Although many researchers have examined the phenomenon of intertidal zonation and its structuring processes in rocky habitats, similar studies concerning soft-bottom habitats are relatively uncommon. The bivalve assemblage of Polymesoda caroliniana (Corbiculidae) and Rangia cuneata (Mactridae), common in the shallow subtidal and intertidal zones of the mesohaline-oligohaline regions of southeastern United States estuaries, allows some analogies to previously studied rocky intertidal communities in that the adults of these bivalves are large (20-70 mm in shell length), and move very little, making the populations relatively easy to census and manipulate. I conducted field surveys and manipulative experiments on populations of R. cuneata and P. caroliniana between 1982 and 1984 in the Ochlockonee-Sopchoppy estuary of northwestern Florida. The emphasis of the research was description of the vertical distribution of members of each species, and analysis of factors controlling these distributions, including recruitment, physiological factors, disturbance, and potential competitive effects. Results indicate that R. cuneata is a subtidal inhabitant whose upper bound is controlled by physical factors, including physiological tolerances to such factors, and probably a lack of sufficient time for feeding and respiration. Recruitment of R. cuneata is highly variable, and results in populations dominated by single age classes. P. caroliniana is shown to be an intertidal inhabitant. The lower bound of the P. caroliniana population is determined, in an ecological sense, by larval settlement, but in an evolutionary time frame is probably controlled by biological factors such as predation and disturbance by predators and bioturbators. P. caroliniana seems to recruit regularly, but juvenile mortality is high, so recruitment to the adult population is low. No competitive effects between adult P. caroliniana and R. cuneata were found. / Source: Dissertation Abstracts International, Volume: 49-03, Section: B, page: 0601. / Major Professor: William Heard. / Thesis (Ph.D.)--The Florida State University, 1987.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76259 |
| Contributors | Marelli, Dan Christian., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 145 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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