RESEARCH STATEMENT
AMANDA L. KELLEY
Overview
I am a Marine Biologist
interested in understanding the
resiliency of marine species to
ocean change. From a broad
perspective, my research focuses
on organism-environment
interactions in coastal marine
ecosystems, with the goal of
understanding how this overarching element will contribute
to the outcome of species
response to global environmental
change (e.g., temperature and
pH), and physiological mechanisms that influence the successful establishment of non-native species.
Notably, both of my research interests are strongly linked to studying marine populations in the
Anthropocene, an era where human impact will play a strong role in structuring coastal marine
populations/communities and altering marine resources.
In practice, I take an integrative approach that includes using comparative physiological
techniques, microscopy, and variety of molecular laboratory assays to characterize the responses of
marine species to abiotic factors across many levels of biological organization. I also use oceanographic
sensors to inform both field and laboratory experiments. Environmental monitoring provides ecological
context that links cellular and organismal processes with the dynamic, changing ocean environment. My
current research interests- to examine the physiological responses of marine species to ocean change,
coupled with my previous work- characterizing the physiological mechanisms that facilitate invasion
success, leave me poised to strongly contribute to any research program. Below I describe these projects,
and further, highlight how these experiences will help me to grow and further develop my research
program as an Assistant Professor.
Global Change Biology
The response of larval Sterechinus neumayeri, to future ocean change. As research performed in
association with my postdoc fellowship, this is the most recently ongoing work for me. It does, however,
link directly to concepts and questions that are applicable in all coastal oceans, namely that of complex
chemical and physical oceanography and changes in these patterns that will impact the ecology of coastal
marine ecosystems. For example, future climate change predictions for the Southern Ocean include
increased temperature, decreased salinity, and ocean acidification- [OA] [1]. I am evaluating how early life
history stages of S. neumayeri, the Antarctic echinoid, will respond to the future, multi-stressor scenario.
Using an integrative approach, I am currently assessing the physiological response of S. neumayeri by
measuring O2 consumption as a proxy for metabolism, and quantifying larval size, which will provide an
organismal metric to measure the fitness costs associated with development under the synergistic
stressor regime. Concomitant with whole-organism measurements, I am evaluating how broad scale gene
expression is modulated under the multi-stressor conditions using RNAseq. This information can provide
mechanistic insight into the physiological processes that are utilized to attempt a return to homeostasis.
RESEARCH STATEMENT
AMANDA L. KELLEY
This work is a step forward in providing evidence regarding the resiliency of marine calcifiers to dynamic,
future ocean change.
The relationship between ocean
acidification and reduction in larval size. I
am investigating the mechanistic basis
driving the reduction in larval size of S.
neumayeri during development under OA.
Because cell proliferation is especially
critical for growth in early larval
developmental stages, I am particularly
interested in understanding the effect of
future OA conditions on an organism’s
ability to regulate intracellular pH- pHi.
Early life history stages of echinoids from
temperate, tropical and polar regions,
Variation in larval area in Sterechinus neumayeri reared under control
including S. neumayeri [2], are particularly (blue) and elevated (yellow) pCO2 conditions.
sensitive to OA, resulting in a reduction in larval size throughout early development, suggesting that this
is a “cost of living” associated with development under hypercapnia. Furthermore, OA has been shown to
impose a level of stress sufficient to impair an organism’s ability to control pHi, resulting in intracellular
acidosis [3]. Biomedical studies illustrate that intracellular acidosis negatively influences downstream cell
cycle regulatory pathways that initiate cell cycle arrest, and therefore have been a target of cancer
research [4-6]. Using fluorescence microscopy, I will measure pHi in larvae reared under hypercapnia, and
genes involved in cell cycle regulation, DNA synthesis, and apoptosis will be screened for expression levels
using the quantitative method, digital droplet PCR. Results from this study will contribute to the currently
limited knowledge of the mechanistic link between future OA conditions and the observed reduction in
larval size of sea urchins during development.
Coupling laboratory experiments with environmental data. In order to accurately parameterize studies that
investigate the response of marine biota to OA, it is critical to have environmental data that can be used
as a baseline to explore future OA trajectories that are ecologically relevant. I have been involved in the
deployment and recovery of Durafet-based autonomous pH sensors in McMurdo Sound, Antarctica. This
work has yielded the first ever continuous time-series pH data set from the Antarctic continent over a
seven-month period [7]. Using this new found knowledge, I conducted the first ever ocean acidification
study in Antarctica
that incorporated
the alkalinization
event that was
captured using pH
sensor technology.
Over-summer pH measurements from McMurdo Sound, Antarctica. Left panel- Jetty site at McMurdo
Station. Right panel- Cape Evans site.
RESEARCH STATEMENT
AMANDA L. KELLEY
Temperate coastal ocean: The response of marine calcifiers to OA and hypoxia. Similar to my work in
Antarctica, I am interested in linking coastal marine processes to physiological performance in temperate
marine ecosystems. Upwelling events in coastal regions of western North America produce both acidic
and hypoxic conditions that are predicted to become more severe as the ocean continues to absorb
increasing amounts of anthropogenic CO2 [8]. I am currently collaborating on a project with graduate
students in the Hofmann Lab that explore the interaction of OA and Oxygen content by co-locating pH
and O2 sensors inside and outside macrophyte beds to parameterize these environments. Kelp forests
have the potential to buffer the effects of acidic and hypoxic upwelling events, and therefore may be of
particular interest for future conservation efforts. Using our experimental CO2 system at UCSB, we have
initiated preliminary studies that explore the response of larval Kelletia kelletii, Kellet’s Whelk to OA
conditions, with the goal of performing out-plant experiments inside and outside of kelp forests next
spring. Finally, we will pair the out-plant experiment with a laboratory experiment that examines this
species’ response to the interacting effects of OA and hypoxia.
Invasion Biology
Mechanisms that facilitate invasion success. The main thrust of my Ph.D work was to better understand
the patterns and processes involved in the establishment of invasive marine species. Specifically, this
work focused on the phenotypic response of Carcinus maenas, the European green crab, to variations in
environmental temperature along the recipient range on the west coast of North America. I examined
how temperature affected (1) population level phenotypes, (2) organismal thermotolerance, and (3)
molecular response to heat and cold shock. I was interested in discerning whether crabs sampled from
different sub-populations would exhibit different physiological properties, and if site-specific
augmentation of those properties were in part responsible for the success of this globally invasive
species. Moreover, characterizing the thermal physiology of an invasive organism can be used as a
predictive tool for estimating the probable distribution of such species in novel environments, or during
range expansion [9].
(1) Population level phenotypes. For ectotherms, variations in environmental temperature can produce a
biogeographic gradient in body size across a species’ range. This type of phenotypic response to
temperature is called the temperature-size rule for ectotherms, as rearing under warmer conditions can
result in a reduction in body size. To test whether this invasive population of green grabs demonstrated a
biogeographic variation in body size, crabs were collected and carapace width measured from 10 sites
spanning from Central California to Vancouver Island over a 5 year period. A 5 year mean temperature
was generated for each site using NOAA Buoy data. I also conducted a literature review of C. maenas size
and temperature across its native range. Adult body size was significantly correlated with environmental
temperature in both the native and invaded ranges, conforming to the temperature size-rule for
ectotherms. Forces that shape the phenotypic trajectory of species may play an important role in both
invasion dynamics and subsequent ecological impacts [10].
(2) Organismal thermotolerance. Taking a comparative approach, I collected animals from the range
edges of this population, including a warm acclimated site- California, USA [CA], and cold-acclimated sitePipestem Inlet, British Columbia, Canada [BC]. Crabs sampled from BC had a significantly lower, upper
RESEARCH STATEMENT
thermal tolerance (critical thermal maxima) after lab
acclimation of 6 and 23°C when compared to the CA
population when given heat stress [11]. These results
highlight the ability of the BC population to down
regulate its upper organismal thermotolerance to
reflect the colder environment that it now inhabits,
mirroring native ectotherms that have had millennia to
make adaptive changes to their genome. For this
species, it is likely that altering the scope of thermal
tolerance, after acclimation, is one physiological process
that has proved to be vital to invasion success.
AMANDA L. KELLEY
* p < 0.05 and ** p =0.001, t-test; error bars represent
standard error.
Organismal-level thermotolerance measurements can impart a great deal of ecologically
applicable information regarding the potential distribution of an invasive species within the context of a
new environment. C. maenas were initially introduced in San Francisco Bay, CA, in 1989, however, range
expansion has been primarily northward, highlighting this population’s response to cold temperature as
an eventual limiting factor for further range expansion. Cold tolerance capacity was determined in the
laboratory by holding crabs sampled from
Vancouver Island, British Columbia, near the present
northern limit for the northeast Pacific population,
to an overwintering thermal profile generated from
Sitka, Alaska, USA. These crabs were physiologically
capable of overwintering north of their present
range boundary, highlighting the ability of this
population to physiologically withstand cold stress,
and persist, outside their present range limit [12].
(3) Molecular response to heat and cold shock. To assess whether the site-specific variation organismal
thermotolerance was manifested at the molecular level, I compared the cellular response to heat stress in
crabs sampled from the aforementioned sites, BC and CA, after lab acclimation to 6 and 23°C. I found
site-specific regulation of the protein chaperone Heat shock protein 70- Hsp70, a molecular mechanism
found to be crucial to the establishment and maintenance of the upper thermal tolerance threshold. The
BC group had a significantly lower level of Hsp70 after acclimation to 6°C, indicating that C. maenas from
colder habitats given cold acclimation possess an overall lower thermal set point for Hsp70 induction [11].
This result suggests that they are more thermally sensitive than their warm-acclimated counterparts.
Variations in the threshold of thermal set points across a
geographic range are likely to be beneficial because overor under-expression of Hsps can directly affect the fitness
of an organism. I then compared these how these
subpopulations compared in response to cold shock. I
measured the cell cycle regulator cyclin D1 protein, and
found that the BC crabs down regulated cyclin D1 after
cold shock relative to control levels, suggesting that cell
proliferation was reduced in suboptimal conditions [12].
** p =0.001, t-test; error bars represent standard
CA crabs made no cyclin D1 adjustment to cold shock.
error.
RESEARCH STATEMENT
AMANDA L. KELLEY
Future ResearchI feel I could strongly contribute to any marine science/biology department, and provide valuable
experience integrating organism-environment studies in the context of global environmental change.
Through my postdoctoral work, I’ve gained considerable proficiency in building and maintaining CO2
experimental systems, and would be able to develop as a faculty member. In conjunction with
establishing laboratory studies using the CO2 system, I can also add multi-stressor components to this
experimental system, including temperature and O2 content, for example. This could bridge to studying
coastal hypoxia, a growing issue in the United States [13]. My experience with larval culturing can be used
to assess how local early life stage invertebrates respond to environmental stress that is associated with
global environmental change. For example, research projects on economically important mariculture
species such as Callinectes sapidus- the blue crab, or Metacarcinus magister- the Dungeness crab could
be very important for the regional economy and would open up funding opportunities from agencies, e.g.
Sea Grant, the National Science Foundation and NOAA. I can establish a coastal sensor network using
oceanographic sensors, e.g., pH, oxygen, temperature, and potentially contribute to a growing sensor
network. If given the opportunity, I would also be able to continue my research studying abiotic factors
that affect the distribution and abundance of invasive marine species, as the need for such work is a
critical element outlined by The National Invasive Species Council. The procurement of research funding
is of great importance to me, and I will continue to apply for grants in my field of study. Also, my research
background would allow for collaborations with colleagues from diverse backgrounds with the goal of
securing future funding in particularly critical fields of study.
References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Stocker, T.F., et al., Climate Change 2013. The Physical Science Basis. Working Group I Contribution to the Fifth Assessment Report of
the Intergovernmental Panel on Climate Change-Abstract for decision-makers. 2013, Groupe d'experts intergouvernemental sur
l'evolution du climat/Intergovernmental Panel on Climate Change-IPCC, C/O World Meteorological Organization, 7bis Avenue de la
Paix, CP 2300 CH-1211 Geneva 2 (Switzerland).
Yu, P., C, et al., Growth attenuation with developmental schedule progression in embryos and early larvae of Sterechinus neumayeri
raised under elevated CO2. PloS one, 2013. 8(1): p. e52448.
Stumpp, M., et al., Digestion in sea urchin larvae impaired under ocean acidification. Nature Climate Change. 3(12): p. 1044-1049.
Bobik, A., et al., Ethylisopropylamiloride-sensitive pH control mechanisms modulate vascular smooth muscle cell growth. American
Journal of Physiology - Cell Physiology, 1991. 260(3): p. C581-C588.
Takasu, T., et al., Apoptosis and Perturbation of Cell Cycle Progression in an Acidic Environment after Hyperthermia. Cancer Research,
1998. 58(12): p. 2504-2508.
Rich, I.N., et al., Apoptosis of leukemic cells accompanies reduction in intracellular pH after targeted inhibition of the
Na+/H+exchanger. Blood, 2000. 95(4): p. 1427-1434.
Kapsenberg, L., et al., Near-shore Antarctic pH variability has implications for the design of ocean acidification experiments. Sci. Rep.,
2015. 5.
RA, F., et al., Evidence for upwelling of corrosive “acidified” water onto the continental shelf. Science, 2008. 320: p. 1490.
Kelley, A.L., The role thermal physiology plays in species invasion. Conservation Physiology, 2014. 2(1).
Kelley, A., et al., Biogeographic variation in body size of Carcinus maenas, the European green crab. Marine Biology, 2015. In press.
Kelley, A.L., C.E. de Rivera, and B.A. Buckley, Intraspecific variation in thermotolerance and morphology of the invasive European
green crab, Carcinus maenas, on the west coast of North America. Journal of Experimental Marine Biology and Ecology. 409(1-2): p.
70-78.
Kelley, A., C. Rivera, and B. Buckley, Cold tolerance of the invasive Carcinus maenas in the east Pacific: molecular mechanisms and
implications for range expansion in a changing climate. Biological Invasions, 2013: p. 1-11.
Hagy, J.D., et al., Hypoxia in Chesapeake Bay, 1950–2001: Long-term change in relation to nutrient loading and river flow. Estuaries,
2004. 27(4): p. 634-658.