Scientific Data Analysis
My research studies the ecology of deep-sea chemosynthetic communities at scales from the population dynamics of a single species to the metacommunity dynamics of hydrothermal vents and cold seeps around the world. In addition to fieldwork, I primarily apply a computational approach to my ecological analysis. Today it’s more important than ever to leverage all the deep-sea data at our disposal to answer ecological questions. Even though we continue to discover new deep-sea species and communities regularly, these habitats are increasingly being threatened by human impacts such as deep sea mining and oil and gas exploration
The lifespan and population dynamics of centuries-old tubeworms
Vent and seep tubeworms have long fascinated the scientific community since Riftia pachyptila was first discovered at the Galapagos Rift vents in 1977. These vestimentiferan tubeworms receive all their energy from chemosynthetic symbiotic bacteria and serve as a foundation species at both hydrothermal vents and cold seeps. Riftia made headlines when it was found to be the fastest-growing marine invertebrate, and a few years later the cold-seep tubeworm species Lamellibrachia luymesi took the record of longest-lived non-colonial animal known to science. L. luymesi and another species Seepiophila jonesi form the foundation of cold-seep communities in the Gulf of Mexico between 300m and 950m and have both been shown to reach ages over 250 years, but the lifespan of a third species of tubeworm, Escarpia laminata, found deeper than 1000m in the Gulf of Mexico was unknown. Using in situ growth data collected by my collaborators and the growth model developed for L. luymesi, I modeled how the annual growth rate of these tubeworms changes over their lifetime and used this data to simulate their growth. I also estimated the mortality and recruitment rates to construct a full population simulation that captures the growth rate variability among individual tubeworms and finds how many years it takes to reach size distributions that resemble real tubeworm aggregations in nature. My simulations support the lifespan estimate that large E. laminata individuals reach ages over 300 years old. This work was recently published in The Science of Nature and has been covered in a number of press releases. |
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Examining the range of seep influence on the surrounding deep sea
Cold seeps are thought of ecologically as discrete, island-like communities. Seep-associated communities are constrained to localized areas around a seep, but this does not isolate the surrounding deep sea habitat and organisms from the influence of seep chemistry. The hydrocarbons and hydrogen sulfide released at seeps are necessary for chemosynthesis but toxic to non-adapted species, forcing other deep-sea organisms to keep their distance from younger or more active seep sites. As the seep community matures, the flow of seepage is reduced and eventually blocked off by the microbial production of authigenic carbonate, which serves as an attractive hard substrate for the settlement of corals and other suspension feeders. The deep Gulf of Mexico is home to hundreds of active seep sites as well as abundant cold-water coral communities. These communities are often within close proximity to one another, offering an ideal ecosystem within which to characterize the ecological boundary around a cold seep. My study uses data collected by WHOI’s AUV Sentry, which pairs downward-looking photographs of the seafloor with concurrently collected water chemistry data. By visually examining the distribution of seep and non-seep species in the photos and creating a fine-scale map of the habitat, I can determine which abiotic seepage factors are most important in determining species’ distributions and how far geographically this influence extends around the center of the seep. |
Characterizing a novel hybrid habitat and analyzing global metacommunity dynamics
Hydrothermal vents and cold seeps are both chemosynthetic habitats whose communities share many similar organisms related at the genus level or higher, but these ecosystems have always been considered distinct given the vastly different geological features required to create each. Hydrothermal vents are relatively ephemeral habitats where heated water laden with hydrogen sulfide and minerals rapidly flows out of the seafloor, and they are found at seafloor spreading centers and back arc basins. Cold seeps are found along passive and active margins around the world and can be created by a number of different geological conditions, but all are characterized by the slow seepage of fluids containing hydrogen sulfide and/or methane and other hydrocarbons at ambient temperatures. Cold seeps also tend to be more stable habitats with the potential to persist for over a thousand years at a single site. This dichotomy was challenged in 2009 when a hybrid “hydrothermal seep” site was found off the Pacific coast of Costa Rica. The habitat appeared to be another cold seep, but upon closer inspection, warm shimmering water and hydrothermal vent endemic species were found at the site. I am characterizing this community and putting it in context with other nearby Costa Rica margin seeps and with vent and seep communities around the world. By drawing on both quantitative community data collected using the same sampling equipment as well as presence-absence qualitative community data from the literature I hope to shed light on whether this novel site is more seep-like or vent-like and how it fits into the global biogeography of chemosynthetic habitats. |
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