A Coupled Modeling and Empirical Approach to the Study of the Life History and Physiological Ecology of Cold Seep Vestimentiferans and Communities

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A coupled modeling and empirical approach to the study of the life history andphysiological ecology of cold seep vestimentiferans and communities.Seep vestimentiferans and their symbionts are primary producers that provide complexhabitat structure in a non-toxic setting for a diverse assortment of seep-endemic and non-endemicheterotrophic species. As such, they are arguably the most important keystone speciesin widespread areas of seepage on the continental slope. Recent work has demonstrated that onespecies (at least) of seep vestimentiferan is extremely long-lived and can support its autotrophiclife style with the uptake of dissolved gasses across buried portions of its body. Thus, in manyways, the seep vestimentiferans are analogous to long-lived, ecosystem-structuring, woody plantspecies in a terrestrial environment.We will develop models to address resource acquisition and allocation, life histories, andcommunity productivity of cold seep vestimentiferans that will guide and focus field andlaboratory studies of cold seep vestimentiferan communities. We propose to work on the upperLouisiana Slope of the Gulf of Mexico at a depth range of 540 to 1,000m and will includecommunities on both hard substrata and sediment that are exposed to a range of sulfideconcentrations. We will use empirical studies and comparative methods to develop, test thepredictions of, and refine, Dynamic Energy Budget models, while at the same time addressingspecific hypotheses concerning vestimentiferan aggregation physiology and ecology.Our in situ work will be guided by these mathematical models and interfaced with veryefficient and quantitative collection methods that will maximize the information gleaned fromeach collection and provide material for future studies, thereby minimizing our short and long-termimpact on the communities. Growth rates of thousands of individuals will be measured andthese data used to estimate the longevity and to calculate the resources allocated to growth byeach vestimentiferan species. We will determine whether "roots" (posterior extensions that canbe used to mine sulfide from within sediments) are a general feature of seep vestimentiferans andwhether they are environmentally induced. The models will be used to explore the relativeimportance of root sulfide uptake to the sustenance of aggregations in different situations and theimplications of vestimentiferan sulfide demand on biogeochemical models of sulfide production.To facilitate this, environmental concentrations of sulfide and diffusion distances across roottubes and tissues will be measured, and concentrations and sulfide binding properties of thehemoglobins in the different species will be determined. The biomass, size frequency,distribution, and reproductive state of the vestimentiferans will be determined for intactaggregations and collections processed so that the species richness and biomass of all associatedfauna in each collection can also be determined. This will allow us to formulate life historymodels, to scale up the models of individuals to the levels of aggregations, and to model excessproduction and its use by associated fauna.Fisher has extensive experience with the Gulf of Mexico seep communities and has visitedthe sites. Shea is a theoretical ecologist with experience in life-history modeling of terrestrialand aquatic autotrophic systems. The proposed approach will significantly increase ourunderstanding of these widespread and productive deep-sea communities and their impact on thesurrounding deep sea, and will provide a modeling framework to focus related and futureinvestigations. The proposed studies will yield basic insights on the ecology, physiology andreproductive biology of deep-sea systems in general and chemoautotrophic systems in particular.They will also provide new theory, and tests for existing theory on the evolution of life historystrategies.