Mexican Caribbean Research Articles

Nutritional composition of manatee’s diet in the Western Caribbean: from the river to the reef

The endangered Greater Caribbean manatee (Trichechus manatus manatus), one of the largest aquatic herbivores in the Caribbean, plays a crucial role in nutrient recycling within the ecosystem, and the study of its feeding ecology is important for its conservation. Despite several studies determining the items consumed by manatees, there remains limited understanding of their nutritional significance for the species in the Western Caribbean. This study, aimed to analyze the bromatological composition of the food components in the manatee’s diet in the Mexican Caribbean across three distinct environments. We manually collected aquatic and semi-aquatic primary producers potentially part of the manatee diet in marine, brackish and riverine areas of the southern region of Quintana Roo, Mexico. Then, we analyzed them for moisture, crude protein, crude fiber, ash, ether extract, digestible nutrients, and digestible energy. We present the initial data on nutrient values in the manatee diet in the Caribbean, establishing a foundation for exploring the factors that influence spatial, temporal, and species-specific variations in nutrient content at a regional level. Our bromatological analysis demonstrated that the most nutritionally important plants for manatees, based mainly on protein content and freshwater contribution, include the seagrasses Halodule wrightii, Syringodium filiforme, Thalassia testudinum, the water lily Pontederia crassipes, and Vallisneria sp. Effective habitat management for manatees is crucial for their survival, ensuring that feeding resources are maintained in both enough quantity and high quality. Given its nutritional significance for manatees, we recommend that seagrasses in the region should be prioritized as conservation targets.

Thermal Conductivity, Density and Calorific Value of Sargassum Fluitans and Sargassum Natans Species

In this study, we obtained the values of the thermodynamic properties of sargassum that includes S. fluitans and S. natans species, which are the ones that most arrive at the coasts of the Mexican Caribbean. The sargassum samples, collected at the coast, were dried in a direct type of solar dryer and their final relative humidity was 15% dry base. Two physical models were designed to construct biscuits of 0.0127 m in diameter and 0.0063 m in length, which were used to obtain the density and calorific value and those used for thermal conductivity, were 0.069 m in diameter and 0.008 m thick. The density resulted in 660.62 𝑘𝑔/𝑚3 . To determine the calorific value, a commercial calorimetric pump was used, and the value obtained was 17,950 𝑘𝐽/𝑘𝑔. For thermal conductivity, a device that employs the hot plate and guard method was designed and built and its value was 0.346 𝑊/𝑚°𝐶. These values indicate that it is possible to use dehydrated sargassum to produce energy, which has approximately a value of 75% of that obtained for sugar cane bagasse. With these three values and using the thermal diffusivity definition equation, this last parameter was calculated in 2.917 × 10−11 𝑚2 /𝑠.

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.

Assessment of Leachate Generated by Sargassum spp. in the Mexican Caribbean: Part 2, Mobility of Metals

The spread of sargassum on beaches in Africa, Brazil, Central America, and the Caribbean has increased to become a social, environmental, and economic problem. In recent years, the presence of biomass on the coasts of the Mexican Caribbean has been recorded as ≈2360 m3 Km−1, reaching up to 200 m wide in the northern part of the coasts. Its removal from the coast and, later, the continent is one of the strategies implemented to mitigate its impact on land. Several studies have reported the seasonality of and geographic variation in sorbed metals in sargasso. However, it is unknown whether these metals can mobilize or remain in sargassum tissue once they reach accumulation sites. This study included seawater, sargassum tissue as a consortium, and S. natans and S. fluitans, as well as the leachate generated in the process of degradation per se and percolated by rain. Of the 10 metals evaluated (As, B, Fe, Zn, Mn, Cd, Al, Ni, Cu, and Pb for water, tissue, and leachate), only B is recurrent in water from the north of the Mexican Caribbean, in addition to traces of Al and Fe. Meanwhile, in tissue, the results coincide with those of previous studies, where As is recurrent, although its concentration varies with the mentioned variability. The leachate showed that four to eight metals of those present in the tissue were detected, including As, Fe, and Al, which represent a potential impact on coastal systems and infiltration into shallow water table areas.

The Environmental Legal Framework of Mexican Caribbean Dunes: A Retrospective Case Study of Vegetation and Coastal Dune Loss in the Sian Ka’an Biosphere Reserve

The Mexican Caribbean coastal dune is protected by national and international environmental legislation. However, through permits, concessions and authorizations for changes in land use, the coastal dune has been fragmented or suppressed, mainly for touristic activities, causing a decline in protective and ecological ecosystem services. In this study, we evaluated the strength and weakness of Mexican legislation to protect the Caribbean coastal dune ecosystem and estimated the historical and current effects on coastal dune vegetation and dune geomorphology, associated with legal allowances of land use change in the Sian Ka’an Biosphere Reserve (SKBR). Legislation at the federal, state and local level were critically reviewed, and with remote sensing techniques and the Remotely Piloted Aircraft System (RPAS), we conducted a case study in the SKBR to estimate coastal dune vegetation alteration trends during the period 2011–2020 and modifications on the dune geomorphology associated with land use change allowances. At the federal (four laws), state (eight laws) and local (nine Local and Territorial Planning Programs (POEL and POET) levels, we found a lack of consensus and alignment between regulations, starting with a lack of definition of ecosystems subject to protection. For coastal dunes, none of them consider topography, ecological function and a way to identify it in the field, making the surveillance highly complex and favoring land use changes, the removal of vegetation and dune geomorphology alteration. Remote sensing techniques showed that areas with land use authorizations exhibit negative vegetation cover trends (Mann–Kendall <−0.4), indicating a decline in vegetation cover density that is mostly anthropogenically induced. The RPAS analysis demonstrated drastic alterations to complete elimination of the coastal dune geomorphology in areas with land use change. In the Mexican Caribbean, the loss of coastal dune and associated ecosystem by the lack of congruent legislation threatens the environmental stability of the coastal areas.

Chemical and isotopic composition of rainwater in the eastern Yucatan peninsula, Mexico

Given that rain is the component of precipitation that reaches the surface of the earth, and aiming to contribute to the global efforts of rainwater monitoring, we present information regarding the origin of ions and their relationship with isotopic patterns and the source of moisture for rainwater in the Mexican Caribbean, which not only may be useful for pollution and atmospheric studies, but also for estimating groundwater recharges, understanding dust nuisances, and offering information about water quality for rainwater harvesting. In this paper, we describe the chemical composition of rainwater in terms of major ions, isotopic composition, and the most probable sources of moisture in the Caribbean coastal zone of Mexico, considering the three main climatic seasons in this area. The chemistry of rainwater displayed a noticeable influence from sea-salt spray, land-blown dust, and anthropogenic impacts such as agriculture and biomass burning. We identified the predominant terrestrial origin of calcium, namely anthropogenic contributions of sulfates and nitrates, plus potassium from sea spray and anthropogenic emissions. The local meteoric water line is δ2H = 8.2 δ18O + 13.8 (R² = 0.9601) suggesting enrichment due to evaporative losses, various moisture sources and local climatic effects. Although isotope composition was not different by site, it was by season, as opposed to water chemistry. We conclude that the water chemistry responds to the local conditions of the air column below the clouds, while the isotope composition is influenced by the origin of moisture and the physical conditions in which water evaporates and condenses as well.

Dissolved inorganic nutrients in a reef lagoon influenced by submarine groundwater discharge in the Mexican Caribbean

Submarine groundwater discharge (SGD) worldwide has been considered an important source of dissolved inorganic nutrients, pathogens, and terrestrial materials transported from land to sea. However, nutrient behavior associated with SGD in the Mexican Caribbean has long been ignored. Here, we investigate the variability in nutrient and pathogen distribution during a neap-spring diurnal cycle in the Nohoch-Teek fringing reef influenced by SGD during the “nortes” season. The spatio-temporal behavior of nitrate and silicate followed three patterns during a neap-spring diurnal cycle: 1) An increasing trend from the beginning to the end of the day; 2) A spatial gradient with decreasing values from SGD-Teek towards the coral reef; and 3) The highest concentrations in the SGD-Teek and southwest of SGD-Teek. No significant differences were recorded in the temporal behavior (p > 0.05); however, the highest concentrations were observed during the lowest spring tide. The ammonium exhibited an increasing trend from the beginning to the end of the day. Significant differences were recorded regarding temporal behavior, with variations during the morning and afternoon of both spring and neap tides, with the highest concentrations recorded in the afternoon. The spatial distribution of phosphate was more homogeneous. The presence of pathogens was evidenced in addition to the variation in the spatial and temporal behavior of nutrient input through SGD. The correlation between salinity and water level suggests that sea level variations influenced the flow. Silicate as tracers proved efficient, showing a predominant flow towards the southwest during both neap and spring tides, with the maximum extent recorded during the spring tide.

Effect of Sargassum on the Behavior and Survival of the Earthworm Eisenia Fetida.

The massive influx of Sargassum natans and S. fluitans to the shores of the Mexican Caribbean has raised concerns regarding their potential impact on soil quality and health in coastal and agroecosystems. The effects of Sargassum accumulation remain largely unexplored. This study aimed to assess the impact of Sargassum on soil ecosystems by examining the behavior and survival of the epigean earthworm Eisenia fetida. The earthworm was exposed to varying concentrations of Sargassum (0, 25, 50, 75, and 100%) in two toxicological tests. Results from the avoidance test demonstrated that E. fetida exhibited strong aversion (> 80%) to a diet containing 100% Sargassum. Conversely, the acute test revealed minimal mortality, but growth decreased with increasing Sargassum concentrations. These findings can serve as early warning bioindicators for assessing the environmental risk posed by Sargassum in soil ecosystems.

Size-frequency, length-weight, and length-length relationship of two species of halfbeaks (Family: Hemiramphidae) from the north coast of the Yucatan peninsula, Mexico

Size-frequency, length-weight, and length-length relationships for Hemiramphus brasiliensis (Linnaeus, 1978) and Hyporhamphus unifasciatus (Ranzani, 1841) from the north coast of the Yucatan peninsula in the Gulf of Mexico were studied. All specimens were collected from the artisanal fishery of halfbeaks, which is under an exploratory fishery license. Five thousand two hundred-one individuals (5,134 H. brasiliensis and 67 H. unifasciatus) were sampled and analyzed. The size-frequency analysis showed that individuals of H. brasiliensis among 31.5 to 34.5 cm of total length (TL) class dominated the fishery samples; however, the separation index (≥2) detected two modes in the last months of the year, identifying a cohort with a length below the average (24.5 to 26.5 cm TL). The isometric growth pattern was found in females and pooled sex in H. unifasciatus, and positive allometric growth was found in males and H. brasiliensis. The TL was 9 and 4.5% greater than the fork length for H. brasiliensis and H. unifasciatus, respectively. The size of H. brasiliensis (45.5 cm TL) exceeds the reported in previous studies from the Gulf of Mexico and the Mexican Caribbean Sea, and a new record of maximum length for H. unifasciatus (31cm TL) was reported to the FishBase database.

Extraction and identification of plastic debris in Sargassum spp. from the beaches of Cancun and Cozumel, Mexico

The beaches of the Mexican Caribbean have been affected by the arrival of pelagic sargassum since 2011, which has caused economic losses in the area. This research consisted on the evaluation and identification of recovered plastic particles (Rpp) from pelagic sargassum collected at eleven beaches in Cancun and Cozumel. The Rpp were extracted manually before and after washing the sargassum, as well as by filtering the water used to wash it. The Rpp were classified by their size and color using optical microscopy; obtaining that these corresponded to secondary shape plastics and are mostly white in color (35.56 %). They were classified as microplastics (90 %), mesoplastics (9 %) and macroplastics (1 %). Also, Rpp were analyzed by Fourier transform infrared spectroscopy (FTIR) and compared with FTIR spectra of standard plastics, namely, polyethylene (PE), polypropylene (PP) and polystyrene (PS); It was found that the Rpp corresponded to PE (47 %) and PP (41 %). Finally, to corroborate wear or changes in the morphology of the Rpp, they were evaluated by environmental scanning electron microscopy; and wear, fractures and holes were observed on the surface of the particles; this result could be attributed to mechanical wear by ocean waves, as well as exposure to solar radiation for long periods.

Microbiomes of three coral species in the Mexican Caribbean and their shifts associated with the Stony Coral Tissue Loss Disease.

Stony Coral Tissue Loss Disease (SCTLD) has caused widespread coral mortality in the Caribbean Region. However, how the disease presence alters the microbiome community, their structure, composition, and metabolic functionality is still poorly understood. In this study, we characterized the microbial communities of the tissues of apparently healthy and diseased SCTLD colonies of the species Siderastrea siderea, Orbicella faveolata, and Montastraea cavernosa to explore putative changes related to the presence of SCTLD. Gammaproteobacteria, Alphaproteobacteria, and Bacteroidia were the best represented classes in the healthy tissues of all coral species, and alpha diversity did not show significant differences among the species. The microbial community structure between coral species was significantly different (PERMANOVA: F = 3.46, p = 0.001), and enriched genera were detected for each species: Vibrio and Photobacterium in S. siderea, Spirochaeta2 and Marivivens in O. faveolata and SAR202_clade and Nitrospira in M. cavernosa. Evidence of SCTLD in the microbial communities was more substantial in S. siderea, where differences in alpha diversity, beta diversity, and functional profiles were observed. In O. faveolata, differences were detected only in the community structure, while M. cavernosa samples showed no significant difference. Several microbial groups were found to have enriched abundances in tissue from SCTLD lesions from S. siderea and O. faveolata, but no dominant bacterial group was detected. Our results contribute to understanding microbial diversity associated with three scleractinian coral species and the shifts in their microbiomes associated with SCTLD in the Mexican Caribbean.

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.

Seasonal and interannual fluctuations in the abundance of fish recruits in a reef lagoon from the Mexican Caribbean

Seasonal and interannual fluctuations in the abundance of fish recruits in a reef lagoon from the Mexican Caribbean

Optimization of hydrochar synthesis conditions for enhanced Cd(II) and Pb(II) adsorption in mono and multimetallic systems

The characterisation of hydrochars derived from Sargassum biomass collected along the Mexican Caribbean coast reveals their favourable morphology and chemical composition for incorporating metal ions, including Cd(II) and Pb(II). Among the synthesized materials, HCS-3, produced at 180 °C with a 2 h residence time, exhibited superior yield, specific area, carbon content, and capacity for removing Cd(II) and Pb(II). Adsorption equilibrium studies demonstrate the presence of adsorption processes during Cd(II) and Pb(II) retention on HCS-3, with adsorption capacities slightly exceeding 140 and 340 mg g⁻1, respectively. Notably, HCS-3 shows a greater affinity for Pb(II) over Cd(II) when both elements are present concurrently. The physicochemical analysis through FTIR spectroscopy, functional group analysis, point of zero charge determination, SEM/EDS, and other techniques evidenced that HCS-3 possesses favourable characteristics to serve as a heavy metal adsorbent. These findings underscore the efficacy of hydrochars from Sargassum biomass in removing heavy metals, suggesting their potential as superior adsorbents compared to traditional or novel materials, and advising its possible versatility for other pollutants. Utilizing these hydrochars could mitigate the economic and environmental impact of Sargassum biomass by repurposing it for valuable applications.

Fine‐grained sediment production by endolithic sponges on Caribbean coral reefs

AbstractEndolithic sponges are key players in carbonate cycling on coral reef systems. While their bioerosion of reef framework is relatively well studied, their role in biogenic sediment generation is poorly understood. In this study, the sedimentary attributes and production rates of eight Caribbean endolithic sponge species were characterized. The findings revealed notable species‐specific variations in sediment production rates (range: 1.0–6.3 kg CaCO3 m−2 yr−1), alongside consistency in sediment characteristics (modal sizes ranging from 39 to 48 μm). The species‐specific rates were used to explore reef‐scale variations in sponge‐derived sediment generation across 50 reef sites in the Mexican Caribbean. Significant between‐site variability was observed, with estimated annual sediment production ranging from < 0.01 to 0.84 kg m−2 of reef. Production was primarily driven by sponge abundance, with discernible spatial variations in the contributions of different species, which could be related to variability in local environmental conditions. The rapidity at which these sediment producers can utilize dead coral substrates, coupled with their positive response to the changing marine environment, highlights the growing importance of these sponges in modern degraded Caribbean reef systems.

Monitoring drift and associated biodiversity of nearshore rafts of holopelagic Sargassum spp. in the Mexican Caribbean

Recent recurrent inundations of holopelagic Sargassum species (sargasso) in the tropical North Atlantic warrant studies to increase our understanding of this phenomenon. We carried out a multidisciplinary study to determine the drift and associated biota of sargasso rafts in nearshore waters of a reef system in the Mexican Caribbean, during the 2020–2022 influx seasons. Home-designed trackable drifting buoys revealed notorious influence of winds stronger than 4–5 m s−1 on the rafts´ displacement. At lower wind velocities, the drift was almost entirely determined by currents; local topography played a role in concentrating or dispersing the algae. Video cameras attached to the drifting buoys allowed for non-invasive identification of free-swimming ichthyofauna, recording low specific richness with a dominance of species of the Carangidae family. Sargasso associated biota was sampled with a dipnet. The small motile macrofauna was abundant and diverse, with a dominance of few species. Epibionts (epifauna and epiphytic algae) showed low specific diversity, while the microbial communities were dominated by (potentially pathogenic) Vibro spp. Small motile macrofauna was the only biota group with new records for the study region. Differences among sampling events were observed in the associated community; suggesting large inherent variability of the rafts´ biota. The information on wind, coastal hydrodynamics and topography on the displacement of the sargasso rafts will allow for better predictions of strandings, and information on associated non-native biota or dominant microbial species helped identify groups that should be closely monitored; thereby aiding in targeted management actions for mitigating the impacts of the inundations.

First report of Carybdea xaymacana Conant, 1897 (Cnidaria, Cubozoa, Carybdeida) in Colombia

Carybdea xaymacana Conant, 1897 is a box jellyfish belonging to the family Carybdeidae and is currently recorded from the Mexican Caribbean (State of Quintana Roo), Puerto Rico, the Bahamas, Jamaica, Panama, and Venezuela. Here, we report for the first time the presence of this species in Colombia, based on collections made in three departments of the Colombian Caribbean. Documenting the extension in the distribution range of this species is of great importance due to its ecological role in regional ecosys-tems.

A stranding of pantropical spotted dolphin (Stenella attenuata) near Tulum, Quintana Roo, Mexico confirms the presence of the species in the Mexican Caribbean

Abstract Strandings and opportunistic sightings represent an invaluable source of information on cetacean’s biodiversity in the Mexican Caribbean. Here, we document the stranding and rescue of two pantropical spotted dolphins Stenella attenuata (mother and male calf) near Tulum (Quintana Roo, Mexico), which died without a clear diagnosis of cause of death. This case confirms the occurrence of S. attenuata, increasing the number of local aquatic mammals to 20. As most of the other small cetaceans in this region, the conservation status of the species remains undefined, and more research is needed to better understand ecological and biological aspects of its population.

Steroid Hormone Profiles and Demographic Data for Green Turtles (Chelonia mydas) Inhabiting the Mexican Caribbean Coast

Steroid Hormone Profiles and Demographic Data for Green Turtles (Chelonia mydas) Inhabiting the Mexican Caribbean Coast

Mangrove ecosystems as fundamental habitats for fish from the Mexican Caribbean: An evaluation between a conserved and restoration zone

Mangrove ecosystems can function as a habitat for many juvenile marine fish species, with provisions of food and refuge. Seemingly, these ecosystems have been extensively reduced due to anthropogenic activity, as is widespread land use and road construction along the coastline. Nonetheless, much needed restoration efforts have increased tremendously over time. This study analyzes fish community, and the manner in which habitats in the mangrove ecosystem are used, comparing two mangrove zones, a conserved zone (healthier state) and one undergoing restoration. Hydrologically, no significant differences were registered (KW p>0.05). Of the 24 species registered, marine species were dominant in the conserved zone and estuarine species dominant in the restoration zone. Juvenile fishes were more abundant in the conserved mangrove zone, with a higher proportion of adults found in the restoration zone. According to Hutcheson’s t test, fish diversity showed significant statistical differences between sites combined with distinct climatic seasons. The Canonical Correspondence Analysis (CCA) indicated a relationship between secondary freshwater species Floridichthys polyommus and Cyprinodon artifrons and greater salinity and temperature, whereas marine species had a higher relationship with well oxygenated sites. A high number of marine fish species in juvenile stage in the conserved area may relate to mangroves functioning as nurseries. This can serve as a useful indicator by managers taking an integral approach to evaluate and monitor present and future mangrove restoration programs and pathways.