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Traditional surface area and volume quantification techniques for scleractinian corals are often destructive or inaccurate. Therefore, non-destructive 3D scanning methods have been applied as minimally invasive alternative. However, it remains largely unknown how the reproducibility of the measurement is affected by the complexity of the coral colonies. It is also unclear how the scanning procedure (handling, exposure to air, and light of the scanner) impacts the corals' health. In this study, we used a high-end handheld 3D scanner, which combines a structured-light with an image-based approach, to investigate the reproducibility of surface area and volume measurements as well as handling effects. Corals with different shape complexity, covering branching and massive species, were used as model organisms. The variance of repetitive scans ranged from 0.13% to 1.31% for volume and from 0.09% to 0.58% for surface area calculations. Linear regression models indicated that reproducibility decreases with increasing complexity of the coral. Excessive scanning caused an increase or decrease of growth rates, depending on the studied species. However, it did not impair coral health. We conclude that 3D scanning is a highly precise, reproducible, and minimally invasive method for coral surface area and volume measurements, which allows for quick processing of large datasets. Detailed technical recommendations for the application of 3D scanning in coral research are provided in the manuscript.

A yellow-pigmented, Gram-stain-negative, motile and rod-shaped bacterium, strain M1A16, was isolated from the internal tissue of a sponge of the genus Haliclona, which was long-term cultured in the CEMarin aquaria system at Justus Liebig University of Giessen. The strain grew well at 20-32 °C (optimum 25 °C), in the presence of 0-6 % NaCl (optimum 3 %), and at pH 5.5-9.0 (optimum pH 7.0-8.0). Phylogenetic analysis based on its 16S rRNA gene sequence placed the strain within the monophyletic cluster of the genus Winogradskyella with highest sequence similarity to Winogradskyella jejuensis CP32 (98.3 % 16S rRNA gene sequence similarity). Sequence similarities to all other type strains were 98.0 % or less. DNA-DNA hybridization of strain M1A16 with W. jejuensis CP32 resulted in hybridization values of 44.1 % (reciprocal 68.1 %). Major cellular fatty acids of strain M1A16 were iso-C15 : 1 G (18.1 %), iso-C15 : 0 (13.7 %), C16 : 1ω7c (12.9 %), iso-C17 : 0 3-OH (10.6 %) and iso-C16 : 0 3-OH (10.2 %). The overall polyamine content was very low with major components being cadaverine, spermidine and sym-homospermidine. The major quinone was menaquinone MK-6. The polar lipid profile contained predominantly phosphatidylethanolamine, two unidentified aminolipids and two unidentified lipids devoid of a detectable functional group. The genomic DNA G+C content was 32.7 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic analyses, strain M1A16 represents a novel species of the genus Winogradskyella, for which the name Winogradskyella haliclonae sp. nov. is proposed. The type strain is M1A16 (=DSM 103138=CCM 8681=LMG 29588=CIP 111091).

Marine sponges host highly diverse but specific bacterial communities that provide essential functions for the sponge holobiont, including antimicrobial defense. Here, we characterized the bacterial microbiome of the marine sponge Haliclona cnidata that has been in culture in an artificial marine aquarium system. We tested the hypotheses (1) that the long-term aquarium cultured sponge H. cnidata is tightly associated with a typical sponge bacterial microbiota and (2) that the symbiotic Bacteria sustain bioactivity under harmful environmental conditions to facilitate holobiont survival by preventing pathogen invasion. Microscopic and phylogenetic analyses of the bacterial microbiota revealed that H. cnidata represents a high microbial abundance (HMA) sponge with a temporally stable bacterial community that significantly shifts with changing aquarium conditions. A 4-week incubation experiment was performed in small closed aquarium systems with antibiotic and/or light exclusion treatments to reduce the total bacterial and photosynthetically active sponge-associated microbiota to a treatment-specific resilient community. While the holobiont was severely affected by the experimental treatment (i.e., bleaching of the sponge, reduced bacterial abundance, shifted bacterial community composition), the biological defense and bacterial community interactions (i.e., quorum sensing activity) remained intact. 16S rRNA gene amplicon sequencing revealed a resilient community of 105 bacterial taxa, which remained in the treated sponges. These 105 taxa accounted for a relative abundance of 72-83% of the bacterial sponge microbiota of non-treated sponge fragments that have been cultured under the same conditions. We conclude that a sponge-specific resilient community stays biologically

Marine sponges thrive in benthic environments despite intense spatial competition and predator pressure. The sessile filter-feeders usually compensate their lack of physical defense and behavioral escape by a high level of bioactivity. In the stinging black sponge (Haliclona cnidata sp. nov.), these chemical defense mechanisms are complemented by "cellular weapons"-functional nematocysts likely acquired from cnidarians (kleptocnidism). Whereas, kleptocnidism might be facilitated by a close contact with cnidarian donors, preliminary investigations suggest that the stinging black sponge sustains nematocysts even if kept apart from cnidarians. As the underlying mechanisms causing this phenomenon remain unknown, the development of its nematocysts was studied in both presence and absence of potential cnidarian donors. First, we compared inherent nematocysts of adult sponge individuals with foreign nematocysts of co-cultivated cnidarians to identify potential donors. Second, we experimentally assessed the donor-independent and donor-dependent development of inherent and foreign nematocysts within cultures of sponge cell aggregates (SCAs). The inherent nematocysts comprised two specific types that both differed from those of the eight co-cultivated cnidarians. Specifically, we showed that the number of sponge-inherent nematocysts increased in SCAs over time in the absence of potential donors. Numbers of supplied foreign nematocysts, however, did not increase in the SCAs. We conclude that the observed increase of inherent nematocysts is due to the maturation of nematocyst precursor cells. Given these findings, we here propose the precursor hypothesis of sponge kleptocnidism. Accordingly, nematocyst precursors or immature nematocyte-nematocyst complexes might be initially acquired by sponges through filtration, maintained in sponge tissues, and nurtured to fully functioning nematocyte-nematocyst complexes. The underlying evolutionary processes are likely facilitated by bacteria-derived secondary metabolites and photosynthetically active dinoflagellates. Schellenberg et al. Precursor Hypothesis Sponge Kleptocnidism Due to a simple body plan and the in vitro proliferation capacity of sponge cells, H. cnidata sp. nov. may serve as a novel evolutionary model system to further assess fundamental research questions regarding kleptocnidism. This study not only sheds new light on kleptocnidism in sponges, it also calls for a holobiontic view at defense mechanisms that involves the actual sponge, cnidarian nematocysts, dinoflagellate endosymbionts, and a complex microbial community.Life Science Identifier (LSID): urn:lsid:zoobank.org:act