Dr. Katrin Heindel

Microbialites in coral reefs

The post-Last Glacial Maximum (LGM) reef-succession at Tahiti typically consists of coral framework encrusted by coralline algae and later by thick microbial carbonate crusts (up to 15 cm), so called microbialites. Microbialites are microbial induced carbonates (cf, stromatolites). These reef-microbialites make up as much as 80% of the reef volume. Similar deglacial microbialites occur in coral reefs off Vanuatu, whereas only thin crusts were observed in Holocene coral reefs off Belize and from the Maldives. After sea-level stabilized approximately 6000 years ago, microbialites ceased to form in coral reefs. Their occurrence in post-LGM reefs is believed to reflect environmental change during the last sea-level rise.

In order to improve our understanding of the genesis of reef-microbialites, my research focuses on microbes and processes, which induced the formation of these microbialites. Thus, I investigate microbialites from different fossil coral reefs in different oceans influenced by varying environmental conditions (influx of sediment, continental basement, nutrient-level-changes):

Tahiti (Central Pacific, volcanic island, barrier reef)
Vanuatu (South-West Pacific, volcanic island, fringing reef)
Belize (Caribbean Sea, crystalline basement, barrier reef)
The Maldives (Indian Ocean, atoll)

My major interest is to unravel the (palaeo-) environmental significance and genesis of reef-microbialites for a better understanding of environmental changes linked to the last sea-level rise.

Methods:
Integration of sedimentological, bio-geochemical, and palaeontological data-sets for generating palaeoenvironmental models.

• study of microbioerosion patterns
• analysis of lipid biomarkers
• analysis of trace elements (LA-ICP-MS)
• analysis of stable isotopes (high resolution: MicroMill)
• structural and petrographical studies
• sediment composition analysis

Figures, right-hand side: Microbialite samples of Vanuatu and Tahiti. Typical deglacial reef-succession: corals ( light-coloured areas) encrusted by coralline red algae (thin white layers) and laminated and dendritic microbialites (grey to brownish crusts). Scale in upper figure: 2 cm.

Dr. Max Wisshak, GeoZentrum Nordbayern (University of Erlangen)

Dr. Jürgen Titschack, GeoZentrum Nordbayern (University of Erlangen)

Prof. Dr. Eberhard Gischler, Palaeontology (Johann Wolfgang Goethe-University, Frankfurt)

Prof. Dr. Guy Cabioch, Institut de Recherche pour le Développement (IRD), Paris

Dr. Benjamin Brunner, Max Planck Institut for Marine Microbiology (Bremen)

Peer review articles:

Heindel K., Titschack J., Dorschel B., Huvenne V.A.I & Freiwald A. (in press). Sediment composition and facies prediction mapping of a cold-water coral mound (Propeller Mound, Porcupine Seabight, NE Atlantic). Continental Shelf Research.

Heindel K., Birgel D., Westphal H. & Peckmann J. (in press). Formation of deglacial microbialites in coral reefs off Tahiti (IODP 310) involving sulfate-reducing bacteria. Palaios.

Westphal H., Heindel K., Brandano M. & Peckmann J. (2010). Genesis of microbialites as contemporaneous framework components of coral reefs, deglacial of Tahiti (IODP 310), Facies, 56, 337-352.

Heindel K., Westphal H. & Wisshak M. (2009). Data report: bioerosion in the reef framework, IODP Expedition 310 off Tahiti (Tiarei, Maraa, and Faaa sites). In Camoin, G.F., Iryu, Y. McInroy, D.B., and the Expedition 310 Scientists, Proceedings IODP, 310: Washington, DC (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.310.201.2009

Heindel K., Wisshak M. & Westphal H. (2009). Microbioerosion in Tahitian reefs: A record of environmental change during the last deglacial sea-level rise (IODP 310). Lethaia, 42, 322-340.

Others:

Heindel K., Birgel D., Peckmann J., Kuhnert H. & Westphal H. (2009). Sulfate-reducing bacteria as major players in the formation of reef-microbialites during the last sea-level rise (Tahiti, IODP 310). Geochimica et Cosmochimica Acta, 73 (13), Goldschmidt Conference, A514-A514.

Heindel K. (2009). Environmental control of the genesis of Tahitian reef microbialites during the last deglacial sea-level rise. - PhD thesis at the Geosciences Department, University of Bremen. http://nbn-resolving.de/urn:nbn:de:gbv:46-diss000113590

Westphal H., Freiwald A., Hanebuth T., Eisele M., Gürs K., Heindel K., Michel J., Reumont J.V. (2007): Report and preliminary results of Poseidon Cruise 346, MACUMA – Modern atypical tropical carbonates in the upwelling off Mauritania. Reports, FB Geowissenschaften, University Bremen, 260: 49.

Heindel K. (2004): Palaeoenvironmental reconstructions at a Carbonate Mound: Propeller Mound/ Porcupine Seabight.- unpublished masters thesis, Institute of Palaeontology, University of Erlangen-Nürnberg.

“Environmental control of the genesis of Tahitian reef-microbialites during the last deglacial sea-level rise”


Advisor: PD Dr. Hildegard Westphal

During IODP Expedition 310 “Tahiti Sea-Level”, drowned Pleistocene to Holocene barrier reef terraces have been drilled on the slope of the volcanic island of Tahiti (French Polynesia, Central Pacific). The Tahitian deglacial reef-succession typically consists of coral framework encrusted by coralline algae and later by thick microbialites (up to 15 cm), which make up as much as 80% of the coral reef-core volume. This large volume of microbialites is uncommon for modern shallow-water coral reefs. The genesis of deglacial microbialites and the conditions favoring their formation are still under discussion.

Geobiological, geochemical, and sedimentological analyses were performed on laminated and dendritic deglacial microbialites in order to investigate the organisms, processes and environmental conditions leading to their formation.

Keywords: lipid biomarkers, microbioerosion, radiocarbon dating, LA-ICP-MS (trace element composition), X-ray diffraction (XRD), stable isotopes

To identify the microbes in the reef-microbialites of Tahiti, lipid biomarkers have been successfully used for the first time. Bacterially-derived branched fatty acids (10-Me-C16:0, iso- and anteiso-C15:0 and -C17:0) and mono-O-alkyl glycerol ethers (MAGEs) are very abundant in microbialites off Tahiti and Vanuatu. These branched fatty acids as well as MAGEs are biomarkers of intermediate to high specificity for sulfate-reducing bacteria (SRB). Both branched fatty acids and MAGEs are relatively enriched in 13C compared to the other lipids, agreeing with a different source of the bacterial lipids. No lipid biomarkers indicative of cyanobacteria were preserved in the microbialites.

The contents of Al, Si, Fe, Mn, and Ba as well as the abundance of pyroxene, plagioclase, and magnetite in the microbialites reflect strong terrigenous influx with Tahitian basalt as the major source. Chemical weathering of the basalt most likely elevated nutrient levels in the Tahiti reefs. This fertilization presumably led to an increase in primary production and organic matter formation, boosting heterotrophic sulfate reduction. Based on the observed biomarker patterns, sulfate-reducing bacteria were apparently involved in the formation of microbialites in the coral reefs off Tahiti during the last deglaciation.

The encrustation of the corals took place within the photic zone, which is demonstrated by the dominance of traces produced by phototrophic microbioeroders (microendoliths) in corals and microbialites, mainly low-light specialists. Microbioerosion and radiocarbon ages demonstrate that the encrustation by microbialites was almost coeval to coral growth. This implies an encrustation horizon (microbialite growth layer) shortly below the reef-top. The microbioerosion patterns mainly represent deeper euphotic to dysphotic conditions, which is very deep for zooxanthellate coral growth. The explanation could be the higher primary productivity, which is thought to have reduced the light availability (illumination). This possibly resulted in condensation of the photic zones (“telescoping effect”), giving the impression of deeper water depths and agrees with microbioerosion patterns typical for deeper euphotic to dysphotic water depths.

Heindel K., Westphal H., Peckmann J., Birgel D., Kuhnert H., Wisshak M., Brandano M., and Cabioch G. (2009). Microbialites in deglacial coral reefs off Tahiti (IODP 310). - 27th IAS Meeting of Sedimentologists, Alghero, Italy, Talk.

Heindel K., Birgel D., Kuhnert H., Westphal H., and Peckmann J. (2009). Formation of post-glacial Tahitian coral reef-microbialites (IODP 310): a new model favoring sulfate-reducing bacteria. - IMOG, Bremen, Germany, Poster.

Heindel K., Birgel D., Peckmann J., Kuhnert, H. and Westphal H. (2009). Sulfate-reducing bacteria as major players in the formation of reef-microbialites during the last sea-level rise (Tahiti, IODP 310). - Goldschmidt, Davos, Schweiz, Talk.

Heindel K., Birgel D., Westphal H. and Peckmann J. (2008). Origin of laminated microbialites in coral reefs from the last deglaciation off Tahiti (IODP 310). - International Kalkowsky-Symposium "Geobiology of Stromatolites", Göttingen, Germany, Talk.

Heindel K., Birgel D., Westphal H., Peckmann J. and Wisshak, M. (2008). A geochemical and geobiological study of microbialites in post-LGM reefs off Tahiti (IODP 310). - 1st Euromarc Conference, Nice, France, Talk.

Heindel K., Birgel D., Westphal H. and Peckmann J. (2008).  Biogeochemical signals of last deglacial Tahitian reef-microbialites (IODP 310). - 26th IAS Meeting of Sedimentology/ Sediment, Bochum, Germany, Talk.

Heindel K., Birgel D., Westphal H. and Peckmann J. (2008). Microbial crusts in Tahitian reefs: geochemical & geobiological signals as record of last deglacial environmental changes (IODP 310). - Geochemical Seminar, ICBM (University of Oldenburg), Germany, invited Talk.

Heindel K., Birgel D., Westphal H. and Peckmann J. (2008). Microbial crusts in Tahitian reefs as record of environmental change during the last deglacial sea-level rise (IODP #310). - Geology of Coral-Rich Carbonate Systems (ESF & IODP), Sicily, Italy, Talk.

Heindel K., Westphal H., Wisshak M., Birgel D. & Peckmann J. (2007). Microbialites in IODP #310 cores (Tahiti) - nature and environmental conditions. - 2nd Post-Expedition Meeting, Papeete, Tahiti, Talk.

Heindel K., Birgel D., Peckmann J. & Westphal H. (2007). Microbial crust genesis as response to rapid environmental changes during the last deglacial sea-level rise - IODP Expedition #310 "Tahiti Sea-Level". - GV Tagung, Bremen, Poster.

Heindel K., Wisshak M. & Westphal H. (2007). The last deglacial sea-level rise: timing of microbial encrustation of corals as indicated by microbioerosion - IODP Expedition # 310 “Tahiti Sea-Level”. - 13th Bathurst Meeting of Carbonate Sedimentologists, Norwich, England, Talk.

Heindel K., Westphal H., Camoin G., Seard C., Birgel D., Peckmann J., IODP Expedition 310 Scientists (2007). Microbialite-dominated coral reefs as response to abrupt environmental changes during the last deglacial sea-level rise. IODP Expedition #310, Tahiti. - EGU General Assembly, Wien, Österreich, Poster.

Camoin G., Westphal H., Séard C., Heindel K., Yokoyama Y., Matsuzaki H., Vasconcelos C., Warthmann R., Webster J., Expedition 310 Scientists (2007). Microbialites : a major component of the last deglacial reef sequence from Tahiti. Environmental significance and sedimentological roles. - EGU General Assembly, Wien, Österreich, Poster

Westphal H., Camoin G., Peckmann J., Heindel K., Séard C., Eisenhauer A., IODP Expedition 310 Scientists (2006). Reef response to last deglacial rapid sea-level rise: the microbialite question (IODP Expedition #310). - Seal’ AIX (Sea Level Changes), Aix-en-Provence, Frankreich, Poster.

Heindel K., Freiwald A. (2003). Analyzing deep-water coral-rich sediment cores with CT: Propeller Mound, Northern Porcupine Seabight. - 2nd International Symposium on Deep-Sea Corals, Erlangen, Poster.

28th Dec 2006- 15th Jan 2007
Poseidon cruise 346 from Las Palmas (Canaries) to the Shelf of Mauritania. Due to a saisonal upwelling atypical - tropical carbonate sediments develop at the Mauritanian shelf and at the continental margin (so called cold-water coral-reefs). Both carbonate ranges were sampled during the cruise.

15th July - 4th August 2002
Poseidon cruise 292 from Reykjavik (Iceland) to Galway (Ireland). Aim of the cruise was the documentation, mapping and sampling of several cabonate mounds at the Hatton- and Rockall Bank and within the Porcupine Seabight.

23rd April - 22nd July 2001
Basic geological and biological research and conservation work at the Kiang West National Park (Gambia, West Africa).