrass/chemistry model to investigate the ability for an estuarine seagrass meadow to buffer the acidity of incoming oceanic water (i.e., to counteract ocean acidification). Overall, buffering capacity was found to be relatively weak, about equivalent to turning back the clock a few decades, which is a small offset to the 150 years of ocean acidification that has already occurred and is worsening. Thus the results suggest that while buffering does occur, it is not enough for long-term ocean acidification mitigation. However, there were brief periods of time when buffering capacity was high; that coupled with new information about how organisms can adapt to changing environments, as well as other potential mitigation approaches, provide potential opportunities to use seagrass as part of a broader strategy to ameliorate local ocean acidification in estuaries. The model for this work was parameterized specifically to Tomales Bay, a northern California large estuary, however the resulting publicly available box-model is designed so that it can be tested under varying conditions.

This work is a contribution of the Seagrass Ocean Acidification Amelioration Workshop of the Bodega Marine Laboratory, financial support for which was provided by California Sea Grant and the Coastal & Marine Sciences Institute of the University of California, Davis. Partial support was provided by the National Science Foundation.

This summer Alex Makic and Adrian Urrea have been working in the lab as undergraduate researchers.

Alex, from Colorado College, majoring in Physics with an Emphasis in Environmental Science, worked for a month in the lab on helping to analyze drone imagery taken above Los Penasquitos Lagoon and adjacent beaches to examine morphological changes over time as part of a California Division of Boating & Waterways funded project. He returns to college in early August, but has already made excellent progress this summer! In addition to working with us, he also worked with Octavio Aburto’s lab assessing Mangrove habitats in Baja California.

Adrian was part of a team of students who worked with Jeff Crooks and I during the 2018 Spring quarter to develop a bio-sensor. Adrian has continued to work in the lab this summer, further developing the sensor which will measure oyster shell gape to study how they respond to surrounding conditions. He is working to improve the sensor, add components (temperature and heart-rate sensors), finalize its calibration, run a field test, and build more of them!

18 – 21 June 2018, Giddings attended and presented at the NSF sponsored Workshop on the future of coastal and estuarine modeling. Presentations ranged from numerical discretization schemes, to nonhydrostatic versus hydrostatic code, to the state of the art in wave model-hydrodynamic model coupling. It was a very interesting several days discussing where we are in coastal and estuarine modeling and what are the major hurdles as well as opportunities ahead.