Description: Sponges (Porifera) are abundant and diverse members of benthic filter feeding communities in most marine ecosystems, from the deep sea to tropical reefs. A characteristic feature is the associated dense and diverse prokaryotic community present within the sponge mesohyl. Previous molecular genetic studies revealed the importance of host identity for the community composition of the sponge-associated microbiota. However, little is known whether sponge host-specific prokaryotic community patterns observed at 97% 16S rRNA gene sequence similarity are consistent at high taxonomic ranks (from genus to phylum level). In the present study, we investigated the prokaryotic community structure and variation of 24 sponge specimens (seven taxa) and three seawater samples from Sweden. Results show that the resemblance of prokaryotic communities at different taxonomic ranks is consistent with patterns present at 97% operational taxonomic unit level.

Description: Marine sponges (Phylum Porifera) are globally distributed within marine and freshwater ecosystems. In addition, sponges host dense and diverse prokaryotic communities, which are potential sources of novel bioactive metabolites and other complex compounds. Those sponge-derived natural products can span a broad spectrum of bioactivities, from antibacterial and antifungal to antitumor and antiviral compounds. However, most analyses concerning sponge-associated prokaryotes have mainly focused on conveniently accessible relatively shallow sampling locations for sponges. Hence, knowledge of community composition, host-relatedness and biotechnological potential of prokaryotic associations in temperate and cold-water sponges from greater depths (mesophotic to mesopelagic zones) is still scarce. Therefore, we analyzed the prokaryotic community diversity of four phylogenetically divergent sponge taxa from mesophotic to mesopelagic depths of Antarctic shelf at different depths and locations in the region of the South Shetland Islands using 16S rRNA gene amplicon-based sequencing. In addition, we predicted functional profiles applying Tax4Fun from metagenomic 16S rRNA gene data to estimate their biotechnological capability and possible roles as sources of novel bioactive compounds. We found indications that cold and deep-water sponges exhibit host-specific prokaryotic communities, despite different sampling sites and depths. Functional prediction analysis suggests that the associated prokaryotes may enhance the roles of sponges in biodegradation processes of xenobiotics and their involvement in the biosynthesis of secondary metabolites.

Description: Glass sponges (Porifera, Hexactinellida) are conspicuous habitat-forming members of many Antarctic shelf communities. Despite their ecological importance, in-situ species identification remains problematic as it is traditionally based on micro- scopic analysis of spicules. External morphological features, in contrast, have largely been disregarded, so that different species have been mislabeled or lumped together when their identification was based on image material. In this paper, we provide a straight-forward guideline for in-situ identification of the most common rossellid sponges of the Antarctic shelf based on macroscopic characteristics. To determine diagnostic macroscopic characteristics of Anoxycalyx (Scolymastra) joubini and eight Rossella species, we combined examination of trawl-collected specimens, previous species descriptions and in-situ image material from the eastern Weddell Sea. Our study revealed that the smooth-walled species A. joubini, R. nuda and R. vanhoeffeni, previously often mixed up, can be distinguished by the form of their basal spicule tuft, their surface structure and their overall body form. The previously synonymized species R. racovitzae and R. podagrosa can be distinguished by their markedly different habitus. Based on our results, the so-called ‘R. racovitzae budding type’ in fact refers to R. podagrosa which occurs regularly in the eastern Weddell Sea. The species R. villosa, R. levis, R. fibulata and R. antarctica can be distinguished by the appearance of their conules, protruding spicules and overall body form. We conclude that macroscopic characteristics are helpful means for identification of Antarctic rossellid sponge species. This approach enables species-specific quantitative studies of Antarctic glass sponge grounds based on increasingly used non-invasive imaging technology.

Description: Die obere Wasserschicht des Südpolarmeers ist reich an Pflanzennährstoffen wie Nitrat und Phosphat, trotzdem ist die biologische Produktion in großen Teilen des Südozeans relativ gering, denn es mangelt am Spurennährstoff Eisen. Die Tiere am Meeresboden sind auf Nahrung in Form von organischen Partikeln angewiesen, die von oben in die Tiefe absinken. Welche Nahrung und wie viel davon steht den Tiefseeorganismen hier überhaupt zur Verfügung? Welche Tiere – insbesondere welche Schwämme – kommen mit diesen Bedingungen gut zurecht? Darüber sollte eine Polarstern-Expedition Aufschluss geben

Description: There are few sponges known from the end-Ordovician to early-Silurian strata all over the world, and no records of sponge fossils have been found yet in China during this interval. Here we report a unique sponge assemblage spanning the interval of the end-Ordovician mass extinction from the Kaochiapien Formation (Upper Ordovician-Lower Silurian) in South China. This assemblage contains a variety of well-preserved siliceous sponges, including both Burgess Shale-type and modern type taxa. It is clear that this assemblage developed in deep water, low energy ecosystem with less competitors and more vacant niches. Its explosion may be related to the euxinic and anoxic condition as well as the noticeable transgression during the end-Ordovician mass extinction. The excellent preservation of this assemblage is probably due to the rapid burial by mud turbidites. This unusual sponge assemblage provides a link between the Burgess Shale-type deep water sponges and the modern forms. It gives an excellent insight into the deep sea palaeoecology and the macroevolution of Phanerozoic sponges, and opens a new window to investigate the marine ecosystem before and after the end-Ordovician mass extinction. It also offers potential to search for exceptional fossil biota across the Ordovician-Silurian boundary interval in China.

Description: In the Southern Ocean, that is areas south of the Polar Front, long-term oceanographic cooling, geographic separation, development of isolating current and wind systems, tectonic drift and fluctuation of ice sheets amongst others have resulted in a highly endemic benthic fauna, which is generally adapted to the long-lasting, relatively stable environmental conditions. The Southern Ocean benthic ecosystem has been subject to minimal direct anthropogenic impact (compared to elsewhere) and thus presents unique opportunities to study biodiversity and its responses to environmental change. Since the beginning of the century, research under the Census of Marine Life and International Polar Year initiatives, as well as Scientific Committee of Antarctic Research biology programmes, have considerably advanced our understanding of the Southern Ocean benthos. In this paper, we evaluate recent progress in Southern Ocean benthic research and identify priorities for future research. Intense efforts to sample and describe the benthic fauna, coupled with coordination of information in global databases, have greatly enhanced understanding of the biodiversity and biogeography of the region. Some habitats, such as chemosynthetic systems, have been sampled for the first time, while application of new technologies and methods are yielding new insights into ecosystem structure and function. These advances have also highlighted important research gaps, notably the likely consequences of climate change. In a time of potentially pivotal environmental change, one of the greatest challenges is to balance conservation with increasing demands on the Southern Ocean’s natural resources and services. In this context, the characterization of Southern Ocean biodiversity is an urgent priority requiring timely and accurate species identifications, application of standardized sampling and reporting procedures, as well as cooperation between disciplines and nations.

Description: Die Hexactinellida (Unterkambrium bis Rezent) sind das vielleicht am besten begründete Monophylum innerhalb der Porifera. Sie sind Adelphotaxon C'Schwestergruppe") der Pinacophora (Demospongiae/Calcarea-Taxon), von denen sie seit mindestens dem frühesten Kambrium abgespalten sind. Durch ihre Syncytiale Weichkörperorganisation unterscheiden sich die Hexactinellida signifikant von allen anderen Spongien. Die den Demospongiae am nächsten verwandte Gruppe stellt, entgegen gängigen Vorstellungen, wahrscheinlich nicht die Hexactinellida, sondern die Calcarea. Die kieseiigen Spicula der Hexactinellida sind wahrscheinlich als eine echte funktionelle und konstruktionsmorphologische Homoplasie unabhängig von denen der Demospongiae entstanden. Daraus ergibt sich die zwingende Schlußfolgerung, daß Spicula nicht zum Grundmuster der Porifera gehören. Spicula von der Symmetrie des rectilinearen Triaxons (Grundform: das reguläre Hexactin) mit quadratischem Axialfilament sind innerhalb der Porifera einmalig. Vergleichende Untersuchungen über die Weichkörper-Organisation diverser Hexactinellida wurden im Rahmen dieses Studiums durchgeführt. Dabei stellte sich heraus, daß sich diesbezüglich die verschiedenen Großtaxa der Hexactinellida anscheinend nur unwesentlich von einander unterscheiden; d.h. sie haben sich von ihrem Grundmuster kaum weiterentwickelt. Eine gezielte Überprüfung der außerordentlich vielfältigen hexactinelliden Nadeltypen ergab ferner, daß sich diese verschiedenen Spiculatypen, einschließlich der Amphidisken, alle vom regulären Hexactin ableiten, und dass keine grundsätzlich neuen Spicula dazugekommen sind. Die Hexactinellida, deren Vertreter sich im Laufe der mindestens 580 Millionen Jahre ihrer Existenz kaum verändert haben, verkörpern somit eine extrem konservative (wenn nicht gar die konservativste) Gruppe des Tierreiches. Die Hexactinellida gliedern sich in die Adelphotaxa Hexasterophora und Amphidiscophora (seit dem Unterordovizium bzw. Obersilur nachgewiesen). Aufgrund ihrer nicht-rigiden Sklerenskelette waren die Amphidiscophora aus der fossilen Überlieferung, außer isolierter Amphidisken aus Schlämmproben, bisher fast unbekannt. Infolge der sehr günstigen Fossilisationsbedingungen des Oberkretazischen Amagerkalks (Bornholm, Dänemark) können aus diesen Schichten mehrere amphidiscophoride Gattungen erstmalig nachgewiesen werden: Monorhaphis, Hyalonema sowie wahrscheinlich Pheronema. Einige Hexasterophora sind im Besitz rigider (diktyonaler) Sklerenskelette, wodurch sie besser erhaltungsfähig sind als nicht-rigide (lyssakine) Formen. Die Namen "Diktyonina" und "Lyssakina" (Zirm 1877), sind jedoch Bezeichnungen für nicht-monophyletische Gruppierungen. Sie sind deshalb aus der taxonomischen Systematik zu eliminieren und nur rein deskriptiv im morphologischen Sinne zu verwenden. Hexactinellida von diktyonalem Skelettbau umfassen die Taxa Hexactinosa und die Lychniscosa. Diese jedoch sind höchst wahrscheinlich keine Schwestergruppen, sondern haben ihre diktyonalen Sklerenskelette mitsamt den verschiedenen Kanalsystemen und basalen Anheftungsmodi, durch ihre Anpassung an dieselben Lebensräume im Mesozoikum voneinander unabhängig, konvergent erworben. Als eindeutiges Monophylum innerhalb der Hexactinosa wird die Gruppe Sceptrulen-tragender Hexactinellida begründen, hier ist der Name Sceptrulophora für diese Gruppe vorgeschlagen. Das Monophylum Sceptrulophora umfaßt die Schwestergruppen Clavularia und Scopularia (seit der Mitteltrias eindeutig dokumentiert). Die Lychniscosa (seit dem Bathonium nachgewiesen) sind wahrscheinlich aus einer lyssakinen Gruppe der Hexasterophora hervorgegangen. Übereinstimmende Hexaster deuten darauf hin, daß ihr Adelphotaxon innerhalb der Euplectellidae zu suchen sein dürfte. Für das vermutete Euplectellidae/Lychniscosa-Taxon wird daher der Name Graphiocomida vorgeschlagen. Beim verbreiteten Besitz von Codonhexastem innerhalb sowohl der Rossellidae als auch Euplectellidae könnte es sich um eine Synapomorphie handeln. In diesem Falle wären Rossellidae und Graphiocomidae Schwestergruppen, und das sich daraus ergebende Monophylum wäre als Taxon nominal zu benennen. Die lyssakinen Rossellidae und Euplectellidae sind jedoch aufgrund ihres geringen Erhaltungspotientials in der fossilen Überlieferung kaum dokumentiert. Z. Zt. ist von den Euplectellidae nur die Gattung Regadrella mit zwei fossilen Arten (davon eine erst 1990 durch die Autorin aufgestellt) aus der Oberkreide bekannt. Die Rossellidae lassen sich aufgrund isolierter, diagnostisch signifikanter Hexaster bis in den Oberlias zurückverfolgen. Erste körperlich erhaltene, gesicherte, fossile Vertreter der Rossellidae werden hier aus dem Oberkretazischen Arnagerkalk dokumentiert. Als ultra-konservative Gruppe eignen sich die Hexactinellida für palökologische Rekonstruktionen, sofern ihre ökologischen Ansprüche und limitierenden Faktoren bekannt sind (was bisher kaum der Fall war). Die Hexactinellida sind ausgesprochene k-Strategen und benötigen als solche stabile Biotope. Sie sind an normalmarine, nicht-turbulente Environments mit geringer Strömungsenergie gebunden (Einzige bisher bekannte Ausnahme ist die in nächster Umgebung hydrothermaler Quellen eingenischte Art Caulophacus cyanae). Strukturierte Meeresboden mit einem moderaten Relief scheinen bevorzugte Siedlungsräume dieser Spongien zu sein. Beim Vorhandensein der entsprechenden Ökofaktoren sind die Hexactinellida bathymetrisch tolerant. Einzelne Gruppen können jedoch an Verhältnisse angepaßt sein, die nur in bestimmten Wassertiefen verwirklicht sind. Auch haben sich solche kritischen Tiefen im Laufe der Erdgeschichte mehrmals geändert. Beispielsweise bildeten im Oberjura die Hexactinellida Spongien-Mounds in zwar geringeren Wassertiefen, jedoch unter ökologischen Rahmenbedingungen, die den rezenten Lebensräumen ähnlich sind. Eine entscheidende ökologische Transformation in der Geschichte der Hexactinellida stellt ihre Einnischung auf den ausgedehnten Schelfregionen des Mesozoikums dar. Diese ging mit verschiedenen evolutiven Neuerwerbungen einher, u.a. mit dem Auftreten der Sceptrulophora ab der Mitteltrias und der Lychniscosa im mittleren Jura. Ein bedeutender Faunenschnitt innerhalb der diktyonalen Hexactinellida (Hexactinosa und Lychniscosa) muß während der frühen Oberkreide stattgefunden haben. Anscheinend nur wenige hexactinose Gruppen überlebten diese Krise; z.B. die Laocaetis-Gruppe, die vom Jura bis Rezent durchgeht. Ihre maximale Diversität und eine große räumliche Entfaltung erreichten die Hexactinellida während der höheren Oberkreide. Diese Blüte ist durch den großen Vielfalt diktyonaler Formen -Hexactinosa und Lychniscosa- aus den Schichten der höheren Oberkreide Norddeutschlands offensichtlich. Aufgrund der neuen reichen Oberkretazischen Hexactinellidenfauna des Amagerkalks darf dieses Maximum ebenfalls für die weniger erhaltungsfähigen und deshalb selten dokumentierten, lyssakinen Hexactinellida angenommen werden. Seit der oberen Kreide scheinen keine evolutiven Neuerscheinungen dazugekommen zu sein. Während des späten Mesozoikums war die Diversität der rigiden Hexactinellida, insbesondere der Lychniscosa, somit wesentlich größer, als es heute der Fall ist. Zur Bildung riffähnlicher Strukturen mit Hexactinellidendominanz ist es jedoch seit dem Oberjura anscheinend nicht mehr gekommen. Es ist kein "katastrophales Aussterben" an der Kreide-/Tertiär-Grenze zu verzeichnen. Das Erlöschen vieler hexactinellider Gruppen dürfte mit der sukzessiven Reduktion ihrer Lebensräume, der mesozoischen Schelfgebiete, Zusammenhängen.

Description: The Hexactinellida (earliest Cambrian - Recent) may be the best established monophylum within the Porifera. They are the adelphotaxon ("sister group") of the Pinacophora (Demospongiae/Calcarea-taxon), from which they have evolved separately at least since the ealiest Cambrian. Because of the syncytial organization of their soft tissues, Hexactinellida fundamentally differ from all other sponges. Contrary to other current phylogenetic assumptions, the closest relatives of the Demospongiae within the Porifera probably are not the Hexactinellida but the Calcarea. The siliceous spicules of Hexactinellida appear to have evolved convergently to those of Demospongiae as a true functional and constructive morphological homoplasy. Thus follows consequently the conclusion that spicules do not belong to the poriferan basic pattern. Spicules of rectilinear triaxial symmetry (basic type is the regular hexactin), with an axial filament that is square in cross section, represent a unique character within the Porifera. The soft tissue organization of various Hexactinellida was the subject of comparative studies. It appears that in this respect the different hexactinellid major taxa show little variation. This implies minor evolution of these groups from their basic pattern. Examination of the extraordinarily diverse assemblage of hexactinellid spicule types shows that these in shape and size so variable forms, including the amphidiscs, all derived from the regular hexactin. No other, basically new spicule-types have ever been introduced. Thus, one of the most conservative groups (or maybe even the most conservative one) within the animal kingdom is represented by the Hexactinellida, whose members hardly underwent any changes during the time of at least 580 m.y. of their existence. The Hexactinellida comprise the adelphotaxa Hexasterophora and Amphidiscophora (documented since the Early Ordovician and Late Silurian, respectively). Owing to their non-rigid skeletons, fossil Amphidiscophora have been very poorly known, except as isolated amphidiscs from dissolved sedimentary rocks. As a result of the very advantageous conditions of fossilisation within the Coniacian Amagerkalk (Bornholm, Denmark) several amphidiscophoran genera have now been documented for the first time within the fossil record: Monorhaphis, Hyalonema, and probably Pheronema. Some Hexasterophora possess rigid (dictyonal) spicular skeletons, which increase their preservation potiential compared with the non-rigid (lyssacine) groups. The names "Dictyonina" and "Lyssacina", however, cover non-monophyletic groupings. These designations are to be eliminated from taxonomic systematics and should be restricted to a merely morphological descriptive sense. Hexactinellida of dictyonine organization comprise the taxa Hexactinosa and Lychniscosa. These apparently do not represent sister groups. Most probably the dictyonal skeletons together with rigid channel systems and diverse modes of basal attachment evolved convergently within these groups as an independent adaptation to the same environments during the Mesozoic. Within the hexactinosans the Sceptrulophora (sceptrule-carrying hexactinellids) are established as undoubtedly monophyletic. The Sceptrulophora comprise the sister groups Clavularia and Scopularia (first definite documentation from the Middle Triassic). The Lychniscosa (first appearence in the Bathonian) probably arose from some lyssacine group of the Hexasterophora. Corresponding hexasters seem to indicate that their adelphotaxon may be found within the Euplectellida. For the assumed Euplectellidae/Lychniscosa-taxon, the name Graphiocomida is suggested. The widespread occurrence of codonhexasters within both the Rossellidae and Euplectellidae may be interpreted as synapomorphic. In this case Rossellidae and Graphiocomidae would be sister groups, and the monophylum thus established would need a taxonomic nominal designation. However, owing to their poor preservation potiential, the lyssacine Rossellidae and Euplectellidae are hardly documented within the fossil record. At present the Euplectellidae are known from one genus with two fossil species only (one of which was described by the author as late as 1990), both from the Upper Cretaceous. On account of significant hexasters, the Rossellidae can be traced back to the Liassic. The first definite rossellids preserved as entire body fossils are here documented from the Upper Cretaceous Arnagerkalk. The Hexactinellida as an ultra-conservative group are useful for palecological reconstructions to the degree that their ecological limiting factors and requirements are known (which has been hardly the case until now). Hexactinellids are explicite k-strategists and thus require stable biotopes. They are restricted to normal marine non-turbulent environments with moderate current energies (currently only one exception is known: Caulophacus cyane created its ecological niche in the vicinity of hydrothermal vents). Structured bottoms with moderate reliefs appear to be preferred habitats for these sponges. Under the conditions of these crucial ecofactors, the Hexactinellida are bathymetrically tolerant. However, some groups may be adapted to specific conditions that are realized only at certain water depths. Such critical water depths have changed several times in the course of Earth history. During the Late Jurassic, for example, the hexactinellids built sponge mounds at water depths shallower than their recent habitats, but under comparable ecological conditions. A main ecological transformation within the stratigraphic history of Hexactinellida is represented by their colonization of the extensive Mesozoic shelf regions. This new settlement was combined with various evolutionary achievements, e.g. the occurrence of the Sceptrulophora from the Middle Triassic and that of the Lychniscosa from the Middle Jurassic. A significant faunal extinction within the dictyonal Hexactinellida (Hexactinosa and Lychniscosa) must have taken place some time at the beginning of the Early Cretaceous. Only a few hexactinosans appear to have survived this crisis; e.g. the Laocaetis-group continues from the Jurassic until today. The Hexactinellids reached their maximal diversity and a wide distribution during the Late Cretaceous. This flourishing is exhibited by the notable development of dictyonal hexactinellids − hexactinosans and lychniscosans − in the late Cretaceous of Northern Germany. On account of the recently documented rich hexactinellid fauna from the Coniacian of the Arnagerkalk, this climax can be assumed to have affected the less fossilizeable lyssacine hexactinellids as well. There does not seem to have been any further evolutionary development after this period. Thus, during the Late Mesozoic, rigid Hexactinellida, especially the Lychniscosa, occurred in a diversity much higher than they do today. However, since the Late Jurassic they appearently no longer created reef-like build-ups. No "catastrophic extinction" can be proven at the Cretaceous/Tertiarv-Boundarv. The reduction of the hexactinellids to a great extent seems to be correlated with the successive restriction of their habitats in the Mesozoic shelf areas.

Description: thesis

Description: DFG, SUB Göttingen