The Epibiotic Microbiota of Wild Caribbean Sea Urchin Spines Is Species Specific

Abstract

Caribbean sea urchins are marine invertebrates that have experienced a decline over the years. Studies on sea urchins have focused primarily on the microbiome of the coelomic fluid or the gut microbiota. In this study, the epibiota community associated with four wild Caribbean sea urchin species, Lytechinus variegatus, Echinometra lucunter, Tripneustes ventricosus, and Diadema antillarum, was characterized for the first time. Using 57 sea urchin animal samples, we evaluated the influence of animal species, trophic niches, and geographical location on the composition of the epibiotic microbiota. We found significant differences in the bacterial biota among species and trophic niches, but not among geographical locations. L. variegatus exhibited the highest alpha diversity with high dominance of Fusobacteria, Planctomycetes, and Cyanobacteria, whereas T. ventricosus and D. antillarum were dominated by Firmicutes. T. ventricosus inhabiting the seagrass biotope dominated by Thalassia testudinum meadows had mostly Endozoicomonas. In contrast, samples located in the reef (dominated by corals and other reef builders) had a higher abundance of Kistimonas and Photobacterium. Our findings confirm that the epibiotic microbiota is species-specific, but also niche-dependent, revealing the trophic networks emerging from the organic matter being recycled in the seagrass and reef niches. As echinoids are important grazers of benthic communities, their microbiota will likely influence ecosystem processes.

Rhodobacteraceae dominate the core microbiome of the sea star Odontaster validus (Koehler, 1906) in two opposite geographical sectors of the Antarctic Ocean

“…Relevant contributions of bacteria belonging to Fusobacteriaceae and Planctomycetaceae were found in some individuals of O. validus collected in the Ross Sea area; these bacteria have been already found in association with other Antarctic marine organisms ( Webster and Bourne, 2007 ; Kim et al, 2020 ; Rodríguez-Barreras et al, 2023 ) and considered key players in global carbon and nitrogen cycles ( Olsen, 2014 ; Dedysh and Ivanova, 2019 ). Interestingly, our results indicated the presence of bacteria belonging to the Thermaceae family in some of our individuals of O. validus .…”

Recent molecular techniques to strengthen ecological studies in echinoderms

“…The 16S ribosomal RNA (16S rRNA), present in all bacteria and archaea, serves as a molecular marker to identify and classify microbial taxa (Hakim et al, 2019). By analyzing the 16S rRNA gene sequences, researchers can unravel the intricate relationships between echinoderms and their associated microbial communities, shedding light on the potential roles of these microbes in echinoderm health, nutrition, and overall ecological functioning (Lima-Mendez et al, 2015;Rodríguez-Barreras et al, 2023). The 16S rRNA gene is a widely used molecular marker for studying microbial diversity and community structure.…”

“…In addition to symbiotic interactions, 16S rRNA sequencing has provided insights into the dynamic nature of the microbiome in echinoderms. Studies have revealed variations in the microbial community composition across different developmental stages, habitats, and environmental conditions (Ketchum et al, 2021;Marangon et al, 2023;Rodríguez-Barreras et al, 2023). These findings suggest that the echinoderm microbiome is influenced by both intrinsic factors and extrinsic environmental factors, highlighting the importance of considering the context-dependent nature of microbial associations in echinoderm research.…”