Introduction: In 2023, the fourth mass bleaching event caused by a heatwave was recorded. This event affected virtually all of Mexico’s coral reefs. The bleaching began in August in the Veracruz Reef System National Park (PNSAV). For the first time, a bleaching event of this magnitude was recorded and monitored in the southwestern Gulf of Mexico. Objective: To estimate the extent and prevalence of bleaching in the corals of the PNSAV, as well as to monitor its progression. Methods: Two-minute videos were recorded at a constant depth and speed, with the camera positioned 1 m above the seafloor. The depths studied ranged from 0.5 to 25 m, and each reef was analyzed at least twice at two of the three pre-established depth levels. The selected reefs were visited four times over a 20-month period to record changes in bleaching prevalence. Results: A total of 58,668 scleractinian coral colonies belonging to 35 species were recorded. The overall prevalence of bleaching in 2023 was 70.5%, decreased to 56% in February 2024, and continued to decline to 15% bleaching in May 2025. Among the most abundant species (n > 100 colonies), prevalence ranged from 21.41% for Madracis decactis to 91.37% for Montastraea cavernosa. By reef, prevalence in 2023 ranged from 28.72% at Anegadilla to 96.15% at Blanquilla. There was no significant change by depth or distance from the coast, although a change was recorded over time (from Set.. 12 to Oct. 20), with prevalence being higher toward the end. Due to rising temperatures, the corals in the PNSAV were subjected to cumulative heat stress (Degree Heating Weeks) of 20 °C-week. Conclusions: Although bleaching prevalence values were like those in other Caribbean regions, corals in the PNSAV showed recovery over a 20-month period. During the study, some species were observed to be more susceptible to bleaching than others.
Introduction: The presence of invasive species causes impacts on ecosystems where they are introduced, as they have adaptations that allow them to tolerate a wide range of environmental conditions. Procambarus clarkii, commonly known as the red swamp crayfish, is distributed worldwide and generates negative impacts on aquatic ecosystems, including those of the Colombian Andes. Objective: To characterize the diet of P. clarkii and evaluate its relationship with physicochemical variables in three water bodies of the Upper Chicamocha Irrigation District, Boyacá, Colombia. Methods: Biological material was collected in the Alto Chicamocha Irrigation District (Boyacá, Colombian Andes) during dry, transition, and rainy seasons using specialized folding hexagonal nets. Physicochemical variables were measured at each sampling point. After collecting, the material was taken to the Hydrobiology Laboratory of La Salle University for the analysis of stomach contents and morphometric study of the different life cycle stages. Results: The most frequent stomach contents were Unidentified Organic Matter (MONI) with 40.2 %, Unidentified Animal Material (MANI) with 35.2 %, and Plant Material (MV) with 7.0 %. Principal Component Analysis (PCA) revealed that sampling sites differed according to water quality gradients (PC1: 35.9 %) and nutrient profile (PC2: 27.3 %). Simple linear regressions identified relationships between specific food categories and environmental variables: Arthropod Remains (RA) were positively associated with flow (R² = 0.71, p < 0.01), while MV showed associations with conductivity, nitrites, and pH.Conclusion: The diet of P. clarkii demonstrates trophic plasticity, linked to environmental conditions and food availability in Andean lotic and lentic systems. The presence of fish remains and the association of certain food categories with eutrophication indicators in stomach contents underscore its potential to alter ecological dynamics in freshwater systems with anthropogenic impact, reinforcing global evidence of its invasive success.
Introduction: The coral microbiome comprises a stable core microbiome that supports host health and homeostasis, as well as a rare biosphere that enhances the capacity to respond to environmental disturbances. Objective: To characterize the core microbiome and rare bacterial biosphere associated with Acropora palmata, Orbicella faveolata, and Porites porites from the Mexican Caribbean across sites with different levels of anthropogenic stress. Methods: The composition of the core microbiome and rare bacterial biosphere was analyzed using high-throughput sequencing of the 16S rRNA gene. Results: The core microbiome represented 9.7% of the total sequences (50 ASVs) and was dominated by Amoebophilaceae, Rhodobacteraceae, and Woeseiaceae. At the genus level, Candidatus_Amoebophilus was prevalent across all coral species, while Delftia characterized A. palmata and P. porites, and Pelagibius and Woeseia dominated in O. faveolata and P. porites. The rare biosphere was more diverse (1,585 ASVs; 11.9%), with O. faveolata showing the highest richness and dominated by Rhodobacteraceae, Kiloniellaceae, and Vibrionaceae, including Vibrio, Woeseia, Limibaculum, and Desulforhopalus. Beta diversity analyses revealed significant differences among coral species and across anthropogenic gradients, with host identity explaining most of the variation in core microbiomes. The rare biosphere also showed significant variation, although much of this variability remains unexplained. SIMPER analysis identified the ASVs that contributed most to the observed differences. In the core microbiome, the main contributing ASVs were affiliated with the genera Candidatus_Amoebophilus, Delftia, Pelagibius, and Woeseia, whereas, in the rare biosphere, the ASVs contributing most to the observed differences were affiliated with Pelagibius, Tistlia, Woeseia, Desulforhopalus, and Vibrio. Additionally, 23 putative metabolic functions were predicted, with aerobic chemoheterotrophy, fermentation, and sulfur respiration being the most common. Conclusions: These findings highlight the complementary roles of the core microbiome and rare biosphere in structuring coral microbial communities, supporting resilience, and serving as potential candidates bioindicators of environmental change in the Mexican Caribbean.
Introduction: Coral reefs harbor high biodiversity and have great ecological, social, and economic importance. However, multiple local and global stressors increasingly degrade these ecosystems. Among global stressors, rising SST (Sea Surface Temperature) stands out, and studies on remote reefs provide a unique opportunity to assess its effects. Objective: This study aimed to determine the effects of the 2015 marine heatwave on coral condition at two remote reef crests in the Gulf of Cazones, southern Cuba. Methods: In October 2015, we surveyed three sites across two reef crests and used 2012 data from the same area to assess changes in reef condition. We used a 10 m linear transect for field sampling and obtained time series of SST and accumulated heat stress from 1998 to 2015. Results: The mean SST in 2015 was 0.56–0.59 °C higher than the 17-year average (i.e., 1998-2014), with 298–303 days exceeding the average SST, while maximum SST values reached 31.94–31.97 °C across the three sites. Accumulated heat stress reached approximately 11 °C-weeks, a value never previously recorded for these reef crests. Bleaching affected 56–77 % of corals in response to accumulated heat stress in 2015, with recent mortality ranging from 4.5 % to 31.3 %. The generalized linear mixed-effects model showed that coral bleaching significantly predicted the probability of recent mortality at the colony level. Between 2012 and 2015, live coral cover decreased significantly at all three sites, with losses of up to 44 %, accompanied by declines in Acropora palmata relative abundance and cover of ~ 19 % and ~ 43 %, respectively. Conclusions: Accumulated heat stress during the 2015 marine heatwave was the main driver of the intense coral bleaching event, accompanied by coral mortality and substantial losses of live coral cover, as well as declines in A. palmata relative abundance and cover at two reef crest sites, which is concerning because it is the keystone shallow reef-building species in the Caribbean Sea.
Introduction: Caribbean coral reefs have undergone long-term shifts toward macroalgal dominance, potentially constraining coral recovery and restoration outcomes. At Wave of Change (WOC) Reef, an active restoration site in the Mexican Caribbean, previous monitoring has documented high macroalgal cover, yet its intra-annual dynamics and environmental drivers remain poorly understood. Objectives: To (1) determine whether macroalgal cover follows a recognizable intra-annual pattern or responds primarily to episodic events; (2) evaluate whether the functional composition of the benthic algal assemblage, described in terms of growth forms, remains stable or shifts over time; and (3) identify the environmental drivers that best explain macroalgal variability. Methods: Fortnightly photographic benthic surveys were conducted from August 2024 to August 2025 along seven permanent 10-m transects, with 70 photoquadrats (1 m²) collected per sampling event. High-resolution photoquadrats were analyzed using the ReefCloud AI platform. Environmental variables included in situ temperature and underwater illuminance obtained from HOBO loggers, while additional environmental data (Secchi disk transparency, PAR, chlorophyll a, salinity, nitrate, phosphate, and pH) were obtained from the SIMAR database. Temporal patterns and relationships were assessed using non-parametric analyses, redundancy analysis, and beta regression models. Results: Upright macroalgae and algal turfs showed marked temporal variability and alternated in dominance, whereas crustose coralline algae remained consistently low. Dictyota and Halimeda dominated the upright macroalgal assemblage, representing 41.26 % and 22.78 % of its relative composition, respectively. Nitrate was the only significant environmental predictor of benthic algal composition, explaining 21.6 % of the variance and showing contrasting associations with upright macroalgae (negative) and algal turfs (positive). Conclusions: High-resolution benthic monitoring provides an ecological context for interpreting coral restoration trajectories beyond coral performance alone. Integrating AI-assisted benthic assessments into restoration programs can strengthen long-term evaluation and adaptive management at WOC Reef and other restoration sites in the Mexican Caribbean.
