Influence of sediments and tungsten traces on the skeletal structure of Pseudodiploria: a reef building scleractinian coral from the Veracruz Reef System National Park, Mexico / Influencia de los sedimentos y trazas de tungsteno en la estructura del esqueleto de Pseudodiploria un coral escleractinio constructor de arrecifes del Parque Nacional Sistema Arrecifal Veracruzano, México

Abstract:Coral reefs are under intense conditions of stress caused by the anthropogenic activities in coastal areas and the increase of human population. Water effluents from urban and industrial areas carry large amounts of sediments and pollutants affecting corals populations, inducing bioerosion, increasing diseases and promoting the development of algae that compete for space with corals. In the Veracruz Reef System National Park (VRSNP) coral reefs are strongly affected by human activities carried out in the area. Gallega and Galleguilla reefs are among the most affected by wastewater discharges from the industrial (petrochemical and metallurgical) and urban areas in their vicinity. To assess the potential impact of this contamination on corals in the VRSNP, a chemical composition and morphology study of 76 Pseudodiploria colonies collected in reefs Gallega, Galleguilla, Isla Verde and Isla de Enmedio, was performed. Fragments of ~10 cm2 were collected and boric acid at 0.5 % was used to remove tissue from the skeleton; once clean, the morphology of each sample was determined with a scanning electron microscope (SEM). Subsequently, to test the chemical composition, an energy dispersion spectroscopy of X-ray chemical microanalysis (EDSX) was performed in the SEM. We found that corals from Gallega and Galleguilla reefs, located closer to human populations, presented high levels of tungsten and the skeleton exhibited multiple perforations. In contrast, corals from the farthest offshore reefs (Isla Verde and Isla de Enmedio) exhibited lower levels of tungsten and fewer perforations in their skeleton. These results demonstrated that anthropogenic activities in the NPVRS are affecting corals skeleton, highly damaging and promoting their bioerosion. The presence of traces of tungsten in the skeleton of corals is an evidence of the damage that waste discharges are causing to coral reefs. Discharges of large amounts of contaminants promoted the growth of harmful species that grow and develop into the corals skeleton, causing its bioerosion, and making them susceptible to disease and physical damage. This study is the first evidence of the effects of contamination on these species; therefore, further studies are necessary to determine the impact of pollution on their biology and survival. Rev. Biol. Trop. 64 (3): 1077-1089. Epub 2016 September 01.

ResumenLos arrecifes de coral se encuentran bajo condiciones intensas de estrés causado por las actividades antropogénicas y el incremento de las poblaciones humanas en las zonas costeras. Las descargas de aguas de origen urbano e industrial transportan sedimentos y contaminantes que afectan a las poblaciones de corales, induciendo la bioerosion, el aumento de enfermedades en los corales y promueven el desarrollo de algas que compiten por espacio con los corales. En el Parque Nacional Sistema Arrecifal Veracruzano (NPVRS) los arrecifes de coral son afectados fuertemente por las actividades humanas que se llevan a cabo en la zona. Los arrecifes Gallega y Galleguilla son de los más afectados por las descargas de aguas residuales provenientes de la industria (petroquímica y metalúrgica) y de áreas urbanas que desembocan sus aguas en las proximidades de los arrecifes. Para evaluar el posible impacto de las descargas de aguas en los corales del NPVRS, se realizó un estudio de la composición química y morfología de 76 colonias de Pseudodiploria en los arrecifes Gallega, Galleguilla, Isla Verde e Isla de Enmedio. Se recolectaron fragmentos de ~10 cm2, el tejido del esqueleto fue removido utilizando ácido bórico al 0.5 %. Una vez limpia la muestra, la morfología fue analizada con un microscopio electrónico de barrido (SEM), posteriormente, para analizar la composición química de las muestras, realizamos una espectroscopia de dispersión de energía o micro-análisis químico de rayos X (EDSX) en el SEM. Encontramos que los corales de los arrecifes Gallega y Galleguilla que se encuentran ubicados cerca de poblaciones humanas, presentan altos niveles de tungsteno y el esqueleto exhibe múltiples agujeros. En contraste, los corales de los arrecifes más lejanos (Isla Verde e Isla de En medio) mostraron niveles más bajos de tungsteno y un menor número de agujeros en su esqueleto. Nuestros resultados demuestran que las actividades antropogénicas en el NPVRS, están afectando el esqueleto de los corales y promueven la bioerosión. Las descargas de grandes cantidades de contaminantes hacia las zonas costeras, promueven el crecimiento de especies dañinas que crecen y se desarrollan dentro del esqueleto de los corales, causando bioerosión del esqueleto, haciéndolos susceptibles a enfermedades y daños físicos. Debido a que este estudio es la primera evidencia de los efectos de la contaminación sobre esta especie de corales, son necesarios más estudios para determinar el impacto de la contaminación sobre su biología y la supervivencia de los corales.

Composition and biological activities of the aqueous extracts of three scleractinian corals from the Mexican Caribbean: Pseudodiploria strigosa, Porites astreoides and Siderastrea siderea

Scleractinian corals (stony corals) are the most abundant reef-forming cnidarians found in coral reefs throughout the world. Despite their abundance and ecological importance, information about the diversity of their toxins and their biological activities is very scarce. In this study, the chemical composition and the biological activities of the aqueous extracts of Pseudodiploria strigosa, Porites astreoides and Siderastrea siderea, three scleractinian corals from the Mexican Caribbean, have been assessed for the first time. Methods: Toxicity of the extracts was assessed in crickets; the presence of cytolysins was detected by the hemolysis assay; the vasoconstrictor activity was determined by the isolated rat aortic ring assay; the nociceptive activity was evaluated by the formalin test. The presence of phospholipases A2 (PLA2), serine proteases, and hyaluronidases was determined by enzymatic methods. Low-molecular-weight fractions were obtained by gel filtration chromatography and ultrafiltration. Results: Extracts from the three species were toxic to crickets, induced hemolysis in human and rat erythrocytes, produced vasoconstriction on isolated rat aortic rings, and presented phospholipase A2 and serine-protease activity. Despite the fact that these corals are not considered to be harmless to humans, the extracts generated significant nociceptive responses. The matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry analysis of the low-molecular-weight fractions revealed the presence of peptides within a mass range of 3000 to 6000 Da. These fractions were toxic to crickets and two of them induced a transitory vasoconstrictor effect on isolated rat aortic rings. Conclusion: This study suggests that scleractinian corals produce low-molecular-weight peptides that are lethal to crickets and induce vasoconstriction.

Preliminary results with a torsion microbalance indicate that carbon dioxide and exposed carbonic anhydrase in the organic matrix are the basis of calcification on the skeleton surface of living corals / Los resultados preliminares con una microbalanza de torsión indican que el dióxido de carbono y la anhidrasa carbónica expuesta en la matriz orgánica son la base de la calcificación en la superficie del esqueleto de los corales vivos

Ocean acidification is altering the calcification of corals, but the mechanism is still unclear. To explore what controls calcification, small pieces from the edges of thin plates of Agaricia agaricites were suspended from a torsion microbalance into gently stirred, temperaturecontrolled, seawater. Net calcification rates were monitored while light, temperature and pH were manipulated singly. The living coral pieces were sensitive to changes in conditions, especially light, and calcification was often suspended for one or two hours or overnight. The mean calcification rate increased from 0.06 in the dark to 0.10 mg.h-1.cm-2 (T test, n=8, p<0.01) in low light (15 μmol.s-1.m-2) and showed a positive linear relationship with temperature. With a reduction of mean pH from 8.2 to 7.6 the mean calcification rate in the light (65 μmol.s-1.m-2) increased from 0.19 to 0.28 mg.h-1.cm-2 (T test, n=8, p<0.05) indicating a dependency on carbon dioxide. After waterpiking and exposure of the skeletal surface/organic matrix to seawater, calcification showed an astonishing initial increase of more than an order of magnitude then decreased following a non-linear generalised Michaelis-Menten growth curve and reached a steady rate. Calcification rate of the freshly waterpiked coral was not influenced by light and was positively correlated with temperature. For a mean pH reduction from 8.1 to 7.6 the mean calcification rate increased from 0.18 to 0.32 mg.h-1.cm-2 (T test, n=11, p<0.02) again indicating a dependency on carbon dioxide. Calcification ceased in the presence of the carbonic anhydrase inhibitor azolamide. Staining confirmed the presence of carbonic anhydrase, particularly on the ridges of septae. After immersion of waterpiked corals in seawater for 48 hours weight gain and loss became linear and positively correlated to temperature. When the mean pH was reduced from 8.2 to 7.5 the mean rate of weight gain decreased from 0.25 to 0.13 mg.h-1.cm-2 (T test, n=6, p<0.05) indicating a dependence on carbonate. At a pH of 6.5 the skeleton lost weight at a rate of 1.8 mg.h-1.cm-2. The relationship between net calcification and pH (n=2) indicates that wt gain turns to loss at pH 7.4. These experiments confirm that calcification is a two-step process, involving secretion of a layer of organic matrix incorporating carbonic anhydrase to produce an active calcifying surface which uses carbon dioxide rather than carbonate. It is also unlikely that the calcifying surface is in direct contact with seawater. Inorganic deposition or dissolution of the skeleton in exposed dead areas of coral is a different phenomenon and is carbonate related. The wide range in results from this and other studies of calcification rate and carbon dioxide may be explainable in terms of the ratio of “live” to “dead” areas of coral.

La acidificaión de los océanos está alterando la calcificón de los corales. Sin embargo, el mecanismo no es todavía claro. Para explorar que controla la calcificación piezas pequeñas del borde de láminas delgadas de Agaricia agaricites fueron suspendidas de una microbalanza de torsión en agua de mar ligeramente agitada y con temperatura controlada. La tasa neta de calcificación fue monitoreada mientras se manipulaba la luz, temperatura y pH. Las piezas de coral vivo fueron sensibles a cambios en las condiciones, especialmente de luz, y la calcificación se suspendía por una o dos horas o de un día para otro. La tasa media de calcificación aumentó de 0.06 en la oscuridad a 0.10 mg h-1 cm-2 (prueba T, n=8, p<0.01) en luminosidad baja (15 μmol s-1 m-2) y mostró una relación lineal positiva con la temperatura. Con una reducción en el pH promedio de 8.2 a 7.6 la tasa de calcificación media en la luz (65 μmol.s-1.m-2) aumentó de 0.19 a 0.28 mg h-1 cm-2 (prueba T, n=8, p<0.05) indicando una dependencia de dióxido de carbono. Después de remover el tejido y exponer la superficie de los esqueletos/matriz orgánica a agua de mar, la calcificación tiene un marcada aumento inicial de más de un orden de magnitud y después decrese siguiendo una curva generalizada Michaelis-Menten de crecimiento no-lineal hasta alcanzar una tasa estable. La tasa de calcificación de esqueletos recién limpiados no estaba influenciada por la luz y estaba positivamente correlacionado con la temperatura. Pra una reducción media de pH de 8.1 a 7.6 la tasa media de calcificaión aumentó de 0.18 a 0.32 mg h-1 cm-2 (prueba T, n=11, p<0.02) de nuevo indicando la dependencia en el dióxido de carbono. La calcificación cesó en la presencia de azolamida un inhibidor de la anhidrasa carbónica. Tinciones confirmaron la presencia de anhidrasa carbónica, particularmente en las crestas de los septos. Después de sumergir esqueletos sin tejido en agua de mar por 48 horas la ganancia y pérdida de peso se volvió lineal y relacionada positivamente con la temperatura. Cuando el pH promedio se reducía de 8.2 a 7.5 la tasa media de ganacia de peso decrecía de 0.25 a 0.13 mg h-1 cm-2 (prueba T, n=6, p<0.05) indicando una dependencia en carbonato. A un pH de 6.5 la tasa de pérdida de peso esquelético fue de 1.8 mg h-1 cm-2. La relación entre calcificaión neta y pH (n=2) indican que la gancia de peso se vuele pérdida a pH 7.4. Estos experimentos confirman que la calcificación es un proceso de dos pasos, involucrando la secreción de la capa de matriz orgánica que incorpora anhidrasa carbónica para producir una superficie de calcificación activa que usa dióxido de carbono en vez de carbonato. Es también poco probable que la superficie de calcificación esté en contacto directo con el agua de mar. La depositación o disolución inorgánica del esqueleto en áreas expuestas de corales muertos en un fenómeno diferente y está relacionado a los carbonatos. El gran ámbito de resultados de este y otros estudios sobre tasas de calcificación y dióxido de carbono pueden ser explicados en términos de la razón entre las zonas vivas y muertas de los corales.

Suppression subtractive hybridization PCR isolation of cDNAs from a Caribbean soft coral

Transcriptomic studies of marine organisms are still in their infancy. A partial, subtracted expressed sequence tag (EST) library of the Caribbean octocoral Erythropodium caribaeorum and the sea fan Gorgonia ventalina has been analyzed in order to find novel genes or differences in gene expression related to potential secondary metabolite production or symbioses. This approach entails enrichment for potential non-“housekeeping” genes using the suppression subtractive hybridization (SSH) polymerase chain reaction (PCR) method. More than 500 expressed sequence tags (ESTs) were generated after cloning SSH products, which yielded at least 53 orthologous groups of proteins (COGs) and Pfam clusters, including transcription factors (Drosophila Big Brother), catalases, reverse transcriptases, ferritins and various “hypothetical” protein sequences. A total of 591 EST sequences were deposited into GenBank [dbEST: FL512138 - FL512331, GH611838, and HO061755-HO062154]. The results represent proof of concept for enrichment of unique transcripts over housekeeping genes, such as actin or ribosomal genes, which comprised approximately 17 percent of the total dataset. Due to the gene and sequence diversity of some ESTs, such sequences can find utility as molecular markers in current and future studies of this species and other soft coral biogeography, chemical ecology, phylogenetics, and evolution.

Metabolitos secundarios, letalidad y actividad antimicrobiana de los extractos de tres corales y tres moluscos marinos de Sucre, Venezuela

Secondary metabolites, lethality and antimicrobial activity of extracts from three corals and three marine mollusks from Sucre, Venezuela. The study of biochemical activity of extracts obtained from marine organisms is gaining interest as some have proved to have efficient health or industrial applications. To evaluate lethality and antimicrobial activities, some chemical tests were performed on crude extracts of the octocorals Eunicea sp., Muricea sp. and Pseudopterogorgia acerosa and the mollusks Pteria colymbus, Phyllonotus pomum and Chicoreus brevifrons, collected in Venezuelan waters. The presence of secondary metabolites like alkaloids, unsaturated sterols and pentacyclic triterpenes in all invertebrates, was evidenced. Additionally, sesquiterpenlactones, saponins, tannins, cyanogenic and cardiotonic glycosides were also detected in some octocoral extracts, suggesting that biosynthesis of these metabolites is typical in this group. From the lethality bioassays, all extracts resulted lethal to Artemia salina (LC50<1.000μg/ml) with an increased of lethal activity with exposition time. P. pomum extract showed the highest lethality rate (LC50=46.8μg/ml). Compared to the octocorals, mollusks extracts displayed more activity and a greater action spectrum against different bacterial strains, whereas octocorals also inhibited some fungi strains growth. Staphylococcus aureus was the most susceptible to the antimicrobial power of the extracts (66.7%), whereas Pseudomonas aeruginosa, Candida albicans and Aspergillus niger were not affected. The antibiosis shown by marine organisms extracts indicates that some of their biosynthesized metabolites are physiologically active, and may have possible cytotoxic potential or as a source of antibiotic components. Rev. Biol. Trop. 58 (2): 677-688. Epub 2010 June 02.

A los extractos crudos de los octocorales Eunicea sp., Muricea sp. y Pseudopterogorgia acerosa y de los moluscos Pteria colymbus, Phylonotus pomum y Chicoreus brevifrons, se les realizaron pruebas químicas, las cuales evidenciaron en todos ellos, la presencia de metabolitos secundarios como alcaloides, esteroles insaturados y triterpenos pentacíclicos. Sólo se detectaron sesquiterpenlactonas, saponinas, taninos, glicósidos cianogénicos y glicósidos cardiotónicos en algunos de los extractos de los octocorales, lo cual sugiere que la biosíntesis de estos metabolitos es propia de este grupo de organismos. Asimismo, se evaluó la actividad letal y antimicrobiana de los extractos de los octocorales y moluscos. En el bioensayo de letalidad, todos los extractos resultaron letales frente al crustáceo Artemia salina (CL50<1.000μg/ml). La actividad letal incrementσ con el tiempo de exposiciσn. El extracto de P. pomum presentó la mayor actividad letal (CL50=46.8μg/ml). En los ensayos de actividad antimicrobiana, los extractos orgαnicos de los moluscos presentaron una mayor actividad y un espectro de acción mayor contra diferentes cepas de bacterias, respecto a los octocorales; aunque estos últimos también inhibieron el crecimiento de algunas cepas de hongos. Staphylococcus aureus, fue la bacteria más susceptible al poder antimicrobiano de los extractos (66.7%), mientras que la bacteria Pseudomonas aeruginosa y los hongos Candida albicans y Aspergillus niger, no fueron afectados. La antibiosis mostrada por los extractos de los diferentes invertebrados marinos estudiados, indica que algunos de los metabolitos biosintetizados por éstos son fisiológicamente activos con posible potencial citotóxico y/o antibiótico.

Response to short term ultraviolet stress in the reef-building coral Pocillopora capitata (Anthozoa: Scleractinia)

Coral reefs are impacted by a range of environmental variables that affect their growth and survival, the main factors being the high irradiance and temperature fluctuations. Specimens of Pocillopora capitata Verrill 1864 were exposed to photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) for 32h under laboratory conditions. We examined lipid peroxidation (MDA), antioxidant enzyme activities (SOD, CAT, GPx and GST), chlorophyll a (Chl a), carotenoid pigments (CPs), mycosporine-like amino acids (MAAs), and expulsion of zooxanthellae. Our results revealed that corals exposed to UVR had relatively low levels of carotenoids and antioxidant enzyme activities compared to those exposed to PAR, as well as lower CPs/Chl a ratios. Although MAAs and CPs are rapidly produced as non-enzymatic antioxidants in response to UVR in corals, these were not sufficient, even in the dark phase of the experiment, to mitigate the damage caused by formation of reactive oxygen species (ROS), which caused breakdown of the symbiotic relationship between the zooxanthellae and the host animal to an extent 33 times greater than in the PAR treatment. In this study, it could be possible to distinguish that, parallel to the short-term adjustments, such as the amount of pigment in the algae or the sensitivity of the photosynthetic response reported in other species of coral, P. capitata exhibits at the enzymatic level a series of responses oriented to resist the effects derived from the propagation of ROS and, thus, to adapt to and maintain its reproductive capacity in shallow oceanic environments that commonly exhibit high UVR levels. Nevertheless, as a result of the inappropriate location of the artificial intercommunication structure of the Juluapan Lagoon with respect to the arrecifal area of study and therefore of the tides influence, other variables, such as the changes in short-term in turbidity, sediment inputs, nutrients, temperature and osmolarity, can act in combination and cause irreversible damage. The implementation of a management plan for the coralline reefs of the Mexican Pacific coast is required. Rev. Biol. Trop. 58 (1): 103-118. Epub 2010 March 01.

Los arrecifes de coral se ven afectados por una serie de variables ambientales que afectan su crecimiento y supervivencia, siendo los principales factores la alta irradiación y las fluctuaciones de temperatura. Los especímenes de Pocillopora capitata Verrill 1864 fueron expuestos a radiación activa fotosintéticamente (PAR) y radiación ultravioleta (RUV) por 32h en condiciones de laboratorio. Nosotros determinamos las concentraciones de peroxidación lipídica (MDA), actividades de enzimas antioxidantes (SOD, CAT, GPx y GST), clorofila a (Chl a), pigmentos carotenoides (CPS), aminoácidos tipo micosporina (MAAS), y la expulsión de las zooxantelas. Nuestros resultados muestran que los corales expuestos a los rayos UV presentaban niveles relativamente bajos de carotenoides y actividad de las enzimas antioxidantes en comparación con los expuestos al PAR, así como tasas de CPs/Chl a bajas. Aunque MAAs y CPs se producen rápidamente como antioxidantes no enzimáticos en respuesta a la radiación ultravioleta en los corales, éstos no fueron suficientes, incluso en la fase oscura del experimento, para mitigar los daños causados por la formación de especies reactivas de oxígeno (ROS), lo que provocó una ruptura en la relación simbiótica entre las zooxantelas y el coral con una relación 33 veces mayor que en el tratamiento de PAR. A nivel enzimático, P capitata presentó una serie de ajustes orientados a resistir los efectos derivados de la propagación de ROS y con ello favorecer su adaptación y capacidad reproductiva en ambientes oceánicos caracterizados por altos niveles de UVR.

Antimicrobial activity of tissue and associated bacteria from benthic sea anemone Stichodactyla haddoni against microbial pathogens.

Associated bacteria from Stichodactyla haddoni are found maximum in tentacle tissues than the body tissue. There are eight associated bacterial species viz., Alcaligenes sp, Corynebacterium sp, Aeromonas sp, Sporosarcina sp, Renibacterium sp, Camobacterium sp1, Camobacterium sp2 and Salinococcus sp were recorded. The culture extracts from the associated bacterial species showed sensitivity against human bacterial and fungalpathogens. However, the hexane tissue extract of sea anemone showed maximum sensitivity (24 mm dia.) against the fish bacterial pathogen Aeromonas hydrophila than the other chosen pathogens. Comparatively the tissue extracts showed promising antimicrobial sensitivity than the cell free extracts of associated bacteria, and hence, the tissue samples from the sea anemone Stichodactyla haddoni is recommended for further exploration of novel antimicrobial drugs than the associated bacteria.

Relationship between anthropogenic impacts and bleaching-associated tissue mortality of corals in Curaçao (Netherlands Antilles) / Relación entre los impactos antropogénicos y la mortalidad tisular asociada al blanqueamiento de corales en Curaçao (Antillas Holandesas)

Chronic anthropogenic impacts can have a negative effect on coral health and on coral energy budgets needed for regeneration of lesions. I therefore hypothesise that during massive bleaching events, the degree of corals showing bleaching-related tissue mortality is higher in areas subject to chronic anthropogenic impacts than in relatively pristine areas. In the present study, the degree of bleaching and bleaching-related tissue mortality was estimated for eight abundant coral species in Curaçao, at the onset of a massive Caribbean bleaching event in 1995, and three months afterwards. To study the possible effects of anthropogenic disturbances, the study was done at four unpolluted control sites, two polluted sites (sedimentation, sewage), and four sites at the mouth of lagoons with outflow of nutrient-rich, warm and turbid seawater. No pattern of an overall difference in bleaching between impacted and control sites was found for the degree of bleaching. However, the percentage of corals showing bleaching-related tissue mortality was higher at the impacted sites than at the control sites for the total number of corals and for corals with < 50% of their surface area bleached. Highest and most significant values of tissue mortality were found at a reef site experiencing chronic pollution by raw sewage. The data thus suggest that unfavourable conditions caused by anthropogenic influences, such as increased sedimentation, eutrophication and seawater temperature, have an additional negative effect on the tissue survival of coral colonies during bleaching episodes. Rev. Biol. Trop. 54 (Suppl. 3): 31-43. Epub 2007 Jan. 15.

Los impactos antropogénicos crónicos pueden tener efectos negativos en la salud y en las cantidades de energía necesarias para la regeneración de lesiones en los corales. Mi hipótesis fue que durante los casos de blanqueamiento masivo, el grado en que los corales muestren mortalidades de tejido relacionadas con el blanqueamiento, será mayor en áreas sujetas a impactos antropogénicos crónicos que en áreas relativamente prístinas. Estimé los grados de blanqueamiento y mortalidad tisular en ocho especies de coral abundantes en Curaçao, durante el comienzo de un de blanqueamiento masivo en el Caribe en 1995 y tres meses después. El estudio se realizó en cuatro sitios control no contaminados, dos sitios contaminados (sedimentación, aguas residuales), y cuatro sitios en la boca de lagunas con aguas tibias, ricas en nutrientes y turbias. En general, no se encontró ningún patrónx de diferencias en el grado de blanqueamiento entre sitios. Sin embargo, el porcentaje de corales que mostraron mortalidad tisular relacionada con el blanqueamiento fue mayor en los sitios impactados que en los controles, tanto en el número total de corales como en corales con <50% de su superficie blanquedada. Los valores más altos y más significativos de mortalidad tisular se encontraron en un arrecife que experimentaba contaminación crónica por aguas residuales crudas. La información sugiere que las condiciones desfavorables causadas por la influencia antropogénica, como el incremento en la sedimentación, eutrofización y la temperatura del agua, tienen un efecto negativo adicional en la supervivencia del tejido de las colonias de coral, durante el blanqueamiento.

Development and field application of a molecular probe for the primary pathogen of the coral disease white plague type II

Abstract: One of the current problems in the field of coral disease research is that of tracking coral pathogens in the natural environment.A promising method to do this is by use of pathogen-specific molecular probes. However,this approach has been little used to date.We constructed,and validated in the laboratory,a fluoro-chrome-labeled molecular probe specific to Aurantimonas coralicida ,the bacterial pathogen of the Caribbean coral disease white plague type II (WPII).We then used the probe to test field samples of diseased coral tissue for the presence of this pathogen.Probe design was based on a unique subset (25 nucleotides)of the complete16S rRNA gene sequence derived from a pure culture of the pathogen.The pathogen-specific probe was labeled with the fluorochrome GreenStar*™FITC (fluorescein isothiocyanate,GeneDetect Ltd,New Zealand).As a control, we used the universal eubacterial probe EUB 338,labeled with a different fluorochrome (TRITC,tetra-methyl-rhodamine isothiocyanate).Both probes were applied to laboratory samples of pure cultures of bacteria, and field samples collected from the surface of the disease line of corals exhibiting signs of white plague (types I and II),healthy controls,and corals with an uncharacterized disease ("patchy necrosis ").All samples were analyzed using fluorescence in situ hybridization (FISH).We have determined that the probe is specific to our laboratory culture of the coral pathogen,and does not react with other bacterial species (the eubacterial probe does).The WPII pathogen was detected in association with diseased coral samples collected from coral colonies on reefs of the Bahamas (n=9 samples)exhibiting signs of both WPI and WPII.Diseased (and healthy)tissue samples (n=4)from corals exhibiting signs of "patchy necrosis "were also assayed.In this case the results were negative, indicating that the same pathogen is not involved in the two diseases.Incorporation and use of pathogen-specific probes can...

Chlorophyll a and turbidity patterns over coral reefs systems of La Parguera Natural Reserve, Puerto Rico

Abstract:Studies of temporal and spatial changes in phytoplankton biomass and turbidity provide essential information on coral reef ecosystem function and health.Fluctuation of phytoplankton biomass responds to several factors including nutrient inputs,both anthropogenic and natural,while turbidity is mostly affected by sediment resuspension or transport from terrestrial systems.These parameters can be used as sentinels of significant environmental factors "modifying "coral reef systems.A chlorophyll a concentration (Chl a )and turbidity (Turb)in situ logger was installed at 10 stations from June 4 to July 7,2003 in La Parguera Natural Reserve (Southwestern Puerto Rico)to assess short-term temporal and geographic variation in patterns of phytoplankton biomass and turbidity at pre-selected sites as part of an interdisciplinary long-term study.Average station Chl a variation was 0.17-1.12 µg l-1 and 0.2-23.4 NTU for Turb.Results indicate that the western near-coastal stations had higher levels of Turb and Chl a .The easternmost mid shelf station,Romero reef,was similar to coastal stations probably due to nutrient and suspended sediment inputs from a source external to our study area to the east,Guánica Bay.Comparisons between different sampling days indicate significant differences between days for most stations suggesting that one-time discrete sampling may not be representative of average water column conditions and illustrate the dynamic nature of coral reef systems.Further work is warranted to assess seasonal changes that integrate short-term (daily)variability in both Turb and Chl a.