Caribbean Beaches Research Articles

Coccoloba uvifera L. associated with Scleroderma Bermudense Coker: a pantropical ectomycorrhizal symbiosis used in restoring of degraded coastal sand dunes.

Coccoloba uvifera L. (Polygonacaeae), named also seagrape, is an ectomycorrhizal (ECM) Caribbean beach tree, introduced pantropically for stabilizing coastal soils and producing edible fruits. This review covers the pantropical distribution and micropropagation of seagrape as well as genetic diversity, functional traits and use of ECM symbioses in response to salinity, both in its native regions and areas where it has been introduced. The ECM fungal diversity associated with seagrape was found to be relatively low in its region of origin, with Scleroderma bermudense Coker being the predominant fungal species. In regions of introduction, seagrape predominantly associated with Scleroderma species, whereas S. bermudense was exclusively identified in Réunion and Senegal. The introduction of S. bermudense is likely through spores adhering to the seed coats of seagrape, suggesting a vertical transmission of ECM colonization in seagrape by S. bermudense. This ECM fungus demonstrated its capacity to enhance salt tolerance in seagrape seedlings by reducing Na concentration and increasing K and Ca levels, consequently promoting higher K/Na and Ca/Na ratios in the tissues of ECM seedlings vs. non-ECM plants in nursery conditions. Moreover, the ECM symbiosis positively influenced growth, photosynthetic and transpiration rates, chlorophyll fluorescence and content, stomatal conductance, intercellular CO2, and water status, which improved the performance of ECM seagrape exposed to salt stress in planting conditions. The standardization of seagrape micropropagation emerges as a crucial tool for propagating homogeneous plant material in nursery and planting conditions. This review also explores the use of the ECM symbiosis between seagrape and S. bermudense as a strategy for restoring degraded coastal ecosystems in the Caribbean, Indian Ocean, and West African regions.

Multifunctional characterization of cement-Sargassum composites for application as bioconstruction materials

Utilizing solid waste biomass developing of construction materials presents an environmental mitigation opportunity by gradually replacing conventional materials that generate diverse ecological impacts. This approach aligns with circular economy and green chemistry principles, promoting the creation of sustainable materials. This research analyzes the use of brown algae from the Sargassum genus for bioconstruction applications through its mix with Portland cement. The mass influx of pelagic Sargassum species onto Caribbean beaches since 2011 has significantly impacted the environment, economy, and human health. The valorization of Sargassum is crucial for effective management and impact reduction. The study encompasses four key stages: (a) collection and processing of the algae, (b) development of a construction material composed of Portland cement and Sargassum at concentrations of 5 wt.% and 7.5 wt.%, (c) multifunctional characterization of the composite material, encompassing physical chemistry and thermal, optical and mechanical properties, and (d) an economic-environmental evaluation of using the construction material for housing in the Mexican Caribbean to enhance thermal insulation and reduce electric energy consumption associated with air conditioning. Test specimens of the composite material reveal compressive strength ranging between 78 and 347 kg/cm2, solar spectrum absorbance between 54% and 70%, and thermal conductivity between 0.65 and 1 W/mK. The economic-environmental analysis indicates that employing the construction material in 5% of households in the state of Quintana Roo, Mexico, could lead to annual reductions in energy consumption of approximately 67 GWh, with savings exceeding US$33,000, and environmental yearly mitigation equivalent to 4.1 TnNOx, 5.2 TnCH4, and 33,262 TnCO2. These results suggest promising prospects for incorporating Sargassum into construction materials, offering potential environmental and economic benefits. The composite material demonstrates optical, thermal, and mechanical functionality.

From Inundations to Golden Opportunity: Turning Holopelagic Sargassum spp. into a Valuable Feed Ingredient through Arsenic Removal

For over a decade, numerous Greater Caribbean and Western African coasts have received enormous masses of holopelagic Sargassum spp. (sargasso). A promising use of this beached biomass as a feed ingredient in the animal industry is restricted by its high arsenic (As) content. This proof of concept aimed to demonstrate that simple, low-cost processes involving hot water (either fresh or seawater) and/or citric acid can remove arsenic from the sargasso. Sargasso collected from a Mexican Caribbean beach in December 2023 had a total arsenic level of 62.2 mg/kg, which decreased to 7.2 mg/kg after treatment with hot freshwater (90 °C for 15 min), and then further decreased to 0.8 mg/kg when followed up with a citric acid treatment. Sargasso collected in March 2024 had total arsenic of 89 mg/kg, which was lowered to 2.6 mg/kg by applying hot freshwater and citric acid sequentially. Employing only citric acid reduced the arsenic concentration to 8.0 mg/kg, while treating the sargasso only with hot seawater reduced the As level to 10.1 mg/kg. Thus, simply using hot water, either fresh or seawater, lowered the arsenic levels to acceptable levels for the animal feeding sector. These straightforward and potentially cost-effective methods may transform the restraint of high arsenic contents into a valuable opportunity to use these seaweeds as animal feed.

Effect of desalination of Sargassum algae on its potential use as a stabilizer in sustainable earth-based bricks

Since 2011, Caribbean beaches have been flooded by massive quantities of pelagic Sargassum, causing environmental, health and financial problems. The use of Sargassum ash as a stabilizer in the manufacture of bricks can help mitigate the economic impact of Sargassum grounding by adding value. This study assesses the effect of the Pelagic Sargassum algae desalination process on the properties of the biomass as well as the potential application of their ash as a stabilizer in soil-based bricks. Fresh Sargassum algae was subjected to two cycles of immersion in water, then calcined under different conditions (temperature and time) and characterized. The desalinated Sargassum ash (SA) was used to partially replace cement in the stabilization of earth bricks. Characterization of raw and desalted Sargassum shows a reduction in ash content from 28.44 to 17.25 % after desalination. Furthermore, the thermo gravimetric analysis show a slight reduction in the initial degradation temperature between 204 and 602 °C, which is associated with a reduction in the amount of residual char from 35 % to 27 %. The results of the XRF analysis of the SA showed a very low alumiosilica content (SiO3 + Al2O3 < 4 %), but a significant increase in CaO content after desalination from 21.96 to 50.17 %. The XRD results of the SA are consistent with the XRF analysis which reveals that the desalination process significantly increased the CaCO3 content from 19 to 67 %, while KCl decreased significantly from 26 to 8 %. Furthermore, the characterization of the composites reveal that partial substitution of 10 wt% cement by SA calcined at 700 °C for 2 h has no significant effect on water absorption, density, compressive strength and chemical composition of earth bricks. This material could help reduce pollution linked to the decomposition of sargassum on Caribbean coasts and beaches, as well as greenhouse gas emissions linked to cement production.

Development of a Binderless Particleboard from Brown Seaweed Sargassum spp.

Since 2010, huge quantities of Sargassum spp. algae have been proliferating in the Atlantic Ocean and stranding on Caribbean beaches, causing major economic, environmental, and health problems. In this study, an innovative high-density binderless particleboard was developed using uniaxial thermo-compression coupled with a cooling system. The raw material consisted of ground Sargassum seaweeds pre-treated by twin-screw extrusion with water to remove sea salt. The raw material and the particleboards were produced by using various analytical techniques such as Dynamic Vapor Sorption (DVS), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), or Thermogravimetric Analysis (TGA). The experimental conditions for thermo-compression (temperature, pressure, time) were evaluated. The best thermo-compression conditions tested were 200 °C, 40 MPa pressure for 7.5 min. This resulted in a particleboard with high density (up to 1.63 ± 0.02 g/cm3) and high flexural strength/modulus (up to 32.3 ± 1.8 MPa/6.8 ± 0.2 GPa, respectively), but a low water contact angle of 38.9° ± 3.5°. Thermal analyses revealed the effect of alginates on the mechanical properties of particleboards. This work opens the door to a new way of adding value to Sargassum seaweed, using the whole algae with minimal pre-treatment.

From the closet to the shore: Fashion waste pollution on Colombian Central Caribbean beaches

This paper examines the environmental effects of fashion waste on the central Caribbean coast of Colombia, highlighting significant ecological issues in coastal areas. A survey of 27 beaches found 503 items of fashion waste, mainly shoes and sandals, with an average density of 0.93 items/m2. The distribution of this type of waste varies notably across different beach types, with exposed, rural, and remote beaches showing higher accumulation, indicating a relationship between beach characteristics and waste concentration. Primary sources of this waste include riverine transport, coastal tourism, and poorly managed sewage systems, impacting urban, rural, and village beaches differently. The study reveals that longshore currents and oceanic movements, significantly influence the transport and fate of this waste, with exposed beaches accumulating more fashion waste than sheltered ones. The presence of driftwood also plays a vital role in trapping fashion waste along coastlines. The findings highlight the need for effective management strategies to mitigate the impact of fashion waste, providing crucial insights for local and national coastal managers and implications for managing fashion waste in the Southern Caribbean and similar regions worldwide.

EROSION PROCESS IN THE CARIBBEAN SANDY BEACHES

Beach erosion is a widespread phenomenon on Caribbean beaches, with rates of coastline retreat between 2.2 and 0.5 m/year and higher reports in some areas. Different investigations indicate the combination of natural and anthropogenic causes and highlight the current influence of climate change related sea level rise. It is recorded as a generalizing trend the landward displacement of the beach profile, with sand transfer above the dunes and sand bars in a process that fits better the model proposed by Dean and Maurmeyer (1983) than the recognized model by Brunn (1962).

Presence of microplastics deposited in Sargassum sp. on sandy beaches

The atypical massive arrival of Sargassum sp. on the Mexican Caribbean beaches, mainly in summer, has increasingly become a major problem in the last decade, not only because of the economic and aesthetic impact it has caused on this region, but also due to the associated environmental effects. For instance, macroalgae could cause the transport and deposition of plastic waste on the shore. Thus, a study was carried out, which focused on quantification of the microplastics (MP) present in deposited Sargassum sp. on five sandy beaches, as well as in the sand under the macroalgae, and then, observing and comparing the results of both samples. In the case of the sand samples, the methodology used was based on what was reported by Alvarez-Zeferino et al., 2020, while for the Sargassum sp. samples, the methodology was fully developed as there was no reference methodology for this type of sample. The presence of MP was reported in all the samples from the five beaches. In sand, the concentration range was 17.6–52.8 MP/m2, with an average of 29.6 ± 10.4 MP/m2, while for Sargassum sp. the average was 15.7 ± 2.8 MP/ kgFW with a range of 11.2–19.3 MP/kgFW. The results point out that higher concentrations of MP in Sargassum sp. relate to higher concentrations of MP in the sand. This might suggest that Sargassum sp. spills would transport MP, becoming an additional source of plastic pollution on beaches.

Carbon Materials Prepared from Invading Pelagic Sargassum for Supercapacitors' Electrodes.

Since 2011, substantial amounts of pelagic Sargassum algae have washed up along the Caribbean beaches and the Gulf of Mexico, leading to negative impacts on the economy and the environment of those areas. Hence, it is now crucial to develop strategies to mitigate this problem while valorizing such invasive biomass. This work deals with the successful exploitation of this pelagic Sargassum seaweed for the fabrication of carbon materials that can be used as electrodes for supercapacitors. Pelagic Sargassum precursors were simply pyrolyzed at temperatures varying from 600 to 900 °C. The resultant carbonaceous materials were then extensively characterized using different techniques, such as nitrogen adsorption for textural characterization, as well as X-ray photoelectron (XPS), Fourier transform infrared spectroscopies (FT-IR) and scanning electron microscopy (SEM), to understand their structures and functionalities. The electrochemical properties of the carbon materials were also tested for their performance as supercapacitors using cyclic voltammetry (CV), the galvanostatic method and electrochemical impedance spectroscopy analyses (EIS). We managed to have a large specific surface, i.e., 1664 m2 g-1 for biochar prepared at 800 °C (CS800). Eventually, CS800 turned out to exhibit the highest capacitance (96 F g-1) over the four samples, along with the highest specific surface (1664 m2 g-1), with specific resistance of about 0.07 Ω g -1.

Urbanization driving Ocypode quadrata burrow density, depth, and width across Caribbean beaches

Globally, sandy beaches support local economies and are the most commonly-used type of coastline. This importance is perhaps most striking in the Caribbean; however, no study has assessed the morphological features of the U.S. Virgin Islands (USVI) sandy beaches or evaluated how their biodiversity is influenced by human activities. We addressed these gaps by sampling eight St. Thomas, USVI, beaches with different urbanization levels (Stumpy Bay, Santa Maria Bay, Caret Bay, Neltjeberg Bay, Lindberg Bay, Magens Bay, Coki Point Beach, and Sapphire Beach) multiple times during high- and low-tourist season. At each sampling site and occasion, we measured environmental features (i.e., grain size, waves, and slope), urbanization variables (e.g., solid waste, traffic of vehicles, and beach cleaning) and ghost crab (Ocypode quadrata) population parameters (i.e., burrow density, depth, and width). We found that all studied beaches have similar morphodynamic features, being generally characterized as wave dominated reflective. Urbanization variables were the main drivers of ghost crab populations, with visitor frequency, distance to urban center, and evidence of vehicles on sand exerting stronger roles than variations in physical beach characteristics. Overall, our results provide important information on the morphology of USVI beaches and the impact of beach use. We expect these results will increase understanding of the drivers and threats to local sandy beach biodiversity, inform future management decisions for the territory, while creating a baseline for ghost crab studies in the U.S. Virgin Islands.

Use of semantic segmentation for mapping Sargassum on beaches.

The unusual arrival of Sargassum on Caribbean beaches is an emerging problem that has generated numerous challenges. The monitoring, visualization, and estimation of Sargassum coverage on the beaches remain a constant complication. This study proposes a new mapping methodology to estimate Sargassum coverage on the beaches. Semantic segmentation of geotagged photographs allows the generation of accurate maps showing the percent coverage of Sargassum. The first dataset of segmented Sargassum images was built for this study and used to train the proposed model. The results demonstrate that the currently proposed method has an accuracy of 91%, improving on the results reported in the state-of-the-art method where data was also collected through a crowdsourcing scheme, in which only information on the presence and absence of Sargassum is displayed.

Polycentric Governance, Coordination and Capacity: The Case of Sargassum Influxes in the Caribbean

The merits of polycentric climate governance have attracted considerable discussion. On the one hand, polycentric governance offers an alternative to top-down state-centric forms that have so far proven elusive. On the other, highly networked systems increase coordination challenges. Less attention has been paid to the varying capacities required to achieve coordination. In this article we explore the coordination of polycentric governance via a case study of sargassum influx management in the Caribbean. Since 2011, large quantities of sargassum seaweed have been washing up on Caribbean beaches with adverse socio-economic impacts. Our analysis of sargassum management policies reveals that a nascent polycentric system has generated significant cooperation in policy development and application across the region. However, there remain national capacity deficits to engage in this form of governance and to implement agreed actions. We conclude that advocates of a polycentric climate governance regime need to consider how capacity shapes participation, to the advantage of the largest and strongest. Polycentric governance can be useful for solving disparate cross-border environmental problems, but it also imposes a cost on the smallest that has thus far been unacknowledged and undertheorized.

Covid-19 and Sargassum blooms: impacts and social issues in a mass tourism destination (Mexican Caribbean).

When the COVID-19 pandemic reached the Mexican Caribbean in late March 2020, this world-renown tourist destination had already been struggling with Sargassum influxes for 5 years. The nature and magnitude of these two impacts are not directly comparable, but both have contributed to profoundly transforming the region. As extreme COVID-19 containment measures were implemented nationwide, the tourism industry contracted by 98% as over 23 million visitors failed to arrive in 2020 and 400 daily flights stopped landing at Cancun Airport. Sargassum accumulations on Caribbean beaches, and their collection, containment and removal had been a challenging socioeconomic issue in the Caribbean region years before the COVID-19 pandemic shut down the tourist industry. We explore Beck’s concept of a risk society as an approach to these socioenvironmental impacts. We analyze five premises about risk society, combining them with a mainly ethnography methodology involving 61 informants. We present the results in terms of impacts. Using the concept of trajectory based on pandemic event chronology, we review the main stages of the pandemic during the research period (May to July 2020) and how the studied population worked to prevent virus infection and spread. We employ narratives to analyze risk perception both of the Sargassum influx and the pandemic. The discussion highlights the importance of moving beyond nature/society dichotomies and dualisms. In summary, the profound transformations caused by these impacts provide a unique opportunity for the Mexican Caribbean to reconstitute itself in a way that encompasses the world risk society concept, perhaps in a more socially and environmentally resilient incarnation.

Activity patterns of Cybotus estriatus (LeConte, 1878) (Coleoptera: Tenebrionidae) on a Caribbean beach

Sandy beach ecosystems are extreme environments in which darkling beetles (Tenebrionidae) have been usually reported as a dominant component of the fauna. The abundance and richness of tenebrionids in arid zones is facilitated by specific physiological, morphological, and behavioural traits, such as limited activity patterns or the use of suitable microhabitats. Activity patterns of tenebrionid beetles have been investigated mainly in large-size species, but the response of small species remains basically unknown. Considering this, we developed a study in a Caribbean beach in Costa Rica with the aim of identifying daily activity patterns of Cybotus estriatus (LeConte, 1878), a darkling beetle of 2–3 mm in length relatively frequent in the circum-Caribbean beaches. In addition, we assessed how vegetation cover influences the abundance of this small tenebrionid species. Observations were performed between 7:00 h to 18:30 h, within a range of temperatures from 28°C to 47°C. Cybotus estriatus exhibits a bimodal activity pattern similar to those observed for other tenebrionids. It remains active at a temperature range of 35°C to 44°C, but shows a higher activity around 10:00 h and 15:30 h, at temperatures between 38°C and 42°C. We also found a strong dependence of C. estriatus on beach vegetation, providing the first data on the effect of vegetation cover in small tropical beetles inhabiting sand beaches. Our results suggest that body size may not be the critical factor determining activity in tenebrionids, and that preserving the natural vegetation in sandy beaches is essential to maintain the biodiversity of these ecosystems.

Trace elements in pelagic Sargassum species in the Mexican Caribbean: Identification of key variables affecting arsenic accumulation in S. fluitans

Since 2014, the Mexican Caribbean beaches have received massive influxes of the brown seaweed Sargassum (S. fluitans III, S. natans I and S. natans VIII), causing serious ecological and economic effects. Concentrations of arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), and zinc (Zn) were determined over an annual cycle in pelagic Sargassum species from massive influxes into the Mexican Caribbean. The contribution of trace elements, polysaccharides (alginate and fucoidans), and their main functional groups (uronic acids and sulfate) to arsenic content in Sargassum fluitans — the most abundant species in the Sargassum influx — is discussed. Arsenic was recorded in all samples, yielding mean concentrations of 74.2 ± 2.84 mg kg−1. Significant differences were found between species for As, Cu, Fe, and Pb, but not for Cd and Zn; also, S. fluitans showed significant differences in metal content between seasons for all elements, as well as in alginate and uronic acids from fucoidan. The season of the year, copper, iron, uronic acids, and sulfate content in fucoidan were the main variables associated with arsenic accumulation in S. fluitans as evidenced with a Generalized Linear Model. Arsenic content in Sargassum biomass exceeded the maximum allowable level in the rainy season; therefore, the content of this trace element should be carefully monitored for safe usage of Sargassum biomass.

Caribbean-Wide, Negative Emissions Solution to Sargassum spp. Low-Cost Collection Device and Sustainable Disposal Method

Sargassum spp. blooms exacerbated by climate change and agricultural runoff are inundating Caribbean beaches, emitting toxic fumes and greenhouse gases through decomposition. This hurts tourism, artisanal fishing, shore-based industry, human health, standards-of-living, coastal ecology, and the global climate. Barriers, collection machinery, and Sargassum valorization have been unable to provide sufficient, sustainable, or widespread relief. This article presents a total Sargassum management system that is effective, low-impact, and economically scalable across the Caribbean. Littoral Collection Modules (LCMs), attached to artisanal fishing boats, collect Sargassum in nets which are brought to a barge. When full, the barge is towed to the deep ocean where Sargassum is pumped to ~150–200 m depth, whereafter it continues sinking (Sargassum Ocean Sequestration of Carbon; “SOS Carbon”). Costing and negative emissions calculations for this system show cleanup costs &lt;$1/m3 and emissions reduction potential up to 1.356 → 3.029 tCO2e/dmt Sargassum. COVID-19 decimated Caribbean tourism, adding to the pressures of indebtedness and natural disasters facing the region. The “SOS Carbon strategy” could help the Caribbean “build back better” by establishing a negative emissions industry that builds resilience against Sargassum and flight shame (“flygskam”). Employing fishermen to operate LCMs achieves socioeconomic goals while increasing Sargassum cleanup and avoiding landfilling achieves sustainable development goals.

Microplastics pollution on Colombian Central Caribbean beaches

The growing literature on microplastics (MPs) in coastal and marine environs reflects the seriousness of this pollutant category. Diverse litter studies on Colombia's Central Caribbean Coast have not presented detailed study of MPs' typology, magnitude or distribution. This baseline study presents for first time the MPs problem on 23 beaches in 75 km coastal reach between Punta Roca and Galerazamba, on the central Colombian Caribbean Coast. The Microplastics Pollution Index (MPPI) and Coefficient of Microplastic Impact (CMPI) were developed and applied along with the Environmental Status Index (ESI) and their integration through sector analysis, and mapping using Agglomerative Hierarchical Clustering and Multidimensional Scaling, and Principal Components Analysis. Microplastics abundances (densities) ranged from 2457 to 557 MPs/kg, similar to other global beaches and bays. The MPs Index for the 23 beaches classified 8 beaches as “Moderate,” 10 beaches as “High” and 5 as “Very High.” Microplastic fibers were the dominant typology at 83% of the combined beaches total (ranging from Moderate to Very High for individual beaches).

Collective view: mapping Sargassum distribution along beaches.

The atypical arrival of pelagic Sargassum to the Mexican Caribbean beaches has caused considerable economic and ecological damage. Furthermore, it has raised new challenges for monitoring the coastlines. Historically, satellite remote-sensing has been used for Sargassum monitoring in the ocean; nonetheless, limitations in the temporal and spatial resolution of available satellite platforms do not allow for near real-time monitoring of this macro-algae on beaches. This study proposes an innovative approach for monitoring Sargassum on beaches using Crowdsourcing for imagery collection, deep learning for automatic classification, and geographic information systems for visualizing the results. We have coined this collaborative process “Collective View”. It offers a geotagged dataset of images illustrating the presence or absence of Sargassum on beaches located along the northern and eastern regions in the Yucatan Peninsula, in Mexico. This new dataset is the largest of its kind in surrounding areas. As part of the design process for Collective View, three convolutional neural networks (LeNet-5, AlexNet and VGG16) were modified and retrained to classify images, according to the presence or absence of Sargassum. Findings from this study revealed that AlexNet demonstrated the best performance, achieving a maximum recall of 94%. These results are good considering that the training was carried out using a relatively small set of unbalanced images. Finally, this study provides a first approach to mapping the Sargassum distribution along the beaches using the classified geotagged images and offers novel insight into how we can accurately map the arrival of algal blooms along the coastline.

Plastic pollution on the Colombian central Caribbean beaches

Along 24 beaches of the Central Caribbean Coast of Colombia, plastic items were collected and grouped into 43 different typologies. The average plastic abundance was 4.54 items/m2 being eight typologies responsible for 82% of all plastic collected. The application of the Clean Coast Index (CCI) and the Plastic Abundance Index (PAI) allows categorization of the study area as “Extremely Dirty” coastal strip with a “Very High Abundance” of plastics. Beaches were statistically grouped into three specific types: moderate, bad and extremely bad environmental conditions. The typology and magnitudes of plastics found in the study area suggest a combination of sources that primarily include dumping and direct activities on the beach. Plastic medical and sanitary waste, ocean/waterway items, and plastic items related to smoking-related activities also were observed.

Saint Lucia Works to Release Itself from &lt;em&gt;Sargassum&lt;/em&gt;’s Stranglehold

Nearly 10 years ago, Caribbean beaches experienced a sudden onslaught of Sargassum. Today residents continue to explore ways to mitigate the seaweed’s damage to local health and livelihoods.