From let to right: Amanda Newsom (Ph.D. student), Melody Young (REU student), Dr. Cynthia Hays (BML post-doc), Omar Bonilla (REU student), Dr.
Matt Bracken (post-doc), Laura Rodriguez (Ph.D. student), Susan Williams, Cascade Sorte (Ph.D. student), Teresa DiMarco (lab assistant), Emily Jones (lab assistant), Albert Carranza (Staff Research Associate). Missing:
Kaiko'o Victor (REU student)
The Williams Lab, Summer 2006
Top row: Terry Fei Fan Ng (U. South Florida), Cascade Sorte (Ph.D.
student), Dr. Randall Hughes, Dr. Matt Bracken Bottom row: Eric Fan (undergrad, UCD), Sara Friberg (REU student; New Mexico Institute of Mining & Technology), Susan Williams, Albert Carranza (Research Associate), Amanda Newsom (Ph.D. student)
Absent: Laura Rodriguez (in Baja California)
Research Interests:
My research focuses on the ecology of nearshore marine ecosystems, particularly seagrass and seaweed beds and coral reefs. These ecosystems are highly productive and provide a number of ecosystem 'services' such as recycling of organic matter and providing habitat and food for numerous marine species including economically valuable ones. These ecosystems are found at the land-sea margin, a highly variable, stressful, and disturbed environment. Their component organisms are stressed from exposure to air and warming ocean waters and disturbed by anthropogenic activities including habitat destruction and invasions by non-native species. The ecosystems I study have protected status due to their value to humans, and I am committed to communicating research results to resource agencies and policy makers charged with their management (see Public Service). My focus on environmental stress and change has evolved from my career-long interest in how communities and ecosystems function, including how variation in resource availability influences resources acquisition and allocation and how species interactions (competition, herbivory) influence plant function and biogeochemical processes.
Ecology and conservation of seagrass and seaweed beds.
Seagrasses are protected under the US Clean Water Act and the loss of seagrass from deliberate causes must be mitigated. I found that the transplanting eelgrass (Zostera marina) to mitigate its loss has eroded the genetic diversity so important for its long term adaptation to the rapid changes (ocean warming, sea level rise, eutrophication) occurring in its estuarine and nearshore habitats. More importantly, transplanted eelgrass populations with low levels of genetic diversity grow slower than populations with higher genetic diversity, even over the short time period mandated for evaluation of mitigation success. These and my previous results on eelgrass genetic diversity provided the basis for the National Marine Fisheries Service to modify eelgrass mitigation policy in southern California.
Williams, S.L. 2001. Reduced genetic diversity in eelgrass transplantations affects both individual and population fitness. Ecological Applications 11:1472-1488.
Williams, S.L. and R.J. Orth. 1998. Genetic diversity and structure of natural and transplanted eelgrass populations in the Chesapeake Bay. Estuaries 21:118-128.
Williams, S.L. and C.A. Davis. 1996. Population genetic analyses of transplanted eelgrass (Zostera marina) reveal reduced genetic diversity in southern California. Restoration Ecology 4:163-180.
Ecology and management of marine invasive species.
Marine invasive species are one of the top environmental concerns for the ocean. Research in my lab has focused on the ecological effects of the non-native Asian mussel (Musculista senhousia), the stinging anemone (Bunodeopsis sp.), and the ‘killer’ seaweed (Caulerpa taxifolia) on seagrasses in southern California. We have identified the double threat that the Asian mussel and eutrophication pose for eelgrass.
Nearshore marine ecosystem function.
Seaweed Biodiversity and Ecosystem Function-
Dr. Matt Bracken and I have been funded by the National Science Foundation to evaluate the consequences of nonrandom biodiversity changes in intertidal seaweed assemblages on primary production and nutrient acquisition. Most studies to date have addressed the influence of random changes in biodiversity on community structure and function, yet we know that diversity changes in predictable, nonrandom ways in response to eutrophication, physical stress, and herbivory.
Moorea Coral Reef LTER-
I am a collaborator in the Moorea Coral Reef project supported by the National Science Foundation. I am addressing the environmental controls on nitrogen fixation by coral reef algal turfs.
This research complements my long-standing interest in how herbivory and nutrients interact to influence the primary production and nitrogen cycling by seagrasses and seaweeds.
Williams, S.L. and R.C. Carpenter. 1997. Grazing effects on nitrogen fixation in coral reef algal turfs. Marine Biology 130:223-231.
Williams, S.L. and M.H. Ruckelshaus. 1993. Eelgrass and epiphytes: the relative effects of nitrogen availability and mesoherbivory. Ecology 74:904-918.
Interactive Effects of Herbivory and Stress on Seaweed Resource
Acquisition, Allocation, and Fitness.
This study is a collaborative NSF-sponsored project with Dr. Megan
Dethier (Friday Harbor Laboratories, U. Washington). Using the high
intertidal rockweed, Fucus gardneri, as a model, we are investigating
how herbivory and stress interact to influence how seaweeds gain
resources (carbon) through photosynthesis, how they allocate resources
to key processes of growth, reproduction, herbivore-deterrent compounds
(polyphenolics), and storage. Ecological theory predicts that organisms
should make trade-offs among such processes when challenged by the
environment. While the effects of herbivory on seaweed metabolism
and populations are well-described, and there is considerable literature
on temperature and desiccation effects, the interaction between
herbivory and stress has not been investigated. Fucus is stressed
over a sharp gradient in physical factors across its intertidal
distribution over a tidal cycle and among seasons. (See Fucus Research.)
We have measured photosynthesis of Fucus from 14 sites on San Juan
Island, Washington, in both water and air to determine its carbon
balance (resource capital), accompanied by measurements of mannitol
and laminaran (brown seaweed storage products analogous to starch
in green plants), polyphenolics, growth, and reproduction to evaluate
resource allocation patterns. We have manipulated herbivory and
stress in the field and in controlled outdoor mesocosms, making
similar measurements.
Our preliminary results indicate that, at our sites, stress is
more important than herbivory in influencing growth, polyphenolic
concentration, and perhaps reproduction. Resource acquisition through
photosynthesis is limited more by the amount of time Fucus spends
exposed to air than how desiccated it is at low tide, although desiccation
does reduce photosynthetic rates. Fucus is remarkably tolerant to
large increases in temperature. If these effects are important beyond
the level of an individual, the population growth rates of Fucus
living in different environments should reflect the differences.
To test this, in collaboration with Dr. Jeff Wright, we are constructing
a demographic model to estimate population growth rates across the
intertidal distribution of the seaweed.
My research focuses on the ecology of nearshore marine ecosystems, particularly seagrass and seaweed beds and coral reefs. These ecosystems are highly productive and provide a number of ecosystem 'services' such as recycling of organic matter and providing habitat and food for numerous marine species including economically valuable ones. These ecosystems are found at the land-sea margin, a highly variable, stressful, and disturbed environment. Their component organisms are stressed from exposure to air and warming ocean waters and disturbed by anthropogenic activities including habitat destruction and invasions by non-native species. The ecosystems I study have protected status due to their value to humans, and I am committed to communicating research results to resource agencies and policy makers charged with their management (see 
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