A need exists for information on sedimentary microbes, expecially at the level of specific populations, and particularly with respect to their interactions with benthic macrofauna. Two examples were documented. / First, biochemical and conventional analyses were used to characterize the microbial food resources and digestive efficiency of Ptychodera bahamensis, an enteropneust hemichordate. Sediment was collected from freshly extruded fecal casts and adjacent feeding depressions. There were no significant differences between casts and depressions in granulometry, density of meiofauna, and concentrations of photopigments. Nematodes in casts were larger than those in depressions. Total phospholipid, ester-linked fatty acids (PLFA) were 30% lower and phospholipid phosphate was 49% lower in casts. Concentrations of 33 fatty acids were lower in casts, indicating that the hemichordate digests a wide variety of microorganisms. Only 18:1$\omega$7c, characteristic of Gram-negative organisms, was not lower in casts than in depressions. P. bahamensis either cannot digest this functional group of bacteria or contributes gut microbes containing 18:1$\omega$7c to sediment passing through its alimentary canal. / Second, the same methods were used to characterize the microbial populations within the burrow of Callianassa trilobata, a decapod crustacean. Sediment was collected from the burrow lining, burrow matrix, and ambient, subsurface sediment. The lining and matrix were composed of fine-grained material compared to sandy, ambient sediment. Meiofauna were most abundant in ambient sediment, not in the burrow as has been found for other species of macrofauna. Lipid analyses indicated that relative to the matrix and ambient sediment, the lining abounds with pro- and eukaryotic biomass. PLFA were assigned to functional groups of microorganisms to assess spatial variations in the absolute abundance and relative proportions of microbial populations. Dominance of prokaryotes was pronounced in all three areas, especially the matrix. The lining was the most aerobic location, but anaerobic microhabitats simultaneously harbored sulfate-reducing bacteria. The ratio of Gram-positive to Gram-negative bacteria increased from lining to matrix to ambient sediment. The Trans/cis ratio of 16:1$\omega$7 indicated that prokaryotes in the matrix were starved. / Source: Dissertation Abstracts International, Volume: 49-03, Section: B, page: 0601. / Major Professor: Paul A. LaRock. / Thesis (Ph.D.)--The Florida State University, 1987.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76253 |
| Contributors | Dobbs, Frederick Courtrite., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 109 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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