Mexican Caribbean Research Articles

Impact of SCUBA divers on the coral reefs of a national park in the Mexican Caribbean

ABSTRACT Coral reefs provide numerous ecosystem services and host more than 20% of marine biodiversity. However, the impact of recreational SCUBA diving on coral reefs is not often quantified in marine protected areas. We quantified the impact of divers on coral reefs in five sites within the National Park Reefs of Puerto Morelos, Mexico during high and low tourist seasons. We recorded the number and types of impacts on coral reefs done by divers during 30 minutes and the occurrence of endangered Acropora spp. The impacts most frequently recorded were "touching coral" and "creating sediment clouds" in the shallowest site, during the low season. A warning system was adopted by the Park based on the results. Making this information available for decision-making is crucial for ensuring the sustainable management of tourism, contributes to the conservation of fragile coral reef ecosystems, and ensures the sustianbility of livelihoods that rely on them.

Sensitivity Analysis of OTEC-CC-MX-1 kWe Plant Prototype

The Mexican Caribbean Sea has potential zones for Ocean Thermal Energy Conversion (OTEC) implementation. Universidad del Caribe and Instituto de Ciencias del Mar y Limnologia, with the support of the Mexican Centre of Innovation in Ocean Energy, designed and constructed a prototype OTEC plant (OTEC-CC-MX-1 kWe), which is the first initiative in Mexico for exploitation of this type of renewable energy. This paper presents a sensitivity analysis whose objective was to know, before carrying out the experimental tests, the behavior of OTEC-CC-MX-1 kWe regarding temperature differences, as well as the non-possible operating conditions, which allows us to assess possible modifications in the prototype installation. An algorithm was developed to obtain the inlet and outlet temperatures of the water and working fluid in the heat exchangers using the monthly surface and deep-water temperature data from the Hybrid Coordinate Ocean Model and Geographically Weighted Regression Temperature Model for the Mexican Caribbean Sea. With these temperatures, the following were analyzed: fluctuation of thermal efficiency, mass flows of R-152a and water and power production. By analyzing the results, we verified maximum and minimum mass flows of water and R-152a to produce 1 kWe during a typical year in the Mexican Caribbean Sea and the conditions when the production of electricity is not possible for OTEC-CC-MX-1 kWe.

Population discrimination of the French grunt, Haemulon flavolineatum (Desmarest, 1823) between the Campeche Bank and the Mexican Caribbean Sea, inferred by microsatellite loci

Genetic structure of the French grunt Haemulon flavolineatum, population was determined in four localities, two located in the Campeche Bank (Cayo Arcas and Alacranes) and two in the Mexican Caribbean (Puerto Morelos and Banco Chinchorro) using microsatellite loci. Intra- and inter-population genetic variabilities, and genetic distances were evaluated. The Monmonier’s maximum-difference algorithm was used to identify population structure and the putative genetic barriers across the oceanographic landscape. Overall expected heterozygosity (He) was lower (0.81) than the observed heterozygosity (Ho = 0.85). Inbreeding index indicated an excess of heterozygotes occur within the whole study area (FIS = -0.039); while fixation index denoted genetic significant differences between localities (FST = 0.033). Nei’s genetic distances were wider between Puerto Morelos and Alacranes (0.232), while the narrower were observed between Alacranes and Cayo Arcas (0.106). Monmonier’s algorithm revealed three putative barriers: the first one separated the Campeche Bank from the Caribbean, the second one separated Puerto Morelos from Chinchorro, and finally the third one separated Cayo Arcas from Alacranes. Regional currents allow dispersion of H. flavolineatum between distant populations of the Mesoamerican Barrier Reef and the Gulf of Mexico, but they are not enough to homogenize the populations to form a panmictic population.

The Conservational State of Coastal Ecosystems on the Mexican Caribbean Coast: Environmental Guidelines for Their Management

The accelerated rate of environmental degradation of the Mexican Caribbean coast is alarming. In this work, spatial analysis procedures were applied to study relationships among wave and wind climates, water quality, and environmental degradation of the principal coastal ecosystems. We found an increasing North-South gradient in the preservation state of the coastal ecosystems, related to the degree of anthropization of the coastline. In the north, all analysed stressors exert high pressure on coral reefs, seagrass meadows, mangroves, and dunes, and cause chronic coastline erosion. The coastal ecosystems of the central and southern regions are more mature and healthier, and the most significant stressor is reduced water quality. The north has been most hit by high-intensity hurricanes, the frequency of which has increased in the Mexican Caribbean over recent decades. The status of conservation of the ecosystems, added to the long-term intensification of environmental pressures, particularly high-intensity hurricanes, will induce further deterioration if a coordinated management scheme is not adopted by decision-makers. To ensure effective coordinated management, plans should be made on a regional scale using shared guidelines. Spatial analysis procedures aid in prioritizing and adapting the shared guidelines depending on the identified major stressors and the preservation state of each region in the Mexican Caribbean.

Quantity and quality of prey available for the whale shark (Rhincodon typus, Smith 1828) at the Mexican Caribbean aggregation site

Prey availability is the major driver of the presence of whale sharks in the aggregation sites around the world. The northern Mexican Caribbean is one of the most important feeding sites for the whale shark (Rhincodon typus, Smith 1828), at which two sources of food are available. Trophic ecology concepts considers that the organisms should satisfy their energy requirements taking not only abundant food but also of good quality. However, scarce studies have been conducted to explorer trophic preferences. Therefore, the aim was to assess the energy density of zooplankton (quality) and zooplankton biomass (quantity) and its spatial and temporal variation related to the whale shark aggregation. Marine surveys were conducted around the three historic zones of more whale sharks sighted, between June and September 2016 to measure physic-chemical parameters, collect zooplankton samples, record whale shark and calorimetric analysis from zooplankton were performed. The whale shark distribution and abundance were mostly regulated by food quantity composed mainly by fish eggs, evidencing the food quality as a lesser factor. However, analyzing food with whale shark presence, the quality food was relevant around July and September when good quality and quantity food was available. Which jointly allowed the largest aggregation of whale sharks. A relationship between these parameters should be constantly evaluated to better understand the trophic function, as also a thermodynamic approach is recommended to be included in future whale shark monitoring.

NMR Metabolic Profiling of Sargassum Species Under Different Stabilization/Extraction Processes.

The genus Sargassum is well represented by benthic and pelagic species, some of which form massive aggregates that can travel long distances due to the force of the ocean currents. Although they constitute an essential habitat for fish and invertebrate species, large accumulations of Sargassum in coastal areas generate several economic, environmental, and health impacts. It is important to recognize the species forming these aggregates, and identify the metabolites they produce, allowing for its exploitation, and therefore, better management practices. NMR metabolic profiling is a technique that can discriminate samples while detecting their unique or differential chemical features, and has been successfully used in the study and classification of several algal species. The present investigation studied the metabolic profiling of Sargassum species found on strandings at Puerto Morelos (Quintana Roo) east coast of the Mexican Caribbean. PCA of the 1 H-NMR profiles corresponding to S. natans, S. natans (morphotype VIII), S. fluitans, and a benthic Sargassum buxifolium allowed the discrimination of samples amongst them. Furthermore, discrimination between the two forms of S. natans was also possible. The PCA loading plot revealed that glutamine and glutamate have the highest influence in the clustering of the benthic Sargassum, while a high abundance of lactate, Myo-inositol, and trimethylamine is a unique feature from the S. natans morphotype VIII. Additional PLS-DA models showed that a heat-drying process improved the extraction of metabolites. Maceration and microwave-assisted extraction with water-ethanol led to similar profiles and thus any of them could be used in future investigations.

Local dynamics of a white syndrome outbreak and changes in the microbial community associated with colonies of the scleractinian brain coral Pseudodiploria strigosa.

Reef corals in the Mexican Reef System have been severely affected by the emergence of a white syndrome that resembles both White Plague II and SCTLD descriptions. Meandroid scleractinian coral species are among the most severely affected. To gain insight into this affliction we conducted a broad study in the brain coral Pseudodiploria strigosa at a rear reef site in the NE Mexican Caribbean. We describe macro and microscopical signals of the disease, characterize the outbreak dynamics, the tissue histopathology, explore immunological responses in the individuals, and compare microbial assemblages associated with the surface mucus layer of healthy and unhealthy colonies. At the study site, the white syndrome outbreak on P. strigosa showed a high incidence rate in summer-fall and a low one in winter, as well as low survival expectation of diseased colonies at the end of the study. After 306 days of observation, out of 96 tracked colonies, eight remained apparently healthy and seven were diseased. No effective resistance to colony disease progression was observed once white syndrome signs developed. Tissue loss rate during the study varied among colonies (mean = 10.8 cm2, s.d. = 7.8 cm2) suggesting a complex relation between causal agents and colony resistance. The deterioration of tissues was evidenced from the basal to the surface body wall of polyps (up to 66% hypertrophy and liquefactive necrosis in unhealthy colonies), implying that microscopic alterations begin before macroscopic signals develop, suggesting this may be a systemic disease. We measured high levels of phenoloxidase (two orders of magnitude higher PO activity than P. strigosa affected by BBD) and antibacterial activity without significant reduction in unhealthy samples from the mucus layer, indicative of an enhanced immunological response. Results showed that opportunistic bacteria dominated damaged colonies, where six genera of the Bacteroidia class were found with significant changes in unhealthy colonies after DeSeq2 analysis. Nevertheless, histological observations did not support infection of the tissues. The opportunistic overload seems to be contained within the mucus layer but may be associated with the mortality of tissues in a yet unclear way. Future research should focus on experimental infections, the tracking of natural infections, and the immunocompetence of corals in the face of environmental pressures due to local, regional, and global impacts. If environmental deterioration is the primary cause of the continuing emergence and re-emergence of lethal coral diseases, as has been proposed by many authors, the only true option to effectively help preserve the coral reef biodiversity and services, is to restore the environmental quality of reef waters at the local scale and reduce greenhouse gases at the global scale.

Stable carbon and nitrogen isotopes in Panulirus argus phyllosomas in the Mexican Caribbean

The spiny lobster Panulirus argus (Latreille, 1804) is a commercially important fishery resource in the Caribbean Sea. The complex life cycle of P. argus, particularly during its pelagic life (phyllosoma larvae) is influenced by various oceanographic factors and makes it difficult to develop basic studies about its trophic ecology. The δ13C and δ15N values of the phyllosoma larvae sampled off the SE coast of Quintana Roo, Mexico contributes to assess the migration, feeding and trophic level of the early and intermediate stages of the P. argus life cycle. The δ13C values of the phyllosomas (−18‰ to −22‰) are characteristic of pelagic food resources in oligotrophic oceanic regions, also rich in lipids (ratio C:N 5 to 6). From stage I to IV, the observed δ15N value was enriched by 2.8‰ and remain without change between stages IV and VI, this isotopic equilibrium with the diet was reached between 60 and 70 days of life. The observed enrichment of 15N in P. argus phyllosoma larvae of the Mexican Caribbean suggests a change in trophic level from the early (I–III) to the intermediate stages (IV–VI), during which P. argus larvae remain feeding at the same trophic level.

Absolute configuration by vibrational circular dichroism of anti-inflammatory macrolide briarane diterpenoids from the Gorgonian Briareum asbestinum

The four new briarane diterpenoids 2-butyryloxybriarane B-3 (2), 9-acetylbriarenolide S (3), briarenolide W (4), and 12-isobriarenolide P (5), along with briarane B-3 (1) and the five known diterpenes 6–10 were isolated from the gorgonian coral Briareum asbestinum collected from the Mexican Caribbean Sea. The structures were elucidated by 1D and 2D NMR and MS measurements. Since the structure of briarane B-3 (1) was only suggested and published without any spectroscopic support, it was herein confirmed, and the supporting data are now provided. In addition, 1 provided the opportunity to explore the sensitivity of vibrational circular dichroism (VCD) to determine the configuration of a single stereogenic center in the presence of eight other stereogenic centers in a molecule possessing a highly flexible ten-member ring. A single-crystal X-ray diffraction study, in which the Flack and Hooft parameters of 1 were determined, further confirmed that briarane B-3 is (1S,2S,6S,7R,8R,9S,10S,11R,17R)-1. This paper reports for first time the use of VCD in briarane diterpenes and with the presence of chlorine atoms. Biological evaluation of seven isolated compounds evidenced a moderate anti-inflammatory activity for compounds 6 and 9 but it did not show any cytotoxic, antiviral, antibacterial, and topoisomerase inhibitory activity.

Goliath grouper Epinephelus itajara oral history, use, and conservation status in the Mexican Caribbean and Campeche Bank

The Atlantic goliath grouperEpinephelus itajarais highly vulnerable to overfishing, yet little is known of its population status in Campeche Bank (southern Gulf of Mexico) and the Mexican Caribbean. By reviewing landings records, historical literature, and the local ecological knowledge of fishers, we documented historical practices, uses, and changes in the abundance and distribution of the goliath grouper in these regions. In both the Mexican Caribbean and Campeche Bank, goliath grouper populations were notably impacted by commercial fishing activities in the 1970s and 1980s. The catches during this period could only be sustained for a few years, after which the fishery collapsed. Our results from Campeche Bank indicate that populations persist in an area currently occupied by oil platforms. In the Mexican Caribbean, the extirpation of the goliath grouper may be close at hand, with local exceptions like that of Chetumal Bay. The results of our study indicate that the local goliath grouper populations are in critical danger of extinction, which must be taken into account during the next IUCN Red List regional assessment. In addition, the goliath grouper should be included in the Mexican list for endangered species (NOM-059-SEMARNAT).

A Sea Turtle Population Assessment for Florida's Big Bend, Northeastern Gulf of Mexico

Coastal waters of Florida’s Big Bend, Gulf of Mexico (GOM) once supported one of the largest sea turtle fisheries in the United States. To fill an information gap in this region on abundance and distribution of sea turtles, we used vessel—based distance sampling and active capture methods to characterize current foraging aggregations near the St. Martins Marsh Aquatic Preserve. Over 10 sampling periods between 2012—2018, we completed 513 km of transects and recorded 819 turtles among 4 species—green turtle (Chelonia mydas, n = 624), Kemp’s ridley (Lepidochelys kempii, n = 147), loggerhead (Caretta caretta, n = 47), and a single hawksbill (Eretmochelys imbricata). Turtle densities in 4 study plots within the 200 km2 study site ranged from 57—221 immature green turtles/km2, 16—56 immature Kemp’s ridleys/km2, and 1—14 juvenile—to—adult loggerheads/km2. Of 200 green turtles captured, 67.5% showed skin tumors consistent with fibropapillomatosis, a frequency similar to that from urbanized estuaries of Florida’s east coast. The largest green turtles (> 60 cm straight standard carapace length), abundant in the southern portion of our study area, are of note because this size class is uncommonly recorded within US territorial waters. Analyses of green turtle mtDNA haplotypes found contributions from rookeries in the western GOM, Mexican Caribbean, and Costa Rica. Although Big Bend protected areas were principally designed to conserve marine and coastal habitats, these regulatory zones have also effectively encompassed a hotspot for foraging sea turtles.

Trophic overlap of lionfish (Pterois volitans) and two native predators (Lutjanus apodus and Cephalopholis cruentata) in the western Caribbean

Abstract Impact of invasive species on native biota may be due to predation, competition for space or food, or indirect effects. Lionfish (Pterois volitans), invasive in the western Atlantic, is a voracious generalist predator, so it is expected to have a significant trophic overlap with native fishes of comparable size and habits. The goal of this study was to determine the diets of potential competitors of the lionfish, in particular a grouper, Cephalopholis cruentata (Graysby), and a snapper, Lutjanus apodus (Schoolmaster), and to compare them to the diet of lionfish in Xcalak, southern Mexican Caribbean. Stomach contents were analyzed and electivity and diet overlap were estimated. The trophic overlap between the lionfish and the two putative competitors, especially the grouper, was high, including prey that was consumed by the predators in higher proportion than the relative abundance of the prey in the environment, and probably at the same time of day. Lionfish and grouper shared as important diet items Stegastes sp., Halichoeres sp., Brachyura, and Palaemonidae, and most full stomachs were found during the early morning. The hypothesis of competition between them for particular prey is supported, so we advise to continue the culling programs of lionfish and also to monitor the abundance of the possible native competitors.

Nuevos registros de moluscos (Gastropoda, Bivalvia) de la isla de Cozumel, Quintana Roo, Méxic

Background: Marine gastropods and bivalves are some of the most diverse invertebrate groups in nature, but in Mexico a better knowledge of their taxonomic composition is required. Although there are important studies on mollusks in the Mexican Caribbean, some areas such as Isla Cozumel have been barely studied. Goals: To identify new records of Cozumel marine gastropods and bivalves. Methods: The specimens were collected mainly from transects in sandy substrates and revision of rocky surfaces. Results: Eight families and eight genera were identified, from which six species of gastropods and three of bivalves are new records, which increases the knowledge of the marine malacofauna of the region. The new records represent 11.76% and 27.27% respectively of the total fauna of gastropods and marine bivalves known on the coasts of Isla Cozumel, which is 51 and 11 species for each of the two classes of mollusks. The main biogeographic affinity of the new records is the Caribbean. Conclusions: The study area has a 87.93% of the known marine gastropods for the state of Quintana Roo. The total marine bivalve species in the study area constitute 13.92% of the fauna of this mollusk class for the state. Although the main malacogeographic affinity of the new marine mollusk records is the Caribbean, the study area belongs to a transition zone with the Carolinean province. None of the new records is endemic. All the gastropod and bivalve species indicated as new records are can be found in at least four malacological subprovinces.

Presence of Polyphenols Complex Aromatic “Lignin” in Sargassum spp. from Mexican Caribbean

In recent years, the massive influx of pelagic Sargassum spp. has generated great interest in the scientific community, highlighting the urgency of addressing the physiology and biochemical composition of these species. Until now, the presence of lignified cells in the tissue of Sargassum natans and Sargassum fluitans has not been reported. Although ‘‘lignin-like’’ compounds have been identified in green algae, the presence of true lignin in the Sargassum genus has not been confirmed. Our work is the first report of lignified cells forming the secondary cell wall in these Sargassum. This study used histological techniques applied to thick sections for identifying lignin-like tissues in Sargassum spp. The dyes as Safranin O and Toluidine have been used to differentiate lignin and cellulose in conducting tissue and to indicate the presence, absence, and distribution of these compounds in tissues. This work is the initial study of the cell wall heteropolymers structure and arrangement in Sargassum spp., providing insights into the unique cell wall architecture of these seaweeds.

A Framework to Manage Coastal Squeeze

The coastal zone is in a critical state worldwide, due to the loss and fragmentation of its ecosystems. Much of this is caused by long-term anthropic local, regional, or global actions, which drive coastal squeeze processes. Most of the criteria to evaluate the effects of coastal squeeze are focused on merely identifying its effect on the coastal zone. Here, we propose a framework to manage (identify, analyze, quantify, and tackle) the effect of coastal squeeze. This DESCR framework examines the relations between Drivers, Exchanges, and States of the environment to subsequently evaluate the chronic, negative Consequences and determine possible Responses. To illustrate the application of the DESCR framework, the coastal zone of Puerto Morelos, in the Mexican Caribbean, was studied using this approach. We analyzed the systemic interactions among the coastal ecosystems in this area, such as coral reefs, seagrass beds, beach, coastal dunes, and mangroves, which have been altered over the last decades, resulting in a severe coastal squeeze. Recommended responses include urgent measures for ecosystem management to mitigate the coastal squeeze.

A Prospective Study of the Exploitation of Pelagic Sargassum spp. as a Solid Biofuel Energy Source

This study presents a prospective study for the potential exploitation of pelagic Sargassum spp. as a solid biofuel energy source. It was carried out in three stages. First we conducted a morphological, physical-chemical, and structural characterization using scanning electron microscopy (SEM), infrared spectroscopy (FTIR), and X-ray diffraction (DRX), respectively. Second we evaluated the material’s functional properties as a solid biofuel based on its calorific value and the quantification of polymeric components like hemicellulose, cellulose, and lignin, as well as thermogravimetric and differential analysis to study the kinetics of its pyrolysis and determine parameters like activation energy (Ea), reaction order (n), and the pre-exponential factor (Z). Third we analyzed the energetic potential considering the estimated volume of pelagic Sargassum spp. that was removed from beaches along the Mexican Caribbean coast in recent years. Results of the kinetic study indicate that Sargassum spp. has an enormous potential for use as a complement to other bioenergy sources. Other results show the high potential for exploiting these algae as an energy source due to the huge volumes that have inundated Caribbean, West African, and northern Brazil shorelines in recent years. As a solid biofuel, Sargassum spp. has a potential energy the order of 0.203 gigajoules (GJ)/m3. In the energy matrix of the residential sector in Mexico, its potential use as an energy source is comparable to the national consumption of firewood. The volume of beachcast Sargassum spp. that was removed from ~8 km of coastline around Puerto Morelos, Mexico in 2018–2019, could have generated over 40 terajoules/year of solid biofuel.

Incidence of 49 elements in the blood and scute tissues of nesting hawksbill turtles (Eretmochelys imbricata) in Holbox Island

Due to progressive urban development along the Mexican Caribbean coastline, it is crucial to gauge the impact of anthropogenic contamination of marine ecosystems through biomonitoring procedures. In the current study, we quantified the concentration of 49 inorganic elements in the blood and scute tissues of clinically healthy nesting hawksbill sea turtles (Eretmochelys imbricata). The elements were classified into four groups: Group A: essential mineral elements with toxic potential; Group B: non-essential elements with high toxicity; Group C: toxic non-essential minority elements and Trace Elements (TE); and Group D: rare-earth elements (REE) and other TE. Almost all the samples in both tissues showed perceptible levels of all the quantified elements. The only element identified with a correlation between blood and scute was arsenic (As), which could indicate a fast excretion through this type of keratinized tissue. The bio-accumulation of inorganic elements is a complex process, requiring the simultaneous examination of different tissues to evaluate the exposure. Our study reinforces the usefulness of scute tissue as a non-invasive sampling technique for the evaluation of persistent pollutants in marine turtles.

Functional developmental states of the Greater Caribbean coral reefs

Trophic networks are the way by which energy is distributed through the ecosystem and out of it. Each ecosystem at a particular functional developmental state (FDS) has attributes that can be measured and understood through the food web. Trophic interactions can further our understanding of the FDS of coral reefs that can be associated with their geomorphological structure; however, the number of the states is presently unknown. Thus, we investigated the geomorphology of a set of the Greater Caribbean coral reefs, describing gradients of coral reef FDS. Eleven coral reefs in the Gulf of Mexico and 17 reefs in the Caribbean Sea were examined, including fringing reefs and platform reefs (submerged and emergent with and without sandy-island cay). For each coral reef, nine ecosystem developmental attributes and five topological indices were estimated from trophic models. Using non-metric multidimensional scaling and analysis of similarities, we found a gradient of maturity consisting of eight FDS. Early states correspond to fringing reefs (Punta Nizuc, Mahahual) in the Mexican Caribbean, and later states correspond to emerging platform reefs without (Palo Seco, Blanquilla) and with sandy-island cay (Cayo Cochinos, Media Luna). Using topological indices as variables and the eight FDS as nominal variables in a partial redundancy analysis, we confirmed that energy flow control increases with maturity and degree of geomorphological and physical structural complexity. On the contrary, betweenness centrality, the number of connections, and the number of predator–prey interactions decrease with functional maturity.

Updated Distribution Range of Toadfishes (Sanopus Smith 1952, Batrachoididae) in the Southern Gulf of Mexico and Mexican Caribbean

Worldwide, toadfishes (Batrachoididae) comprise 83 species belonging to 23 genera. In the western Atlantic, there are seven genera and 23 species, and the genus Sanopus Smith 1952 has six species with limited geographic distribution range in the Gulf of Mexico (GOM) and Caribbean Sea (CS). This work compiled and reviewed information from scientific literature and database revisions on distribution range of Sanopus species, with emphasis in the southern GOM and Mexican CS. Sanopus astrifer, S. reticulatus, and S. splendidus showed updated records from their type locality, while S. barbatus, S. greenfieldorum, and S. johnsoni had no change in distribution. We recommend improving sampling effort for recording Sanopus based on direct underwater visual census and sample collections to expand opportunities to update species distribution range, increase biological data, and provide information to assess conservation status of these species in the region.

An updated checklist of ctenophores (Ctenophora: Nuda and Tentaculata) of Mexican seas

Ctenophores are one of the most conspicuous and frequent groups of the gelatinous zooplankton community, but their regional diversity in tropical and subtropical latitudes remains largely unknown. We provide an overview and update of the current knowledge of the diversity in Mexican seas, including ocean and coastal-neritic environments of the Gulf of Mexico, the Mexican Caribbean Sea, and the Mexican Pacific Ocean. Ctenophore records were reviewed based on the available scientific and gray literature, the Naturalista network (www.naturalista.mx), and the ctenophore species collected in the Gulf of California by the Monterey Bay Aquarium Research Institute. A total of 33 taxa (Class Nuda and Tentaculata) were found to occur in Mexican seas, of which 12 of the 33 taxa (36.4 % of the total) were recorded in the Gulf of Mexico, 7 (21.2 %) in the Mexican Caribbean Sea, 25 (75.8 %) in the Gulf of California, 11 (33.3 %) in the Eastern Tropical Pacific, and only 1 (3.0 %) are known in the Northeastern Pacific. Up to nine taxa included in our account represent first records for Mexico (i.e., Bathocyroe fosteri, Kiyohimea usagi, Lampocteis cruentiventer, Leucothea sp., Aulacoctena sp., Haeckelia beehleri, Charistephane fugiens, Bathyctena chuni, and Hormiphora californensis). Due to the lack of data on benthic ctenophores and the sparse studies on oceanic and deep-living species, it is expected that the list will grow as new surveys are performed in the deep sea. The lack of long-term studies on Mexican ctenophores have limited our capacity to draw valid conclusions on their abundance, total diversity, endemicity, and trophic ecology in Mexico.