Massive hard coral loss after a severe bleaching event in 2010 at Los Roques, Venezuela / Pérdida masiva de coral duro después de un evento de blanqueamiento severo en 2010 en Los Roques, Venezuela

Thermal anomalies have become more severe, frequent and well-documented across the Caribbean for the past 30 years. This increase in temperature has caused coral bleaching resulting in reef decline. At Los Roques National Park, Venezuela, temperature has been monitored at four reef sites. In mid-September 2010, seawater temperature reached 30.85°C at 5 m depth in Los Roques, an archipelago only slightly affected by previous bleaching events. For example, bleaching in Los Roques in 2005 was mild compared to the rest of the Caribbean and to the results in this study. In 2010, seawater temperatures remained above 29.0°C from mid-August until the first week of November, resulting in +16 Degree Heating Weeks by that time. Our annual survey of four reef sites indicated that 72% of 563 scleractinian colonies were partial or totally bleached (white) or pale (discolored) in October 2010. In February 2011, there were still 46% of coral colonies affected; but most of them were pale and only 2% were bleached. By February, coral cover had declined 4 to 30% per transect, with a mean of 14.3%. Thus, mean coral cover dropped significantly from 45 to 31% cover (a 34% reduction). In addition to bleaching, corals showed a high prevalence (up to 16%) of black band disease in October 2010 and of white plague (11%) in February 2011. As a consequence, coral mortality is expected to be larger than reported here. Reef surveys since 2002 and personal observations for more than 20 years indicated that this bleaching event and its consequences in Los Roques have no precedent. Our results suggest that reef sites with no previous record of significant deterioration are more likely to become affected by thermal anomalies. However, this archipelago is relatively unaffected by local anthropogenic disturbance and has a high coral recruitment, which may contribute to its recovery.

Durante las últimas décadas las anomalías térmicas han sido más frecuentes y severas en el Caribe, quedando pocos arrecifes exentos de eventos masivos de blanqueamiento (EMB). En el Parque Nacional Los Roques, Venezuela, un archipiélago poco afectado previamente por EMB, la temperatura del agua a 5m de profundidad alcanzó 30,85°C en septiembre 2010, y fue >29,0°C entre mediados de agosto y la primera semana de noviembre en cuatro arrecifes. El 72% de 563 colonias de escleractinios estaban blanqueadas o pálidas para octubre de 2010, mientras que para febrero 2011, el 46% de las colonias aún estaban afectadas. Para febrero 2011, la cobertura béntica coralina promedio disminuyó de 45 a 31%. Además, los arrecifes mostraron una alta prevalencia (de hasta 16%) de enfermedad de banda negra en Octubre 2010, y de plaga blanca (11%) en Febrero 2011. Como consecuencia, es probable que la mortalidad coralina resulte mayor a la reportada acá. Sin embargo, Los Roques es poco afectado por perturbaciones antropogénicas y cuenta con un alto reclutamiento de corales, lo cual podría contribuir a su recuperación.

Severity of the 1998 and 2005 bleaching events in Venezuela, southern Caribbean

This study describes the severity of the 2005 bleaching event at 15 reef sites across Venezuela and compares the 1998 and 2005 bleaching events at one of them. During August and September 2005, bleached corals were first observed on oceanic reefs rather than coastal reefs, affecting 1 to 4% of coral colonies in the community (3 reef sites, n=736 colonies). At that time, however, no bleached corals were recorded along the eastern coast of Venezuela, an area of seasonal upwelling (3 reefs, n=181 colonies). On coastal reefs, bleaching started in October but highest levels were reached in November 2005 and January 2006, when 16% of corals were affected among a wide range of taxa (e.g. scleractinians, octocorals, Millepora and zoanthids). In the Acropora habitats of Los Roques (an oceanic reef), no bleached was recorded in 2005 (four sites, n=643 colonies). At Cayo Sombrero, a coastal reef site, bleaching was less severe in 1998 than in 2005 (9% of the coral colonies involving 2 species vs. 26% involving 23 species, respectively). Our results indicate that bleaching was more severe in 2005 than in 1998 on Venezuelan reefs; however, no mass mortality was observed in either of these two events. Rev. Biol. Trop. 58 (Suppl. 3): 189-196. Epub 2010 October 01.

En este estudio se describe la severidad del evento de blanqueamiento del 2005 en 15 arrecifes coralinos de Venezuela, y se compara con el ocurrido en 1998 para uno de esos arrecifes. Los primeros corales blanqueados se observaron en agosto y septiembre 2005, en arrecifes oceánicos en lugar de costeros, afectando entre 1 y 4% de las colonias coralinas (3 arrecifes, n= 736 colonias). Para ese momento, tampoco se había detectado blanqueamiento en áreas oceánicas de la costa este de Venezuela (3 arrecifes, n= 181 colonias), donde ocurre una surgencia estacional. En arrecifes costeros, el blanqueamiento comenzó en octubre pero alcanzó su máximo entre noviembre 2005 y enero 2006, afectando hasta el 16% de los organismos de una variedad de taxa (e.g. escleractinios, octocorales, Millepora, zoántidos). En los hábitats de Acropora de Los Roques, no se observó blanqueamiento en el 2005 (4 sitios oceánicos, n= 643 colonias). En Cayo Sombrero, un arrecife costero, el blanqueamiento fue menos severo en 1998 comparado con el de 2005 (9% de colonias coralinas de 2 especies vs. 26% de colonias de 23 especies, respectivamente).Estos resultados indican que el blanqueamiento del 2005 fue más severo que el de 1998 en los arrecifes de Venezuela, sin embargo, no ocurrió mortalidad masiva asociada a ninguno de los dos eventos.

What can two years of monitoring tell us about Venezuelan coral reefs? The Southern Tropical America node of the Global Coral Reef Monitoring Network (STA-GCRMN)

In spite of their economic importance, coral reef communities of the world are rapidly decreasing, and an adequate management planification is needed. The benthic and fish communities of Dos Mosquises Sur and Madrizquí at Los Roques National Park, and Caiman and Cayo Norte at Morrocoy National Park, in Venezuela were monitored during 2003 and 2004. The CARICOMP method was used to describe the benthic community, and the AGRRA protocol was applied to the fish community assessment. The benthic cover of five broad living categories (i.e. corals, algae, sponge and octocorals) differed across the sites (Nested ANOVA, p < 0.05), but there were no statistical differences between parks. Despite being on different parks, the benthic cover in Dos Mosquises Sur and Cayo Norte was similar (76% based on Bray-Curtis), whereas Caiman differed greatly (57- 68%) from all other sites. The cover of hard coral, algae, sponges and octocorals was similar between 2003 and 2004 in all four sites. Similarly, the fish community structure of both parks did not change over time, and was dominated by herbivores (Pomacentridae, Scaridae and Acanthuridae). However, commercially important carnivores (e.g. Lutjanids and Serranids) were more abundant in Los Roques than in Morrocoy. Although it was expected that the benthic cover and fish community would reflect greater differences between Los Roques and Morrocoy, only the fish community appeared healthier in Los Roques, whereas Cayo Norte (Morrocoy), had a coral cover similar or higher than both sites of Los Roques. Thus, our results suggest that in Venezuela, oceanic reef sites are not necessarily ‘healthier’ (i.e. higher coral cover) than land-influenced coral communities. The addition of three new sites and the reincorporation of Caiman has improved and expanded the monitoring capabilities in Venezuela and it represents the first step towards the consolidation of a coral reef monitoring program for the country. Rev. Biol. Trop. 58 (Suppl. 1): 51-65. Epub 2010 May 01.

En este estudio se describe la condición de las comunidades bentónicas e ictícolas en cuatro arrecifes que fueron monitorizados durante 2003 y 2004 en Venezuela: Dos Mosquises Sur y Madrizquí en el Parque Nacional Archpiélago Los Roques y Caimán y Cayo Norte en el Parque Nacional Morrocoy. Para ello, empleamos los protocolos de CARICOMP y AGRRA para describir la comunidad bentónica e ictícola, respectivamente. La cobertura de los cinco principales grupos bentónicos difirió entre arrecifes (ANOVA anidado, p < 0.05) más no entre parques. A pesar de pertenecer a diferentes parques la estructura de la comunidad bentónica entre Dos Mosquises Sur y Cayo Norte mostró un índice de similitud (Bray-Curtis) de 76%, mientras que Caiman difirió entre 57 y 68% con respecto a todos los arrecifes. Como se esperaba, la cobertura coralina, algas esponjas y octocorales no cambió entre 2003 y 2004. De forma similar, la comunidad de peces tampoco cambió en el tiempo y estuvo dominada por especies de herbívoros (Pomacentridae, Scaridae and Labridae). Sin embargo, en Los Roques los carnívoros de importancia comercial (e.g. lutjanidos y serranidos) fueron más abundantes que en Morrocoy. Aunque se esperaba encontrar diferencias en la comunidad bentónica e ictícola de Los Roques y Morrocoy, solo la de peces reflejó las diferencias, encontrándose en mejor estado de salud en Los Roques, mientras que CNOR, localizado en Morrocoy, presentó una cobertura similar o ligeramente mayor que los arrecifes localizados en Los Roques. Por lo tanto, los resultados de este estudio muestran que los arrecifes oceánicos no necesariamente se encuentran en mejor estado que los costeros. La inclusión de 3 nuevos sitios y la reincorporación de Caimán ha expandido y mejorado las capacidades de monitoreo de Venezuela y representa el primer paso hacia la creación de un sistema de monitoreo de arrecifes en el país.

Algunas características funcionales de las comunidades bacterianas del mucus asociado a tejidos sanos y con síndrome de banda amarilla / Some functional characteristics of the bacterial communities of the mucus associated to healthy fabrics and with syndrome of yellow band

Se caracterizaron y compararon algunas propiedades funcionales de las comunidades bacterianas asociadas a la capa de mucopolisacáridos en tejidos sanos y enfermos con banda amarilla del coral Montrastrea annularis. Tres colonias con este síndrome fueron seleccionadas y se colectó una muestra de mucus asociado a tejidos normales y afectados de cada individuo, succionando cuidadosamente la superficie de cada colonia con jeringas estériles de 5ml. Se tomaron muestras de agua con 1m encima de cada colonia con frascos esterilizados de 10ml. Las muestras se trasladaron al laboratorio en cavas con hielo para el aislamiento de cepas bacterianas (48h) con métodos microbiológicos estándar. Se seleccionaron aleatoriamente 25 cepas de cada muestra para realizar pruebas bioquímicas y estudiar las características de las comunidades bacterianas heterotróficas en cada comportamiento. Se estudió la hidrólisis de azúcares, degradación de citrato, lípidos y proteínas redicción de nitratos y actividad ureásica, y crecimiento aeróbico, y anaeróbico. Las características funcionales de cada se compararon mediante análisis de agrupamiento. Las comunidades bacterianas asociadas al mucus de tejidos enfermos tuvieron mayor proporción (60 por ciento) de bacterias capaces de degradar lípidos y proteínas, y mostraron alta actividad ureásica (40 por ciento) comparada con las muestras de agua (10 por ciento). Más del 70 por ciento de las cepas estudiadas redujeron nitratos a nitritos y crecieron en condiciones aeróbicas y anaeróbicas. La alta actividad lipolítica y proteolítica, y la gran proporción de bacterias capaces de desdoblar úrea en el mucus asociado a tejidos enfermos pudieran estra relacionadas con el desarrollo del síndrome de Banda Amarilla y con la mortandad de tejidos en colonias enfermas

Evaluacion de las actividades del buceo recreativo sobre la estructura comunitaria de algunos arrecifes del Parque Nacional Archipielago de Los roques, Venezuela / Evaluation of the impact of recreational dive activity on the community structure of some coral reefs at Los Roques Archipelago National Park, Venezula

In order to evaluate if snorkeling had significant effects on coral community structure, three different coral reefs (Madrizqui, Pelona de Rabusqui and Crasqui) located at Archipelago Los Roques National Park, Venezuela, were surveyed. For each site, the coral community structure of two different areas, one subjected to intense snorkeling use (FB) and other not frequently used (PFB), were compared. Community structure was determined with 1 m2-quadrants and 20 m-long transects. These communities were described in terms of species richness, diversity (Shannon-Wiener) and evenness indexes, live and dead coral cover and cover of other organisms (sponges, octocorals and algae). Comparisons within sites were performed with a Kruskall-Wallis test. A total of 24 species of scleractinian corals were found. Live coral cover ranged from 29.9 +/- 26.43 (Crasqui) to 34.55 +/- 6.43 (Madrizqui), while dead coral cover ranged from 32.51 +/- 2.86 (Madrizqui) to 60.78 +/- 21.3 (Pelona de Rabusqui). The PFB areas showed higher live coral cover compared to FB areas; however, significant differences were only found in Crasqui and Pelona de Rabusqui (p < 0.05). Species richness, diversity and evenness were variable and no trends were observed between FB and PFB areas. The frequency of both damaged and diseased colonies were low (< 1), most damages observed were natural (parrotfish predation). Damages caused by divers such as fin impacts, were not found at the reefs studied. These results suggest that, currently, diving pressure is not as high to cause massive loses of live coral cover in these reefs. However, the lack of strict controls for these activities might produce long-term changes in the structure of these coral communities.

Estado actual de las enfermedades y otros signos de deterioro coralino en siete arrecifes del Parque Nacional Archipielago de Los Roques, Venezuela / Present state of diseases and other signs of reef deterioration at seven coral reefs at Los Roques Archipelago National Park, Venezuela

This work was aimed to determine the incidence of coral diseases in six different reef sites at the Parque Nacional Archipielago de Los Roques, Venezuela: Arrecife de herradura, Arrecife costanero, both at Dos Mosquises Sur Key, Boca de Cote, Carenero, Crasqui and Pelona de Rabusqui. Each reef was surveyed by using ten 10 m2-band transects (10 x 1 m), placed parallel to the long axis of the reef within a depth gradient ranging from 1 to 9 m depth. All healthy and injured corals, along each band transect, were counted and identified to species level. Additionally, all diseases and recent mortality that were still identifiable on each colony were also recorded. The occurrence of diseased colonies and other signs of reef decline between localities were compared by means of a Chi2 test. The absolute, relative and mean incidence was estimated for each disease and other signs of damage observed for all coral species surveyed at each site. The overall incidence of coral diseases was low for all the localities surveyed, only 6.04 of the 3 344 colonies observed, showed signs of diseases. The most important diseases recorded were the Yellow-Blotch Disease (YBD) and Dark Spots Disease (DSD) with 2.1 +/- 1.52 y 2.1 +/- 2.54, respectively. Significant differences were found in the incidence of coral diseases between reef sites (Chi2 p < 0.05). Finally, the occurrence of colonies injured by parrotfish bites and pomacentrids was higher compared with the incidence of coral diseases for all the reefs surveyed. In conclusion, currently the proportion of healthy colonies at Los Roques coral reefs is higher than the percentage of both diseased and injured colonies.

¿Las enfermedades en corales escleractinidos: un nuevo problema en el arrecife de Cayo Sombrero, Parque Nacional Morrocoy, Venezuela? / Disease in scleractinian corals: a new problem in the reef at Cayo Sombrero, Morrocoy National Park, Venezuela?

At the beginning of 1996 coral reefs in Morrocoy National Park, Venezuela, suffered an unprecedented mass mortality event. As a consequence, live coral cover dropped to 2-10. One of the few reefs that kept live coral cover over 35 was Cayo Sombrero; nonetheless, the presence of some coral diseases has been detected within the past 2 years, representing a new source of coral mortality. Due to this situation, this study started a monitoring program on the incidence of coral diseases and syndromes in the reef of Cayo Sombrero. The CARICOMP protocol was used in order to evaluate reef health. Ten parallel band-transects (20 x 2m) where established at two depth intervals: Five between 3-8 m and five between 8-12 m, and the frequency of both, healthy and unhealthy colonies of each coral species was recorded along each band transect. In addition to other sources of coral damage (predation, siltation, etc), significant differences in disease incidence between the two depths intervals were tested with a Kruskall-Wallis test. The main problems observed were coral diseases such as yellow band (4.2), dark spots (1.61) and white plague-II (1.4), mainly affecting Montastraea faveolata, M. annularis and Siderastrea siderea. Siltation, affecting massive colonies, such as Colpophyllia natans and Diploria strigosa; algae overgrowth, predation, anchor damage, and bleaching. Significant differences were found in the incidence of unhealthy (Kruskall-Wallis, p < 0.05) bleached (Kruskall-Wallis, p < 0.05) and colonies affected by siltation (Kruskall-Wallis, p < 0.05). More than 60 of the 585 coral colonies surveyed at both depths were found to be healthy, indicating that the Cayo Sombrero reef is still in good conditions compared to other localities in the Park. This study stresses the need to conduct early monitoring programs that survey coral disease incidence as a source of mortality for this coral reef.

White plague disease outbreak in a coral reef at Los Roques National Park, Venezuela

Coral diseases have been reported as a major problem affecting Caribbean coral reefs. During August 2000, a coral mortality event of White Plague Disease-II (WPD-II) was observed at Madrizqui Reef in Los Roques National Park, Venezuela. This disease was identified as the major cause of coral mortality, affecting 24 of all colonies surveyed (n = 1 439). Other diseases such as Black Band Disease (BBD), Yellow Blotch Disease (YBD), Dark Spots Disease (DSD) and White Band Disease (WBD) were also recorded, but showed a lower incidence (0.14-0.97). Two depth intervals, D1 (5.5-6.5 m) and D2 (9-9.5 m) were surveyed with two sets of three band transects 50 x 2 m long, placed parallel to the long axis of the reef. All healthy and injured corals, along each band transect, were counted and identified to species level. Additionally, all diseases and recent mortality that were still identifiable on each colony also were recorded. The incidence of colonies affected by WPD-II ranged from 12.8 to 33 among transects, where thirteen species of scleractinian corals showed several degrees of mortality. The species most affected were Montastraea annularis (39.13), M. faveolata (26.67), M. franksi (9.86), Stephanocoenia intersepta (7.25), Colpophyllia natans (6.96), Diploria labyrinthiformis (2.99), Mycetophyllia aliciae (2.03), M. cavernosa (1.74), and D. strigosa (1.45). WPD-II was more common in the deeper strata (9-9.5 m), where 63 of the surveyed colonies were affected, although the disease was present along the entire reef. Presently, it is imperative to determine how fast the disease is spreading across the reef, how the disease spreads across the affected colonies and what the long-term effects on the reef will be.

Environmental factors affecting tissue regeneration of the reef--building coral Montastraea annularis (Faviidae) at Los Roques National Park, Venezuela

In this study, the rates of tissue regeneration and recovery from injuries that emulated the bites of either butterfly or parrotfish on colonies of Montastraea annularis exposed to different sedimentation regimesp were determined. Two small reef patches were chosen close to key Dos Mosquises, north of the Venezuclan mainland. Sixteen colonies (8 treatments + a single replicate) were artificially damaged at each patch and their recovery was monitored for three months by photographic means. The lesions were inflicted using two different techniques: scratching the polyps with a hard-nylon brush to resemble parrotfish (Scaridae) damages (Lesions Type 1) or jetting out the tissue with a syringe to simulate butterflyfish (Chaetondontidae) bites (Lesions Type 2). The diameter of the wounds ranged from 5 (small lesion) to 8 cm (large lesions) and both kinds were inflicted on the top and bottom of the colonies, with a single replicate for each treatment. The main factors affecting the recovery of the colonies' surface were lesion features (type, position and size), turbidity and chiefly, the sedimentation rate...

Relación entre la incidencia de enfermedades y la estructura de tallas y especies en corales del Parque Nacional Archipiélago de los Roques, Venezuela / Relationship between disease incidence and size structure and species of corals at the Archipiélago de Los Roques National Park, Venezuela

Este trabajo tiene como objetivo determinar si la incidencia de las enfermedades que afectan a corales escleractínidos es independiente del tamaño de las colonias y de las especies afectadas. Se seleccionó un total de siete estaciones de muestreo ubicadas en cinco de los cayos más visitados del Parque Nacional Archipiélago de Los Roques. En cada localidad, se establecieron diez transectas de 10 x lm paralelas a la costa, entre 3 y 9m de profundidad. Sobre éstas se identificaron las especies de coral y las colonias sanas y enfermas presentes. Se estimó el tamaño de las colonias enfermas midiendo sus diámetros máximo y mínimo. Se identificaron 4 intervalos de tallas según el área obtenida. Para comprobar si la incidencia de enfermedades era independiente del tamaño de las colonias y de las especies afectadas, se construyeron tablas de contingencia a partir de los valores de incidencia observados, reunidas para todas las localidades y profundidades estudiadas. Las enfermedades más comunes en los arrecifes estudiados fueron banda amarilla, lunares oscuros, banda negra, banda blanca y la plaga blanca. Se encontraron diferencias significativas entre la frecuencia de las diferentes enfermedades y las distintas especies afectadas (X²=398,10; gl=25; alfa=0,05). La enfermedad de banda amarilla afectó principalmente a las especies M.annularis y M.faveolata, la de lunares oscuros fue observada principalmente sobre S.siderea, S.intersepta y M.annularis. La enfermedad de banda blanca sólo fue registrada sobre A.cervicornis y la de banda negra afectó principalmente a M.annularis y D.strigosa. Se encontraron diferencias significativas entre la frecuencia de las diferentes enfermedades registradas y los distintos intervalos de tallas de las colonias afectadas (X²=43,81; gl=24; alfa=0,05)

Población de Lytechinus variegatus (Echinoidea: Toxopneustidae) y caracterÝsticas estructurales de las praderas de Thalassia testudinum en la Bahía de Mochima, Venezuela / Population of Lytechinus variegatus (Echinoidea: Toxopneustidae) and structural characteristics of seagrass of Thalassia testudinum in Mochima Bay, Venezuela)

To compare the general features of Thalassia testudinum seagrass at Mochima Bay with sea urchin (Lxtechinus variegatus) abundance and distribution, three T. testudinum seagrass beds were selected, from the mouth (strong wave exposure) to the inner bay (calm waters). Each site was surveyed by using 5 line transects (20 m long) parallel to the coast and 1 m2 quadrats. In situ measurements of T. testudinum cover, shoot and leaf density were taken. Estimation of dry biomass for each seagrass fraction (leaves, rhizomes and roots) and leaf length were obtained from 25 vegetation samples extracted per site using cores (15 cm diameter). A multivariate analysis of variance (Manova) and a less significative difference test (LSD) were performed to examine differences between sites and within sites at different depths. A stepwise multiple regression analysis was done, dependent variable was sea urchin density; independent variables: vegetation values at each site. The only seagrass species found in the three sites was T. testudinum, and cover was 56-100, leaf density 100-1000 leaf/m2, lengths 6-18.8 cm and shoot density 20-475 shoots/m2. The highest sea urchin densities were found at Isla Redonda and Ensenada Toporo (1-3.6 ind/m2), the lowest at Playa Colorada (0.6-0.8 ind/m2). Significant differences in seagrass features between sites were obtained (Manova p < 0.001), but not between depths (Manova p < 0.320). The regression coefficient between sea urchin density and seagrass parameters was statistically significant (r2 = 0.154, p < 0.007), however, total biomass was the only variable with a significant effect on sea urchin distribution (beta = 0.308, p < 0.032). The other variables did not explain satisfactorily L. variegatus abundance and distribution.

Programa caricomp: monitoreo a largo plazo de los ecosistemas marinos del Parque Nacional Morrocoy, Venezuela / Carimp program: long-term monitoring of marine ecosystems at Morrocoy National Park, Venezuela

Se reportan los resultados recabados durante la ejecución del programa CARICOMP (Caribbean Coastal Marine Productivity). Este programa tiene como objetivo principal estudiar la estructura y funcionamiento de los tres principales ecosistemas costeros del Caribe: bosques de manglares, praderas de fanerógamas marinas y arrecifes coralinos. En estos estudios participan actualmente más de 12 laboratorios de nueve países caribeños, formando una red de centros integrados. En Venezuela el programa está representado por la Fundación La Salle y por el INTECMAR (USB), instituto que ha monitoreado rutinariamente estos ambientes en el Parque Nacional Morrocoy durante casi una década, desde 1992 hasta el presente. Así, se han registrado variables fisicoquímicas y biológicas en varias localidades, determinándose la estructura, composición y productividad de estos sistemas marinos. Esta información permite establecer comparaciones con los datos obtenidos por los otros laboratorios, proporcionando una base de datos local y regional lo suficientemente robusta como para documentar (a largo plazo) respuestas de umbral de estos ecosistemas a los cambios globales, incluyendo impactos humanos y cambios climáticos