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18 resultados encontrados para: AUTOR: Vega Zepeda, Alejandro
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1.
Artículo
PDF
Resumen en: Inglés |
Resumen en inglés

An emerging disturbance for Caribbean reefs is the massive arrival of pelagic Sargassum, which deteriorates water quality due to the production of leachates. The highest arrivals of Sargassum took place when broadcasting corals spawned. We experimentally determined the effect of Sargassum leachates on swimming behavior of Acropora palmata larvae through five treatments (control, stain (simulating 100% leachate color), and 25%, 50% and 100% Sargassum leachate concentrations) during 30 min (10 min of videos and 20 min of post-observations). In the videos, larvae with leachates reduced swimming speed, were positively geotactic, the percentage of individuals that swam in a spiral pattern increased, and most behavioral displacements occurred at lower frequencies than larvae without leachates. Moreover, symptomatic spiral behavior was higher in the presence of leachates, suggesting that this behavior may be an effect of pollution. During post-observations, most larvae with leachates were motionless. This is the first time that Sargassum leachates have been documented modifying larval swimming behavior, which may reduce larval dispersion and genetic diversity. We suggest that a future evaluation of the effects of leachates at lower concentrations and over longer periods of exposure is needed. The resilience of corals may be compromised if Sargassum arrivals become frequent events.


2.
Tesis - Maestría
*En proceso técnico. Solicítelo con el bibliotecario(a) de SIBE-Chetumal
Efecto de los lixiviados de Sargassum spp. pelágico en el comportamiento natatorio de las larvas del coral Acropora palmata / Francisco Antonio Martínez
Antonio Martínez, Francisco ; Hénaut, Yann (director) ; Cetz Navarro, Neidy Pauline (asesora) ; Vega Zepeda, Alejandro (asesor) ;
Chetumal, Quintana Roo, México : El Colegio de la Frontera Sur , 2019
Clasificación: TE/579.888 / A5
Nota: En proceso técnico. Solicítelo con el bibliotecario(a) de SIBE-Chetumal
Resumen en español

Una perturbación emergente para los arrecifes del Caribe es el arribo masivo de sargazo pelágico, el cual deteriora la calidad del agua debido a la producción de lixiviados. Los picos de la afluencia de sargazo en el Caribe mexicano pueden coincidir con el periodo de desove de corales liberadores de gametos. En este estudio, las larvas del coral Acropora palmata (Lamarck, 1816) fueron expuestas a cinco tratamientos (testigo, colorante café y tres concentraciones de lixiviados de sargazo al 25 %, 50 % y 100 %) durante 30 minutos (10 minutos de filmación + 20 minutos de observaciones) para determinar si los lixiviados modifican el comportamiento natatorio de las larvas. En las filmaciones se observó que las larvas con lixiviados redujeron la velocidad de nado, aumentaron el porcentaje de individuos nadando en espiral, fueron geotácticamente positivas y la mayoría de los pares de comportamiento cinético mostraron baja frecuencia comparado con las larvas sin lixiviados. Las respuestas de las larvas ocurrieron independientemente de las concentraciones de lixiviados. El comportamiento sintomático de nado en espiral fue mayor en presencia de lixiviados, sugiriendo que este comportamiento podría ser un efecto de la contaminación. Durante las observaciones posteriores a las filmaciones, la mayoría de las larvas con lixiviados permanecieron inmóviles comparado con las larvas sin lixiviados. Por primera vez, se reporta a los lixiviados de sargazo como un disturbio que modifica el comportamiento natatorio de las larvas, los cuales podrían reducir la dispersión de las larvas y el incremento de colonias provenientes de la reproducción sexual de A. palmata. Se sugiere evaluar los efectos de los lixiviados en larvas expuestas a menores concentraciones y con mayor tiempo de exposición. La resiliencia de los corales puede ser rebasada si el arribo masivo de sargazo se convierte en un evento frecuente.

Índice

RESUMEN
INTRODUCCIÓN
ARTÍCULO: Leachate effects of pelagic Sargassum spp. on larval swimming behavior of the coral Acropora palmata
Abstract
Introduction
Results
Discussion
Materials and Methods
References
Acknowledgements
Supplementary Information
CONCLUSIONES
LITERATURA CITADA


3.
Tesis - Maestría
*En proceso técnico. Solicítelo con el bibliotecario(a) de SIBE-Chetumal
Recuperación parcial de los pastos marinos después de la marea marrón de Sargassum de 2015 en el Caribe mexicano / Stephany Manzo Melchor
Manzo Melchor, Stephany ; Vega Zepeda, Alejandro (director) ; Tussenbroek, Brigitta Ine van (codirectora) ; Callejas Jiménez, Mariana (asesora) ;
Chetumal, Quintana Roo, México : El Colegio de la Frontera Sur , 2019
Clasificación: TE/579.888097267 / M3
Nota: En proceso técnico. Solicítelo con el bibliotecario(a) de SIBE-Chetumal
Resumen en español

Las costas del Caribe mexicano fueron afectadas por la Marea marrón de Sargassum (denominada “Sbt”) en 2015. En 2018, la granulometría, densidad, biomasa y profundidad de arraigo (PA) de los pastos marinos, y la edad de T. testudinum fueron evaluadas en Cancún y Xahuayxol en tres zonas (Z1: 0-20 m, Z2: 30-50 m y Z3: 60-100 y 60-200 m, respectivamente)). La biomasa (Cancún) y la densidad (Xahuayxol) de los pastos marinos fueron comparados con datos previos. La pradera de Cancún tuvo menor extensión (100 m) que la de Xahuayxol (200 m). En Cancún, la densidad, la biomasa y la PA fueron diferentes entre zonas. En la Z1, H. wrightii fue especie exclusiva, con la mayor densidad. En la Z2, S. filiforme tuvo mayor densidad y biomasa que T. testudinum, mientras que en la Z3 ocurrió lo opuesto. El 84 % de los haces de T. testudinum se reclutaron desde 2017 en la Z2 y el 53 % desde 2016 en la Z3. En Xahuayxol, la densidad y la biomasa fueron diferentes entre zonas; la PA en la Z1 fue menor a las Z2 y Z3. En la Z1, H. wrightii fue la única especie presente, con baja densidad y biomasa entre sonas. En la Z2, T. testudinum y S. filiforme presentaron mayor densidad y biomasa que en la Z3. Desde 2016 se reclutaron el 100 % de los haces de T. testudinum en la Z2 y el 71 % en la Z3. Las comparaciones entre años sugiere la recuperación parcial de las praderas de ambos sitios. H. wrightii se pudo recuperar por semillas; T. testudinum con haces sobrevivientes; y S. filiforme con haces sobrevivientes y/o semillas. Aunque los pastos marinos pueden recuperarse del impacto de la Sbt, la llegada de futuros arribos masivos de Sargassum puede disminuir su resiliencia.

Índice

RESUMEN
INTRODUCCIÓN
ARTÍCULO
RESUMEN (INGLÉS)
INTRODUCCIÓN
MATERIALES Y MÉTODOS
RESULTADOS
DISCUSIÓN
AGRADECIMIENTOS
RESUMEN (ESPAÑOL)
REFERENCIAS
43 CONCLUSIONES GENERALES
LITERATURA CITADA


4.
- Artículo con arbitraje
PDF
Resumen en: Inglés |
Resumen en inglés

The arrival of large masses of drifting Sargassum since 2011 has caused changes in the natural dynamics of Caribbean coastal ecosystems. In the summer of 2015, unprecedented and massive mats of S. fluitans and S. natans have been observed throughout the Mexican Caribbean including exceptional accumulations ashore. This study uses stable isotopes to assess the impact of Sargassum blooms on the trophic dynamics of the Diadema antillarum sea urchin, a keystone herbivore on many Caribbean reefs. Bayesian models were used to estimate the variations in the relative proportions of carbon and nitrogen of assimilated algal resources. At three lagoon reef sites, the niche breadth of D. antillarum was analysed and compared under massive influx of drifting Sargassum spp. vs. no influx of Sargassum blooms. The effects of the leachates generated by the decomposition of Sargassum led to hypoxic conditions on these reefs and reduced the taxonomic diversity of macroalgal food sources available to D. antillarum. Our trophic data support the hypothesis that processes of assimilation of carbon and nitrogen were modified under Sargassum effect. Isotopic signatures of macroalgae associated with the reef sites exhibited significantly lower values of 15N altering the natural herbivory of D. antillarum. The Stable Isotopes Analysis in R (SIAR) indicated that, under the influence of Sargassum blooms, certain algal resources (Dictyota, Halimeda and Udotea) were more assimilated due to a reduction in available algal resources. Despite being an abundant available resource, pelagic Sargassum was a negligible contributor to sea urchin diet.

The Stable Isotope Bayesian Ellipses in R (SIBER) analysis displayed differences between sites, and suggests a reduction in trophic niche breadth, particularly in a protected reef lagoon. Our findings reveal that Sargassum blooms caused changes in trophic characteristics of D. antillarum with a negative impact by hypoxic conditions. These dynamics, coupled with the increase in organic matter in an oligotrophic system could lead to reduce coral reef ecosystem function.


5.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Did the community structure of a coral reef patch affected by a ship grounding recover after 15 years? Merging historical and recent data sets
Victoria Salazar, Isael ; Hernández Arana, Héctor Abuid (coaut.) ; Meave, Jorge A. (coaut.) ; Ruíz Zárate, Miguel Ángel (coaut.) ; Vega Zepeda, Alejandro (coaut.) ; Carricart Ganivet, Juan P. (coaut.) ; López Adame, Haydée (coaut.) ;
Contenido en: Ocean & Coastal Management Vol. 144, (July 2017), p. 59–70 ISSN: 1532-2416
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

Shifts in dominance from coral to other benthic groups in coral reefs have raised concerns about the persistence of coral reefs and their ability to provide ecosystem services. Acute disturbances such as ship groundings offer the opportunity to examine the dynamics of successional processes in coral reefs, since understanding them is a prerequisite for their proper management. In this study, we investigated whether a ship grounding area in a reef located in a marine protected area in Cancún, Mexico, showed signs of recovery 15 years after the incident. We evaluated the reef's composition and structure by taking samples at three different scales (reef scale, 1 m², and 0.01 m²). In these samples, we analysed coral density and recruitment, the abundance of five functional algal groups, and the abundance of the grazer sea urchin Diadema antillarum. If recovery had already occurred, we expected the impacted sector to have a community composition and structure similar to that of a contiguous, non-impacted sector. Using historical information, we found indications of a long-term phase shift, with Porites astreoides being the dominant coral species some time ago and at all scales of analysis; this species also showed intense recruitment. In agreement with previous studies of Caribbean reefs, architectural complexity was low. The algal cover was similar in impacted and non-impacted sectors though the density of sea urchins differed between them. Fifteen years after the ship grounding and despite the enforcement of the prohibition of tourism and fishing activities at the site, the impacted sector does not show signs of recovery. On the contrary, like other reefs in the Caribbean Sea, the non-impacted sector is becoming degraded due to the loss of reef builder key species and the increase of the algae-covered area, mirroring the path observed in the impacted sector.


6.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Severe impacts of brown tides caused by Sargassum spp. on near-shore Caribbean seagrass communities
Van Tussenbroek, Brigitta I. ; Hernández Arana, Héctor Abuid (coaut.) ; Rodríguez Martínez, Rosa E. (coaut.) ; Espinoza Ávalos, Julio (coaut.) ; Canizales Flores, Hazel M. (coaut.) ; González Godoy, Carlos E. (coaut.) ; Barba Santos, M. Guadalupe (coaut.) ; Vega Zepeda, Alejandro (coaut.) ; Collado Vides, Ligia (coaut.) ;
Contenido en: Marine Pollution Bulletin Vol. 122, no. 1-2 (September 2017), p. 272-281 ISSN: 0025-326X
Nota: Solicítelo con su bibliotecario/a
Resumen en español

From mid-2014 until the end of 2015, the Mexican Caribbean coast experienced a massive in fl ux of drifting Sargassum spp. that accumulated on the shores, resulting in build-up of decaying beach-cast material and near-shore murky brown waters (Sargassum-brown-tides, Sbt). The effects of Sbt on four near-shore waters included reduction in light, oxygen (hypoxia or anoxia) and pH. The monthly influx of nitrogen, and phosphorus by drifting Sargassum spp. was estimated at 6150 and 61 kg km−¹ respectively, resulting in eutrophication. Near-shore seagrass meadows dominated by Thalassia testudinum were replaced by a community dominated by calcareous rhizophytic algae and drifting algae and/or epiphytes, resulting in 61.6–99.5% loss of below-ground biomass. Near-shore corals suffered total or partial mortality. Recovery of affected seagrass meadows may take years or even decades, or changes could be permanent if massive influxes of Sargassum spp. recur.


7.
Artículo - Ponencia
*Solicítelo con su bibliotecario/a
Spatial chlorophyll fluorescence analysis of Banco Chinchorro using terra and aqua MODIS products
Lazcano Hernández, Hugo Enrique (autor) ; Alvarado Barrientos, María Susana (autora) ; López Adame, Haydée (autora) ; Vega Zepeda, Alejandro (autor) ; Hernández Arana, Héctor Abuid (autor) ;
Contenido en: Research in Computing Science Vol. 143 (November 2017) ISSN: 1870-4069
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

Annual average data of four MODIS (Aqua and Terra) products were analyzed, compared and used to explore temporal trends of indicative parameters of net primary productivity and physiological state of phytoplankton in Banco Chinchorro, a coral reef located southeast of the Yucatan Peninsula. The parameters evaluated were: chlorophyll a concentration (Chl a), normalized fluorescence (NFLH), instantaneous photosynthetic active radiation (iPAR) and sea surface temperature (SST4). According with MODIS Aqua, the first results indicate that between 2002 and 2016, there was a small and steady decrease in NFLH (slope m = -0.0008). The temporal trends found were compared against hydro-meteorological events recorded in the region such as tropical storms and hurricanes. Due to lack of information about spatial fluorescence in the study region, the aim of this document is establishes a point of reference for future research, and define a methodology which can be replicated in other regions.


8.
- Artículo con arbitraje
Resumen en: Inglés |
Resumen en inglés

This study assessed the coral reef condition of two marine protected areas in the Caribbean: Guanahacabibes National Park, Cuba, and Costa Occidental de Isla Mujeres-Punta Cancun-Punta Nizuc National Park, Mexico, in a two-year period. The analyzed indicators for corals were live coral cover, diameter and height of the colonies, ancient and recent mortalities and abundance of recruits, which were evaluated in quadrats of 1 m² . In addition, it was estimated the coverage by morphofunctional groups of macroalgae in 25 × 25 cm quadrats and the density of the Diadema antillarum urchin in 1 m² quadrats. The results showed differences between countries at broad spatial scales (hundreds of kilometers). Reefs of both MPAs seem to be in different stages of changes, which have been associated with deterioration of Caribbean reefs, toward the dominance of more resistant, non-tridimensional coral species, causing a decrease of the reef complexity that may leads to the reefs to collapse. At scales of kilometers (within MPAs), a similar pattern was found in reefs of GNP-Cuba and different trends were observed in reefs of CNP-Mexico. The observed differences between CNP-Mexico sites appear to be associated with the current tourism use patterns.


Resumen en: Inglés |
Resumen en inglés

Knowledge of the current condition of reef communities is essential for the implementation of marine protected areas (MPAs). In 2014, we assessed the conditions of reefs of two MPAs in the Caribbean: Guanahacabibes National Park (Guanahacabibes), Cuba and Costa Occidental de Isla Mujeres - Punta Cancun - Punta Nizuc National Park (Cancun), Mexico. Within each of the two MPAs studied, we examined two reefs. We took data from fifteen 10-m long transect lines. Indicators included coral cover, diameter of coral colonies, old and recent coral mortalities and coral diseases. The abundance of coral recruits and the density of Diadema antillarum were assessed in 1 m2 quadrats. The cover of groups of macroalgae was obtained from 25 25 cm quadrats. Our data illuminated distinct stages in the loss of reef structure similar to what has been seen by other investigators, particularly the change in the dominance of coral species and the deterioration of the three-dimensional structure of reefs. The Cuevones site (in Cancun), which has been closed to tourism for fifteen years, remains dominated by corals, with a high coral cover (33.36%), but with a species dominance (principally Porites astreoides), different from the lead species observed in the Caribbean a few decades ago. The reefs of Guanahacabibes (Laberinto and Yemaya) subject to a low diving intensity appear to be at an earlier stage of changes than the Cancun reefs. The coral indicators remains similar to previous reports, so perhaps this can be slowed or reversed. Meanwhile, Manchones in Cancun showed the lowest coral cover (11.49%) and the lowest recruit density (0.6 recruits/m2), probably due to the joint action of the natural pressures and to the heavy influx of visitors these reefs receive.


10.
- Artículo con arbitraje
Reclutamiento del coral Acropora palmata sobre sustratos de dos materiales
Cetz Navarro, Neidy Pauline (coaut.) ; Espinoza Ávalos, Julio (coaut.) ; Vega Zepeda, Alejandro (coaut.) ; Cerón Flores, Ana I. (coaut.) ; Raigoza Figueras, Rodolfo (coaut.) ; Carpizo Ituarte, Eugenio de Jesús (coaut.) ;
Contenido en: Revista de Biología Marina y Oceanografía Vol. 51, no. 3 (diciembre 2016), p. 643-653 ISSN: 0718-1957
PDF PDF
Resumen en: Español | Inglés |
Resumen en español

Durante el reclutamiento de los corales, las características de los sustratos influyen en la densidad y la distribución espacial de los reclutas. Se evaluó la influencia del material (conchuela y arena) y de 4 combinaciones denominadas grupos (conchuela/arriba, conchuela/abajo, arena/arriba y arena/abajo) en la distribución de los reclutas del coral Acropora palmata en las 4 áreas de los sustratos utilizados (cara superior, caras laterales, caras inferiores y base). En los materiales utilizados, el número de reclutas por sustrato fue mayor en la conchuela (mediana= 15,0) que en la arena (2,0). En las áreas del sustrato, la cara superior en la conchuela y las caras superior y laterales en la arena tuvieron mayor número de reclutas que las otras áreas del sustrato; cabe señalar que las caras superiores fueron las que recibieron más luz durante el acondicionamiento de los sustratos. En los grupos, el número de reclutas por sustrato fue mayor en los grupos de conchuela (conchuela/arriba ≈ conchuela/abajo) que en los de arena (arena/arriba > arena/abajo). El relativo bajo número de reclutas de A. palmata que se obtuvo (12500 m-²) fue, sin embargo, 3-4 órdenes de magnitud mayor que la obtenida en arrecifes del Caribe (3-39 m-²), con una abundancia dominada por corales oportunistas que no proveen las cualidades ecológicas de A. palmata. La siembra en el campo de reclutas obtenidos en acuario permanece como una alternativa viable para recuperar las poblaciones de esta especie en peligro crítico de extinción, la cual contribuye sustancialmente en la complejidad estructural de arrecifes coralinos del Caribe.

Resumen en inglés

During recruitment of corals, substrate characteristics influence the density and the spatial distribution of recruits. The influence of the material (limestone and sand) and of 4 groups arrangements (limestone/up, limestone/down, sand/up and sand/ down) in the distribution of the Acropora palmata recruits in 4 areas of the substrate used (upper face, side faces, bottom faces and base) was evaluated. The number of recruits per substrate was higher in limestone (median= 15.0) than in sand (2.0). Regarding the areas of recruitment, the upper face in limestone and the upper and side faces in sand presented greater number of recruits than the other areas of the substrate; notably the upper faces received more light during the conditioning of the substrates. Concerning the groups, the number of recruits per substrate was higher in limestone groups (limestone/up ≈ limestone/down) than in sand groups (sand/up > sand/down). The relatively low number of A. palmata recruits obtained (12500 m-²) was, however, 3-4 orders of magnitude higher than the recruits obtained in Caribbean coral reefs (3-39 m-²), with an abundance dominated by opportunistic corals that do not provide the ecological qualities fulfilled by A. palmata. The implantation in the field of recruits obtained in aquarium remains as a viable alternative to recover populations of this critically endangered coral species, which substantially contributes to the structural complexity of Caribbean coral reefs.