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Abstract Hemichordata has always played a central role in evolutionary studies of Chordata due to their close phylogenetic affinity and shared morphological characteristics. Hemichordates had no meiofaunal representatives until the surprising discovery of a microscopic, paedomorphic enteropneust Meioglossus psammophilus (Harrimaniidae, Hemichordata) from the Caribbean in 2012. No additional species have been described since, questioning the broader distribution and significance of this genus. However, being less than a millimeter long and superficially resembling an early juvenile acorn worm, Meioglossus may easily be overlooked in both macrofauna and meiofauna surveys. We here present the discovery of 11 additional populations of Meioglossus from shallow subtropical and tropical coralline sands of the Caribbean Sea, Red Sea, Indian Ocean, and East China Sea. These geographically separated populations show identical morphology but differ genetically. Our phylogenetic reconstructions include four gene markers and support the monophyly of Meioglossus. Species delineation analyses revealed eight new cryptic species, which we herein describe using DNA taxonomy. This study reveals a broad circumtropical distribution, supporting the validity and ecological importance of this enigmatic meiobenthic genus. The high cryptic diversity and apparent morphological stasis of Meioglossus may exemplify a potentially common evolutionary ‘dead-end’ scenario, where groups with highly miniaturized and simplified body plan lose their ability to diversify morphologically.

Globally, coral reef ecosystems are undergoing significant change related to climate change and anthropogenic activities. Yet, the Cuban archipelago of Jardines de la Reina (JR) has experienced fewer stressors due to its geographical remoteness and high level of conservation. This study examines the surface and benthic reef water microbial communities associated with 32 reef sites along the JR archipelago and explores the relationship between the community composition of reef microorganisms examined using bacterial and archaeal small subunit ribosomal RNA gene (16S rRNA gene) sequencing compared to geographic, conservation/protection level, environmental, physicochemical, and reef benthic and pelagic community features. Reef nutrient concentrations were low and microbial communities dominated by picocyanobacteria and SAR11 and SAR86 clade bacteria, characteristic of an oligotrophic system. Reef water microbial community alpha and beta diversity both varied throughout the archipelago and were strongly related to geography. Three sites in the western archipelago showed unique microbial communities, which may be related to the hydrogeography and influences of the channels linking the Ana Maria gulf with the Caribbean Sea. Overall, this work provides the first extensive description of the reef microbial ecology of the Caribbean’s ‘Crown Jewel’ reef system and a framework to evaluate the influence of ongoing stressors on the reef microorganisms.

Mollusk death assemblages are formed by shell remnants deposited in the surficial mixed layer of the seabed. Diversity patterns in tropical marine habitats still are understudied; therefore, we aimed to investigate the taxonomic, phylogenetic, and functional diversity of mollusk death assemblages at regional and local scales in coral reef sands and seagrass meadows. We collected sediment samples at 11 sites within two shallow gulfs in the Northwestern Caribbean Sea and Southeastern Gulf of Mexico. All the shells were counted and identified to species level and classified into biological traits. We identified 7113 individuals belonging to 393 species (290 gastropods, 94 bivalves, and nine scaphopods). Diversity and assemblage structure showed many similarities between gulfs given their geological and biogeographical commonalities. Reef sands had higher richness than seagrasses likely because of a more favorable balance productivity-disturbance. Reef sands were dominated by epifaunal herbivores likely feeding on microphytobenthos and bysally attached bivalves adapted to intense hydrodynamic regime. In seagrass meadows, suspension feeders dominated in exposed sites and chemosynthetic infaunal bivalves dominated where oxygen replenishment was limited. Time averaging of death assemblages was likely in the order of 100 years, with stronger effects in reef sands compared to seagrass meadows. Our research provides evidence of the high taxonomic, phylogenetic, and functional diversity of mollusk death assemblages in tropical coastal sediments as result of the influence of scale-related processes and habitat type. Our study highlights the convenience of including phylogenetic and functional traits, as well as dead shells, for a more complete assessment of mollusk biodiversity.

The recent rise in ocean temperatures, accompanied by other environmental changes, has notably increased the occurrence and spread of diseases in Octocorallia, many species of which are integral to shallow tropical and subtropical coral reef ecosystems. This study focuses on the understanding of these diseases, which has been largely limited to symptomatic descriptions, with clear etiological factors identified in only a fraction of cases. A key example is the multifocal purple spots syndrome (MFPS) affecting the common Caribbean octocoral sea fan Gorgonia ventalina, linked to the gall-forming copepods of the genus Sphaerippe, a member of the widespread family, Lamippidae. The specialized nature of these copepods as endoparasites in octocorals suggests the potential for the discovery of similar diseases across this host spectrum. Our investigation employed four molecular markers to study disease hotspots in Saint Eustatius, Curaçao, northwest and southwest Cuba, and Bonaire. This led to the discovery of a group of copepod species in these varied Caribbean locations. Importantly, these species are morphologically indistinguishable through traditional methods, challenging established taxonomic approaches. The observed diversity of symbionts, despite the host species’ genetic uniformity, is likely due to variations in larval dispersal mechanisms. Our phylogenetic analyses confirmed that the Lamippidae copepods belong to the order, Poecilostomatoida (Copepoda), and revealed their sister group relationship with the Anchimolgidae, Rhynchomolgidae, and Xarifiidae clades, known for their symbiotic relationships with scleractinian corals. These results add to our understanding of the evolutionary and ecological interactions of copepods and their hosts, and the diseases that they cause, and are important data in a changing climate.

Cryptofaunal nematodes, those living on the hard substrate of the coral reefs, are largely unknown in terms of diversity and assemblage structure. We described nematode assemblages at seven sites spanning about 200 km along Jardines de La Reina, a well-preserved reef system in the Greater Antilles. We identified about 3000 nematodes, mostly of the families Desmodoridae and Chromadoridae; the most abundant species were Croconema cinctum, Desmodora communis, and Euchromadora vulgaris. The regional richness was moderate with 70 observed species (0.95 confidence interval: 65–75 species) and 75 extrapolated species (0.95 CI: 68–83 species). This richness was lower than in other reef biotopes, maybe reflecting evolutionary constraints due to interactions with stony corals. The local expected richness at 100 individuals was similar among sites, with a median of 26 species (0.95 CI: 20–34 species), and likely caused by diversification rate and evolutionary time acting at the same pace on populations. The taxonomic β-diversity was high and without differences among sites (median: 0.85; 0.95 CI: 0.33–1), probably due to significant substrate heterogeneity at 10-cm scale. The prevalence of replacement over richness difference suggests that local processes (e.g., environmental filtering and competition) contribute more to β-diversity than niche availability, which would be largely similar across the reef terraces. Contrary to our expectations, no gradient of assemblage structure occurred, nor significant effect of benthic cover on nematodes. However, nematode functional structure showed a conservative set of biological traits reflecting adaptations to hydrodynamic regime: armed oral cavity/intermediate colonizing capability/ornamented cuticles/conical tail. Our results provide insights about the taxonomic and functional diversity of nematodes and highlight the vast knowledge gaps about the processes ruling the meiofauna community structure in coral reefs.

Se describen los patrones de distribución de la macro- y meiofauna en un arrecife de coral (Punta Francés, Archipiélago Cubano, Mar Caribe). La densidad y la composición por taxa para la macrofauna y meiofauna y la diversidad de especies y de caracteres biológicos para nemátodos se compararon entre cuatro hábitats: pastos marinos, arenazo, coral muerto y fondo duro. Se detectaron consistentes patrones espaciales de distribución los cuales fueron explicados por una combinación compleja de características del hábitat. La relación señal/ruido en los datos dedistribución de la macrofauna fue lo suficientemente fuerte para detectar cambios entre hábitats pero el tamaño de los dispositivos demuestreo no fue adecuado para representar los patrones reales en el medio natural. Los patrones de distribución de la meiofauna fueron afectados por el tipo de sustrato (sedimento versus fondo duro) el cual a su vez seguramente depende del régimen hidrodinámico. Los nemátodos dominaron en los pastos marinos y los copépodos en los otros tres hábitats. La densidad de especies e individuos y la riqueza de especie de nemátodos fueron más altas en los hábitats sedimentarios debidos probablemente a mayor estabilidad física, mayor nicho espacial y más disponibilidad de alimento. La variación en la diversidad fue alta y similar entre pares de hábitats con la excepción de los hábitats en fondo duro que tuvieron menor diferenciación. La mayoría de los nemátodos que habitan sobre sustratos duros mostraron rasgos morfológicos que les permiten adaptarse al régimen hidrodinámico y a la disponibilidad de alimento (biofilm/algas), esto es cuerpo pequeño y robusto, dientes para raspar, cutícula ornamentada y capsula cefálica. Fue evidente un control físico sobre las comunidades de nemátodos pero las interacciones bióticas pueden jugar un papel más importante en pastos marinos y arenazos comparado a los hábitats de sustrato duro. La diversidad de especies de nemátodos, en términos de α- y β-diversidad fue alta a la escala del arrecife coralino en Punta Francés.

Se estudió la biomasa de macroalgas en la bahía de Cienfuegos con el objetivo de determinar su variación espacio-temporal. Los valores medios de biomasa oscilaron entre 7.5 (Playa Alegre en febrero-01) y 1055 gm -2 (Junco Sur en octubre 00). El grupo de las formas carnosas fue el dominante en todas las estaciones de colecta, representado principalmente por las especies Hypnea spinella (C. Agardh) Kützing, Acanthophora spicifera (M. Vahl) Børgesen, Gracilaria blodgettii Harvey, y Chondrophycus papillosus (C. Agardh) Garbary & Harper. El lóbulo norte, caracterizado por mayor impacto de la urbanización e industrialización, presentó menor diversidad de macroalgas en comparación con la estación del lóbulo sur. Hypnea spinella y Gracilaria spp, especies tolerantes a amplios rangos de condiciones ecológicas fueron dominantes en las estaciones del lóbulo norte. En la estación ubicada en el lóbulo sur se registró la mayor diversidad. Esta estación evidencia mejores condiciones oceánicas, lo cual está sustentado por la abundancia de Chondrophycus papillosus (C. Agardh) Garbary & Harper, característica de aguas más limpias. Se observó una notable variación temporal en los valores de biomasa en todas las estaciones. En las estaciones del lóbulo norte se registró el mayor valor de biomasa en el período lluvioso, lo cual puede ser debido a una mayor entrada de nutrientes durante ese período. En la estación del lóbulo sur se registró el mayor valor de biomasa en el período de seca, registrándose un sobrecrecimiento de un alga verde filamentosa que al parecer fue estimulado por una mayor transparencia y disposición de luz en el agua en esta época del año.

Se describen los patrones espaciales de diversidad de nemátodos marinos de vida libre en relación con la profundidad; se muestreó en cuatro horizontes de profundidad (intermareal, 1 m, 5 m y 10 m) y dos sitios someros tropicales de la costa NW de Cuba: Bacunayagua y Miramar. Los patrones se describieron en base a la identidad de las especies y los rasgos biológicos. La riqueza de especies fue similar entre los horizontes de profundidad, con un rango de 12 a 18 especies; la riqueza fue también similar entre sitios con 30 y 33 especies en Bacunayagua y Miramar respectivamente. La variación en la diversidad fue más alta entre los horizontes intermareal y los submareales lo que sugiere que el micro-hábitat tiene un papel importante. La profundidad no tiene un efecto importante sobre la diversidad de nemátodos en las costas estudiadas tanto en términos de riqueza de especies como de variación en la diversidad. El tipo de micro-hábitat y la hidrodinámica pueden explicar los patrones de β-diversidad dentro de los sitios. La variación de la diversidad entre sitios fue mayor que la variación relacionada con la profundidad sugiriendo que un patrón regional en la β-diversidad puede estar presente. Los rasgos biológicos constituyeron un enfoque complementario útil para analizar los patrones de diversidad e indicaron la prevalencia de nemátodos adaptados a un estilo de vida epífito y los efectos de dos potenciales determinantes de la diversidad: el micro-hábitat y la hidrodinámica.

Las comunidades de la infauna (macro- and meiobentos) y varios factores abióticos fueron muestreados en cuatro estaciones en la Bahía de La Habana, Cuba, en junio del 2006. Una comparación de concentración de contaminantes con valores de referencia indicó que la bahía está fuertemente contaminada. Varios tipos de contaminantes (hidrocarburos del petróleo, metales pesados y pesticidas organoclorados) fueron detectados en los sedimentos y se registró eutrofización en el agua. Existieron diferencias en la naturaleza de la contaminación entre las ensenadas: las más contaminadas fueron Marimelena, fundamentalmente por metales de origen industrial (Cr, Co, Mn, Ni, V) y Atarés, principalmente por metales de origen urbano (Pb y Zn) y enriquecimiento orgánico. Las comunidades de la infauna estuvieron fuertemente impactadas en el número de taxa y la densidad; y una defaunación casi total ocurrió en la ensenada más impactada. Solo especies de nemátodos marinos de vida libre tolerantes a la contaminación (Sabatieria pulchra, Terschellingia longicaudata, and Parodontophora xenotricha) estuvieron presentes en muy bajas densidades en los sedimentos. La explicación más plausible de estos resultados es los efectos de la contaminación sobre la infauna. El régimen hidrodinámico aparentemente modula los efectos de la contaminación sobre las comunidades de nemátodos en el canal de entrada de la bahía por aumentar la cantidad de micro-hábitat disponible y/o facilitar los procesos de colonización.

El Archipiélago Cubano contiene una gran fracción de la diversidad regional pero no existen estudios recientes sobre el mesozooplancton. Nuestro objetivo fue caracterizar la fracción de tamaño grande (> 500 μm) del mesozooplancton a través de cuatro hábitats costeros (manglar, pasto marino, fondo sin vegetación y arrecife de coral) en tres cuencas (o golfos: Ana María, Batabanó y Guanahacabibes). Además, probar la hipótesis de que el golfo y el tipo de hábitat tienen un efecto significativo sobre la estructura del mesozooplancton en relación con la dispersión y la selección respectivamente. El muestreo incluyó 71 arrastres de plancton en 28 sitios con una red cónica de 500 μm de apertura de malla. En total, se identificaron 41049 organismos de 30 grupos taxonómicos y 3551 quetognatos de ocho especies. La estructura de la comunidad del mesozooplancton fue típica de regiones tropicales con diversidad alta, abundancia baja y dominancia de Copepoda y Chaetognatha. Larvas y huevos contribuyeron en gran proporción a la abundancia sugiriendo la importancia del mesozooplancton costero para los ciclos de vida de muchas especies y reafirmando la función de los arrecifes de coral como áreas de desove. La mayoría de los taxa del mesozooplancton tuvieron amplia distribución a través de los golfos y los hábitats probablemente asociado a un régimen oceanográfico complejo. El factor golfo tuvo efectos significativos sobre la estructura del mesozooplancton comparado con el tipo de hábitat, indicando la importante función de las barreras a la dispersión entre golfos y una selección débil por parte del tipo de hábitat costero. Se registraron ocho especies de quetognatos, con Parasagitta megalophthalma y Sagitta helenae siendo nuevos registros para el Archipiélago cubano. La relación débil entre los quetognatos y el tipo de hábitat probablemente reflejó la tolerancia ecológica amplia de las especies costeras.

La bahía de la Habana es uno de los sistemas estuarinos más contaminados del mundo debido a la influencia negativa de desechos urbanos e industriales originados en la ciudad de la Habana. El impacto sostenido de la contaminación durante décadas prácticamente ha defaunado el sistema bentónico lo que dificulta el monitoreo de la calidad ambiental. En este trabajo se comparan las comunidades de nemátodos de vida libre entre los años 2006 y 2016 para evaluar los cambios en los sedimentos y estimar si la calidad ambiental ha mejorado en el lapso de 10 años. Los nemátodos fueron colectados en cuatro sitios en la Bahía en 2006 y 2016 e identificados hasta nivel de especie empleando la misma metodología. La bahía de La Habana ha mejorado algunas variables ambientales en 2016 comparado con 2006. Sin embargo, persisten efectos negativos y sinérgicos sobre la nematofauna como hipoxia y toxicidad por metales pesados e hidrocarburos del petróleo. Los nemátodos tuvieron comunidades empobrecidas y dominadas por dos especies cosmopolitas, detritívoras y tolerantes: Terschellingia longicaudata y Sabatieria pulchra. La síntesis de la información ambiental indica que la calidad ambiental de la bahía de la Habana continúa siendo precaria y que existe la necesidad de reformular el programa de mitigación dado que la reducción de la contaminación no ha mejorado significativamente a las comunidades bentónicas.

The coral reef system Jardines de la Reina ( JR) includes one of the most remarkable Marine Protected Areas in the Caribbean due to its extension and high level of conservation. However, the diversity of small invertebrates (organisms with body size less than 0.5 mm) in JR is unknown. For this reason, we propose to make the first taxonomic checklist of free-living marine nematodes associated with coralline bottoms in JR. During the Alucia expedition in 2017, we studied six sites in the reef terrace (5m–10 m depth), distributed in the west, center and east of the JR archipelago. We identified 1 546 nematodes belonging to 70 species, 20 families, and six orders. The best represented orders were Chromadorida (20 genera), Desmodorida (18 genera) and Enoplida (13 genera). The most abundant species were Croconema cinctum, Euchromadora vulgaris, Desmodora communis, Chroma- dora brevipapillata, and Dichromadora amphidiscoides. Ten species were new records for Cuba Chromadorina epidemos, Desmoscolex campbelli, Draconema ophicephalum, Meta- desmodora amphidiscata, Oncholaimus sp., Paracyatholaimus intermedius, Perepsilonema ritae, Praeacanthonchus sp, Prochromadorella mediterranea and Zalonema vicentei. Received: 21-04-2022 Accepted: 09.08.2022 Editor: Yander L. Diez

Diversity of free-living marine nematode assemblages in the Southwestern Gulf of Mexico (SW GoM) is scarcely studied. Here, we aimed (1) to analyze the influence of a water depth gradient on the species richness, feeding type and taxonomic composition of assemblages; and (2) to document the regional diversity of free-living nematodes in the SW GoM. We sampled 63 sites along a water depth gradient from 186 to 3774 m during four oceanographic cruises. We found clear variations along the depth gradient of bottom water (temperature, salinity, and dissolved oxygen) and sediment variables (grain size and organic content). We identified 1881 nematodes belonging to 108 genera, 33 families, ten orders, and two classes. The abundance and species richness decreased with water depth. However, the expected number of species for a same level of abundance did not change along the depth gradient likely because the scarcity of food was compensated by reduced environmental stress (e.g., higher oxygen content and physical stability). Microbial sucker was the most abundant feeding type indicating the important role of sediment bacteria in the nematode’s diet. Species composition varied along the depth gradient with dominance in the upper slope sites of species of Comesomatidae tolerant to reduced sediments (e.g., Dorylaimopsis sp., Sabatieria spp., and Setosabatieria hilarula). Many congeneric species typical of deep sea were restricted to the deepest sites such as Acantholaimus spp., Ledovitia spp., Desmoscolex spp., and Halalaimus spp. The nematode regional diversity of SW GoM was 154 species, but the Chao 1 estimator indicated a richness of about 194 species and a highest limit of 246 species. The accumulation curves of richness were non-asymptotic suggesting a substantial fraction of undiscovered richness. Our study increased the free-living nematode fauna of GoM in 144 species (76%) respect to Hope’s list (2009). The large diversity of nematodes stands out the necessity of further studies to unravel the environmental drivers of α- and β-diversities and highlights the potential of this taxon for monitoring the deep sea of the Gulf of Mexico.

Understanding the impact of marine protected areas on the distribution and composition of fishes is key to the protection and management of coral reef ecosystems, and especially for fish-based activities such as SCUBA diving and recreational fishing. The aim of this research is to compare the ichthyofauna structure in three areas in the eastern part of Los Canarreos archipelago in Cuba with different management schemes: Cayo Campos-Cayo Rosario Fauna Refuge (CCCR), Cayo Largo Ecological Reserve (CL) and non-protected area (nMPA), and considering habitat differences and depth variation. A total of 131 video transects were conducted using diver operated stereo-video (stereo-DOV) in November, 2015 in backreef and forereef along the CCCR, CL and the adjacent nMPA. We recorded 84 species and 27 functional groups suggesting high complementarity of functions. Several multispecies schools were observed along surveys, which explain the biomass peaks in some sites, mainly for Lutjanidae, Haemulidae and Carangidae. A concerning issue was the bare representation of critical functional groups and threatened species. The effect of sites nested within habitats was significant and the most important driver structuring fish assemblages, while MPA condition was not evident. Favorable habitat features (habitat heterogeneity and surrounding coastal ecosystems) are likely enhancing fish assemblages and counteracting the effects of pouching derived from insufficient management. We recommend immediate actions within a strategy of precautionary management including, but not limited to, the appointment of staff for the administration of CL, frequent monitoring and effective enforcement.

Diversity patterns of free-living marine nematodes in tropical seagrass beds are understudied. Here, we describe the species richness and assemblage composition of nematodes in 13 seagrass sites covering the whole Cuban archipelago. Nematodes were collected from Thalassia testudinum seagrass beds and identified to species level. We provide a checklist of nematode species from seagrass beds. The species richness of nematode assemblages is high, with 215 species, 138 genus, 35 families, seven orders and two classes. That γ-diversity is higher than other studies and points to seagrass beds as diversity hotspots of free-living marine nematodes. Local species richness in seagrass bed sites is about 57 ± 17 species and broadly similar across the sites, despite the environmental heterogeneity. The geographical distance plays a weak, but significant, role on the decay of similarity likely affected by limited dispersal of nematodes. The pairwise similarity values, related to poor-coloniser nematodes, were twice more affected by the distance than those related to good-colonisers, possibly due to differential success of transport and settlement.

Shorelines are being eroded at an accelerated rate in certain sectors of the Cuban Archipelago due to natural and anthropogenic processes. Cayo Jutías, in the northwestern coast of Cuba, has undergone transformation in the last decades including a shoreline retreat of around 10 m y-1 and subsequent flooding of the coastal infrastructure. The causes of this accelerated modification are unclear but two drivers seem to be important: the modification of the natural dynamics because of the construction of a land bridge, and a high exposure to meteorological events. Therefore, we aimed to describe the recent coastal evolution of Cayo Jutías based on the coupling of aerial and satellite imagery and sediment records from cores. We used two aerial photographs and three satellite images derived from Google Earth to verify the changes that have occurred in the study area in the period 1970-2017. Three cores were collected in November 2016 to analyze the sedimentary records of texture and composition. Hurricane and storms are the main natural processes affecting the coastal evolution of shoreline in Cayo Jutías, likely in conjunction with sea level rise. Human intervention, mainly the building of the land bridge, likely exacerbated the shoreline changes. The island behaved as a drift sector, with erosion on the northeast end, sediment transport westwards along shoreline, and accumulation on the southwestern end. Received: 07-01-2021 Accepted: 23-09-2021 First published: 10-01-2022 Editor: Julia Azanza

Abstract High‐throughput sequencing has the potential to describe biological communities with high efficiency yet comprehensive assessment of diversity with species‐level resolution remains one of the most challenging aspects of metabarcoding studies. We investigated the utility of curated ribosomal and mitochondrial nematode reference sequence databases for determining phylum‐specific species‐level clustering thresholds. We compiled 438 ribosomal and 290 mitochondrial sequences which identified 99% and 94% as the species delineation clustering threshold, respectively. These thresholds were evaluated in HTS data from mock communities containing 39 nematode species as well as environmental samples from Vietnam. We compared the taxonomic description of the mocks generated by two read‐merging and two clustering algorithms and the cluster‐free Dada2 pipeline. Taxonomic assignment with the RDP classifier was assessed under different training sets. Our results showed that 36/39 mock nematode species were identified across the molecular markers (18S: 32, JB2: 19, JB3: 21) in UClust_ref OTUs at their respective clustering thresholds, outperforming UParse_denovo and the commonly used 97% similarity. Dada2 generated the most realistic number of ASVs (18S: 83, JB2: 75, JB3: 82), collectively identifying 30/39 mock species. The ribosomal marker outperformed the mitochondrial markers in terms of species and genus‐level detections for both OTUs and ASVs. The number of taxonomic assignments of OTUs/ASVs was highest when the smallest reference database containing only nematode sequences was used and when sequences were truncated to the respective amplicon length. Overall, OTUs generated more species‐level detections, which were, however, associated with higher error rates compared to ASVs. Genus‐level assignments using ASVs exhibited higher accuracy and lower error rates compared to species‐level assignments, suggesting that this is the most reliable pipeline for rapid assessment of alpha diversity from environmental samples.

Coral reef ecosystems are incredibly diverse marine biomes that rely on nutrient cycling by microorganisms to sustain high productivity in generally oligotrophic regions of the ocean. Understanding the composition of extracellular reef metabolites in seawater, the small organic molecules that serve as the currency for microorganisms, may provide insight into benthic-pelagic coupling as well as the complexity of nutrient cycling in coral reef ecosystems. Jardines de la Reina (JR), Cuba is an ideal environment to examine extracellular metabolites across protected and high-quality reefs. Here, we used liquid chromatography mass spectrometry (LC-MS) to quantify specific known metabolites of interest (targeted metabolomics approach) and to survey trends in metabolite feature composition (untargeted metabolomics approach) from surface and reef depth (6 – 14 m) seawater overlying nine forereef sites in JR. We found that untargeted metabolite feature composition was surprisingly similar between reef depth and surface seawater, corresponding with other biogeochemical and physicochemical measurements and suggesting that environmental conditions were largely homogenous across forereefs within JR. Additionally, we quantified 32 of 53 detected metabolites using the targeted approach, including amino acids, nucleosides, vitamins, and other metabolic intermediates. Two of the quantified metabolites, riboflavin and xanthosine, displayed interesting trends by depth. Riboflavin concentrations were higher in reef depth compared to surface seawater, suggesting that riboflavin may be produced by reef organisms at depth and degraded in the surface through photochemical oxidation. Xanthosine concentrations were significantly higher in surface reef seawater. 5′-methylthioadenosine (MTA) concentrations increased significantly within the central region of the archipelago, displaying biogeographic patterns that warrant further investigation. Here we lay the groundwork for future investigations of variations in metabolite composition across reefs, sources and sinks of reef metabolites, and changes in metabolites over environmental, temporal, and reef health gradients.

Coral reefs are complex and biodiverse ecosystems that are undergoing significant change. Understanding reef composition and biodiversity at multiple spatial scales is necessary to track both large-scale and more subtle ecosystem changes. The Jardines de la Reina (JR) archipelago, located offshore of the island of Cuba, contains the largest marine protected area (MPA) in the Caribbean Sea but lacks multi-scale studies. In this contribution, we documented the diversity of scleractinian corals, octocorals, algae, and sponges across nested spatial scales spanning four orders of magnitude (101–105 m). In addition, we tested the hypothesis that species diversity followed a gradient along the ca. 200 km of reef tract. Across the archipelago, we examined benthic cover and species diversity within 255 photo-quadrats (25 × 25 cm) at 13 fore reef sites (two sampling locations per site, and 10 photo-quadrats per location). Small-scale (101 m) variability between photo-quadrats characterized the coral reef community structure in JR compared with local- (102 m) and mesoscale (104–105 m) variability. This finding suggests that biological processes (e.g., recruitment, competition) had primacy over hydrodynamics for driving the differences in reef community composition. However, the dominance of algae and low cover and diversity of scleractinian corals suggests the pervasive effects of global change on coral communities despite potential benefits provided by the MPA (e.g., oligotrophy and abundance of herbivores). There was no gradient of benthic community structure along the fore reef tract of JR; instead, a patchy distribution occurred in response to more subtle drivers acting at local scales. Overall, our multi-scale comparison was useful for differentiating the impacts of processes potentially impacting the JR reefs, thus providing important information to understand how reef communities are impacted by different environmental and anthropogenic stressors, and the potential benefits of MPAs.

La diversidad de especies de fitoplancton se ha utilizado en la evaluación de disturbios ambientales en hábitats marinos por su relación con los florecimientos algales nocivos (FANs). En agosto del 2017, la expedición científica a bordo del Race for Water brindó la oportunidad de muestrear el fitoplancton frente a la costa de la Ciudad de La Habana, teniendo como objetivos: (i) describir la diversidad y composición del fitoplancton comparando aguas costeras y oceánicas, y (ii) explorar la ocurrencia de especies potencialmente dañinas. Se seleccionaron doce sitios de muestreo entre la Bahía deLa Habana y la desembocadura del Río Almendares, donde se tomaron muestras superficiales de agua con una red de plancton de 20 μm de apertura de malla. Se identificaron 71 especies de fitoplancton, pertenecientes a cinco taxa: 63 Dinophyta, cinco Bacillariophyta, una Chlorophyta, una Charophyta y una Cyanobacteria. Se registraron 21 especies de fitoplancton por primera vez para aguas cubanas. La riqueza de especies observada fue estadísticamente similar para las muestras costeras y oceánicas (44 y 52 especies respectivamente). Sin embargo, los patrones de agrupación del análisis MDS indicaron diferencias en la composición de especies entre las aguas costeras y oceánicas. Quince de las especies identificadas pudieran estar implicadas en FANs: Coscinodiscus spp., Dinophysis caudata, Gambierdiscus sp., Gonyaulax polygramma, Gonyaulax spinifera, Gymnodinium sp. 2, Lingulodinium polyedra,Peridinium quadridentatum, Phalacroma mitra, Phalacroma rotundatum, Prorocentrum cf. compressum, Thalassiosira spp., Tripos fusus, Tripos furca and Trichodesmium thiebautii. La presencia de estas especies sugiere la necesidad de un programa de monitoreo en las aguas cercanas a la Ciudad de La Habana, pues posee alta vulnerabilidad a FANs.

Las macroalgas tienen la habilidad de modificar a las comunidades del bentos, al facilitar o excluir especies que interactúan con su canopia. Los objetivos del estudio fueron: (1) analizar la diversidad, dinámica temporal e interacciones entre macroalgas frondosas, algas coralinas costrosas (ACC) y reclutas/juveniles de coral; y (2) probar el efecto protector de la canopia de macroalgas a partir de un experimento de campo en el veril superior. Las especies dominantes de macroalgas fueron Lobophora cf. variegata y Sargassum sp. Se registraron siete especies de ACC: Porolithon onkodes, Hydrolithon sp., Lithothamnion sp., Neogoniolithon sp. 1, Neogoniolothon sp. 2, Neogoniolithon sp. 3 y Neogoniolithon sp. 4. Los corales jóvenes que dominaron fueron Siderastrea siderea, Porites astreoides y P. porites. La cobertura de macroalgas frondosas y la densidad de reclutas-juveniles de coral variaron entre meses, pero no así la cobertura de ACC. El experimento apoyó la hipótesis del efecto facilitador de la canopia sobre las ACC. Existió evidencia de un efecto inhibidor de las macroalgas frondosas sobre los reclutas/juveniles de coral ya que estos últimos aumentaron su densidad ante la ausencia sostenida de la canopia. Sin embargo, en septiembre disminuyó la densidad de reclutas y juveniles de coral lo que se puede atribuir al impacto del huracán Irma en las cercanías del sitio de estudio. De este modo, en determinados escenarios las macroalgas frondosas pueden presentar un efecto protector a los corales jóvenes.

Chromis cyaneaes una de las especies marinas más comunes y abundantes de los arrecifes cubanos. En este estudio se cuantifica la infracomunidad de parásitos durante el desarrollo ontogenético de Chromis cyanea(Pisces: Pomacentridae) de la costa norte de La Habana, Cuba. Los objetivos son probar que las especies núcleo son responsables de la estructura en la infracomunidad y aparecen antes que las especies raras y estocásticas. Determinar si existe relación entre los descriptores ecológicos de la infraco-munidad parásita con la longitud total. Se capturaron 278 ejemplares de C. cyaneadurante la estación de seca (Abril) del 2010. Se analizó un rango de tallas de 1.5 a 11.5 cm de largo total y se incluyeron ejemplares juveniles y adultos. Se recolectaron 2 861 especímenes parásitos pertenecientes a 20 taxa: Crustacea (5), Nematoda (5), Trematoda (4), Cestoda (2), Monogenea (2), Turbellaria (1) y Ciliophora (1). Los taxa Tetraphyllidea y Anilocra chromisconstituyen el núcleo de la infracomunidad parásita. La secuencia de aparición y la persistencia de estos taxa durante el desarrollo ontogenético apoyan la hipótesis de las especies núcleo. Los cambios en la infracomunidad, a partir de la talla de 6 cm, podrían ser el resultado de un efecto acumulativo unido a cambios en la dieta que provocan la ingestión de nuevos estadíos infectivos. Se concluye que el desarrollo ontogenético de C. cyaneaconstituye una variable importante en la formación de la infracomunidad parásita.

Se describen los patrones espaciales de diversidad de nem{todos marinos de vida libre en relación con la profundidad; se muestreó en cuatro horizontes de profundidad (intermareal, 1 m, 5 m y 10 m) y dos sitios someros tropicales de la costa NW de Cuba: Bacunayagua y Miramar. Los patrones se describieron en base a la identidad de las especies y los rasgos biológicos. La riqueza de especies fue similar entre los horizontes de profundidad, con un rango de 12 a 18 especies; la riqueza fue también similar entre sitios con 30 y 33 especies en Bacunayagua y Miramar respectivamente. La variación en la diversidad fue m{s alta entre los horizontes intermareal y los submareales lo que sugiere que el micro-h{bitat tiene un papel importante. La profundidad no tiene un efecto importante sobre la diversidad de nemátodos en las costas estudiadas tanto en términos de riqueza de especies como de variación en la diversidad. El tipo de micro-hábitat y la hidrodinámica pueden explicar los patrones de β-diversidad dentro de los sitios. La variación de la diversidad entre sitios fue mayor que la variación relacionada con la profundidad sugiriendo que un patrón regional en la β-diversidad puede estar presente. Los rasgos biológicos constituyeron un enfoque complementario útil para analizar los patrones de diversidad e indicaron la prevalencia de nemátodos adaptados a un estilo de vida epífito y los efectos de dos potenciales determinantes de la diversidad: el micro-hábitat y la hidrodinámica. ABSTRACT Depth-related spatial patterns of diversity have been described for freeliving nematode assemblages at four depth horizons (intertidal, 1 m, 5 m and 10 m) at two subtidal rocky shores on the NW coast of Cuba: Bacunayagua and Miramar. The patterns were described based on species identity and biological traits. Species richness was similar across depth horizons ranging from 12 to 18 species; it was also similar between sites with 30 and 33 species for Bacunayagua and Miramar respectively. Diversity variation was higher between the intertidal and the subtidal horizons suggesting that microhabitat plays a key role. Depth was not an important driver of the diversity of nematodes on the studied rocky shores both in terms of species richness and diversity variation. The type of microhabitat and the hydrodynamics may explain the β-diversity patterns within sites. The site-related diversity variation was larger than the depth-related variation suggesting that a regional pattern in β-diversity may be present. The biological traits constituted a useful complementary approach for analyzing diversity patterns indicating the prevalence of nematodes adapted to an epiphytic life-style and the effects of two putative diversity drivers: microhabitat and hydrodynamics.

Free living nematodes are the most abundant and diverse metazoans in aquatic sediments. We used a framework of habitat types to reveal quantitative patterns in species richness (SR), β-diversity, and biological traits (BT). Meiofauna was quantitatively collected from 60 sites within nine habitat types and 24,736 nematodes were identified to species level. We reported a regional richness of 410 ± 12 species for the Cuban archipelago; however, caves and deep waters need to be sampled more intensively. Relationships between SR and abundance supported the dynamic equilibrium model with habitats ordered across gradients of resource availability and physical disturbance. Seagrass meadows were the most specious and freshwater/anchihaline caves the least diverse habitats. Differences in β-diversity likely were due to habitat heterogeneity and limitations for dispersal. The assemblage composition was unique in some habitats likely reflecting the effects of habitat filtering. However, coastal habitats shared many species reflecting high connectivity and dispersal capability of nematodes due to hydrodynamics. The BTs “life strategy”, “trophic group”, and “tail shape” reflected ecological adaptations; but “amphidial fovea” and “cuticle”, likely reflected phylogenetic signatures from families/genera living in different habitats. Habitat type played an influential role in the diversity patterns of aquatic nematodes from taxonomic and functional points of view.

The meiofauna from seagrass meadows in the western sector of the Gulf of Batabanó, Cuba were studied to describe the spatial and temporal variations in community structure. Replicated cores were taken in three locations (arranged in m- and km-scales) and in two seasons (dry and wet). The meiofauna (metazoans between 500 and 45 µm) were identified to major taxa. Temporal changes in the meiofaunal communities could not be detected and they are not linked to the subtle seasonal changes in the water column. A larger variation in community structure was observed in the spatial m-scale (among cores in a station) probably accredited to heterogeneity of microenvironment and biological processes. A second source of variation in the km-scale (among locations) was identified relating to physical processes affecting seagrass meadows: marine currents and anthropogenic disturbances. Distribution patterns of meiofauna across locations coincide with one study from 20 years ago in seagrass beds (i.e. higher densities in area closer to break-shelf and diminution of fauna at southern of Pinar del Río); however, cumulative anthropogenic disturbances on seagrass meadows would most likely explain the depletion of communities observed in our survey in comparison with decades ago. Estimates of meiofaunal density and richness of major taxa from our study (and other areas from the Cuban shelf) are consistently lower than other temperate and tropical sites; possibly caused by low primary productivity due to narrow tidal amplitude and oligotrophic waters. Rev. Biol. Trop. 56 (1): 55-63. Epub 2008 March 31.La meiofauna asociada a pastos marinos en el sector occidental del Golfo de Batabanó, Cuba se estudió para describir las variaciones espaciales y temporales en la estructura de la comunidad. Se tomaron muestras repetidas, a escala de m- y km, en tres localidades y en dos estaciones (seca y lluvia). La meiofauna (metazoos entre 500 y 45 µm) fue identificada hasta grupos taxonómicos principales. No se detectaron cambios estacionales en la estructura de las comunidades de meiofauna ni asociación con los factores abióticos en la columna de agua. La mayor variación en la estructura de la comunidad fue observada a escala espacial de metros (entre muestras en una estación), causada probablemente por la heterogeneidad del micro-ambiente y procesos biológicos. La segunda fuente de variación aparece en escala de kilómetros (entre localidades) y está relacionada a procesos físicos que afectan los pastos marinos: corrientes marinas y disturbios antropogénicos. Los patrones de distribución de la meiofauna a través de las localidades coinciden con un estudio de hace 20 años en pastos marinos (densidades mayores en las áreas más cercanas al borde de la plataforma y menores en el Sur de Pinar del Río); sin embargo, la acumulación de los efectos del impacto antropogénico probablemente explique la disminución de la densidad en las comunidades actuales de meiofauna. Los estimados de densidad de meiofauna y de riqueza de táxones en nuestro estudio (y en otras áreas de la plataforma de Cuba) son coherentemente más bajos que en otros sitios templados y tropicales; la causa posible es la baja productividad primaria debido a la estrecha amplitud de mareas y la oligotrofia de las aguas.

The taxonomy of the family Desmodoridae (Nematoda: Desmodorida) is partially revised based on morphology. The diagnoses of the Desmodoridae and the subfamilies Desmodorinae and Spiriniinae are emended to accommodate re-analyzed morphological features. Eight known species are redescribed and the implication of the new findings for the taxonomy of the group is discussed. Amphispira and Metadesmodora are confirmed as genera inquirendae. Alaimonema and Sigmophoranema, and their corresponding type species, are proposed as inquirendae due to poor descriptions of the type material. The other three species of Sigmophoranema are transferred to the genus Onyx because they bear the diagnostic features of this group: spear-like dorsal tooth and s-shape precloacal supplements. Echinodesmodora, Paradesmodora and Stygodesmodora are transferred to the Spiriniinae based on the absence of a head capsule and on the amphidial fovea being surrounded by cuticle striation. Paradesmodora toreutes is transferred to the genus Acanthopharyngoides as A. toreutes comb. nov. The genus Onepunema does not fit in the family Desmodoridae because of diorchic males; thus, it is regarded as taxon incertae sedis. Lists of valid genera for the two subfamilies are provided. A dichotomic key for the identification of the 14 genera within the Spiriinae is provided.