Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Coral-associated bacterial assemblages play vital roles in the nutrition, physiology, and health of hosts. Therefore, understanding this microbiota is essential to elucidate this symbiotic relationship. The present study characterized the bacterial assemblage of Acropora cervicornis in 2 Mexican Caribbean sites and analyzed the putative metabolic functions of the dominant bacterial genera in coral tissue, as well as the surrounding seawater and sediments. The bacterial assemblages were analyzed using next-generation sequencing from the hypervariable V4 region of 16S rRNA and compared with bioinformatic analyses. The bacterial microbiota associated with A. cervicornis tissue was similar between the 2 study sites but differed from the assemblages of seawater and sediment. The genera Pseudomonas, Candidatus_Midichloria, and Acinetobater prevailed in A. cervicornis tissue. Enterobacter, Vibrio, and Synechococcus dominated in seawater, whereas Thioprofundum, Pleurocapsa, and Ilumatobacter were the most abundant in sediments. Geographical distance notwithstanding, the bacterial assemblages associated with A. cervicornis, seawater, and sediments were similar between the sampling sites, indicating spatial stability was present. In addition, the substrates differed within each site; the genera favoring the main differences among studied substrates were Pseudomonas, Synechococcus, Thioprofundum, Owenweeksia, Pleurocapsa, Candidatus_Puniceispirillum, Candidatus_Midichloria, and Rhodovibrio. The most frequently occurring metabolic functions identified in the substrates were aerobic chemoheterotrophy, sulfur respiration, and nitrogen fixation. The present study enhances our understanding of acroporid coral-associated bacteria in the Mexican Caribbean.

The genus Symbiodinium is a group of mostly endosymbiotic dinoflagellates, commonly known as zooxanthellae, which live in association with marine invertebrates and protists. The objective of the present study was the morphological and molecular identification of 2 strains of Symbiodiniales (SNCETMAR-1 and SNCETMAR-2) isolated from the anemone Actinostella sp. from Bahía de La Paz, Gulf of California. Culture identification was conducted via photomicroscopy, including epifluorescence and scanning electron microscopy. A sequence of the SNCETMAR-2 strain was obtained from the 28S rDNA region. The combination of methods allowed the strains to be identified as Symbiodinium natans-clade A. This taxon is a group of endosymbiotic and free-living organisms, which facilitated the cultivation of the strains in the laboratory. The life cycle of this group presented 2 phases, a motile and a non-motile phase in the coccoid state, the last stage where both sexual and asexual division occur. This study extends the reports of clade A of the family Symbiodiniaceae in the Gulf of California and provides valuable information for its culture, identification, and phylogenetic analysis.

The Polla Drum Umbrina xanti is a commercially important species off the coast of Jalisco. However, as is the case with most of the fisheries in the country, information on the life history of this species is very limited. Thus, this work aimed to analyze the length at sexual maturity, reproductive season, and microscopic description of the gonads, among other aspects. Organisms were collected from 1998 to 2008 with gill nets by artisanal fisheries operating in the central Mexican Pacific. The gonadosomatic index (GSI), sexual maturity stages, oocyte diameter, condition factor, and sexual ratio were analyzed per month. Histology of the gonads was performed, and the average length of maturation was estimated. In total, 1,202 organisms between 17.9 and 42.3 cm TL were captured. The number of females was greater than that of males (1:0.88). The highest percentages of mature individuals occurred in February and in April–May. The GSI had maximum values from January to May. The largest oocyte diameters occurred from March to June. Oocyte development was asynchronous, and the testis showed unrestricted lobular-type development. The average maturation length for females was 27.37 and 28.78 cm for males. Because these average lengths at maturity were less than the average length, we can indicate that more than 50% of the organisms caught by commercial fishing had had a reproductive event.

Lactate is considered one of the main metabolic indicators of stress in sharks because it is closely related to the anaerobic metabolism that occurs during exhaustive exercise. The objective of this study was to evaluate the effect of the tagging process by measuring blood lactate levels in 2 species of sharks. Lactate levels were measured in 17 juvenile sharks, including Rhizoprionodon longurio (n = 8) and Sphyrna lewini (n = 9), captured as bycatch using small pelagic purse seine gear. The results showed that both handling time (P = 0.0012) and species (P = 0.022) significantly affected blood lactate levels, according to the generalized linear model. On the other hand, the differences between species were explained by the higher sensitivity of R. longurio, which showed a greater tendency to present higher lactate values compared to S. lewini (P = 0.0088). For both species, handling time should remain between 15 to 25 min, from capture during seine closure to release, to reduce the probability of mortality. This study has corroborated that the tagging technique in sharks causes high blood lactate levels as a function of handling time and species. However, it is recommended that future studies work with a larger sample in conjunction with post-capture monitoring in order to conclusively establish that lactate is an indicator of animal welfare in relation to handling time and species.

Hermatypic corals living at high latitudes face suboptimal environmental conditions associated with seasonal changes. In the central Gulf of California, the coral Porites panamensis is acclimated to eutrophication, low light availability, and a wide range of seasonal fluctuations in sea surface temperature (SST). The physiological adjustments of its resistance thresholds are associated with phenotypic plasticity. This study evaluated the interannual acclimation responses of P. panamensis to the warm and cold seasons of 2022 and 2023 using the physiological markers of endosymbiont density, chlorophyll a (Chl a) concentration, and the total lipid content in coral tissue. In addition, the abiotic variables of SST, Chl a, particulate organic carbon (POC), and the diffuse attenuation coefficient (Kd490) were compared between seasons. The results indicated a significant difference in endosymbiont density between seasons (cold season: ~4 × 106 cell·cm–2; warm season: ~2 × 106 cell·cm–2), and an increase in the Chl a concentration during the warm season of 2023. We also observed a significant increase in total lipid content in the warm season of 2023. However, seasonal changes did not negatively affect lipid content, likely due to the high concentrations of Chl a and POC throughout the year (2022: 4.47 ± 1.75 mg·m–3; 2023: 403.3 ± 132.2 mg·m–3), suggesting the existence of a potential year-round food source for P. panamensis. Our results indicate that P. panamensis acclimates to seasonal changes in temperature and turbidity. We suggest that regulating mixotrophy could be a key nutritional strategy for P. panamensis to withstand fluctuating environmental conditions. The ability to alternate between different nutritional pathways according to seasonal environmental conditions may allow P. panamensis to distribute throughout the Eastern Tropical Pacific, even inhabiting suboptimal regions for reef development.

The effects of climate change and local impacts, such as disease, hurricanes, and nutrient input, have led to the rapid degradation of reef ecosystems. The implementation of active restoration methods has expanded globally to mitigate the loss of these important habitats. However, many intervention strategies are still under development, and their impact is unknown. The aim of this study was to evaluate the efficiency of self-recovery of live Orbicella faveolata tissue used as donor microfragments from May 2021 to May 2023 in the Puerto Morelos Reef National Park. Digital images were analyzed to measure the recovery of bare area (~1,250 mm2), transverse diameter (mm), longitudinal diameter (mm), and number of new polyps in donor colonies. After 2 years the results showed that the area of bare tissue had an average recovery of 1,065 ± 237 mm2 of living tissue with 97% of tissue recovered. The transverse and longitudinal diameters showed average monthly growth of 0.88 mm and 0.98 mm, respectively, with a recovery of 93–96% and an increase of approximately 18 new polyps by the end of the study period. The removal of live tissue microfragments does not negatively affect healthy donor colonies, which are capable of recovery within a relatively short time frame (24 months). This information reveals the potential of using microtransplants to accelerate live tissue recovery in colonies affected by various stressors. Despite their feasibility in coral species rehabilitation projects, it is necessary to continue investigating the long-term effects related to susceptibility to erosion and disease to establish more appropriate strategies that support the conservation of coral colonies and reef habitats, as well as the provision of ecosystem services.

Sea urchins perform key ecological functions in coral reefs, such as herbivory and erosion of calcareous structures, which intensify at night. The Cayo Arenas reef, Campeche Bank, Mexico, is located far from the coast, which has helped to protect it from direct anthropogenic threats. However, there is no information available on the status of sea urchin populations and the bioerosion processes they perform in the reef. For this reason, we conducted diurnal and nocturnal surveys to characterize urchin density as a function of the diel cycle and to calculate their bioerosive potential. The surveys were conducted at 3 sites with different depths (10–19 m) and varying reef heterogeneity related to 2 components: coral cover and sand cover. All surveys were conducted in July 2023. In general, an abundant population of urchins was observed, which was mainly composed of Diadema antillarum. At night, the abundance (14.5 ± 3.8 ind) and bioerosion rate (1.55 ± 0.53 kg CaCO3·m–2·y–1) were higher than during the day (2.6 ± 0.8 ind and 0.2 ± 0.06 kg CaCO3·m–2·y–1). In addition, depth and reef geomorphology seemed to influence the pattern of urchin density. At sites with high reef heterogeneity, sea urchin density was higher at night, which could be associated with a greater availability of refuge from predators. Our results show an underestimation of urchin population densities in daytime surveys and, therefore, their impact on the ecosystem as bioerosion agents because sea urchins are mostly nocturnal but are commonly surveyed during the day.

Taxonomic and functional diversity patterns of fish in temperate reefs in the Mexican Pacific have not been analyzed in integrative biodiversity studies. Thus, this study compared the taxonomic, phylogenetic, and functional diversity of reef fish in 4 biogeographic provinces: Californian, Cortez, Panamic, and Oceanic Islands. Species checklists were compiled from the literature, museum collections, and monitoring data from 21 sites in marine protected areas (MPAs) and 45 non-protected sites. Based on this data and 6 biological traits (size, mobility, period of activity, gregariousness, position in the water column, and diet), we calculated species richness (S), average taxonomic distinctness (Δ+), number of functional entities (FE), functional redundancy (RED), functional vulnerability (FV), and functional volume (FVol). We registered 1,045 species; the dominant categories were benthic, highly site-attached, diurnal, solitary, medium-sized, and invertivores. The Cortez province showed the highest S and FE values, whereas the Californian province presented the lowest values. Notably, FVol was >70% across the 4 biogeographic provinces, suggesting that the range of ecological functions and processes was maintained across provinces despite their contrasting biodiversity levels, environmental conditions, and evolutionary histories. A “regional backbone” was identified, consisting of 74 species and 58 FE (the fundamental species and shared ecological roles across provinces). At the regional level, low RED (<3 species·FE–1) and high FV (>55% of FEs represented by a single species) were observed. All provinces presented high values of Δ+ (>80%), reflecting the broad range of taxonomic lineages within the region. The MPAs presented higher S and RED than non-protected sites; however, further research is needed to elucidate the positive effects of protection.

Coral reefs are highly diverse ecosystems that provide various environmental services; however, they remain highly threatened. Assessing the health and trends of coral reefs is vital to establishing management strategies that contribute towards their conservation and recovery. One way of contributing to this objective is through monitoring indicators of reef health. In this context, the present study focused on evaluating the health of 4 reef systems located in 2 extensive regions of Mexico: the southwestern Gulf of Mexico (SGM) and the Mexican Caribbean (MC), using the Reef Health Index (RHI). Fieldwork was conducted on 11 reefs in October 2022 in the SGM and in May 2023 in the MC. Data were collected using 5 to 6, 50 × 2 m transects per site, followed by video transects of 50 × 0.50 m to record benthic organisms along the transect. An average RHI score of 3.50 (considered “good”) was obtained for SGM reefs, while for MC reefs, the average RHI score was 2.50 (considered “poor”). These results suggest that, according to the RHI criteria, SGM reefs present a better state of health than their MC counterparts. This difference was mainly influenced by the lower coral cover and higher macroalgae cover associated with the coral-algal phase shift, likely resulting from the rapid coastal development observed along the coasts the MC coast. Lastly, for the SGM, this evaluation represents the first reef health assessment for the Lobos-Tuxpan Reef System Flora and Fauna Protection Area using a rating system coupled to ecologic indicators such as the RHI.

Electroma vexillum is a bivalve native to the Indo-Pacific that was introduced to the Mediterranean Sea. This study provides records of its presence in the Gulf of Mexico. Organism sighting and collection was carried out between 2018 and 2019 and from November 2021 to July 2024 on 2 coasts of northern Veracruz, Mexico. The individuals identified as E. vexillum were small (<6 mm in length), had fragile and thin valves, and were found in the intertidal zone attached to red algae and green algae. The accidental introduction of this species could be related to international maritime transport, as Tuxpan seaport is located north of Veracruz. After 6 years of observations (2018–2024), E. vexillum can be considered an established exotic species in the southern Gulf of Mexico.