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Kristen Delano Walter

Evan D'Alessandro
Tauna Rankin
Kathryn Shulzitski
Sean Bignami

Jared Robbins
Ashton Hogarth
Sarah Mui

In 2004 I received my Master's degree in Marine Science from the School of Marine Science at the College of William & Mary. My previous work spanned a wide range of taxa (including corals, clams, crabs, lobsters, American shad, and Atlantic sturgeon) in a variety of ecosystems in the Chesapeake Bay, Bahamas, and Florida Keys. My interests tend towards population and landscape ecology. I have extensive field experience piloting small boats in the Chesapeake Bay as well as the open ocean and a diverse diving resume that includes the zero visibility, tidally driven conditions in Chesapeake Bay as well as saturation diving in the Florida Keys at the Aquarius Underwater Habitat. I came to RSMAS in 2007 as a Senior Research Associate and currently am involved in a National Science Foundation project assessing linkages in recruitment of Florida Keys reef fishes. My main role in the lab is to organize, coordinate, and execute the NSF project field and labwork, but I also manage the day-to-day group and laboratory needs, oversee undergraduate interns and volunteers, maintain the databases, and collaborate on research projects, permit/grant writing, and manuscript publication.

My research interests broadly include the early life stages of coral reef fishes, the relationship between population stability and biodiversity/habitat complexity, the ecology of fishes on deep (> 30 m) coral reefs, and the effects of short term stochastic, and gradual long term environmental disturbance on reef fish populations. My master's thesis research was centered on an extensive time series of near-reef ichthyoplankton samples collected off Key Largo, Florida. By comparing this data to concurrently collected oceanographic and atmospheric data, we were able to describe the pattern of larval fish supply to this area in terms of both cyclic and stochastic environmental factors (D'Alessandro et al. 2007). This research helps to improve the predictability of recruitment, a key piece of information required for effective reef management.

More recently, I have focused my research on several western Atlantic species of reef fish (several snapper species, Lutjanidae, and the great barracuda, Sphyraena barracuda ) that utilize multiple nearshore environments during their life cycle. These fishes are socio-economically important, yet little is known of their general ecology, especially early life stages. Goals of my dissertation are to describe the early life history (distribution, growth, mortality, diet etc.) of these species and how populations change as they undergo ontogenetic habitat shifts (pelagic larval to nearshore juvenile to reef adult). These processes have been observed in small, abundant, model species but have not been studied in long-lived commercially important species that utilize multiple juvenile back-reef habitats before becoming reef-associated adults. This project tracks cohorts from pelagic larvae collected in net tows, late stage larvae sampled with light traps over the reef, and newly settled and juvenile fish collected with seine nets in nearshore seagrass and hard-bottom habitats. Results from this dissertation will provide valuable early life history parameters for modeling population connectivity and recruitment variability, and further refine our knowledge of which individuals will survive to contribute to adult populations and reproduction.

My research focuses on the early stages of life of coral reef fishes and their influence on population dynamics. The early life stages of many species of coral reef fishes are characterized by considerable and highly variable rates of mortality and these stages (i.e. egg and/or larval) may be the only part of the life cycle where significant dispersal occurs. Therefore processes occurring during early life may dramatically impact the overall condition of surviving individuals, year class strength, and genetic make-up of future populations. The overall goal of my dissertation research is to identify sources of variation and mechanisms important to recruitment and early juvenile life for coral reef fishes in a highly dynamic oceanographic system. Some of my individual objectives are: 1) to d etermine the temporal composition of cohorts of late-stage larvae and early juveniles using genetics and early life history traits, 2) identify traits important to survival during early juvenile life and test for carry-over effects from larval history, and 3) identify the causal mechanisms for trends in early life history traits, such as early juvenile growth.

The vast majority of benthic marine organisms exhibit a complex life cycle with pelagic larvae and relatively sedentary adults. The difficulty in directly observing dispersal events that occur during the pelagic larval phase hinders our understanding of how marine populations are demographically connected. Patterns of population connectivity are determined by biophysical transport, growth, settlement, and survival of larvae and juveniles. Larval mortality is extremely high and variable and can drive patterns of recruitment, thus, potentially influencing adult population structure. Although research programs have historically focused on either offshore or nearshore environments due to requirements in sampling methods, my thesis work is part of a larger study that integrates sampling techniques to track cohorts from the pelagic environment as early- to late-stage larvae through to benthic reef habitat as juveniles up to three weeks old. The first objective of my thesis is to characterize larval distributions and abundances in the Florida Keys and Loop Current. The second objective is to examine the influence of mesoscale eddies on larval distributions and growth rates. Finally, the third objective is to determine patterns of selective mortality in larvae and carry-over in early juveniles with respect to onshore-offshore and upstream-downstream comparisons as well as the influence of eddies. An increased understanding of the factors affecting transport, growth, and survival throughout the most vulnerable life stages will improve our understanding of marine population connectivity and our ability to manage and conserve marine populations.

The early life stages of marine fishes experience incredibly high mortality rates, yet survival and recruitment are critical to the maintenance of biodiversity the replenishment of fishery stocks. As global climate change becomes a more measurable phenomenon, it becomes increasingly important to understand how changing environmental parameters may affect the process of larval development. My proposed research will investigate the impact of predicted climate change, such as CO 2 -induced ocean acidification, increased temperature, and shifting trophic dynamics, on larval development and physiology. Impacts on larvae have the potential to influence individual fishes, the ecology of coral reef fish communities, and possibly even the population connectivity between reefs. An increased understanding of potential future climate impacts on the early life phases of tropical fishes will serve as a foundation from which further research and/or fisheries management decisions can be directed.

Klaus Huebert--NRC Postdoc, Southeast Fisheries Science Center/NOAA, Miami, Florida (klaus.huebert@noaa.gov)

Jennie Boulay-- Graduate Student, Penn State, University Park, Pennsylvania (jnb186@psu.edu)

Lisa Havel -- Graduate Student, Marine Science Institute, The University of Texas, Port Aransas, Texas (lisie530@netscape.net )

Paige Roberts -- Smithsonian Environmental Research Center, Edgewater, Maryland (paigem.roberts@gmail.com)

Kelly Denit -- Program Coordinator Office, National Marine Fisheries Service/NOAA, Washington, DC (Kelly.Denit@mail.nems.noaa.gov)

Kirsten Grorud-Colvert -- PISCO/COMPASS Marine Reserve Science Coordinator, Oregon State University, Corvallis, Oregon (grorudck@science.oregonstate.edu)

Michelle Paddack -- Faculty, Santa Barbara City College, Santa Barbara, California (mjpaddack@sbcc.edu)