Lydia Beuck

Shallow-water Desmophyllum dianthus (Scleractinia) from Chile: characteristics of the biocoenoses, the bioeroding community, heterotrophic interactions and (paleo)-bathymetric implications

We report an unusually shallow-water occurrence of habitat-forming Desmophyllum dianthus (Esper, 1794) from the Chilean fjord region. Most occurrences of the cosmopolitan D. dianthus are known from the bathyal zone. In the northern Chilean fjord region, however, this coral is reported within the euphotic zone. The upper limit of distribution was found at 7 m water depth and is confined to the lower boundary of the low salinity layer. Large accumulations both as living aggregations and as sediment-formers typically occur from 20 m water depth and beyond. The corals prefer to colonise the undersides of rock ledges with downwardfacing corallites. The motivation of this study is to analyse and discuss the existence of an azooxanthellate coral that generally thrives in aphotic environment but here extends into the photic zone by means of screening of bioerosion patterns. Based on the detailed analysis of scratching and boring traces, we compare the ichnocoenosis found within the Chilean D. dianthus with the established bathymetrically indicative ichnocoenoses from other areas around the world. These indicator ichnocoenoses are widely used to reconstruct relative water depths of depositional settings in the geological past. The study of the bioeroding assemblage from two living D. dianthus collected at 28 m water depth in the Renihue Fjord, Chile, shows some remarkable patterns that shed light on the complex way in which the coral’s soft tissue expands and retracts at the apical zone of the corallum in response to in vivo infestation of endolithic algae. The role of this heterotypic interaction is discussed.

Bioerosion patterns in a deep-water Lophelia pertusa (Scleractinia) thicket (Propeller Mound, northern Porcupine Seabight)

This study focuses on bioerosion of an aphotic deep-water coral mound, the Propeller Mound, in the northern Porcupine Seabight. The predominant framework builder is the cosmopolitan cold-water coral Lophelia pertusa. We demonstrate bioerosion patterns within the skeleton of L. pertusa using a new embedding method under vacuum conditions with subsequent scanning electron microscope analysis. Following this method, 23 ichnospecies are documented and related to heterotrophic organism groups such as Bacteria (1), Fungi (12), Bryozoa (1), Foraminifera (3), and Porifera (6). Predominant endolithic sponges in the framework of L. pertusa are Alectona millari and Spiroxya heteroclita. Owing to its characteristic growth and surface ornamentation, trace casts of Spiroxya heteroclita are correlated to the well-known trace fossil Entobia laquea.

Mapping Cold-Water Coral Habitats at Different Scales within the Northern Ionian Sea (Central Mediterranean): An Assessment of Coral Coverage and Associated Vulnerability

In this study, we mapped the distribution of Cold-Water Coral (CWC) habitats on the northern Ionian Margin (Mediterranean Sea), with an emphasis on assessing coral coverage at various spatial scales over an area of 2,000 km2 between 120 and 1,400 m of water depth. Our work made use of a set of data obtained from ship-based research surveys. Multi-scale seafloor mapping data, video inspections, and previous results from sediment samples were integrated and analyzed using Geographic Information System (GIS)-based tools. Results obtained from the application of spatial and textural analytical techniques to acoustic meso-scale maps (i.e. a Digital Terrain Model (DTM) of the seafloor at a 40 m grid cell size and associated terrain parameters) and large-scale maps (i.e. Side-Scan Sonar (SSS) mosaics of 1 m in resolution ground-truthed using underwater video observations) were integrated and revealed that, at the meso-scale level, the main morphological pattern (i.e. the aggregation of mound-like features) associated with CWC habitat occurrences was widespread over a total area of 600 km2. Single coral mounds were isolated from the DTM and represented the geomorphic proxies used to model coral distributions within the investigated area. Coral mounds spanned a total area of 68 km2 where different coral facies (characterized using video analyses and mapped on SSS mosaics) represent the dominant macro-habitat. We also mapped and classified anthropogenic threats that were identifiable within the examined videos, and, here, discuss their relationship to the mapped distribution of coral habitats and mounds. The combined results (from multi-scale habitat mapping and observations of the distribution of anthropogenic threats) provide the first quantitative assessment of CWC coverage for a Mediterranean province and document the relevant role of seafloor geomorphology in influencing habitat vulnerability to different types of human pressures.

Biogeographical distribution of Hyrrokkin (Rosalinidae, Foraminifera) and its host-specific morphological and textural trace variability

The parasitic foraminifer Hyrrokkin sarcophagapredominantly infests the cold-water coral Lophelia pertusaand the co-occurring bivalve Acesta excavata, showing a commensal or parasitic behaviour. It occurs also on some other corals (e.g., Caryophyllia sarsiae), bivalves (e.g., Delectopecten vitreus) and sponges (Geodiasp.), typically in aphotic environments. The aim of the study is to describe its traces from various host substrates, to characterise its parasitic behaviour and to map the geographical distribution of the genus Hyrrokkin. Epoxy-resin casts of H. sarcophagatraces in A. excavata C. sarsiae, D. vitreusand L. pertusa,and of H. carnivoratraces in A. excavata, were SEM analysed. The boring pattern is in all cases characterised by a shallow groove of up to 7 mm in diameter (max. 2 mm deep), from which ‘whip’-shaped extensions protrude vertically into the substrate. In A. excavatathe foraminifer can penetrate the entire valve to the mantle cavity, producing a thick shaft of fused ‘whips’. This parasitic attack is answered by a strong callus formation of the mollusc. One individual foraminifer can repeatedly bypass the organic-rich callus, resulting in a thick aragonite pinnacle. The trace surface texture is xenoglyph and changes with the penetrated host-microstructures. This is especially obvious on deeply penetrating trace portions (e.g., ‘whip’-shaped filaments) and is a strong indication for a chemical penetration mode (etching). The trace of Hyrrokkin is described as Kardopomorphos polydioryxigen. n., isp. n. On the substrates without the shaft, related to parasitic behaviour, Hyrrokkinmight feed directly on adjacent external host tissue. H. sarcophagais known along the North Atlantic continental margin from polar to subtropical latitudes and H. carnivoraoccurs on the continental margin of Mauritania, Congo and Guinea. In the Mediterranean we could document the parasitism of H. sarcophagafrom Last Glacial A. excavata.Traces or detached foraminifer tests occur in Early Pleistocene cold-water coral deposits on Sicily and Rhodes. Recent H. sarcophagahas not been observed above 11°C and is scarce near 5°C water temperature. Hyrrokkinsp. was reported from the Canadian Pacific on fossil sponges and was observed on Acesta patagonicain the Beagle Channel (Chile).

A Giant Boring in a Silurian Stromatoporoid Analysed by Computer Tomography

This study describes the largest known Palaeozoic boring trace, Osprioneides kampto igen, et isp. nov., found within a stromatoporoid Densastroma pexisum from the Upper Visby Formation (lower Wenlock, Silurian) on the island of Gotland, Sweden. Differences between the physical properties of the stromatoporoid and the dense micritic infilling of the borings allowed the application of the CT-scan technology for the 2D and 3D-visualisation of this rare trace. The additional application of a stereoscopic technique on these CT images and movies enhances its value for unravelling spatial orientations. This non-destructive method has a great potential for future macro- as well as microboring analyses. The trace maker, most likely a worm, infested the hosting colony post-mortem with up to 120 mm long borings measuring 5–17 mm in diameter. Smaller forms of Trypanites and Palaeosabella within the same stromatoporoid preferentially occur in the outer coenosteum and occasionally in abandoned borings of O. kampto. The stratigraphic position of O. kampto follows the “Great Ordovician Biodiversification Event” in time, and reflects the increase in diversity of boring species. Borings with penetration depths of 120 mm are, however, unique findings for the Palaeozoic and were not exceeded until some 260 million years later (Bajocian, Middle Jurassic) when the “Mesozoic Marine Revolution” led to convergent reinventions as a result of enhanced predation, grazing pressure, and ecospace competition.

Endolithic sponge versus terebratulid brachiopod, Pleistocene, Italy: accidental symbiosis, bioclaustration and deformity

The dorsal valve of a Pleistocene terebratulid brachiopod, Terebratula scillae Seguenza, 1871, has developed a malignant cyst due to colonisation in vivo by an endolithic sponge. This trace fossil is a compound boring and bioclaustration structure, representing a boring that has grown in unison with the growth of the cyst. The brachiopod has grown to adult size and growthlines indicate that it was colonised by the sponge when about half grown. Malformation of the shell may not have caused the death of the brachiopod and the sponge does not appear to have outlived its host; both symbionts seem to have died more or less simultaneously. This minus-minus relationship of two symbionts is considered to be a case of ‘accidental symbiosis’

Cladorhiza corallophila sp. nov., a new carnivorous sponge (Cladorhizidae, Demospongiae) living in close association with Lophelia pertusa and Madrepora oculata (Scleractinia).

In this study, we describe a new species of cladorhizid sponge, which shows a very peculiar mode of life: It always occurs in association with the scleractinian cold-water corals Lophelia pertusa and Madrepora oculata. Although the sponge lives in nutrient-rich areas, we document its carnivorous feeding behavior. The identity of the new species was verified using molecular markers: the species is very closely related to the North-Atlantic Cladorhiza abyssicola, but it differs distinctly, and forms a monophyletic clade. The two species might be considered very close relatives, probably sister species deriving from a common ancestor.

Some species of Munidopsis from the Gulf of Mexico, Florida Straits and Caribbean Sea (Decapoda: Munidopsidae), with the description of two new species.

During two cruises to the Gulf of Mexico and Caribbean Sea, some specimens of squat lobsters belonging to the genus Munidopsis Whiteaves, 1874 (family Munidopsidae Ortmann, 1898) were collected. The present collection comprises five species, where two are considered as new species: M. karukera, closely related to M. ariadne Macpherson, 2011, from the Mediterranean Sea; and M. tuerkayi, which resembles M. kareenae Ahyong, 2013, from New Zealand. The specimens were caught at six stations between 522 and 1162 m; some were associated with live cold-water corals, such as Lophelia pertusa (Linnaeus, 1758), Enallopsammia profunda (Pourtalès, 1867) and Candidella imbricata (Johnson, 1862).