http://hdl.handle.net/10453/35213 2026-04-10T14:26:49Z http://hdl.handle.net/10453/36159 Title: Variability in microbial community composition and function between different niches within a coral reef. Authors: Tout, J; Jeffries, TC; Webster, NS; Stocker, R; Ralph, PJ; Seymour, JR Abstract: To explore how microbial community composition and function varies within a coral reef ecosystem, we performed metagenomic sequencing of seawater from four niches across Heron Island Reef, within the Great Barrier Reef. Metagenomes were sequenced from seawater samples associated with (1) the surface of the coral species Acropora palifera, (2) the surface of the coral species Acropora aspera, (3) the sandy substrate within the reef lagoon and (4) open water, outside of the reef crest. Microbial composition and metabolic function differed substantially between the four niches. The taxonomic profile showed a clear shift from an oligotroph-dominated community (e.g. SAR11, Prochlorococcus, Synechococcus) in the open water and sandy substrate niches, to a community characterised by an increased frequency of copiotrophic bacteria (e.g. Vibrio, Pseudoalteromonas, Alteromonas) in the coral seawater niches. The metabolic potential of the four microbial assemblages also displayed significant differences, with the open water and sandy substrate niches dominated by genes associated with core house-keeping processes such as amino acid, carbohydrate and protein metabolism as well as DNA and RNA synthesis and metabolism. In contrast, the coral surface seawater metagenomes had an enhanced frequency of genes associated with dynamic processes including motility and chemotaxis, regulation and cell signalling. These findings demonstrate that the composition and function of microbial communities are highly variable between niches within coral reef ecosystems and that coral reefs host heterogeneous microbial communities that are likely shaped by habitat structure, presence of animal hosts and local biogeochemical conditions. 2014-01-01T00:00:00Z http://hdl.handle.net/10453/34503 Title: Radiative energy budget reveals high photosynthetic efficiency in symbiont-bearing corals Authors: Brodersen, KE; Lichtenberg, M; Ralph, PJ; Kühl, M; Wangpraseurt, D Abstract: The light field on coral reefs varies in intensity and spectral composition, and is the key regulating factor for phototrophic reef organisms, for example scleractinian corals harbouring microalgal symbionts. However, the actual efficiency of light utilization in corals and the mechanisms affecting the radiative energy budget of corals are underexplored. We present the first balanced light energy budget for a symbiont-bearing coral based on a fine-scale study of the microenvironmental photobiology of the massive coral Montastrea curta. The majority (more than 96%) of the absorbed light energy was dissipated as heat, whereas the proportion of the absorbed light energy used in photosynthesis was approximately 4.0% under an irradiance of 640 μmol photons m-2 s-1. With increasing irradiance, the proportion of heat dissipation increased at the expense of photosynthesis. Despite such low energy efficiency, we found a high photosynthetic efficiency of the microalgal symbionts showing high gross photosynthesis rates and quantum efficiencies (QEs) of approximately 0.1 O2 photon-1 approaching theoretical limits under moderate irradiance levels. Corals thus appear as highly efficient light collectors with optical properties enabling light distribution over the corallite/tissue microstructural canopy that enables a high photosynthetic QE of their photosynthetic microalgae in hospite. © 2014 The Author(s) Published by the Royal Society. All rights reserved. 2014-04-06T00:00:00Z http://hdl.handle.net/10453/3648 Title: Colonization of the Hawaiian Archipelago via Johnston Atoll a characterization of oceanographic transport corridors for pelagic larvae using computer simulation Authors: Kobayashi, D Abstract: Larval transport between Johnston Atoll and the Hawaiian Archipelago was examined using computer simulation and high-resolution ocean current data. The eff~cts of pelagic larval duration and spawning seasonality on long-distance transport and local retention were examined using a Lagrangian, individual-based approach. Retention around Johnston Atoll appeared to be low, and there appeared to be seasonal effects on both retention and dispersal. Potential larval transport corridors between Johnston Atoll and the Hawaiian Archipelago were charted. One corridor connects Johnston Atoll with the middle portion of the Hawaiian Archipelago in the vicinity of French Frigate Shoals. Another corridor connects Johnston Atoll with the lower inhabited islands in the vicinity of Kauai. Transport appears to be related to the subtropical countercurrent and the Hawaiian Lee countercurrent, both located to the west of the archipelago and flowing to the east. A new analytical tool. termed CONREC-IRC is presented for the quantification of spatial patterns. 2006-01-01T00:00:00Z http://hdl.handle.net/10453/691 Title: Hirsutodontus daleki: a new Ordovician conodont species from the Wiseman's Arm Foundation, Eastern Australia Authors: Furey-Greig, T 2004-01-01T00:00:00Z