Thesis Defense by Stephan Bitterwolf – November 3rd, 2017

Physiological effects of nitrate, light, and intertidal position on the red seaweeds Mazzaella flaccida and Mazzaella splendens

A Thesis Defense by Stephan A. Bitterwolf

Phycology Lab

Friday, November 3rd at 12pm

MLML Seminar Room

Thesis Abstract:

California’s intertidal seaweeds Mazzaella flaccida and Mazzaella splendens reside in different intertidal zones. The yellow-green M. flaccida is found in the high- and mid-intertidal, while the brown-purple M. splendens is found in the mid- and low-intertidal. These differences in intertidal position and blade color, in addition to minute differences in morphology, are typically used to differentiate these species in the field. However, a reciprocal transplant study by Foster (1982) found that, not only can M. flaccida and M. splendens reside in each other’s zone, but the color of M. splendens can change to the yellow-green of M. flaccida. Thus, Foster (1982) suggested that these two species may be conspecifics. Presently, genetic evidence supports the separation of both species, however, little progress has been made towards determining the cause, mechanism, and impact of this chromatic plasticity on thallus physiology. The present study serves to further our understanding of this chromatic plasticity in Mazzaella through a series of field and laboratory experiments. In the field experiment, 360 individuals (180 of each species, 90 controls and 90 experimental) were reciprocally transplanted within the intertidal zones of 3 central California sites. Thereafter, transplants were monitored monthly from June – October for blade size and presence. In October, all transplants were removed for pigment analysis. In the laboratory experiments pigment concentrations of both species were quantified from seaweeds cultured in reduced or replete irradiances and nitrate concentrations. Differences in blade size, pigment composition, and survival between site, intertidal zone, species, and culture treatment were investigated with 2-way ANOVAs and non-parametric tests. In these experiments: (1) greening was documented only for seaweeds in the culture experiments, (2) survival was greatest in the low intertidal zone, (3) high intertidal seaweeds contained greater photoprotective pigment content, (4) M. flaccida exhibited increased capacity to regulate photoprotective pigments, and 5) M. splendens exhibited increased capacity of phycobilin pigments. The results of this study illustrate how these intertidal seaweeds can survive adverse conditions such as nutrient limitation or increased light stress/desiccation by cannibalizing phycobiliproteins and increasing photoprotective pigments. The differing extent of each species to regulate photoprotective and phycobilin pigments supports their current classification as separate species.

Acknowledgements from Stephan: This work would not have been possible without the support I received from mentors, labmates, students, family, and friends. Thanks all :D!

Funding: NSF GRFP, Myers Trust, and MLML Wave.

CDFW Permit: #13419

Thesis Defense by Jen Keliher – October 30th, 2017

Microbial Metagenomes from Cryptofaunal Sponges and Ascidians from Moorea, French Polynesia

A Thesis Defense by Jen Keliher

Invertebrate Zoology and Molecular Ecology Lab

Monday, October 30th at 12pm

MLML Seminar Room

Jen’s thesis is investigating microbial metagenomes from cryptofaunal sponges and ascidians from Moorea, French Polynesia. She is interested in the role of microbes in affecting the health of coral reef invertebrates and how host-associations change in response to human-induced stressors. What excites her most about this research is broadening our understanding of how microbes are integrated in the larger reef system.
Jen is also interested in educational outreach and capacity-building in youth. She currently a Bilingual Education Specialist at the Monterey Bay Aquarium teaching preK-12 school programs and co-leading two middle school programs: Young Women in Science and the Student Oceanography Club. As part of Dr. Geller’s NSF Partnerships for International Research and Education (PIRE) project, Jen is helping build capacity in students involved in the US-Indonesian partnership by having helped with the 2013 Diversity Project class in Bali and by working with Indonesian students.
Jen received her B.S. in Marine Biology with a minor in Interdisciplinary studies from San Diego State University. As an undergraduate Jen worked on a diversity of projects including an endocrine study on Arctic bowhead whales, a genetic study on Mako and Thresher sharks, a behavioral ecology study on resident and transient killer whales, and other ecology projects in the wetland habitats of Baton Rouge, Louisiana and San Diego, California. She is an active member of MLML’s AAUS scientific dive program, volunteers much of her time in her faith community, and is a mentor for undergraduate students in the Enlace Program at Evergreen College in San Jose. 

Thesis Defense by Paul Clerkin – October 30th, 2017

Aspects of The Life History And Taxonomy Of Deep-Sea Chondrichthyans in the Southwestern Indian Ocean

A Thesis Defense by Paul Clerkin

Pacific Shark Research Center

Monday, October 30th at 4pm

MLML Seminar Room


Paul Clerkin graduated cum laude from Cornell University in the winter of 2010 with a double major in Science of Natural and Environmental Systems and Natural Resources.  He also received associate degrees from Sacramento City College with President’s Highest Honors in Biology, Chemistry, Physical Science, Sociology, and Humanities.  His research experience includes storm tracking with the Coastal Processes Division of NOAA, an NSF REU internship at Rutgers University Marine Field Station,  research assistantships in chemistry (at American River college) and Ichthyology (at Cornell's Museum of Vertebrates), and a research voyage aboard a tall ship during SEA's semester at sea.

After completing his undergraduate degree, he served several deployments as a shipboard Certified Fisheries Observer with the National Marine Fisheries Service in the Bering Sea out of Dutch Harbor, Alaska.  In 2011, he began his studies at MLML’s Pacific Shark Research Center under his adviser, Dr. David Ebert.  He has worked with Dr. Ebert to instruct chondrichthyans workshops on the island nations of Mauritius and the Seychelles for the Food and Agriculture Organization of the United Nations.  He also participated in a cruise in the Southern East Atlantic as a shark expert for FAO/UN.

Thesis Abstract:

During the last quarter of a century, the conservation and management of chondrichthyans (collectively, sharks, rays, and chimaeras) has received considerable focus. This is especially true for deep-sea chondrichthyans. As technologically advanced fisheries expand into deeper waters of the high seas, new chondrichthyan species are being discovered and described at an increasing rate. The objectives of this study were to investigate the deep-sea chondricthyan fauna in a remote region of the Southwestern Indian Ocean Offshore and provide descriptions of three species of Chimaeridae previously unknown to science, and collect and analyze biological parameters relating to the life histories of all shark species encountered. Specimens were collected as bycatch in deep-sea fisheries from 46 sites along deepwater seamounts of the Southwest Indian Ocean Ridge and the Madagascar Ridge. Among the species encountered were three relatively large chimaeroids, which upon closer examination, were determined to be distinct from all other known members of the family. A description these three new species is presented. A total of 4009 specimens were examined and sex ratios, size range, smallest mature, largest immature, and length at 50% maturity (LT50) calculated. Detailed information is presented on the reproductive biology, life history, and distribution of 31 species representing 14 genera.

Thesis Defense by Dorota Szuta – October 25th, 2017

Community structure and zonation of Antarctic benthic invertebrates: using a remotely operated vehicle under ice to define biological patterns

A Thesis Defense by Dorota Szuta

Benthic Ecology & Geological Oceanography Labs

Wednesday, October 25th at 4pm

MLML Seminar Room

Dorota Szuta is a Master’s student under the guidance of Dr. Stacy Kim of the Benthic Ecology lab and Dr. Ivano Aiello of the Geological Oceanography lab. She earned her BS degree in Marine Biology at UC Santa Cruz in 2009. After her undergraduate work, she worked in the Benthic Ecology lab as a field diver and lab tech for two years. In her free time, she likes to play music, make art, and pet dogs. Her Master's thesis focuses on communities of benthic invertebrates under ice in Antarctica.

Thesis Abstract:

The Ross Sea, Antarctica is a deep bay of the Southern Ocean that exhibits seasonal sea ice and is adjacent to a permanent ice shelf overlying seawater. Though the shallow-water seafloor communities in the Ross Sea are known to be high in species richness and abundance, the deeper sublittoral zone (approximately 25 m – 200 m) has been generally understudied and, especially under the Ross Ice Shelf, the benthic community composition is largely unknown. In 2008 and 2009, imagery of the seafloor at two sites under the permanent Ross Ice Shelf and two sites under the seasonal ice in the Ross Sea was collected via remotely operated vehicle (ROV) at depths to 300 m. Several patterns in Antarctic benthic communities were seen over multiple environmental gradients. Species abundance typically exhibited a unimodal distribution with depth, reflecting a food limitation at the deep end and potentially ice disturbance on the shallow end. Diversity and depth had quadratic relationship at two of three sites encompassing a depth gradient. In terms of functional groups, the proportion of suspension feeders decreased with depth at one site, and no pattern was found at other sites. The group sessile predators, comprised of several species of anemones, increased with depth proportionally, suggesting that they use a range of feeding strategies to adapt to life at depth. Benthic communities under seasonal ice were different than those under permanent ice shelves, with higher overall species diversity, a greater proportion of suspension feeders, and a degree of magnitude higher abundance.

Thesis Defense: Angela Zepp- October 6th, 2017


Angela Zepp, originally from the landlocked state of Missouri, developed her love for the ocean at a young age but rarely had the opportunity to visit. To pursue her dreams, she moved to California to attended Humboldt State University and developed a love for diving. Fast forward to 2017, where she is completing her Masters Degree at Moss Landing Marine Lab!  


Thesis Abstract

Tripping on Acid for 2 years: Factors driving demographic and temporal variability in pH of the acid weed, Desmarestia herbacea


Angela Zepp

Demographic studies allow for a better understanding of how populations change over time and establish a baseline to examine how biotic and abiotic factors influence populations.  The annual seaweed, Desmarestia herbacea, or the acid weed, accumulates sulfuric acid (H2SO4) within cell vacuoles, likely as a chemical defense mechanism. Whether pH varies ontogenetically is poorly understood. A D. herbacea population in the Stillwater Cove, central California kelp bed was assessed for two years to measure how internal pH varied relative to demographics, season, grazing pressure, and environmental variability. The timing of spring recruitment and fall senescence varied interannually. Sporophyte recruitment occurred during upwelling season in mid-March and thalli reached maximum length during the Oceanic season (July-October) then senesced during the Davidson Current season (November-February). Mean thallus length was inversely related to density with smaller plants present in 2015 when densities were higher.  In contrast in 2016, individuals were significantly larger and density was lower and the senescence period extended into January 2017. The ontogenetic shift in intracellular pH of D. herbacea was seasonal in both years and may be driven by ocean temperature. In 2016, the pH was highest during the recruitment period (1.38 ± 0.14), followed by a decline in pH during the growth period (0.60 ± 0.01), followed by an elevation during the senescence period (0.65 ± 0.02). Benthic invertebrate grazers had a strong, significant and negative effect on the early recruitment of D. herbacea both in permanent plots and an herbivore exclusion experiment. Plots with higher herbivore abundance had significantly lower recruitment. Higher densities of Desmarestia, and smaller plants in 2015 may have been correlated with higher temperatures in 2015 associated with El Niño.  These findings suggest that despite inter-annual variability in demographic patterns, strong, seasonal shifts in intracellular pH may reflect ontogenetic shifts in chemical defense to protect vulnerable growth phases of life history.

Thesis Defense by Mo Wise- September 25th, 2017

Thesis Abstract


Nutrient Dynamics In Tidally Restricted Regions Of The Elkhorn Slough National Estuarine Research Reserve


Maureen M. Wise

Masters of Science in Marine Science

California State University Monterey Bay, 2017

            The Elkhorn Slough, in the heart of the Monterey Bay, includes water bodies that have been isolated from natural tidal flushing cycles by dikes, levees, roads and train tracks.  This partitioning has changed the functionality of these systems primarily through reduced circulation and increased eutrophication. The Elkhorn Slough is surrounded by a patchwork of lands under varied land-uses, including open space, developed properties, and extensive agriculture, which results in high and variable nutrient loading into the surrounding aquatic habitat. Water bodies of restricted flow disproportionately exhibit impacts due to this loading. In this study, nutrient concentrations were measured using both discrete water column sampling methods and in situ osmotic sampling techniques.  Fluxes were measured using flow measurements, ground water flux correlations, benthic chambers, modeled pore water gradients and estimates of Ulva uptake. These measurements were used to quantify the cycling of nitrate, ammonium and phosphate in these pocket regions and has identified systemic nutrient drivers to be surface water flow, Ulva uptake and groundwater inputs. A box model approach was used to determine the degree to which these drivers contributed to overall nutrient concentrations on a seasonal timescale. The systems of study were all in dynamic disequilibrium, rather than steady-state. Nitrate varied from xx to yy on timescales as short as bb. Ammonium varied from ee to ff, and Phosphate varied from  cc to dd on similar timescales.  These variations were large compared to the same nutrients in the adjacent Elkhorn Slough.  Such variability is significant when characterizing these systems, as it is indicative of the nature of nutrient flux in tidally restricted ecosystems and the rapid extremes in chemical composition experienced by the resident biota. The dominant sources of nutrients in these restricted areas also varied in time with surface runoff dominating in the wet season, and ground water inputs (possibly due to agricultural irrigation) dominating in the fall. Ulva uptake and advective flow were the largest loss terms and these too varied significantly in time.  Understanding the key nutrient drivers, as well as the degree to which these drivers influence biogeochemical cycling of nutrients in these systems, informs mitigation projects as to how best manage estuarine regions with structural barriers inhibiting natural flow, a increasingly common feature of the coastal landscape.