Dr. Katrin Heindel

Microbialites in coral reefs

Microbialites are microbial induced carbonates (cf, stromatolites). The formation of microbialites in coral reefs is not yet fully understood. The occurrence of the partly very voluminous and thick microbialites in post-glacial reefs of the world oceans is probably linked to the rapid last sea-level rise and accompanying environmental changes.

My research focuses on the investigation and comparison of post-glacial microbialites in coral reefs from different settings (hinterland, influx of sediment, nutrients, reef-type) in different oceans:

Vanuatu, New Caledonia (fringing reef, Sourthwest-Pacific)
Malediven (Atoll, Indopacific)
Belize (barrier reef, Caribbean Sea)
Tahiti (barrier reef, Central-Pacific)

The major interest is to unravel the (palaeo-) environmental significance and genesis of reef-microbialites for a better understanding of post-glacial 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

Figure, right-hand side: Microbialite samples. Typical deglacial reef-succession of Tahiti: Corals (1) encrusted by coralline red algae (white layers, 2) and laminated and dendritic microbialites (grey, 3 & 4).

Geobiology Group, Prof. Dr. Jörn Peckmann, MARUM (University of Bremen)
Group of PD Dr. Hildegard Westphal, MARUM (University of Bremen)
PalaeoEnvironment Group, Prof. André Freiwald, GeoZentrum Nordbayern (University of Erlangen-Nürnberg)
Dr. Max Wisshak, GeoZentrum Nordbayern (University of Erlangen-Nürnberg)
Prof. Dr. Eberhard Gischler, Palaeontology (Johann Wolfgang Goethe-University, Frankfurt)
Prof. Dr. Guy Cabioch, Institut de Recherche pour le Développement (IRD), Paris

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


Advisors: PD Dr. Hildegard Westphal; Prof. Dr. Jörn Peckmann

During IODP Expedition 310 “Tahiti Sea-Level”, drowned Pleistocene to Holocene barrier reef terraces have been drilled on the slope of the volcanic island Tahiti (French Polynesia, central Pacific). This thesis focuses on the cores of the post-Last Glacial Maximum (LGM) reef sequence. The Tahitian deglacial reef-succession typically consists of zooxanthellate corals, which are encrusted by coralline red algae and subsequently by microbialites. These microbialites (microbial carbonate crusts) are composed of high-magnesium-calcite and show two growth patterns. An initially laminated pattern changes partly to a dendritic pattern during progressive microbialite growth. The large volume of microbialites (up to 80 vol. % of the cores) is uncommon for modern shallow-water coral reefs. This study aims in the investigation of the still poorly understood genesis of these voluminous Tahitian microbialites.

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

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

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 is representative for mostly deeper euphotic to dysphotic conditions, which is very deep for zooxanthellate coral growth.
The elemental composition of the microbial carbonates (relative high contents of Al, Si, Fe, and Ba) and the detected clay- and basalt-derived minerals in the microbialites (mainly phyllosilicates, pyroxene, plagioclase, and magnetite) point to a strong terrigeneous influx from the volcanic island. Thereby increased nutrient levels could be an explanation for an intensified primary productivity during the last deglacial sea-level rise. The higher primary productivity is thought to have reduced the light availability (illumination), which finally resulted in a condensation of the photic zones (“telescoping effect”), giving the impression of deeper water depths.

For the identification of microbes in the reef-microbialites of Tahiti, lipid biomarkers have been successfully used. In the microbialites, terminally-branched fatty acids (iso- and anteiso C15/17) were detected in uncommonly high concentrations for coral reefs. Iso- and anteiso C15/17 fatty acids are typical biomarkers for sulphate-reducing bacteria. Because enzymatic carbon isotope fractionation of heterotrophic sulfate reducers is insignificant, the minor shift between the average δ13C values of the bulk organic matter and the average compound-specific δ13C values of the iso- and anteiso C15 and C17 fatty acids agrees with sulfate reducers as source of the bacterial fatty acids. Clear indications for cyanobacteria or other phototrophic microbes were not found.

The results of this thesis indicate a deglacial reef environment, which was possibly influenced by an intensified primary productivity. It is demonstrated, that sulphate-reducing bacteria dominated the precipitation of the carbonate. Consequently, sulphate reducers played the major role in the genesis of microbialites in the deglacial coral reefs of Tahiti.

Peer review articles:

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

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

Westphal H., Heindel K., Brandano M. & Peckmann J. (published online). Genesis of microbialites as contemporaneous framework components of coral reefs, deglacial of Tahiti (IODP 310), Facies.

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.

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).