Deep-Sea Biologist
Jamie Wagner
RESEARCH
Research Overview
Methane seeps, found on the deep seafloor hundreds to thousands of meters below sea level, are a community that thrives despite the near freezing temperatures, intense pressure, and absence of light. Rather than a sunlight-based ecosystem reliant on photosynthesis to start the food chain, these seeps are a chemosynthetic ecosystem. Here, bacteria convert chemicals like methane and sulfide into energy, in the form of organic molecules that other animals can consume.
I am interested in studying the relationship between these benthic, biological hotspots in the deep sea and the larger ocean ecosystem. Some animals found at seeps have symbiotic relationships with these bacteria. These animals are considered endemic to seeps because their lifestyle depends on the availability of the chemicals found at seeps, and they cannot be found elsewhere in the ocean. I am looking at the spatial relationships between seep endemic fauna and vagrant fauna, which can be found at seeps but which are also able to live in other marine habitats. Further investigation into the distributions and abundances of these seep dwelling animals and their relationships may improve understanding of seep contributions to the larger ocean ecosystem.
I am also delving into how oxygen minimum zones, where oxygen levels are much lower than typical ocean levels, affect ocean life. I have been investigating the differences in life found at seeps inside and outside oxygen minimum zones. These studies can be informative to both potential affects of climate change and expanded oxygen minimum zones, as well as astrobiological studies looking for life on other planets in habitats outside the realm of typical Earth ecosystems.
Below are more details about some of my recent projects:
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Relationships within seeps
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Relationships among seep community biomass, diversity, and physiographic controls such as underlying geology are not well understood. This project (Wagner et al., 2013) looks at how seep endemic fauna are structured over the environmental topography. The study examines a seep field composed of one known and three newly discovered seeps at Blake Ridge Diapir, located about 200 nm off the South Carolina coast. Geophysical and photographic data were collected using an autonomous underwater vehicle (AUV).
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A nested survey approach was used that began with a regional or reconnaissance-style survey using sub-bottom mapping systems to locate and identify seeps and underlying conduits. This survey was followed by AUV-mounted sidescan sonar and multibeam echosounder systems mapping on a mesoscale to characterize the seabed physiography. At the most detailed survey level, digital photographic imaging was used to resolve sub-meter characteristics of the biology. These tools were used to examine the relationship between biomass-dominant invertebrates (mussels, Bathymodiolus heckerae, and clams, Vesicomya cf. venusta) and seafloor physiography. Concentric zonation of mussels and clams at each of the four sites within the seep field suggests the influence of chemical gradients on megafaunal distribution. Data collection and analytical techniques used here yielded high-resolution habitat maps that can serve as baselines to constrain temporal evolution of seafloor seeps, and to inform ecological niche modeling and resource management.
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Seep community in a canyon off the U.S. Northeast Coast.
Photo credit: NOAA, Okeanos Explorer/ROV Deep Discoverer
Dense mussel bed at a seep at Blake Ridge, off the NC/SC coast.
Photo credit: WHOI, AUV Sentry
Relationships among seep endemic and non-endemic fauna
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In addition to characterizing the organization of endemic fauna within a seep, another key question is the sphere of influence methane seeps provide the surrounding area in terms of habitat structure, food sources, and geochemical environment. Understanding the distribution of megafauna relative to the seep environment is a preliminary step toward understanding these ecosystem properties.
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Systematic photo surveys using an autonomous underwater vehicle (AUV) were conducted at 4 methane seeps on the Blake Ridge Diapir and a seep at Cape Fear Diapir. Distributions of dominant seep features (bivalves, carbonates, bacterial mats) were used to define the active seep site. Geospatial mapping indicated that non-seep-endemic taxa (those not hosting chemoautotrophic endosymbionts) either show positive association (e.g., squat lobsters, cake urchins), negative association (e.g., sea urchins, certain sea cucumbers), or no distributional bias (e.g., sea stars, certain fish) to the presence of a seep. Further investigation into these faunal relationships may improve understanding of predictive community assembly rules, as well as clarifying the services that seeps provide to the larger ocean ecosystem.
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Example of different patterns of non-endemic invertebrates around seep endemic organisms, from a seep at Blake Ridge off the NC/SC coast.