Thesis Defense by Alora Yarbrough – July 22nd (Livestream)


"The impacts of climate change on blackeye goby (Rhinogobiops nicholsii) stress responses, reproduction, and offspring fitness"
A Thesis Defense by Alora Yarbrough

Ichthyology Lab

Zoom | Live-Stream | July 22nd, 2022 at 4:00 pm PST


Alora Yarbrough is a graduate student in the Ichthyology Lab at Moss Landing Marine Labs (MLML). She received her BA in Biology from Pepperdine University in 2017. While there, she completed an undergraduate honor's thesis researching the effects of variable incubation conditions on the development of the California grunion which she presented at the Western Society of Naturalists Annual Meeting, the Joint Meeting of Ichthyologists and Herpetologists, and the Society for Integrative and Comparative Biology's Annual Meeting. After graduating, she completed internships with Heal the Bay at the Santa Monica Pier Aquarium and with Disney World's Animal, Science, and Environment Program in Florida. She then accepted a position in Dr. Scott Hamilton's lab at MLML in the fall of 2018.

For her Master's thesis, Alora examined how climate change affects the stress response, reproduction, and offspring fitness of blackeye gobies, a demersal reef fish common off the west coast of the United States and Mexico. In addition to her master's work, Alora joined the MLML IT department as a Help Desk Technician in 2019 through which she implemented projects such as the Student Life Website and headed the first media committee for the annual Open House fundraiser. In April 2022, Alora returned to southern California to join the Yelon Lab at the University of California, San Diego (UCSD) as a staff research associate supporting research investigating cardiac development in zebrafish.


Thesis Abstract

Climate change poses a major threat to marine ecosystems and the organisms living within them. Along with warming and sea level rise, the increasing intensity of ocean acidification and hypoxia events in coastal environments is of large concern. Weakened immune function, tissue damage, and altered reproductive output are only some of the detrimental effects of decreased pH in ocean waters. Hypoxia has also shown major consequences including decreased aerobic scope, altering predator-prey interactions, and inducing hyperventilation. Additionally, animals living in eastern boundary currents, such as off the coast of California, experience a regional phenomenon known as upwelling. As surface waters are directed offshore due to wind patterns, deep, acidic, hypoxic water is brought up to the surface magnifying the effects of ocean acidification and hypoxia for up to two weeks at a time. Both low pH and low amounts of dissolved oxygen (DO) characterize stressful conditions for many marine species. Under stress, one of the main hormones organisms will produce to maintain homeostasis is cortisol, therefore cortisol can act as a marker to determine the relative stress an animal is under. This study evaluated the stress response of adult female blackeye gobies when under both acute and chronic climate change stress by measuring muscular cortisol concentrations at specific time points while under one of four treatments: control (8.1 pH; ~9 mg/L O2), low DO (8.1 pH; 2.0 mg/L O2), low pH (7.3 pH; ~9 mg/L O2), and a combination of low DO and low pH (7.3 pH; 2.0 mg/L O2). In addition, the stress response differs for organisms at varying life stages. Notably, some larval fish species rely entirely on maternally derived hormones supplied by the yolk sac. An increase in cortisol in the yolk supply may impose developmental disadvantages on the larvae, but there is also evidence that it can better equip offspring to face the stressors experienced by their mothers. Therefore, the relationship between maternal and egg cortisol concentrations was investigated with females laying clutches under each of the four treatments. After laying, clutches were split to be incubated under the same conditions their mothers experienced or the control treatment. At 1 day post hatch, offspring physiological fitness was evaluated based on morphometric characteristics and standard metabolic rate. This study found adult female blackeye gobies experiencing acute stress tend to have higher cortisol concentrations than those under chronic stress. When evaluating how stress is translated generationally, a positive relationship between maternal and egg cortisol concentrations was found. However, blackeye gobies were not able to successfully fertilize eggs under the low pH treatment. In addition, clutches with higher initial cortisol concentrations showed trends of increased time to hatching and standard metabolic rate and decreased length and weight at 1 day post hatch. The results of this study suggest decreased pH and dissolved oxygen are harmful to both adult and larval blackeye gobies. Due to the disruption of successful reproduction under low pH and the developmental and physiological disadvantages under low DO, future populations of blackeye gobies could suffer greatly as anthropogenic climate change progresses.


Alora Yarbrough Presents: “The impacts of climate change on blackeye goby (Rhinogobiops nicholsii…

In Memoriam: Dr. Kenneth Coale

From The Director :
It is with heavy hearts that we inform our MLML family that Dr. Kenneth Coale has died today of a sudden aortic tear in his heart. And when we think of Kenneth we think of his kind and generous heart.
Kenneth received his B.A. and Ph.D. from UC Santa Cruz before he joined MLML in 1988 as a post-doc with Dr. John Martin. With John and many others at MLML, Kenneth orchestrated one of the great discoveries of ocean science as they explored the importance of iron as a “fertilizer” for the world’s oceans. Kenneth was a key player in these ocean sampling/experimental cruises, demonstrating that iron is a critical and limiting element in many parts of the oceans. Dr. Coale became an adjunct faculty member of MLML in 1992 and helped teach courses before becoming the Acting Director of the Labs in 1998, then permanent Director in 2001 until his retirement as Director in 2011 and Chemical Oceanographer in 2018. Kenneth was a biogeochemist, studying trace elements, radionucleotides, and trace metal dynamics but really, he had an interest in everything. At seminars and thesis defenses, he was always one of the first to ask a thoughtful, probing question (unless Dr. Cailliet beat him to the punch) no matter the subject. He mentored numerous students at MLML and elsewhere and was a steadfast and vigorous champion of MLML locally and around the world. He will be especially remembered for his clever, compassionate, and witty comments; his passion for building and designing things (an example was his popular fabrication class); and his dedication to the MLML family. He was instrumental in leading the construction of the new Labs that now sit atop the hill. He called MLML the “little marine lab that could”, and his wise leadership and forward thinking was exemplary and deeply appreciated.
We will miss him every day. It’s times like this that Kenneth would comfort us with his thoughtful tribute. And now we are left to comfort each other on our collective loss. We all recognize the great sacrifices and dedication that Kenneth gave in making MLML the special place it is today. Our deepest condolences and love go out to Kenneth’s wife Susan (an MLML alum), son Tyler and daughter-in-law Ashley and their kids Finn and Reed, and daughter Megan.
Jim Harvey
Ivano Aiello

Kenneth Coale was an adjunct faculty member when I joined MLML as an MS student in 1992 and he was director when returned as faculty in 2002. He oversaw the functioning of our facility and program during happy easier times, and harder sadder times. Much of our success is built upon the foundation he laid. Whether you agreed with him or not, collaborated with him or not, taught with him or not … there was never any questioning his intent. It was always for the best of Moss Landing Marine Laboratories …. for all of us. He preached that MLML provisioned the pioneers of the future, and that’s how I will remember him …preaching about how important our work is. That will be his legacy. Our work. Let’s keep doing the good work in honor of our dear friend and leader. I will miss you Kenneth.
Michael H Graham
Professor/Department Chair, Moss Landing Marine Laboratories