研究者詳細 - HUMBLET Marc Andre

講演・口頭発表等 - HUMBLET Marc Andre

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Response of the Great Barrier Reef to sea level and environmental changes over the past 30 ka 国際会議

WEBSTER, J.M., BRAGA, J.C., HUMBLET, M., POTTS, D.C., IRYU, Y., YOKOYAMA, Y., FUJITA, K., BOURILLOT, R., ESAT, T., FALLON, S., THOMPSON, W.G., THOMAS, A.L., KAN, H., MCGREGOR, H., AND HINESTROSA, G.

19th Congress of the International Union for Quaternary Research (INQUA)

Sea level record obtained from submerged the Great Barrier Reef coral reefs for the last 30 ka 国際会議

YOKOYAMA, Y., ESAT, T., THOMPSON, W.G., THOMAS, A.L., WEBSTER, J.M., MIYAIRI, Y., SAWADA, C., AZE, T., MATSUZAKI, H., OKUNO, J., FALLON, S., BRAGA, J.C., HUMBLET, M., IRYU, Y., POTTS, D.C., FUJITA, K., SUZUKI, A., AND KAN, H.

19th Congress of the International Union for Quaternary Research (INQUA)

Late Quaternary development of barrier and fringing reefs of Bora Bora, Society Islands, South Pacific: the influence of subsidence, sea level, and antecedent topography 国際会議

GISCHLER, E., ISAACK, A., HUDSON, H., ANSELMETTI, F., HUMBLET, M., EISENHAUER, A., AND CAMOIN, G.

The 31th annual meeting of the International Association of Sedimentologists

Last glacial to deglacial biotic changes on the Great Barrier Reef from offshore boreholes

HUMBLET, M., WEBSTER, J.M., BRAGA, J.C., IRYU, Y., POTTS, D.C., YOKOYAMA, Y., ESAT, T., FALLON, S., THOMPSON, W.G., AND THOMAS, A.L.

Japanese Geoscience Annual Meeting

開催年月日： 2015年5月

記述言語：英語会議種別：口頭発表（一般）

国名：日本国

IODP Expedition 325 drilled 34 boreholes into submerged reef structures along the shelf edge of the Great Barrier Reef (GBR). The boreholes were drilled between 42 and 167 mbsl at 17 sites along four transects at three geographic locations (Hydrographers Passage, Noggin Pass, and Ribbon Reef). The last glacial to deglacial reef sequence (~8 ka to ~27 ka) varies in thickness from ~5.5 m to ~34 m and consists primarily of coralgal boundstone with various proportions of microbialite. We use a detailed chronostratigraphic scheme based on numerous C14 and U-Th ages to discuss the evolution of the coralgal communities since the last glaciation. Exp. 325 cores show that different phases of sea level change promoted different shallow reef-building coral species at the study sites. The onset of the deglacial (16-19 ka) is characterized by a peak abundance of Seriatopora and Tubipora whereas the following rapid sea level rise (<16 ka) is marked by the dominance of massive Isopora and Acropora with medium- to robust-size branches. The shift in composition of coral communities around 16 ka coincides with the flooding of a pre-LGM MIS2 reef terrace, an event which had a major influence on reef growth and reef composition. We discuss the impact of this event on coralgal communities in the GBR and its significance for Quaternary reef evolution in general.

Response of reef corals to late Quaternary climate changes in the Great Barrier Reef: the Ribbon Reef 5 and Boulder Reef drill cores revisited

HUMBLET, M. AND WEBSTER, J.M.

Meeting of the Japanese Geological Society

開催年月日： 2014年9月

記述言語：英語会議種別：口頭発表（一般）

国名：日本国

The Great Barrier Reef (GBR) of Australia is the largest and most diverse reef ecosystem in the world. Coral cover declined significantly in recent years due to a combination of biological and climatic factors (De'ath et al., 2012). Yet, the GBR as a whole displayed a remarkable resilience during glacial-interglacial cycles, repeatedly reestablishing itself after multiple episodes of emersion (Webster and Davies, 2003). But the particular response of coral communities to Quaternary climate changes remains poorly documented. In an attempt to understand how coral communities responded to long-term natural perturbations, we reexamine two deep boreholes drilled in 1995 in the Ribbon Reef 5 (RR5) and Boulder Reef (BR) at latitude 15°24' S in the northern GBR (International Consortium for GBR drilling). The RR5 core (210 m) is located near the shelf edge 50 km off the Queensland coast and is directly exposed to the ocean swell. The BR core (86 m) was drilled further inshore in a protected muddy inner shelf reef only 15 km from the coast. Webster and Davies (2003) have used the RR5 core to constrain the age of the GBR inception to 452-365 ka (MIS 11) and reported two recurrent coral assemblages in this core and another distinct assemblage in the BR core. However, the details of the coral succession in these cores have not been fully investigated yet. Here we present an in-depth analysis of the variations in coral assemblages in the RR5 and BR cores during the entire history of the GBR. Our aim is to (1) document the initial phase of colonization, (2) evaluate the similarity in taxonomic composition between successive reef-building episodes, (3) examine the influence of terrigenous input on coral communities and their evolution, and (4) compare the coral record of the RR5 and BR cores with that of the IODP 325 cores drilled in submerged reefs along the shelf edge of the modern GBR (Webster et al., 2011).

Geological significance of the mesophotic reef zone: example from the Sekisei Barrier Reef

Marc Humblet, Yasuo Furushima, Toshihiro Maki, and Yasufumi Iryu

Meeting of the Japanese Geological Society

開催年月日： 2014年9月

記述言語：英語会議種別：ポスター発表

国名：日本国

Reef corals and other benthic reef organisms, such as coralline algae, exhibit a non-random distribution along gradients of wave energy and light, i.e. reef zonation (Done, 1983). Fossil reef communities can therefore be used for paleoenvironmental and sea level reconstructions (Montaggioni and Braithwaite, 2009). However, our understanding of the present-day distribution of reef organisms is mostly limited to the shallower reef ecosystem (0-30 m). The deeper reef ecosystem, from 30 m to the bottom of the photic zone, i.e. the mesophotic reef zone, remains largely unexplored. From a biological viewpoint, the mesophotic reef zone is interesting because its exploration can lead to the discovery of new species (Petrescu et al., 2014). It has also an important ecological significance because it marks the transition between photic and non-photic ecosystems. Furthermore, the mesophotic reef zone has been considered a possible refuge for shallow-water species in times of environmental stress (Bongaerts et al., 2010). From a geological viewpoint, the importance of the mesophotic reef zone is twofold: (1) mesophotic reef organisms can be potentially useful paleoenvironmental and sea level indicators, and (2) the seafloor topography in the mesophotic reef zone is the product of the interplay between erosion and reef growth, controlled by eustatic sea level changes, subsidence and uplift.
In 2004 and 2005, video images of the seafloor acquired by a small remotely operated vehicle (ROV) near the Sekisei Lagoon indicate the presence of distinct macrobenthic communities at depths of 30 to 120 m exhibiting a non-random distribution along a depth gradient (Furushima et al., 2005; Humblet et al., 2009). In addition, high-resolution bathymetric data have brought to light a number of interesting topographic features: a ridge and furrow system, gentle slopes and steep escarpments, prominent pinnacles, and mound-like structures. The variety of habitats and associated biota makes the forereef slope of the Sekisei barrier reef an ideal site for conducting a detailed study of the mesophotic reef zone and explore the relationship between seafloor topography and past sea level changes in this region.

Changes in coral assemblages in the Great Barrier Reef since the last glaciation

HUMBLET, M., POTTS, D.C., WEBSTER J.W., YOKOYAMA, Y. AND IODP EXPEDITION 325 SCIENTISTS

Japanese Geoscience Annual Meeting

開催年月日： 2013年5月

記述言語：英語会議種別：口頭発表（一般）

国名：日本国

Drilling into submerged reef structures along the shelf edge of the Great Barrier Reef was carried out during IODP Expedition 325 with the purpose of reconstructing sea level and environmental changes since the Last Glacial Maximum (LGM) and analyzing their impact on reef communities and reef growth. A total of 34 boreholes were drilled between 42 and 167 mbsl at 17 sites along four transects at three geographic locations (Hydrographers Passage, Noggin Pass, and Ribbon Reef). Two basic chronostratigraphic units can be recognized: a last glacial to deglacial reef sequence overlying older Pleistocene reefal and non-reefal deposits. The former varies in thickness from ~5.5 m to ~34 m and consists primarily of coralgal boundstone with various proportions of microbialite. In this study we analyze the variations in coral assemblages since the last glaciation. Exp. 325 cores show that diverse corals, including Faviids, Acropora, Montipora, and Porites, were growing during the last glacial period on the shelf edge. Their distribution was limited to the most distal boreholes during the LGM lowstand. The subsequent deglaciation saw the development of a shallow-water coral assemblage dominated by encrusting to massive Isopora and branching Acropora and Seriatopora as sea level rose. The tops of distal boreholes are marked by a shift to deeper assemblages dominated by encrusting Porites and Montipora reflecting reef drowning and the formation of submerged reef terraces. As sea level kept rising, a shallow-water Isopora-dominated assemblage re-established further upslope and formed a barrier reef before drowning in turn.

Biodiversity of upper mesophotic coral community in Okinawa

SINNIGER, F., HUMBLET, M., AND HARII, S.

Japanese Geoscience Annual Meeting

開催年月日： 2013年5月

記述言語：英語会議種別：口頭発表（一般）

国名：日本国

Mesophotic coral ecosystems (MCEs) are usually found at depth ranging from 30 to over 100 m depth. Mesophotic coral communities are often composed of both eurybathic tolerant species and species adapted to specific condition of the mesophotic zone. The taxonomic composition of such communities is still poorly known, yet important to conduct accurate paleoenvironmental interpretations of fossil reef deposits, especially in studies aiming to reconstruct past sea-level changes. Moreover, from a biological perspective, the Deep Reef Refugia Hypothesis (DRRH) states that mesophotic coral ecosystems, due to their more stable environmental conditions, may act as refugia for shallow water species to survive extreme climatic events and re-colonise shallower reefs in the future.
Recent global environmental changes affected seriously shallow coral reefs around Okinawa. The combination of major bleaching events and several typhoons lead to changes in coral communities with some species apparently extinct from several locations. Around Sesoko Island in the northern part of Okinawa, several corals species disappeared since 1999 and were not recorded since then (van Woesik et al. 2011). Seriatopora hystrix was one of those species.
During the recent survey of a mesophotic coral ecosystem located between Sesoko Island and Motobu Peninsula, high coral diversity and dense communities were found between 35 and 55 m depth including abundant populations of S. hystrix between 39 and 47 m. In order to estimate the coral biodiversity as well as the relationships between shallow and mesophotic corals, several genetic markers, both nuclear and mitochondrial, were sequenced for the samples collected. Symbiotic dinoflagellates were also identified. Here we will present the results of the molecular analyses showing the important coral diversity in this location. Our results also show intraspecific diversity within the population of S. hystrix. The genotypes of those deep populations correspond to genotypes previously observed from shallower reefs as well as to new genotypes. Such results suggest an absence of vertical structuring in Okinawan S. hystrix populations and support the (DRRH). In the future, and if shallow environmental conditions become suitable again for this species, deep populations of S. hystrix might be of critical importance for the re-colonisation of shallow coral reefs.
Reference: van Woesik R, Sakai K, Ganase A, Loya Y (2011) Revisiting the winners and the losers a decade after coral bleaching. Mar Ecol Prog Ser 434: 67-76

Mesophotic Montipora from Kikai-jima

Marc Humblet, Matsuda H., Sasaki K., Machiyama H., and Iryu Y.

Japanese Coral Reef Society annual meeting

開催年月日： 2012年11月

記述言語：英語会議種別：口頭発表（一般）

国名：日本国

In August 2009, dredging operations were carried out ~8 km southwest of Kikai-jima with the main objective of finding fossil reef material (RV Tansei-maru cruise KT-09-16). Seafloor material was collected along 14 transects (~200 to ~600 m in length) at depths ranging from 60 to 140 m (edge of the island shelf). Most of the material recovered consisted of macroids, coral gravels (thickly encrusted and bioeroded), and bryozoan-rich calcareous sand (at the deepest site). Live material consisted mainly of soft corals, gorgonians, and sponges. Thirteen live coral colonies were collected between 70 to 80 m water depth. Among these corals, ten belong to the genus Montipora, two to the genus Leptoseris, and one to the genus Echinophyllia. All colonies are a few centimeters across (max width of 11 cm), very thin (1 to 6 mm), and laminar with free margins. We provide a detailed description of the macro- and micromorphology of Montipora colonies based on optical and SEM imaging. Despite the limited number of colonies studied, analysis of morphological features such as corallite diameter, inter-corallite distance, spinule density and shape, shows that at least two morphological types can be distinguished. We compare the morphological characteristics of the recovered mesophotic Montipora with those of shallow species described in the literature.

Changing Coral Assemblages Since The Last Glacial Maximum: IODP Expedition 325 国際会議

Marc Humblet, Don C. Potts, Jody M. Webster, and IODP Expedition 325 scientists

12th International Coral Reef Symposium

開催年月日： 2012年7月

記述言語：英語会議種別：口頭発表（一般）

国名：オーストラリア連邦

Major goals of the Integrated Ocean Drilling Program (IODP) Expedition 325 (GBREC: Great Barrier Reef Environmental Changes) include reconstructing histories of sea-level change, sea surface temperature variation and reef growth since the Last Glacial Maximum (LGM), and analyzing responses of reef-building corals to post-glacial sea-level rise. Cores were extracted from submerged reef structures along four transects in three localities on the shelf margin, seaward of the modern Great Barrier Reef. 225 m of drill-core were retrieved from 34 holes at 17 sites in depths from 42 to 167 m below present sea level, and from 1.5 to 42 m below the sea floor.
Seven coral assemblages are defined, based on taxonomic and morphological compositions. Their paleoenvironments, by analogy with modern reefs, range from shallow wave-exposed to deep low-energy reef habitats. The initial post-glacial reef assemblage is dominated by shallow-water massive-submassive-branching Isopora with branching Acropora and thin branching Seriatopora. The deeper assemblages consist mainly of encrusting to submassive Montipora and encrusting Agariciidae. Horizontal differences between proximal and distal cores along transects probably reflect changing geomorphological and hydrodynamic regimes across the reef tract as sea level rose. Vertical changes in coral assemblages within a core reflect deepening of the water, leading to ultimate drowning of the coral community and creation of the tops of the submerged reef structures. As sea level rose, shallow reef assemblages re-established further upslope and accumulated several meters of reef structure before drowning in turn.

Response of reef-building corals to post-glacial sea level rise: IODP Expedition 325

Marc Humblet, Don C. Potts, Jody M. Webster, Yusuke Yokoyama, and IODP Expedition 325 scientists

Japan Geoscience Union annual meeting

開催年月日： 2012年5月

記述言語：英語会議種別：ポスター発表

国名：日本国

Major objectives of the Integrated Ocean Drilling Program (IODP) Expedition 325 (GBREC: Great Barrier Reef Environmental Changes) include reconstructing histories of sea-level change, sea surface temperature variation and reef growth since the Last Glacial Maximum (LGM), and analyzing the responses of reef-building corals to post-glacial sea level rise. Submerged reef structures were drilled along four transects in three localities (Hydrographers Passage, Noggin Pass, and Ribbon Reefs) on the shelf edge seaward of the modern Great Barrier Reef. A total of 34 boreholes were cored at 17 sites ranging in depth from 42 to 167 meters below present sea level.
Seven coral assemblages are identified based on coral taxonomy and morphologies. Their paleoenvironments are inferred by comparison with modern coral communities of the Great Barrier Reef and range from shallow wave-exposed to deep low-energy reef habitats. The initial post-glacial coral assemblage is dominated by shallow-water massive-submassive-branching Isopora associated with branching Acropora and Seriatopora. The deeper assemblages consist mainly of encrusting to submassive Montipora and encrusting Agariciidae. Horizontal changes in coral assemblages along transects, from proximal to distal cores, probably reflect the changing reef geomorphology and hydrodynamic regime during sea level rise. Vertical changes within a core reflect an increase in water depth followed by a drowning of the coral community and the formation of the submerged reef tops. As sea level rose, shallow reef assemblages re-established further upslope and accumulated several meters of reef structure before drowning in turn.

The deep photosynthetic reef ecosystem in the Ryukyu Islands

Humblet, M., Furushima, Y., Yamamoto, H., Maruyama, T., Matsuda, H., Sasaki, K., Machiyama, H., Iryu Y., and Tokuyama, H.

12th annual meeting of the Japanese Coral Reef Society

Deep photosynthetic corals in the Ryukyu Islands: insight from modern and fossil reefs 国際会議

Humblet, M., Furushima, Y., Iryu, Y. and Tokuyama H.

27th annual meeting of the International Association of Sedimentologists

Spatial and temporal variations in Pleistocene coral assemblages in the South and Central Ryukyu Islands

Humblet, M. and Iryu, Y.

115th Annual Meeting of the Geological Society of Japan

Responses of Pleistocene coral communities to sea-level changes in the Ryukyu Islands

Humblet, M. and Iryu, Y.

9th Annual Meeting of the Japanese Coral Reef Society

Variations of Pleistocene coral community structure in response to sea level change in the Ryukyu Islands 国際会議

Humblet, M. and Iryu, Y.

21 COE International Symposium: Climate Change: Past and Future

Variations of Pleistocene coral community structure in response to sea level change in the Ryukyu Islands 国際会議

Humblet, M. and Iryu, Y.

SEALAIX06: Sea level changes: records, processes and modelling

Variations of Pleistocene coral community structure in response to sea level change in the Ryukyu Islands 国際会議

Humblet, M. and Iryu. Y.

17th International Sedimentological Congress

Evolution of the Nd and Pb isotopic signatures in deep Labrador Sea clay during the Holocene: implications on deep ocean circulation in the North Atlantic 国際会議

Marc Humblet

EGS-AGU-EUG Joint Assembly

Nd and Pb isotope signatures of the clay-size fraction of Labrador Sea sediments during the Holocene: Implications for the inception of modern deep circulation pattern

Brasseur., R., Humblet, M., Hillaire-Marcel, C., and Fagel, N

3rd VLIZ Young Marine Scientist Day

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