Coral resilience varies across species, with some exhibiting remarkable stability and adaptability, often mediated by their associated microbiomes. Given the species-specific nature of coral-microbiome interactions, investigating the microbiomes of urban-adapted corals provides critical insights into the health, dynamics, and functioning of coral holobionts. In this study, we examined the microbiome of Madracis auretenra, a Caribbean coral from Santa Marta, Colombia, across contrasting environmental conditions. Over two years, we compared the microbiomes of healthy and stressed coral colonies from two distinct reef habitats—urban and protected—using 16S rRNA gene sequencing (V4 region) to assess microbial diversity. Our findings revealed microbial richness and diversity were primarily influenced by seasonal and local factors rather than host-specific traits such as interaction with algae, health status, or microhabitat. These variations were not substantial enough to disrupt the overall microbial community structure, which remained stable across temporal and spatial scales. Dominant taxa included Endozoicomonas, along with Vibrionaceae and Rhodobacteraceae, which form dense ecological interaction networks. Notably, nutrient and oxygen levels emerged as key drivers of microbiome fluctuations, yet Vibrionaceae populations exhibited exceptional temporal stability. These findings highlight the presence of a well-structured and resilient coral microbiome with minimal seasonal variability, even in urban-influenced environments. We propose that the dominance of Endozoicomonas and the stability of Vibrionaceae populations play a pivotal role in maintaining microbiome balance, ultimately contributing to the ecological resilience of M. auretenra in dynamic reef habitats.

Coral disease outbreaks pose a major threat to reef ecosystems, often leading to widespread mortality and declines in coral cover. A key factor predicted in disease susceptibility is the coral microbiome, which is thought to protect corals from pathogens like Vibrio coralliilyticus . However, this protective function has not been empirically demonstrated with live coral, nor is it well understood how these microbiome‐pathogen interactions contribute to the observed variation in virulence among different V. coralliilyticus strains. This study investigated the role of the Hawaiian rice coral ( Montipora capitata ) microbiome in susceptibility to infection by endemic and non‐endemic strains of V. coralliilyticus . Laboratory infection experiments revealed that antibiotic‐induced dysbiosis generally increased host susceptibility, though infection rates varied between strains. Notably, the type of M. capitata colour morph did not influence infection outcomes, and induced dysbiosis did not affect susceptibility to another pathogen, Pseudoalteromonas piratica . Additionally, the quorum sensing genes vcpR and aphA were examined for their roles in V. coralliilyticus pathogenicity in relation to the host microbiome. These findings underscore the protective function of the coral microbiome and highlight the complexity of host‐pathogen interactions, contributing to a deeper understanding of coral disease dynamics and informing future mitigation strategies.

La Reserva El Caduceo, ubicada en San Martín, Meta, es un área que ha experimentado notables modificaciones en la complejidad estructural de la vegetación de bosques y sabanas debido al efecto de diferentes actividades de cultivo y ganadería, las cuales pueden afectar la riqueza de las comunidades de aves que allí habitan. Este estudio corto muestra una evaluación de la composición y abundancia a nivel de familias y grupos tróficos de aves en esta reserva durante la época lluviosa de 2020. Se llevaron a cabo censos visuales con límite de tiempo en dos estaciones correspondientes a dos hábitats: bosque de galería y sabana con pequeños núcleos de bosque. Además, se estimaron algunos índices ecológicos para cada estación de muestreo. Se observó un total de 18 familias, de las cuales la familia Tyrannidae fue la más abundante en la sabana y la familia Psittacidae la más recurrente en el bosque de galería. La densidad de aves fue mayor en el bosque de galería (2,19 ind/m2), observando además que en esta estación las densidades de aves se encuentran equitativamente repartidas entre las familias registradas, en contraste con la estación de sabana. Por otro lado, el grupo trófico dominante en ambas estaciones fueron los “insectívoros”. Estos resultados preliminares podrían indicar una relación directa entre la complejidad estructural vegetativa, la recuperación del bosque de galería en esta zona y la composición de aves y grupos tróficos predominantes. No obstante, futuros estudios con mayor duración y monitoreos constantes son necesarios para confirmar esta observación inicial.

Improving the availability of new sources of probiotics is essential to continue implementing alternative solutions to improve coral health; one such source is urban corals. However, little is known about urban coral’s health status and whether they can harbor bacteria exhibiting probiotic traits. Here, we explored the status of the urban coral Madracis auretenra and the presence of probiotic traits in its associated culturable bacteria. After assessing ecological attributes, we observed a similar abundance (cover %) when comparing patches of M. auretenra occurring in both an urban site and a marine protected area. The urban patch also exhibited a high abundance of vibrios in coral tissues and signs of ecosystem deterioration. However, this patch showed a “good” health index condition; so, we hypothesized the presence of beneficial bacteria. We isolated 132 bacterial strains from this healthy urban M. auretenra. These bacteria were affiliated with 11 genera, including Vibrio, Shewanella, Bacillus, Exiguobacterium, Priestia, and Niallia, among others. Screenings revealed the predominant presence of potential probiotic traits such as catalase, antiQS, and the production of siderophores activities among the bacterial isolates. We proposed a list of 24 bacterial isolates as probiotic precandidates that jointly exhibited three or more of these traits, among which the Vibrio and Bacilli strains stand out. We provide insights into the health status of this urban coral and its potential as a source of bacteria exhibiting potential probiotic traits.

The global rise of antimicrobial resistance has intensified efforts in bioprospecting, with researchers increasingly exploring unique marine environments for novel antimicrobials. In line with this trend, our study focused on bacteria isolated from the unique microbiome of crustose coralline algae (CCA), which has yet to be investigated for antimicrobial discovery. In the present work, bacteria were isolated from a CCA collected from Varadero Reef located in Cartagena Bay, Colombia. After performing antimicrobial assays against antibiotic-resistant human and marine pathogens, three isolates were selected for genome sequencing using the Oxford Nanopore technology. Genome mining of the high-quality assemblies revealed 115 putative biosynthetic gene clusters (BGCs) and identified genes in relevant biosynthetic pathways across the three genomes. Nonetheless, we hypothesize that the biosynthesis of antimicrobial compounds results from the expression of undescribed BGCs. Further analysis revealed the absence of genes pertaining to the synthesis of coral larvae settling molecule tetrabromopyrrole, commonly produced by CCA-associated bacteria. We also discuss how differential representation of gene functions between the three isolates may be attributed to the distinct ecological niches they occupy within the CCA. This study provides valuable resources for future research aimed at the discovery of novel antimicrobials, particularly in the face of the antibiotic-resistance global crisis, and highlights the potential of specialized marine environments like CCA.

La creciente demanda de proteína acuícola sugiere buscar alternativas biotecnológicas que mejoren el cultivo de especies de interés comercial. En este estudio se evaluó Bacillus firmus C101 como promotor del crecimiento y potencial probiótico, el cual fue caracterizado y posteriormente administrado (106 UFC mL-1 * día) en poslarvas de camarón blanco (Litopenaeus vannamei) y en rotíferos (Brachionus plicatilis sensu stricto). Se observó que B. firmus C101 tiene tolerancia a sales biliares, fuerte actividad fosfatasa y actividad antimicrobiana frente a patógenos como Vibrio alginolyticus y Aeromonas hydrophila, entre otros. Por otro lado, tras su administración por tres semanas a poslarvas de camarón causó un aumento significativo (p < 0,05) en la tasa específica de crecimiento (TEC = 3,8 ± 0,7 % día-1), el incremento de peso diario (ADG = 1,5 ± 0,1 mg día-1) y en la tasa de conversión alimenticia (TCA = 1,5 ± 0,1 %) en comparación con los controles sin adición de esta bacteria (PBS estéril). Así mismo, la administración de B. firmus C101 (106 UFC mL-1 * día) a rotíferos causó un aumento en la tasa de crecimiento poblacional (TC = 20,2 ± 1,5 % día-1), fecundidad (F = 0,4 ± 0,03 huevos individuos-1) y productividad (R = 16,0 ± 0,7 individuos mL-1 * día), después de 48 h de cultivo. Con base en lo anterior y en comparación con otros estudios, se sugiere a B. firmus C101 como potencial probiótico y promotor del crecimiento en poslarvas de camarón, y como primer reporte del efecto de su administración en rotíferos. No obstante, se precisan estudios sobre los posibles mecanismos de acción, y pruebas a escala piloto y comercial para validar estos resultados y su posible transferencia al sector productivo.