Spatial ecology of hydrocarbon seeps in the northern Gulf of Mexico /
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| Other Authors: | , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Chemically reduced compounds (sulfides and methane), which are associated with the natural seepage of hydrocarbons on the Gulf of Mexico on the continental slope south of Louisiana and Texas, support chemosynthetic symbioses among a taxonomically diverse array of metazoans and their bacterial endosymbionts. The fine-scale dispersion patterns of clams, tube worms, and mussels were examined by means of video and emulsion photographs that were taken from camera sleds or manned submarines. Clams of the Vesicomyidae (Calyptogena ponderosa and Vesicomya cordata) occur with the foot and anterior end of the valves thrust into a layer of soft, anoxic sediment while the posterior and siphon are angled up into the oxic water column. Movement in this position produces curvilinear trails up to ~2 m in length. Mixtures of living and dead vesicomyids and their trails were photographed in two aggregations of at least 95 and 140 m in width. Within these aggregations, the distribution of living clams was significantly clustered at a scale of [less than or equal to] 10 m. An undescribed vestimentiferan tube worm of the Lamellibrachiidae (Lamellibrachia n. sp.) occurs with its posterior end variously buried in soft, anoxic sediment or attached to carbonate outcrops while its rigid tube and anterior gas exchange plume extends up to 1.5 m into the oxic water column. Rarely solitary, mature colonies of Lamellibrachia n. sp. form hemispherical "bushes" [greater than or equal to] 2 m in diameter. Their abundance was found to be significantly correlated with the concentrations of extractable hydrocarbons in surface sediments and to be significantly clustered at scales of approximately 5, 20 and 60 m. (The magnitude of these scales differed among seep sites.) Clustering was caused by formation of the bush-like clusters and to localization of seepage. An undescribed mussel (Bathymodiolus n. sp.) possesses chemosynthetic symbionts that can utilize methane. Mussel obtain methane via seawater via following dissolution streams of bubbling gas or via hypersaline pore fluids that seep into seafloor depressions. Spat of Bathymodiolus n. sp. settle or survive preferentially where the concentration of methane is greatest. Consequently, the flowage or pooling of brine delineates the patterns of mussel beds and determines their demographic character. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Oceanography." |
| Physical Description: | ix, 136 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |