Seamounts are largely unexplored undersea mountains rising abruptly from the ocean floor. These unique habitats can support an increased abundance and diversity of organisms, due to increased flow rates, the presence of hard substrates, and potentially, hydrographic larval retention mechanisms. Oceanic islands, sharing geomorphic characteristics, are a subset of seamounts. Suspension feeders, such as deep-sea corals, are common benthic megafauna in these ecosystems. Deep-sea corals are associated with higher levels of diversity and are structure-formers, able to provide habitat and complexity to other organisms. However, most past work addressing deep- sea coral communities in general, on seamounts in particular, have not considered small-scale variation in these communities. Here I show that the subphotic structure- forming megabenthos of an oceanic island is structured along physical gradients at a much smaller scale than previously known. Corals and sponges in the Makapu and #700;u deep- sea coral bed (4.3 km2), offshore of Oahu, Hawaii, were mapped from ~ 320 ' 530 meters depth. The physical environment was surveyed at three spatial scales in order to increase the state of knowledge regarding community-level patterns of these ecosystems and to test the hypothesis of differing communities in the northern and southern regions of the bed. This hypothesis was shown to be partially true, with communities in one region differing from those occupying the other, even within the same depth zone. Local hydrological changes are likely manifesting in regional differentiation. Depth was found to be the strongest structuring gradient. Furthermore, different relief and substrate types hosted unique assemblages, with rugosity acting as an important factor as well. Preliminary analyses of a local crinoid population provided no evidence of nocturnal behavior, as was suspected, but revealed a potential increase in crinoid abundance over time. This work yields new insight on the spatial ecology of seamounts and points out that community changes can occur over narrow (~ 200 meters) depth gradients and be structured by small-scale physiography. Future ecological investigations on seamounts would benefit from collecting faunal and physical habitat data at multiple spatial scales. / A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of
Science. / Summer Semester, 2011. / June 13, 2011. / Includes bibliographical references. / Amy Baco-Taylor, Professor Directing Thesis; Ian MacDonald, Committee Member; Kevin Speer, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_183628 |
| Contributors | Long, Dustin James (authoraut), Baco-Taylor, Amy (professor directing thesis), MacDonald, Ian (committee member), Speer, Kevin (committee member), Department of Earth, Ocean and Atmospheric Sciences (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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