Jürgen Titschack

Growth, deposition, and facies of Pleistocene bathyal coral communities from Rhodes, Greece

Modern and widespread deep-water coral ecosystems have become a major target of research during the last decades. So far, only a few fossil counterparts of such carbonate-secreting deep-water communities have been described. This scarcity might be a result of either, a possible miss-identification as a tropical deposit and/or the rare case of tectonic uplift and subsequent access to these deepwater deposits.

Framework-Forming Scleractinian Cold-Water Corals Through Space and Time: A Late Quaternary North Atlantic Perspective

Framework-forming scleractinian cold-water corals, with Lophelia pertusa and Madrepora oculata being the most common species, show an outstanding concentration in the North Atlantic Ocean. They are unique in their ability to provide habitats for other organisms ranging from microto mega-scale, and some species are even exceptional in their capability to shape the seafloor by forming large C. Wienberg (*) MARUM – Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany e-mail: cwberg@marum.de J. Titschack Marine Research Department, SAM – Senckenberg am Meer, Wilhelmshaven, Germany MARUM – Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany e-mail: jtitschack@marum.de # Springer International Publishing Switzerland 2015 S. Rossi (ed.), Marine Animal Forests, DOI 10.1007/978-3-319-17001-5_16-1 1 three-dimensional structures called coral mounds. Our understanding about the spatial and temporal distribution of cold-water corals and coral mounds and the environmental factors that control coral occurrence and influence mound development increased tremendously during the past 15 years. This synthesis highlights that: (i) species-specific environmental preferences and tolerances need to be considered when describing any coral distribution pattern; (ii) corals and coral mounds are linked to a complex set of multiple environmental variables that must work in concert as each variable might present a stimulator as well as a suppressor for coral occurrence and mound formation; (iii) environmental conditions for mound aggradation are more restrictive than those for coral occurrence; and (iv) the majority of environmental variables influencing the occurrence of corals and mound development are linked to distinct water masses whose characteristics vary with climatic fluctuations. Hence, regional coral distribution pattern and mound aggradation periods are in phase with these fluctuations, even though the specific environmental controls might vary from region to region. Nevertheless, certain data limitations and resulting constraints to generate generalized pattern regarding the climate-related spatiotemporal distribution of cold-water corals and coral mounds still exist and ask for more sophisticated future research strategies.

Mediterranean cold-water corals - an important regional carbonate factory?

This study presents aggradation rates supplemented for the first time by carbonate accumulation rates from Mediterranean cold‐water coral sites considering three different regional and geomorphological settings: (i) a cold‐water coral ridge (eastern Melilla coral province, Alboran Sea), (ii) a cold‐water coral rubble talus deposit at the base of a submarine cliff (Urania Bank, Strait of Sicily) and (iii) a cold‐water coral deposit rooted on a predefined topographic high overgrown by cold‐water corals (Santa Maria di Leuca coral province, Ionian Sea). The mean aggradation rates of the respective cold‐water coral deposits vary between 10 and 530 cm kyr−1 and the mean carbonate accumulation rates range between 8 and 396 g cm−2 kyr−1 with a maximum of 503 g cm−2 kyr−1 reached in the eastern Melilla coral province. Compared to other deep‐water depositional environments the Mediterranean cold‐water coral sites reveal significantly higher carbonate accumulation rates that were even in the range of the highest productive shallow‐water Mediterranean carbonate factories (e.g. Cladocora caespitosa coral reefs). Focusing exclusively on cold‐water coral occurrences, the carbonate accumulation rates of the Mediterranean cold‐water coral sites are in the lower range of those obtained for the prolific Norwegian coral occurrences, but exhibit much higher rates than the cold‐water coral mounds off Ireland. This study clearly indicates that cold‐water corals have the potential to act as important carbonate factories and regional carbonate sinks within the Mediterranean Sea. Moreover, the data highlight the potential of cold‐water corals to store carbonate with rates in the range of tropical shallow‐water reefs. In order to evaluate the contribution of the cold‐water coral carbonate factory to the regional or global carbonate/carbon cycle, an improved understanding of the temporal and spatial variability in aggradation and carbonate accumulation rates and areal estimates of the respective regions is needed.

Two new species of erect Bryozoa (Gymnolaemata: Cheilostomata) and the application of non-destructive imaging methods for quantitative taxonomy.

Two new species of cheilostome Bryozoa are described from continental-slope habitats off Mauritania, including canyon and cold-water coral (mound) habitats. Internal structures of both species were visualised and quantified using microcomputed tomographic (micro-CT) methods. Cellaria bafouri n. sp. is characterised by the arrangement of zooids in alternating longitudinal rows, a smooth cryptocyst, and the presence of an ooecial plate with denticles. Smittina imragueni n. sp. exhibits many similarities with Smittina cervicornis (Pallas, 1766), but differs especially in the shape and orientation of the suboral avicularium. Observations on Smittina imragueni and material labelled as Smittina cervicornis suggest that the latter represents a species group, members of which have not yet been discriminated, possibly because of high intracolony variation and marked astogenetic changes in surface morphology. Both new species are known only from the habitats where they were collected, probably reflecting the paucity of bryozoan sampling from this geographic area and depth range. Both species are able to tolerate low oxygen concentration, which is assumed to be compensated by the high nutrient supply off Mauritania. The application of micro-CT for the semiautomatic quantification of zooidal skeletal characters was successfully tested. We were able to automatically distinguish individual zooidal cavities and acquire corresponding morphological datasets. Comparing the obtained results with conventional SEM measurements allowed ascertaining the reliability of this new method. The employment of micro-CT allows the observation and quantification of previously unseen characters that can be used in describing and differentiating species that were previously indistinguishable. Furthermore, this method might help elucidate processes of colony growth and the function of individual zooids during this process.

Testing the applicability of a benthic foraminiferal-based transfer function for the reconstruction of paleowater depth changes in Rhodes (Greece) during the early Pleistocene

We present paleo-water depth reconstructions for the Pefka E section deposited on the island of Rhodes (Greece) during the early Pleistocene. For these reconstructions, a transfer function (TF) using modern benthic foraminifera surface samples from the Adriatic and Western Mediterranean Seas has been developed. The TF model gives an overall predictive accuracy of ~50 m over a water depth range of ~1200 m. Two separate TF models for shallower and deeper water depth ranges indicate a good predictive accuracy of 9 m for shallower water depths (0–200 m) but far less accuracy of 130 m for deeper water depths (200–1200 m) due to uneven sampling along the water depth gradient. To test the robustness of the TF, we randomly selected modern samples to develop random TFs, showing that the model is robust for water depths between 20 and 850 m while greater water depths are underestimated. We applied the TF to the Pefka E fossil data set. The goodness-of-fit statistics showed that most fossil samples have a poor to extremely poor fit to water depth. We interpret this as a consequence of a lack of modern analogues for the fossil samples and removed all samples with extremely poor fit. To test the robustness and significance of the reconstructions, we compared them to reconstructions from an alternative TF model based on the modern analogue technique and applied the randomization TF test. We found our estimates to be robust and significant at the 95% confidence level, but we also observed that our estimates are strongly overprinted by orbital, precession-driven changes in paleo-productivity and corrected our estimates by filtering out the precession-related component. We compared our corrected record to reconstructions based on a modified plankton/benthos (P/B) ratio, excluding infaunal species, and to stable oxygen isotope data from the same section, as well as to paleo-water depth estimates for the Lindos Bay Formation of other sediment sections of Rhodes. These comparisons indicate that our orbital-corrected reconstructions are reasonable and reflect major tectonic movements of Rhodes during the early Pleistocene.

The Marine Fossil Record at Santa Maria Island (Azores)

Santa Maria is the oldest island of the Azores Archipelago and is remarkably rich in exposed marine fossiliferous sediments and submarine volcanic sequences. This chapter summarises the geological history of the island and reports on the most important palaeontological studies done on the outcrops of Santa Maria since the early studies, during the 19th century. The most important early Pliocene and late Pleistocene (Last Interglacial) fossiliferous deposits are described and palaeoecological reconstructions are presented for each sedimentary succession. The most abundant, diversified and well-studied fossil groups are also reviewed, namely the algae, vertebrates (cetaceans and selaceans), and invertebrates (molluscs, echinoderms, brachiopods, crustaceans and ostracods). We also discuss the palaeontological significance of carbonate sequences in reefless volcanic oceanic islands. Finally, we discuss the importance of applied palaeontology, with products specifically designed for tourism, such as the Museum “House of the Fossils”, the “Route of the Fossils” project, and the “PalaeoPark Santa Maria”, all of them aiming to protect and conserve fossil sites, allowing at the same time, its sustainable use by locals and tourists.

Cavity and pore segmentation in 3D images with ambient occlusion

Many natural objects contain pores and cavities that are filled with the same material that also surrounds the object. When such objects are imaged using, for example, computed tomography, the pores and cavities cannot be distinguished from the surrounding material by considering gray values and texture properties of the image. In this case, morphological operations are often used to fill the inner region. This is efficient, if the pore and cavity structures are small compared to the overall size of the object and if the objects shape is mainly convex. If this is not the case, the segmentation might be very difficult and may result in a lot of noise. We propose the usage of ambient occlusion for the segmentation of pores and cavities. One nice property of ambient occlusion is that it generates smooth scalar fields. Due to this smoothness property, a segmentation based on those fields will result in smooth boundaries at the pore and cavity openings. This is often desired, particularly when dealing with natural objects.

Linking sedimentary sulfur and iron biogeochemistry to growth patterns of a cold-water coral mound in the Porcupine Basin, S.W. Ireland (IODP Expedition 307).

Challenger Mound, a 150-m-high cold-water coral mound on the eastern flank of the Porcupine Seabight off SW Ireland, was drilled during Expedition 307 of the Integrated Ocean Drilling Program (IODP). Retrieved cores offer unique insight into an archive of Quaternary paleo-environmental change, long-term coral mound development, and the diagenetic alteration of these carbonate fabrics over time. To characterize biogeochemical carbon-iron-sulfur transformations in the mound sediments, the contents of dithionite- and HCl-extractable iron phases, iron monosulfide and pyrite, and acid-extractable calcium, magnesium, manganese, and strontium were determined. Additionally, the stable isotopic compositions of pore-water sulfate and solid-phase reduced sulfur compounds were analyzed. Sulfate penetrated through the mound sequence and into the underlying Miocene sediments, where a sulfate-methane transition zone was identified. Small sulfate concentration decreases (<7 mM) within the top 40 m of the mound suggested slow net rates of present-day organoclastic sulfate reduction. Increasing δ(34)S-sulfate values due to microbial sulfate reduction mirrored the decrease in sulfate concentrations. This process was accompanied by oxygen isotope exchange with water that was indicated by increasing δ(18)O-sulfate values, reaching equilibrium with pore-water at depth. Below 50 mbsf, sediment intervals with strong (34)S-enriched imprints on chromium-reducible sulfur (pyrite S), high degree-of-pyritization values, and semi-lithified diagenetic carbonate-rich layers characterized by poor coral preservation, were observed. These layers provided evidence for the occurrence of enhanced microbial sulfate-reducing activity in the mound in the past during periods of rapid mound aggradation and subsequent intervals of non-deposition or erosion when geochemical fronts remained stationary. During these periods, especially during the Early Pleistocene, elevated sulfate reduction rates facilitated the consumption of reducible iron oxide phases, coral dissolution, and the subsequent formation of carbonate cements.