RESUMO
Reef-building corals are the main basis of coral reef ecosystems, and the Orbicella genus is currently the most important in the Caribbean region. Although Orbicella species have been extensively studied, gaps in some southern Caribbean areas still exists on their status, which is crucial for management and conservation plans. In this study, we aimed to describe the population status of Orbicella faveolata and Orbicella annularis in two coastal Marine Protected Areas (MPA) of Venezuela: Morrocoy National Park and Cuare Wildlife Refuge. Between 2018-2020, 16 reefs in five sectors were surveyed using the Atlantic and Gulf Rapid Reef Assessment Protocol. Among the two Orbicella species, O. faveolata was dominant in both MPA´s with higher densities and live cover, varying at both reefs and sectors. The central sector of Morrocoy and reefs from Cuare are the most relevant for Orbicella populations, due to the higher live cover and abundance of reproductive colonies. Diseases were the primary threat recorded for both species. Adequate MPA management is essential for the conservation of the Morrocoy-Cuare coral system, including the reduction of local anthropogenic stress sources, such as oil spills, uncontrolled tourism and sewage discharges.
Assuntos
Antozoários , Conservação dos Recursos Naturais , Recifes de Corais , Animais , Venezuela , Antozoários/fisiologia , Região do Caribe , Parques Recreativos , EcossistemaRESUMO
Coral reefs face escalating threats from global and local stressors, and these challenges are exacerbated in the Caribbean. This study focuses on coral reef structure in Barbados, where a previous study documented reef degradation in the 1990s. As 30 years have passed, we examined the rate of change of reef structure and quantified associated substrate presence along the western reefs of Barbados. Using satellite and geotagged imagery, we analyzed 19 reef structures over the interval 2013 to 2023 along the west coast of Barbados, comparing them to the previous study's findings in 1950 and 1991. We ground-truthed five sites previously categorized as highly degraded reefs to confirm their structural integrity and substrate-type. Results confirmed ongoing reef structural loss, averaging ~ 137.68 m1 annually across all sites. We identified four primary substrate types: coral, algae-covered substrate, rubble, and sand, with algae-covered substrate predominating and projected to persist. Our results underscore the urgency of monitoring reef health and highlight the potential limitations of satellite assessment. This research enhances understanding of reef dynamics and offers a framework for identifying vulnerable areas, which are crucial for effective conservation efforts.
Assuntos
Antozoários , Recifes de Corais , Barbados , Animais , Conservação dos Recursos Naturais , Monitoramento Ambiental/métodos , EcossistemaRESUMO
Coral reefs can mitigate flood damages by providing protection to tropical coastal communities whose populations are dense, growing fast, and have predominantly lower-middle income. This study provides the first fine-scale, regionally modeled valuations of how flood risk reductions associated with hybrid coral reef restoration could benefit people, property, and economic activity along Florida and Puerto Rico's 1005 kilometers of reef-lined coasts. Restoration of up to 20% of the regions' coral reefs could provide flood reduction benefits greater than costs. Reef habitats with the greatest benefits are shallow, nearshore, and fronting low-lying, vulnerable communities, which are often where reef impacts and loss are the greatest. Minorities, children, the elderly, and those below the poverty line could receive more than double the hazard risk reduction benefits of the overall population, demonstrating that reef restoration as a nature-based solution can have positive returns on investment economically and socially by providing protection to the most vulnerable people.
Assuntos
Conservação dos Recursos Naturais , Recifes de Corais , Análise Custo-Benefício , Conservação dos Recursos Naturais/economia , Conservação dos Recursos Naturais/métodos , Florida , Porto Rico , Humanos , Inundações/economia , Ecossistema , Recuperação e Remediação Ambiental/economia , Recuperação e Remediação Ambiental/métodos , Populações VulneráveisRESUMO
The decline in Acropora palmata populations in Colombian reefs has been mainly attributed to diseases outbreaks. The population size structure and prevalence of white pox and white band disease were evaluated in six localities of the Colombian Caribbean. Here, we aimed to isolate enteric bacteria and Vibrios from healthy and diseased coral mucus to relate its presence to the health status of Acropora palmata. The isolated bacteria were identified using molecular analyses with the 16S rRNA gene. Larger colonies had the highest percentage of the prevalence of both diseases. The strains that were identified as Vibrio sp. and Bacillus sp. were common in the healthy and diseased mucus of the holobiont. The Exiguobacterium sp. and Cobetia sp. strains isolated from diseased mucus may indicate maintenance and resilience mechanisms in the coral. Enterococcus sp. and other bacteria of the Enterobacteriaceae family were isolated from some localities, suggesting that probably contamination due to poor treatment of domestic wastewater and contributions from river discharges can affect coral health. The spatial heterogeneity of Colombian coral reefs exhibited variability in the bacteria, wherein environmental alterations can trigger signs of disease.
Assuntos
Antozoários , Antozoários/microbiologia , Animais , Colômbia/epidemiologia , Região do Caribe/epidemiologia , Prevalência , RNA Ribossômico 16S/genética , Recifes de Corais , Vibrio/isolamento & purificação , Vibrio/genética , Vibrio/patogenicidadeRESUMO
Coral bleaching, a consequence of stressed symbiotic relationships between corals and algae, has escalated due to intensified heat stress events driven by climate change. Despite global efforts, current early warning systems lack local precision. Our study, spanning 2015-2017 in the Mesoamerican Reef, revealed prevalent intermediate bleaching, peaking in 2017. By scrutinizing 23 stress exposure and sensitivity metrics, we accurately predicted 75% of bleaching severity variation. Notably, distinct thermal patterns-particularly the climatological seasonal warming rate and various heat stress metrics-emerged as better predictors compared to conventional indices (such as Degree Heating Weeks). Surprisingly, deeper reefs with diverse coral communities showed heightened vulnerability. This study presents a framework for coral reef bleaching vulnerability assessment, leveraging accessible data (including historical and real-time sea surface temperature, habitat variables, and species composition). Its operational potential lies in seamless integration with existing monitoring systems, offering crucial insights for conservation and management.
Assuntos
Antozoários , Mudança Climática , Recifes de Corais , Animais , Antozoários/fisiologia , Temperatura , Ecossistema , SimbioseRESUMO
The low-latitude habitats of the South American reef system have a high endemism and represent important stepping-stones due to the connectivity with Amazon and Caribbean reefs. We provide the first seabed mapping, and analyze the benthic cover and fish assemblages of these extreme reefs. Fleshy macroalgae (2-66% of cover), algal turfs (0-47%), and sponges (3-25%) are the dominant benthic groups. The main reef builders are crustose coralline algae (2-23%) and only four coral species (0 to 18%), mainly the weedy Siderastrea stellata. Cluster analysis distinguished two groups. The first group includes the shallowest reefs (~ 17 m deep) where fleshy macroalgae are abundant together with higher siltation on the reefs (~ 31% covered by sediments). The second group, by contrast, includes the deeper reefs (22.5-27 m), which have much higher algal turf cover, and the lowest sediment cover (4%). The deeper reefs also have the highest cover of corals (18%) and sponges (25%). We recorded a total of 63 fish species, with the deep reefs being the richest. Analysis indicated that the composition of the benthos was considerably more homogeneous across the study area than the composition of fish assemblages, which had a higher turnover of species among reefs. Moreover, we identified the depth of the reef as a variable structuring the benthic assemblages. The fish assemblage is influenced, in turn, by the benthos. Overall, the seabed mapping revealed the existence of a single reef system with high spatial heterogeneity. Our results provide new insights into the structure of these extreme reefs that have evolved under the influence of sediment resuspension, moderate turbidity, and are warmer than other West Atlantic reefs located at middle- and high-latitudes.
Assuntos
Recifes de Corais , Peixes , Animais , Peixes/fisiologia , Biodiversidade , América do Sul , Antozoários/fisiologia , Ecossistema , Alga Marinha/fisiologia , Alga Marinha/crescimento & desenvolvimento , Poríferos/fisiologia , Poríferos/classificaçãoRESUMO
This study aimed to identify ocean- and land-based sources of nutrients to the coral reef communities surrounding the Southern Caribbean islands Aruba, Bonaire, and Curaçao (ABC islands). The composition of water masses around these islands were assessed to depths up to 300 m and three distinct overlying water masses were identified, separated by mixing zones. A fluctuating pycnocline separating surface from deeper (>â¼50 m) water indicated the presence of internal waves. Nutrient profiles were typical of tropical waters with oligotrophic waters occurring above the pycnocline and a deep chlorophyll-a maximum (DCM) just below it (â¼65 m). Concentrations of dissolved nutrients differed among islands. Inorganic nitrogen (DIN) and phosphate concentrations were respectively lowest around Bonaire and Curaçao. The spatial distribution of chlorophyll-a (indicative of phytoplankton biomass), rather than nutrient concentrations, suggested the presence of higher-than-average nutrient concentrations in islands with higher population densities and near urbanized/industrial areas.
Assuntos
Clorofila A , Clorofila , Recifes de Corais , Monitoramento Ambiental , Região do Caribe , Clorofila A/análise , Clorofila/análise , Nitrogênio/análise , Fitoplâncton , Água do Mar/química , Curaçao , Fósforo/análise , Nutrientes/análiseRESUMO
Coral reefs are maintained by a balance between formation (calcifiers) and destructive processes (dissolution and erosion). In eastern tropical Pacific reefs, Porites genus is the second-largest contributor to CaCO3 production, but is affected by bioerosion. In this study, we evaluate the interaction between Lithophaga and Porites in an island reef in the Mexican Pacific by quantifying bioerosion rate, its impact on CaCO3 production, and contrasting growth models. To achieve this, Porites lobata colonies were collected to evaluate calcification and CaCO3 production. Shells of Lithophaga (Leiosolenus plumula) were extracted from corals, and age and length fed into a growth model. Our results indicate a high bioerosion rate (21.9 ± 4.1 %), representing 8.3 % of overall CaCO3 production. Bivalves' age (8 y) was less than corals (12.6 y), and cohort analysis indicates an intense recruitment. We associate this with high productivity derived from the island's oceanography, promoting nutrient enrichment, a plausible scenario for reefs under eutrophication conditions.
Assuntos
Antozoários , Carbonato de Cálcio , Recifes de Corais , Animais , Bivalves , Oceano Pacífico , MéxicoRESUMO
Coral microbiomes play crucial roles in holobiont homeostasis and adaptation. The host's ability to populate broad ecological niches and to cope with environmental changes seems to be related to the flexibility of the coral microbiome. By means of high-throughput DNA sequencing we characterized simultaneously both bacterial (16S rRNA) and Symbiodiniaceae (ITS2) communities of four reef-building coral species (Mussismilia braziliensis, Mussismilia harttii, Montastraea cavernosa, and Favia gravida) that differ in geographic distribution and niche specificity. Samples were collected in a marginal reef system (Abrolhos, Brazil) in four sites of contrasting irradiance and turbidity. Biological filters governed by the host are important in shaping corals' microbiome structure. More structured associated microbial communities by reef site tend to occur in coral species with broader geographic and depth ranges, especially for Symbiodiniaceae, whereas the endemic and habitat-specialist host, M. braziliensis, has relatively more homogenous bacterial communities with more exclusive members. Our findings lend credence to the hypothesis that higher microbiome flexibility renders corals more adaptable to diverse environments, a trend that should be investigated in more hosts and reef areas.
Assuntos
Antozoários , Bactérias , Recifes de Corais , Microbiota , RNA Ribossômico 16S , Animais , Antozoários/microbiologia , RNA Ribossômico 16S/genética , Bactérias/genética , Bactérias/classificação , Brasil , Simbiose , Filogenia , Dinoflagellida/genética , Dinoflagellida/fisiologia , Sequenciamento de Nucleotídeos em Larga Escala , EcossistemaRESUMO
This study explored the transformative journey of community-based natural resource management (CBNRM) in the Bay Islands National Marine Park, Honduras, revealing the interplay of cooperation, funding, and communication in fostering successful conservation initiatives. Using a mixed-method approach, we investigated the historical and legislative process and enabling conditions that led to the transition to CBNRM, based on Gruber's 12 key principles. In regards to the present CBNRM system, we looked at its strengths, its challenges, and whether its functioning is seen as satisfying by local resource-users. Findings showed that key CBNRM principles-including an enabling environment, conflict resolution, research-based decision-making, public trust, and monitoring-fostered the transition. Furthermore, satisfaction with reef management and perceived patrol effectiveness, which are pivotal aspects in CBNRM, exceeded 70% in Roatan. Challenges such as strengthening local institutions and enhancing compliance were identified. Nonetheless, co-managers are actively working to resolve these challenges by focusing on enforcement, diverse funding acquisition mechanisms and community participation. The study underscores the pivotal role of local NGOs and collaborative committees in facilitating successful CBNRM. By providing evidence-based insights, we highlight the efficacy of multilevel, co-management models in resource management and emphasize the value of adaptable strategies. These findings contribute to a deeper understanding of CBNRM dynamics in Latin America and the Caribbean, which may ultimately foster successful conservation initiatives in the Global South.
Assuntos
Conservação dos Recursos Naturais , Conservação dos Recursos Naturais/métodos , Honduras , Participação da Comunidade , Recifes de CoraisRESUMO
The crude oil contamination along the Brazilian Northeast coast significantly impacted reef ecosystems. This study assessed polycyclic aromatic hydrocarbons (PAHs) in seawater, fluorescence of bile PAHs, and biochemical biomarkers in damselfish Stegastes fuscus across four coral reef areas pre- and post-oil contamination. Serrambi (SE) and Japaratinga (JP1) were identified as suitable reference areas. PAH concentrations significantly increased in water post-contamination, predominantly 2 to 3 ring parent and alkylated PAHs. Biliary PAHs naphthalene, phenanthrene, chrysene, pyrene and benzo(a)pyrene increased on Paiva post-spill versus pre-spill to 173 %, 449 %, 334 %, 331 % and 131 %, respectively. Significant increases in ethoxy-resorufin-O-deethylase (EROD) (852 %), catalase (CAT) (139 %) and decrease in lipid peroxidation (LPO) (40 %) and acetylcholinesterase (AChE) (75 %) were verified in Paiva samples. Biliary PAHs and biochemical biomarkers were altered in S. fuscus after exposure to PAHs dissolved from the oil. Stegastes fuscus emerges as a promising sentinel organism for coastal reef oil pollution monitoring.
Assuntos
Biomarcadores , Recifes de Corais , Monitoramento Ambiental , Poluição por Petróleo , Hidrocarbonetos Policíclicos Aromáticos , Água do Mar , Poluentes Químicos da Água , Hidrocarbonetos Policíclicos Aromáticos/análise , Animais , Poluentes Químicos da Água/análise , Brasil , Monitoramento Ambiental/métodos , Água do Mar/química , Perciformes , Bile/química , Fluorescência , Citocromo P-450 CYP1A1/metabolismo , PetróleoRESUMO
Human activities and climate change have accelerated species losses and degradation of ecosystems to unprecedented levels. Both theoretical and empirical evidence suggest that extinction cascades contribute substantially to global species loss. The effects of extinction cascades can ripple across levels of ecological organization, causing not only the secondary loss of taxonomic diversity but also functional diversity erosion. Here, we take a step forward in coextinction analysis by estimating the functional robustness of reef fish communities to species loss. We built a tripartite network with nodes and links based on a model output predicting reef fish occupancy (113 species) as a function of coral and turf algae cover in Southwestern Atlantic reefs. This network comprised coral species, coral-associated fish (site occupancy directly related to coral cover), and co-occurring fish (occupancy indirectly related to coral cover). We used attack-tolerance curves and estimated network robustness (R) to quantify the cascading loss of reef fish taxonomic and functional diversity along three scenarios of coral species loss: degree centrality (removing first corals with more coral-associated fish), bleaching vulnerability and post-bleaching mortality (most vulnerable removed first), and random removal. Degree centrality produced the greatest losses (lowest R) in comparison with other scenarios. In this scenario, while functional diversity was robust to the direct loss of coral-associated fish (R = 0.85), the taxonomic diversity was not robust to coral loss (R = 0.54). Both taxonomic and functional diversity showed low robustness to indirect fish extinctions (R = 0.31 and R = 0.57, respectively). Projections of 100% coral species loss caused a reduction of 69% of the regional trait space area. The effects of coral loss in Southwestern Atlantic reefs went beyond the direct coral-fish relationships. Ever-growing human impacts on reef ecosystems can cause extinction cascades with detrimental consequences for fish assemblages that benefit from corals.
Assuntos
Biodiversidade , Mudança Climática , Recifes de Corais , Extinção Biológica , Peixes , Animais , Peixes/fisiologia , Antozoários/fisiologiaRESUMO
The Tropical Indo-Pacific (TIP) includes about two thirds of the world's tropical oceans and harbors an enormous number of marine species. The distributions of those species within the region is affected by habitat discontinuities and oceanographic features. As well as many smaller ones, the TIP contains seven large recognized biogeographic barriers that separate the Red Sea and Indian Ocean, the Indian from the Pacific Ocean, the central and eastern Pacific, the Hawaiian archipelago, the Marquesas and Easter Islands. We examined the genetic structuring of populations of Cirrhitichthys oxycephalus, a small cryptic species of reef fish, across its geographic range, which spans the longitudinal limits of the TIP. We assessed geographic variation in the mitochondrial cytb gene and the nuclear RAG1 gene, using 166 samples collected in 46 localities from the western to eastern edges of the TIP. Sequences from cytb show three well-structured groups that are separated by large genetic distances (1.58-2.96%): two in the Tropical Eastern Pacific (TEP), one at Clipperton Atoll another occupying the rest of that region and the third that ranges across the remainder of the TIP, from the central Pacific to the Red Sea and South Africa. These results indicate that the ~4,000 km wide Eastern Pacific Barrier between the central and eastern Pacific is an efficient barrier separating the two main groups. Further, the ~950 km of open ocean that isolates Clipperton Atoll from the rest of the TEP is also an effective barrier. Contrary to many other cases, various major and minor barriers from the Central Indo-Pacific to the Red Sea are not effective against dispersal by C. oxycephalus, although this species has not colonized the Hawiian islands and Easter Island. The nuclear gene partially supports the genetic structure evident in cytb, although all haplotypes are geographically mixed.
Assuntos
Variação Genética , Animais , Oceano Pacífico , Variação Genética/genética , Oceano Índico , Citocromos b/genética , Recifes de Corais , Filogenia , FilogeografiaRESUMO
Octocorals are showing resilience to local and global stressors, while the decline in zooxanthellate corals continues. One of the processes that helps explain this ecological succession is the vertical growth of octocorals, which allows colonies to avoid stressors occurring at the substrate level. However, the growth and survival of octocorals could be affected by eutrophication, similar to what has happened with zooxanthellate corals. For this reason, the growth rate, mortality and survival of two octocoral species were determined along a eutrophication gradient in Cuba. A permanent band transect (250 × 2 m) was established on seven frontal reefs, and marked colonies were monitored for one year. The growth rates in height, width and colony area of Eunicea flexuosa and Plexaura kükenthali were significantly greater in the reefs near the polluted river basins. The eutrophication gradient, water visibility, and sediment accumulation on the bottom explained 36-78% of the variability in the growth of both species. The positive and significant correlations between the growth rate and stable nitrogen isotopes in both species and the microbiological variables, suggest that the contributions of dissolved inorganic nitrogen and organic matter from sewage discharge favor the growth of colonies. The eutrophication gradient did not explain the variability in mortality of either species in the short term, while hydrodynamic stress did. The results of this research highlight the resilience of both species and their ability to grow more rapidly in areas with eutrophic conditions, low water visibility, and greater sediment accumulation on the bottom, which may help explain the abundance of octocorals in the western tropical Atlantic.
Assuntos
Antozoários , Recifes de Corais , Monitoramento Ambiental , Eutrofização , Cuba , Antozoários/crescimento & desenvolvimento , Antozoários/fisiologia , AnimaisRESUMO
Coral reefs rely heavily on reef fish for their health, yet overfishing has resulted in their decline, leading to an increase in fast-growing algae and changes in reef ecosystems, a phenomenon described as the phase-shift. A clearer understanding of the intricate interplay between herbivorous, their food, and their gut microbiomes could enhance reef health. This study examines the gut microbiome and isotopic markers (δ13C and δ15N) of four key nominally herbivorous reef fish species (Acanthurus chirurgus, Kyphosus sp., Scarus trispinosus, and Sparisoma axillare) in the Southwestern Atlantic's Abrolhos Reef systems. Approximately 16.8 million 16S rRNA sequences were produced for the four fish species, with an average of 317,047 ± 57,007 per species. Bacteria such as Proteobacteria, Firmicutes, and Cyanobacteria were prevalent in their microbiomes. These fish show unique microbiomes that result from co-diversification, diet, and restricted movement. Coral-associated bacteria (Endozoicomonas, Rhizobia, and Ruegeria) were found in abundance in the gut contents of the parrotfish species Sc. trispinosus and Sp. axillare. These parrotfishes could aid coral health by disseminating such beneficial bacteria across the reef. Meanwhile, Kyphosus sp. predominantly had Pirellulaceae and Rhodobacteraceae. Four fish species had a diet composed of turf components (filamentous Cyanobacteria) and brown algae (Dictyopteris). They also had similar isotopic niches, suggesting they shared food sources. A significant difference was observed between the isotopic signature of fish muscular gut tissue and gut contents, pointing to the role that host genetics and gut microbes play in differentiating fish tissues.
Assuntos
Bactérias , Recifes de Corais , Peixes , Microbioma Gastrointestinal , RNA Ribossômico 16S , Animais , RNA Ribossômico 16S/genética , Peixes/microbiologia , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Herbivoria , Especificidade da Espécie , Isótopos de Carbono/análise , Isótopos de Nitrogênio/análise , Perciformes/microbiologia , Dieta/veterináriaRESUMO
The southwestern tropical Pacific is a key center for the Interdecadal Pacific Oscillation (IPO), which regulates global climate. This study introduces a groundbreaking 627-year coral Sr/Ca sea surface temperature reconstruction from Fiji, representing the IPO's southwestern pole. Merging this record with other Fiji and central tropical Pacific records, we reconstruct the SST gradient between the southwestern and central Pacific (SWCP), providing a reliable proxy for IPO variability from 1370 to 1997. This reconstruction reveals distinct centennial-scale temperature trends and insights into Pacific-wide climate impacts and teleconnections. Notably, the 20th century conditions, marked by simultaneous basin-scale warming and weak tropical Pacific zonal-meridional gradients, deviate from trends observed during the past six centuries. Combined with model simulations, our findings reveal that a weak SWCP gradient most markedly affects IPO-related rainfall patterns in the equatorial Pacific. Persistent synchronous western and central Pacific warming rates could lead to further drying climate across the Coral Sea region, adversely affecting Pacific Island nations.
Assuntos
Antozoários , Temperatura , Fiji , Antozoários/fisiologia , Oceano Pacífico , Animais , Cálcio/metabolismo , Recifes de Corais , Mudança ClimáticaRESUMO
Over the past few decades, corals of the genus Tubastraea have spread globally, revealing themselves to be organisms of great invasive capacity. Their constant expansion on the Brazilian coast highlights the need for studies to monitor the invasion process. The growth, fecundity, settlement, and data on the coverage area of three co-occurring Tubastraea species in the 2015-2016 period were related to temperature variation and light irradiance on the rocky shores of Arraial do Cabo, Rio de Janeiro. Hence, this study sought to understand and compare the current invasion scenario and characteristics of the life history strategy of sun coral species based on environmental variables, considering the uniqueness of this upwelling area in the southwestern Atlantic. For that, we evaluate the fecundity, settlement, and growth rates of corals by carrying out comparative studies between species over time and correlating them with the variables temperature and irradiance, according to seasonality. Field growth of colonies was measured every two months during a sample year. Monthly collections were performed to count reproductive oocytes to assess fecundity. Also, quadrats were scrapped from an area near a large patch of sun coral to count newly attached coral larvae and used years later to assess diversity and percentage coverage. Results showed that corals presented greater growth during periods of high thermal amplitude and in months with below-average temperatures. Only Tubastraea sp. had greater growth and polyp increase in areas with higher light incidence, showing a greater increase in total area compared to all the other species analyzed. Despite the observed affinity with high temperatures, settlement rates were also higher during the same periods. Months with low thermal amplitude and higher temperature averages presented high fecundity. While higher water temperature averages showed an affinity with greater coral reproductive activity, growth has been shown to be inversely proportional to reproduction. Our study recorded the most significant coral growth for the region, an increase in niche, high annual reproductive activity, and large area coverage, showing the ongoing adaptation of the invasion process in the region. However, lower temperatures in the region affect these corals' reproductive activity and growth, slowing down the process of introduction into the region. To better understand the advantages of these invasion strategies in the environment, we must understand the relationships between them and the local community that may be acting to slow down this colonization process.
Assuntos
Antozoários , Fertilidade , Animais , Antozoários/crescimento & desenvolvimento , Antozoários/fisiologia , Fertilidade/fisiologia , Brasil , Espécies Introduzidas , Temperatura , Recifes de Corais , Estações do Ano , Oceano Atlântico , Características de História de Vida , Reprodução/fisiologiaRESUMO
In ecosystems, natural radionuclides are present in the environment and living organisms. The 238U natural decay chain produces multiple radioactive elements, such as 234U, 226Ra, 210Pb, and 210Po. These radionuclides can be found in air, water, rocks, soil, and other biotic and abiotic components, mainly derived from minerals, such as zircon and apatite. In this study, we determined the activity concentration of radionuclides from the 238U decay chain in the sediment of a coastal ecosystem on the southern Mexican coast in the western Caribbean, an ecosystem minimally affected by industrial activities. Methods included high-resolution gamma-ray spectrometry and alpha-particle spectrometry. Results showed that the sediment samples had an activity concentration range of 18.2-36.6 Bq/kg for 238U, 25.0-41.4 Bq/kg for 234U, 10.1-37.3 Bq/kg for 210Pb, and 29.9-46.0 Bq/kg for 210Po. Water samples ranged between 17.9 and 36.3 mBq/L and 27.9-66.0 mBq/L for 238U and 234U, respectively. The activity concentration of these radionuclides in the sediment and water of this area is compared with that of other coral reefs worldwide, providing a radiometric baseline for comparison purposes.
Assuntos
Recifes de Corais , Sedimentos Geológicos , Monitoramento de Radiação , Poluentes Radioativos da Água , Poluentes Radioativos da Água/análise , Sedimentos Geológicos/química , Urânio/análise , Região do Caribe , Ecossistema , Radioisótopos/análiseRESUMO
Seagrass meadows are one of the world's most diverse ecosystems offering habitats for an extensive array of species, as well as serving as protectors of coral reefs and vital carbon sinks. Furthermore, they modify hydrodynamics by diminishing water flow velocities and enhancing sediment deposition, indicating the potential for microplastic accumulation in their sediments. The build-up of microplastics could potentially have ecological impacts threatening to ecosystems, however little is known about microplastic abundance and controlling factors in seagrass sediments. Here we investigated microplastic characteristics and abundances within sediments underlying four seagrass meadow sites on the Turneffe Atoll, Belize. Sediment cores were collected and sub-sampled to include a range of replicate surface sediments (0-4 cm) and depth cores (sediment depths 0-2, 2-5, 5-10, 10-20 and 20-30 cm). These were analysed using 25 µm resolution µFTIR, with spectral maps processed using siMPle software. Microplastics were prevalent across the sites with an abundance range (limit of detection (LOD) blank-corrected) of < LOD to 17137 microplastics kg-1 dw found on the east side of the atoll. However, their abundances varied greatly between the replicate samples. Polyethylene and polypropylene were the most commonly detected polymers overall, although the dominant polymer type varied between sites. There were no differences in the abundance of microplastics between sites, nor could abundance distributions be explained by seagrass cover. However, abundances of microplastics were highest in sediments with lower proportions of fine grained particles (clay, <4 µm) suggesting that hydrodynamics override seagrass effects. Additionally, no patterns were seen between microplastic abundance and depth of sediment. This suggests that microplastic abundance and distribution in seagrass meadows may vary significantly depending on the specific geographical locations within those meadows, and that more complex hydrodynamic factors influence spatial variability at a localised scale.
Assuntos
Monitoramento Ambiental , Microplásticos , Poluentes Químicos da Água , Microplásticos/análise , Sedimentos Geológicos/química , Recifes de Corais , Pradaria , Poluição Química da Água/estatística & dados numéricos , Poluentes Químicos da Água/análise , Belize , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Studies on the occurrence of POPs and other persistent compounds in pristine areas are extremely valuable, as they offer insights on the long-range transportation of POPs and the occurrence of natural compound producers' areas. In this regard, this study aimed to report data of both anthropogenic (polychlorinated biphenyls, PCBs, and polybrominated diphenyl ethers, PBDEs) and natural (methoxylated PBDEs, MeO-BDEs) compounds in tissues of the black triggerfish, Melichthys niger (Tetraodontiformes, Balistidae), specimens (n = 30) sampled in 2018 during a scientific expedition conducted at Trindade Island. Concentrations of ∑28PCBs ranged from 73 to 1052 ng g-1 lw in liver, 334 to 1981 ng g-1 lw in gonads, and 20 to 257 ng g-1 lw in muscle, with the predominance of PCB-180 in liver and PCB-52 in gonad and muscle. Concentrations of ∑7PBDEs ranged from