ABSTRACT

A primary goal of this project is to understand species distributions in the types of communities found at the hydrothermal vents of the East Lau Spreading Center. A species? fundamental ecological niche is defined by its tolerance to abiotic conditions, with the realized niche constrained by negative inter-specific interactions, but also expanded by positive inter-specific interactions. In hydrothermal vent ecosystems the ultimate source of energy and food for the metazoans is the vent fluid, which is emitted from spatially limited areas on the sea floor. As an ecosystem, vents are somewhat atypical in that gradients of primary productivity are positively correlated with gradients of ecological stressors that include toxic chemistry and high temperatures. The resultant strong bottom up controls on species distribution at vents interact with a variety of positive and negative biological interactions to constrain the realized niche of each species.

To meet the goal of this research, the collaborating investigators will use a combination of laboratory studies, analyses of in situ observations and measurements, and manipulative experiments. To define the potential (fundamental) niches of the key, symbiont-containing fauna, they will conduct shipboard experiments in pressurized respirometers and determine their thermal tolerances and preferences, tolerances to high sulfide and low oxygen levels, and determine which sulfur species are used and released by each. In order to define the realized niches of the major fauna they will analyze spatially correlated in situ biological community and hydrothermal fluid physiochemical data. In order to understand the mechanisms that drive the differences between the fundamental and realized niches of the key fauna, they will conduct a series of in situ manipulative experiments to characterize both positive and negative interactions among the foundation species. This proposal will continue a macrobiological component of the Integrated Studies at the Ridge 2000 Lau Basin study site.

In addition to maintaining the high level of public and secondary school outreach activity typical of these scientists, this project will be integrated into the Ridge 2000 GLOBE education program: ?From Local to Extreme Environments (FLEXE).? These scientists will host a member of the FLEXE team on each research cruise and support a graduate student to work with the educator team on the interpretation of the environmental data and imagery collected for development of new GLOBE protocols. This project will also support inter-disciplinary training of at least 5 graduate students, through summer cross-training among labs, and provide research opportunities for 6-10 undergraduate students.

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