Please join me in congratulating the three masters students that defended their thesis research this fall!
- Laurel Lam, Ichthyology
- Alex Olson, Chemical Oceanography
- Holly Chiswell, Chemical Oceanography
Read below to learn the main take-aways of their research!
“Geographic and habitat-based variation in Lingcod (Ophiodon elongatus) demography and life history along the U.S. West Coast”
- Laurel looked at the geographic and habitat-based differences in Lingcod life history and population structure along the U.S. West Coast. Understanding how life-history (i.e. growth, maturity, mortality, condition) of fish can vary is important when accurately managing commercially- and recreationally- important fish stocks.
- She found that as latitude increased (as waters got colder) Lingcod grew slower, lived longer, and matured later than Lingcod from warmer waters. Furthermore, Lingcod from rocky, high-relief habitats grew faster, lived longer, and matured earlier than Lingcod from flat, low relief areas.
- Overall, differences in Lingcod life-history are strongly linked to environmental gradients of sea surface temperature and productivity. Management of Lingcod and other rockfish stocks need to be reflective of these biological differences if we want fish populations to be sustainably harvested in the future.
“The biochemical behavior and speciation of mercury in the sea surface microlayer: implications for transport to watersheds via fog”
- Alex studied how neurotoxic methylmercury (MMHg) found in the ocean (and fish) came to be in marine California coastal fog. He focused on the sea surface microlayer (SML), the thin (10-100 microns) skin of the ocean that separates the marine environment from the atmosphere. This microenvironment is known to accumulate organic material and pollutants.
- Two years and four cruises later, Alex found that MMHg in this layer is 2-30x higher than methylmercury in the water below! This was the first time MMHg was measured in this layer and has implications for this neurotoxin spreading into the marine foodweb faster and or at a higher concentration.
- Alex then tested different types of marine aerosols (natural and synthesized) to see if their creation from the SML meant they transferred MMHg material into the atmosphere (and eventually measured in fog). He found that while these aerosols couldn’t explain all the MMHg in fog, they did contribute a substantial amount (~20%).
- Based on these measurements, much of the MMHg in fog could be coming from a
gaseous form of mercury (Dimethylmercury – DMHg) that breaks down under acidic atmospheric conditions.
“Water Column Methylmercury Production in the California Current”
- The East Coast understanding of mercury cycling is well known, but West Coast cycling of mercury and it’s eventual fate into marine advective fog needed to be better understood.
- Holly looked at water column processes that may contribute methylmercury to the California Current by way of a time series in the Monterey Bay, a 1-D advective diffusive model, lab experiments, and a sediment trap deployment.
- Sinking particles, including fecal pellets, may serve as microenvironments for methylation of mercury and contribute to the West coast cycling of mercury.
Laurel, Alex and Holly join the ranks of 9 other students that defended in 2018, for a total of 12 students that defended this year. In case you missed it, you can always read about recent thesis defenses at the following links:
See you in 2019!