My research focuses on understanding the factors (natural, anthropogenic, physical & biological) that influence community structure in benthic marine ecosystems. While I conduct research in a number of different systems, both pristine and degraded, my primary interests lie in determining how different anthropogenic impacts affect coral reef community structure. When coral reefs undergo degradation, a “phase-shift” usually occurs where reef-building corals are replaced by fleshy macroalgae. Phase-shifts are often considered to be irreversible and the end result is a macroalgal dominated community that lacks the diversity, complexity and structure necessary to support a typical reef assemblage. I have and continue to study various anthropogenic factors that cause phase shifts from coral to algal dominance. Specifically my research focuses on the importance of herbivory (or overfishing) and increased nutrient concentrations (in association with pollution from land) in maintaining the competitive balance between algae and coral. Further, I study the dynamics of introduced and invasive marine species, specifically seaweeds. With this work I have taken a holistic approach by trying to understand a) why these invaders are so successful in their invaded environments, b) what impacts they have on native communities, and c) what management options will be useful in controlling their abundance in the invaded habitats. I have a long-term interest in seaweed invasions especially as related to intentional introductions for the aquaculture industry. My research often goes beyond basic ecology by integrating conservation, restoration, management and sustainability. More recently I have been investigating the interactions of microbes and macrobes on coral reefs and have shown that these indirect interactions may be highly important to overall community structure and function. In the future I plan to begin investigating the potential for reef restoration in an effort to understand if phaseshift reversal is possible.
Shifting Baselines and Remote Reefs
Most of the knowledge that we as scientists have gained from coral reefs has come from studies that have been conducted in the last several decades on reefs that have been highly disturbed (Caribbean, Hawaii, etc). In order to understand what coral reef systems look like and how they function in the absence of human disturbance the Smith lab and several collaborators have been conducting research in the highly remote central Pacific. Research from some of the most remote islands in the tropics has revealed that in the absence of local human disturbance coral reefs may be resilient to climate associated impacts. This research is ongoing and involves detailed experiments, observations, taxonomic catalogues and sample collection and analysis. The results gained from these studies are being used to set targets for the conservation and restoration of degraded reefs elsewhere in the world.
Recovery of Coral Reef Communities from Temperature Induced Bleaching
Using experiments in the Hawaiian Islands we plan to build underwater temperature controlled “domes” to experimentally warm small sections of the reef. After coral bleaching is initiated we will remove the domes and examine how overfishing and/or pollution affect the ability of the reef to recover from these bleaching events. This will represent the first set of experiments to manipulate temperature underwater on a reef using new and innovative technologies. This study will take place at one of the most popular dive sites on Maui and will include a large education and outreach component regarding human impacts on coral reefs.
Coral Reef Resilience & Restoration
Jennifer has been working in the Hawaiian Islands for several years where she has documented significant changes in coral reef communities associated with overfishing, sewage and nutrient pollution as well as the introduction of non-indigenous species and removal of key members of the reef.
Interactions between Coral, Algae & Microbes & Implications for Ecology
Competition for space on coral reefs can be fierce where benthic organisms are often in direct contact with one another. During varying stages of reef degradation it has been suggested that algae may be able to overgrow reef building corals but there has been little evidence to suggest how this actually occurs. Jennifer has been working in collaboration with a multidisciplinary group of researchers to identify that photosynthetic algae can actually cause coral mortality by enhancing microbial activity. The primary trigger for this algal mediated, microbe induced interaction occurs as a result of algae leaking or exuding excess photosynthate or dissolved organic carbon (DOC)-as most other primary producers are known to do. Because DOC can be limiting to bacteria they respond by increasing in abundance and increasing rates of respiration which can lead to a draw down in the oxygen levels where the corals and algae are in contact and this hypoxia causes coral mortality. This new and cutting edge research is the focus of a recent NSF award that Jennifer and her colleagues received and is an active area of research that highlights the complexities of species interactions in natural environments.
Global Change & Marine Communities
The Smith lab is currently expanding this research program in the coming years to look at the effects of OA in the largest survey to date across the US tropical Pacific through collaboration with the National Oceanic and Atmospheric Administration’s Coral Reef Ecosystem Division. This work will provide the most comprehensive understanding of how OA is already affecting tropical marine ecosystems. Additionally, students in the Smith lab are working with engineers to build the first underwater heating device that will be used to study the effects of sea water warming on marine communities in their natural environments. This effort represents a significant technological challenge but if successful will yield the data on the effects of warming on intact marine communities. The results of these global change experiments will be highly important for predicting how incredibly fragile and vulnerable ecosystems such as coral reefs will change in the coming decades.
Too see some highlights of our current research please click here.
Coral Reefs of the New Pacific Remote Island Areas (PRIAs) National Marine Monument
Former President G. Bush designated one of the largest marine protected areas just prior to leaving office in the remote central pacific in 2008. This new monument contains some of the most untouched and likely pristine coral reefs on the planet. Despite the newly protected status of these remote areas we know very little about the coral reef communities that inhabit them. We propose to work with a historical set of archived photographic data from the National Oceanic and Atmospheric Administration’s Coral Reef Ecosystem Division to determine the composition of the coral reefs of these new Monuments. We plan to a) determine whether these remote islands contain some of the most pristine reefs in the US and the world, b) determine if there is any evidence of climate impacts on these reefs, and c) using experiments determine how key aspects of the reef ecosystem differ in comparison to the more degraded reefs that we are accustomed to studying in populated areas.