Comunidades de peces del atolón de Clipperton (Pacífico oriental tropical) y su relación con la cobertura de corales

Clipperton Atoll, one of the most isolated coral reefs worldwide, is of great scientific interest due to its geomorphology and high levels of endemism. This study explored the reef fish assemblage structure of Clipperton Atoll and its relationship with live coral cover. Nine stations were sampled at three sites and three depths (6, 12 and 20 m) around the reef, measuring fish species richness and biomass and hermatypic coral cover (at genus level). We evaluated variation in species richness, biomass and diversity of fish assemblages among sites and depths, as well as the relationship between the entire fish assemblage composition and live coral cover. The results showed that species richness and biomass were similar among sites, but differed across depths, increasing with depth. In contrast, diversity differed among sites but not among depths. Multivariate analyses indicated that fish assemblage composition differed among sites and depths in relation to changes in cover of coral of the genera Pocillopora, Porites, Pavona and Leptoseris, which dominate at different depths. The results showed that fish species richness and diversity were low at Clipperton Atoll and that, in isolated coral reefs with a low habitat heterogeneity and low human disturbance, live coral cover has a significant influence on the spatial variation of the reef fish assemblages. This study highlights the importance of coral habitat structure in shaping coral reef fish assemblages.El atolón de Clipperton, uno de los arrecifes de coral más aislados del mundo, presenta un gran interés científico por su geomorfología y endemismo. Este estudio analizó la estructura de las comunidades de peces de arrecife de este atolón y su relación con la cobertura de coral vivo. Para ello se muestrearon nueve estaciones alrededor del arrecife en tres sitios a tres profundidades (6, 12, 20 m), registrando, la riqueza y biomasa de peces, así como la cobertura de coral hermatípico a nivel de género. Se evaluó la variación de la riqueza, biomasa y diversidad de peces entre sitios y profundidades, así como la relación de la composición y biomasa de peces con la cobertura de coral vivo. Los resultados mostraron que la riqueza y biomasa fueron similares entre los sitios, pero diferentes entre profundidades, ya que incrementan con la profundidad. En contraste, la diversidad difirió entre sitios pero no entre profundidades. Los análisis multidimensionales indicaron que la comunidad de peces fue diferente entre sitios y profundidades, relacionándolo con la cobertura de coral de los géneros Pocillopora, Porites, Pavona y Leptoseris, que dominan a distinta profundidad. Los resultados evidenciaron una baja riqueza y diversidad de peces arrecifales en el atolón de Clipperton. En arrecifes de coral aislados, con baja heterogeneidad de hábitats y poca perturbación humana, la cobertura de coral vivo influye en la variación espacial de las comunidades de peces arrecifales. Este estudio resalta la importancia de la estructura del hábitat de coral en la conformación de las comunidades de peces arrecifales

Variación espacio-temporal de la cobertura de coral del norte del Sistema Arrecifal Mesoamericano, Península de Yucatán, México

Evaluating the response of coral assemblages to different disturbances is important because variations in species composition may have consequences for ecosystem functioning due to their different functional roles in coral reefs. This study evaluates changes in diversity, structure and composition of coral assemblages of the coral reefs of two national parks in the northern sector of the Mesoamerican Barrier Reef System spanning the period from 2006 to 2012, just after the impact of two hurricanes in the area. Coral assemblages in the Cancún National Park included fewer species and lower live coral coverage ( < 15%) than those recorded in Cozumel. In the Cancún National Park, the species with the highest coral cover was Porites astreoides (more than 40% relative cover), and no significant temporal changes were observed in live coral cover and species composition. On the other hand, in the Cozumel National Park the dominant species were Agaricia agaricites, Siderastrea siderea and Porites astreoides, and the coral reefs showed an increase in live coral cover from 16% in 2006 to 29% in 2012. The dynamics of coral assemblages differed between the two parks: while there is an apparent stability in the current composition of the Cancún reefs, the Cozumel reefs show an increase in the abundance of the aforementioned dominant species. However, it is possible that the population characteristics of the species that dominate the coral assemblages in both national parks, such as those of fast population growth and of small colony size, do not entirely fulfill the main function of accretion and habitat heterogeneity, and more research is therefore needed to test this hypothesis.Evaluar la respuesta de las comunidades de coral a diferentes perturbaciones es importante ya que las variaciones en la composición de las especies pueden tener consecuencias en el funcionamiento del ecosistema, debido a los diferentes roles funcionales que cada especie tiene dentro de él. En este estudio se evaluaron los cambios en la diversidad, estructura y composición de las comunidades en los arrecifes de dos Parques Nacionales ubicados en el sector norte del Sistema Arrecifal Mesoamericano, durante el periodo 2006-2012, justo después del impacto de dos huracanes en la zona. En el Parque Nacional Cancún se registraron pocas especies de coral y una cobertura de coral vivo baja ( < 15%) sin cambios temporales significativos; la especie más dominante en este parque fue Porites astreoides con más del 40% de cobertura relativa. Por otro lado, los arrecifes de coral del Parque Nacional de Cozumel mostraron un incremento en la cobertura de coral del 16% en 2006 a 29% en 2012; las especies dominantes, y que incrementaron su cobertura en este periodo, fueron Agaricia agaricites, Siderastrea siderea y P. astreoides. Aunque la dinámica de las comunidades de coral fue diferente en ambos parques, es posible que las características poblacionales de las especies que dominan las comunidades de coral en todos los arrecifes no cumplan por completo con las funciones principales de acreción y heterogeneidad de hábitat; sin embargo se necesita más investigación para poder evaluar esta hipótesis

Análisis multiescala de las comunidades de coral hermatípico del Pacífico Central Mexicano

The Mexican Central Pacific is located in a zone of oceanographic transition between two biogeographic provinces with particular conditions that affect the associated fauna. The objective of this study was to evaluate the variation of hermatypic coral assemblages in this region and to determine their relationship with the heterogeneity of the benthonic habitat and spatial variables. A total of 156 transects were carried out at 41 sites in the years 2010 and 2011. The sampling effort returned 96.7% of the coral richness expected for the area, with a total of 15 species recorded. The results showed that richness, diversity and cover of corals varied only at the site and state scales. However, the composition and coverage of all coral species, as well as the benthonic habitat structure, differed significantly across the study scales (i.e. sites, zones and states). Canonical redundancy analysis showed that variation in the richness, diversity and assemblages of corals was explained by the cover of live corals, articulated calcareous algae, sandy substrate, sponges and fleshy macroalgae. This study suggests that local scale (i.e. site) variation in the coral assemblages of the Mexican Central Pacific is the result of the heterogeneity of the benthonic habitat, while geomorphological and oceanographic characteristics play a greater role at regional scale.El Pacífico Central Mexicano se localiza en una zona de transición oceanográfica entre dos provincias biogeográficas con condiciones ambientales particulares que afectan la fauna asociada. El objetivo del estudio fue evaluar la variación de las comunidades de coral hermatípico de esta región y determinar su relación con la heterogeneidad del hábitat bentónico y variables espaciales. Se realizaron 156 transectos en 41 sitios en los años 2010 y 2011. El esfuerzo de muestreo representó el 96.7% de la riqueza de coral esperada para el área, con un total de 15 especies registradas. Los resultados mostraron que la riqueza, diversidad y cobertura de corales variaron sólo en las escalas de sitio y de estado. En cambio, la composición y cobertura de todas las especies de coral, así como la estructura del hábitat bentónico, fueron significativamente diferentes en todas las escalas estudiadas (i.e. sitio, zona y estado). Los análisis de redundancia canónica mostraron que la variación de la riqueza, diversidad y de las comunidades de corales eran explicadas por la cobertura de coral vivo, algas calcáreas articuladas, sustrato arenoso, esponjas y macroalgas carnosas. Este trabajo sugiere que la variación de las comunidades de coral en el Pacífico Central Mexicano a escala local (i.e. sitio) se debe a la heterogeneidad del hábitat bentónico, mientras que a escala regional, las características geomorfológicas y oceanográficas desempeñan un papel más importante

Ensamblajes bacterianos asociados a especies de coral del Pacífico central mexicano

The functional role of coral-associated bacteria and their contribution to coral health is still largely unknown. The first necessary step to address this gap in the knowledge is based on characterization of the microbial assemblage of the coral and the species-specific, temporal and spatial variation in its diversity. Branched corals (e.g., genus Pocillopora), are the main builders of coral reefs worldwide. This study evaluated the bacteria associated with the mucus and tissues of Pocillopora damicornis and Pocillopora verrucosa, as well as that of the seawater and surrounding sediments, in 6 sites of the Mexican Central Pacific during summer and winter seasons. The molecular techniques DGGE and RFLP were used with the 16S rDNA to assess the most abundant bacterial OTUs. The relationships between the bacterial-coral assemblage and environmental and spatial variables of the reef surroundings were also evaluated, using the multivariate analyses. Twenty different Operational Taxonomic Units (OTU) were obtained, with the highest number presented by the sediments. Specificity of bacterial groups was found for each coral species, as well as between the tissue and mucus of each species. The results showed that the bacterial dominant groups were similar between seasons, but these showed significant spatial variations among substrates within sites, as well as per substrate across all sites. The environmental variables that explained the variation of the dominant bacterial groups in corals and sea water were the coverages of fleshy macroalgae, live coral and sponge. In contrast, variation in the sediments was explained by the coverages of sand, rubble and rock.El papel funcional de las bacterias asociadas a corales y su contribución a la salud del coral es aún desconocido en gran medida. Es necesario que primero se caracterice el ensamblaje microbiano del coral y sus cambios en la diversidad a través de las especies de coral, el espacio y tiempo. Los corales ramificados (e.g., género Pocillopora) son los principales constructores arrecifales a nivel mundial. Este estudio evaluó la estructura bacteriana asociada al mucus y tejidos de Pocillopora damicornis y Pocillopora verrucosa, así como del agua de mar y sedimentos circundantes en 6 sitios del Pacífico central mexicano. Se emplearon las técnicas DGGE y RFLP del ADNr 16S para generar los perfiles de bandeo o evaluar la diversidad. Además, se evaluó la relación del ensamblaje bacteriano-coral con variables ambientales y espaciales del entorno arrecifal (de cada sitio), utilizando análisis multivariados. Se obtuvieron 20 Unidades Taxonómicas Operacionales (OTU) diferentes, siendo los sedimentos los que presentaron mayor número. Se encontró una especificidad de grupos bacterianos para cada especie de coral, así como entre el tejido y mucus de cada especie. Los resultados mostraron que los grupos de bacterias dominantes variaron entre sustratos y entre sitios, encontrando, sólo una variación espacial significativa. Las variables ambientales que explican la variación de los grupos bacterianos dominantes en corales y agua de mar fueron las coberturas de macroalgas carnosas, coral vivo y esponja. En cambio, la variación en los sedimentos fue explicada por las coberturas de arena, escombro y roc

Determinants of reef fish assemblages in tropical Oceanic islands

Diversity patterns are determined by biogeographic, energetic, and anthropogenic factors, yet few studies have combined them into a large‐scale framework in order to decouple and compare their relative effects on fish faunas. Using an empirical dataset derived from 1527 underwater visual censuses (UVC) at 18 oceanic islands (five different marine provinces), we determined the relative influence of such factors on reef fish species richness, functional dispersion, density and biomass estimated from each UVC unit. Species richness presented low variation but was high at large island sites. High functional dispersion, density, and biomass were found at islands with large local species pool and distance from nearest reef. Primary productivity positively affected fish richness, density and biomass confirming that more productive areas support larger populations, and higher biomass and richness on oceanic islands. Islands densely populated by humans had lower fish species richness and biomass reflecting anthropogenic effects. Species richness, functional dispersion, and biomass were positively related to distance from the mainland. Overall, species richness and fish density were mainly influenced by biogeographical and energetic factors, whereas functional dispersion and biomass were strongly influenced by anthropogenic factors. Our results extend previous hypotheses for different assemblage metrics estimated from empirical data and confirm the negative impact of humans on fish assemblages, highlighting the need for conservation of oceanic islands.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR

Coral biodiversity and bio-construction in the northern sector of the mesoamerican reef system

As the impact of anthropogenic activity and climate change continue to accelerate rates of degradation on Caribbean coral reefs, conservation and restoration faces greater challenges. At at this stage, of particular importance in coral reefs, is to recognize and to understand the structural spatial patterns of benthic assemblages. We developed a field-based framework of a Caribbean reefscape benthic structure by using hermatypic corals as an indicator group of global biodiversity and bio-construction patterns in eleven reefs of the northern sector of the Mesoamerican Barrier Reef System (nsMBRS). Four hundred and seventy four video-transects (50 m long by 0.4 m wide) were performed throughout a gradient of reef complexity from north to south (∼400 km) to identify coral species, families and ensembles of corals. Composition and abundance of species, families and ensembles showed differences among reefs. In the northern zone, the reefs had shallow, partial reef developments with low diversities, dominated by Acropora palmata, Siderastrea spp., Pseudodiploria strigosa and Agaricia tenuifolia. In the central and southern zones, reefs presented extensive developments, high habitat heterogeneity, and the greatest diversity and dominance of Orbicella annularis and Orbicella faveolata. These two species determined the structure and diversity of corals in the central and southern zones of the nsMBRS and their bio-construction in these zones is unique in the Caribbean. Their abundance and distribution depended on the reef habitat area, topographic complexity and species richness. Orbicella species complex were crucial for maintaining the biodiversity and bio-construction of the central and southern zones while A. palmata in the northern zones of the nsMBRS

Ensamblajes de peces arrecifales y su relación con el hábitat bentónico de la Isla Isabel, Nayarit, México

This study describes the reef fish assemblages of Isabel Island and their relation with the benthos heterogeneity. A total of 39 visual transects from 19 different localities were performed in the zones North, South, East, and West around the island during December 2002, October 2004, and April 2005. The species composition and their abundance were registered in each transect. Video-transects were also performed to estimate the cover of benthic morpho-functional groups. A total of 9,956 specimens of fishes belonging to 118 species, 85 genera, and 51 families were registered. The 58.3% of the species have biogeographic affinity to the Panamic province. Six endemic species of the Mexican Pacific were registered, including two species endemic to the Gulf of California. According to the biological value index seven species were dominant in the island: Thalassoma lucasanum, Prionurus punctatus, Stegastes flavilatus, Halichoeres dispilus, Acanthurus xanthopterus, Abudefduf troschelii, and Johnrandallia nigrirostris. The indexes of diversity and evenness were not significantly different between the four zones of the island. However, there was a relation between the zones with higher biodiversity (South and East) and some components of the benthic habitat. The principal component analysis found that the cover of corals and rocks are highly related with the dominant species of the island, while the zones with highest proportion of sand, sponges, and gorgonians have less influence on fish diversityEn este estudio se describen los ensamblajes de peces arrecifales de la Isla Isabel y su relación con la heterogeneidad del bentos. Se realizaron 39 transectos visuales en 19 diferentes sitios de las zonas Norte, Sur, Este y Oeste alrededor de la isla durante los meses de diciembre de 2002, octubre de 2004 y abril de 2005. En cada transecto se registró la composición de especies y su abundancia. También se registraron video-transectos para estimar la cobertura de los grupos morfo-funcionales del bentos. Se registraron un total de 9.956 ejemplares de peces de 118 especies, 85 géneros y 51 familias. El 58,3% de las especies presentan afinidad biogeográfica con la provincia Panámica. Se registraron seis especies endémicas del Pacífico mexicano, incluyendo dos endémicas del Golfo de California. De acuerdo con el índice de valor biológico, siete especies fueron dominantes en la isla: Thalassoma lucasanum, Prionurus punctatus, Stegastes flavilatus, Halichoeres dispilus, Acanthurus xanthopterus, Abudefduf troschelii y Johnrandallia nigrirostris. Los índices de diversidad y equidad no fueron significativamente diferentes entre las cuatro zonas de la isla. Sin embargo, se encontró una relación entre las zonas de mayor diversidad (Sur y Este) y algunos componentes del hábitat bentónico. El análisis de componentes principales encontró que las coberturas de coral y roca están altamente relacionas con las especies dominantes de la isla, mientras que las zonas con mayor proporción de arena, esponjas y gorgonáceos influyen en menor medida sobre la diversidad de peces

Additive Diversity Partitioning of Fish in a Caribbean Coral Reef Undergoing Shift Transition

<div><p>Shift transitions in dominance on coral reefs from hard coral cover to fleshy macroalgae are having negative effects on Caribbean coral reef communities. Data on spatiotemporal changes in biodiversity during these modifications are important for decision support for coral reef biodiversity protection. The main objective of this study is to detect the spatiotemporal patterns of coral reef fish diversity during this transition using additive diversity-partitioning analysis. We examined α, β and γ fish diversity from 2000 to 2010, during which time a shift transition occurred at Mahahual Reef, located in Quintana Roo, Mexico. Data on coral reef fish and benthic communities were obtained from 12 transects per geomorphological unit (GU) in two GUs (reef slope and terrace) over six years (2000, 2005, 2006, 2007, 2008, 2010). Spatial analysis within and between the GUs indicated that the γ-diversity was primarily related to higher β-diversity. Throughout the six study years, there were losses of α, β and γ-diversity associated spatially with the shallow (reef slope) and deeper (reef terrace) GUs and temporally with the transition in cover from mound corals to fleshy macroalgae and boulder corals. Despite a drastic reduction in the number of species over time, β-diversity continues to be the highest component of γ-diversity. The shift transition had a negative effect on α, β and γ-diversity, primarily by impacting rare species, leading a group of small and less vulnerable fish species to become common and an important group of rare species to become locally extinct. The maintenance of fish heterogeneity (β-diversity) over time may imply the abetment of vulnerability in the face of local and global changes.</p></div

Bacterial assemblages associated with coral species of the Mexican Central Pacific

El papel funcional de las bacterias asociadas a corales y su contribución a la salud del coral es aún desconocido en gran medida. Es necesario que primero se caracterice el ensamblaje microbiano del coral y sus cambios en la diversidad a través de las especies de coral, el espacio y tiempo. Los corales ramificados (e.g., género Pocillopora) son los principales constructores arrecifales a nivel mundial. Este estudio evaluó la estructura bacteriana asociada al mucus y tejidos de Pocillopora damicornis y Pocillopora verrucosa, así como del agua de mar y sedimentos circundantes en 6 sitios del Pacífico central mexicano. Se emplearon las técnicas DGGE y RFLP del ADNr 16S para generar los perfiles de bandeo o evaluar la diversidad. Además, se evaluó la relación del ensamblaje bacteriano-coral con variables ambientales y espaciales del entorno arrecifal (de cada sitio), utilizando análisis multivariados. Se obtuvieron 20 Unidades Taxonómicas Operacionales (OTU) diferentes, siendo los sedimentos los que presentaron mayor número. Se encontró una especificidad de grupos bacterianos para cada especie de coral, así como entre el tejido y mucus de cada especie. Los resultados mostraron que los grupos de bacterias dominantes variaron entre sustratos y entre sitios, encontrando, sólo una variación espacial significativa. Las variables ambientales que explican la variación de los grupos bacterianos dominantes en corales y agua de mar fueron las coberturas de macroalgas carnosas, coral vivo y esponja. En cambio, la variación en los sedimentos fue explicada por las coberturas de arena, escombro y roca.The functional role of coral-associated bacteria and their contribution to coral health is still largely unknown. The first necessary step to address this gap in the knowledge is based on characterization of the microbial assemblage of the coral and the species-specific, temporal and spatial variation in its diversity. Branched corals (e.g., genus Pocillopora), are the main builders of coral reefs worldwide. This study evaluated the bacteria associated with the mucus and tissues of Pocillopora damicornis and Pocillopora verrucosa, as well as that of the seawater and surrounding sediments, in 6 sites of the Mexican Central Pacific during summer and winter seasons. The molecular techniques DGGE and RFLP were used with the 16S rDNA to assess the most abundant bacterial OTUs. The relationships between the bacterial-coral assemblage and environmental and spatial variables of the reef surroundings were also evaluated, using the multivariate analyses. Twenty different Operational Taxonomic Units (OTU) were obtained, with the highest number presented by the sediments. Specificity of bacterial groups was found for each coral species, as well as between the tissue and mucus of each species. The results showed that the bacterial dominant groups were similar between seasons, but these showed significant spatial variations among substrates within sites, as well as per substrate across all sites. The environmental variables that explained the variation of the dominant bacterial groups in corals and sea water were the coverages of fleshy macroalgae, live coral and sponge. In contrast, variation in the sediments was explained by the coverages of sand, rubble and rock