Hamdan Leila J.

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Hamdan
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Leila J.
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  • Preprint
    Diversity and biogeochemical structuring of bacterial communities across the Porangahau ridge accretionary prism, New Zealand
    ( 2011-07-04) Hamdan, Leila J. ; Gillevet, Patrick M. ; Pohlman, John W. ; Sikaroodi, Masoumeh ; Greinert, Jens ; Coffin, Richard B.
    Sediments from the Porangahau ridge, located off the northeastern coast of New Zealand, were studied to describe bacterial community structure in conjunction with differing biogeochemical regimes across the ridge. Low diversity was observed in sediments from an eroded basin seaward of the ridge and the community was dominated by uncultured members of the Burkholderiales. Chloroflexi/GNS and Deltaproteobacteria were abundant in sediments from a methane seep located landward of the ridge. Gas-charged and organic rich sediments further landward had the highest overall diversity. Surface sediments, with the exception of those from the basin, were dominated by Rhodobacterales sequences associated with organic matter deposition. Taxa related to the Desulfosarcina/Desulfococcus and the JS1 candidates were highly abundant at the sulfate-methane transition zone (SMTZ) at three sites. To determine how community structure was influenced by terrestrial, pelagic, and in situ substrates, sequence data were was statistically analyzed against geochemical data (e.g., sulfate, chloride, nitrogen, phosphorous, methane, bulk inorganic and organic carbon pools) using the Biota-Environmental matching procedure. Landward of the ridge, sulfate was among the most significant structuring factors. Seaward of the ridge, silica and ammonium were important structuring factors. Regardless of the transect location, methane was the principal structuring factor on SMTZ communities.
  • Article
    Shipwreck ecology: understanding the function and processes from microbes to megafauna
    (Oxford University Press, 2023-12-19) Paxton, Avery B. ; McGonigle, Christopher ; Damour, Melanie ; Holly, Georgia ; Caporaso, Alicia ; Campbell, Peter B. ; Meyer-Kaiser, Kirstin S. ; Hamdan, Leila J. ; Mires, Calvin H. ; Taylor, J Christopher
    An estimated three million shipwrecks exist worldwide and are recognized as cultural resources and foci of archaeological investigations. Shipwrecks also support ecological resources by providing underwater habitats that can be colonized by diverse organisms ranging from microbes to megafauna. In the present article, we review the emerging ecological subdiscipline of shipwreck ecology, which aims to understand ecological functions and processes that occur on shipwrecks. We synthesize how shipwrecks create habitat for biota across multiple trophic levels and then describe how fundamental ecological functions and processes, including succession, zonation, connectivity, energy flow, disturbance, and habitat degradation, manifest on shipwrecks. We highlight future directions in shipwreck ecology that are ripe for exploration, placing a particular emphasis on how shipwrecks may serve as experimental networks to address long-standing ecological questions.