Two ophiuroid species, Hemipholis elongata and Ophiophragmus spp. were studied in laboratory microcosms to elucidate patterns of sediment mixing for key bioturbators in the Mississippi Sound, Mississippi. The effects of bioturbation on artificially stratified sediments in microcosms were traced via time-series digital x-radiography. Preliminary results indicate that for three population densities of the brittle stars (comparable to field densities), a steady state volumetric bioturbation rate of 1-2 cm3/d is reached within two months of introduction to a fresh system. The preservation quotient, q, a fractional measure of preserved primary fabric, reached a minimum of 0.5 during the 16-week experiment. Maximum depth of bioturbation appears to be inversely proportional to population density in these species, with individuals in sparser populations also being less mobile. Thus, greater dispersive mixing occurs to shallower depths in sediments hosting greater population densities. In addition, bioturbation rates appear to decrease exponentially with depth, with volumetric reworking at the base of the mixed layer being approximately 1x10-3 those at the surface. Field measurements after event layer deposition showed that re-colonization by the original key bioturbators was not immediate and a lag time of at least 8 months may valid for future modeling attempts in similar settings.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-04042006-114658 |
| Date | 06 April 2006 |
| Creators | Neylon, Skyler |
| Contributors | Samuel Bentley, Robert Carney, Jeffrey Hanor |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-04042006-114658/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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