Search

El Mar Caribe colombiano posee tanto arrecifes coralinos continentales costeros, como oceánicos. A partir de muestreos cuantitativos usando video-transectos de cadena, y análisis multivariados, se determinó que existen esquemas de variación espacial a pequeña (cientos de metros a unos pocos kilómetros) y a gran escala (decenas a cientos de kilómetros) en la composición y abundancia de organismos sésiles. Aunque estos arrecifes conforman una comunidad con las mismas especies de coral y otros organismos, en el sector continental existen exclusivamente las zonas arrecifales de Siderastrea siderea y Agaricia tenuifolia, y en el oceánico son particulares las terrazas prearrecifales y los arrecifes lagunares y periféricos de barlovento. Estas variaciones reflejan las diferentes historias geológicas, condiciones ambientales predominantes, frecuencia y duración de regímenes de perturbación, y estrategias de vida de especies preponderantes. Al interior de los sectores, la estructura de la comunidad parece estar gobenada por el grado de exposición al oleaje, la profundidad y la geomorfología. Las diferentes escalas en las que la comunidad responde al entorno deben ser tenidas en cuenta al tomar medidas de conservación y manejo en los arrecifes coralinos de Colombia.

Neopetrosia proxima (Porifera: Demospongiae: Haplosclerida) is described as a morphologically variable sponge common on shallow reefs of the Caribbean. However, the range of morphological and reproductive variation within putative N. proxima led us to hypothesize that such variability may be indicative of cryptic species rather than plasticity. Using DNA sequences and morphological characters we confirmed the presence of three previously undescribed species of Neopetrosia. Morphological differences of each new congener were best resolved by partial gene sequences of the mitochondrial cytochrome oxidase subunit 1 over nuclear ones (18S rRNA and 28S rRNA). Several new characters for Neopetrosia were revealed by each new species. For example, N. dendrocrevacea sp. nov. and N. cristata sp. nov. showed the presence of grooves on the surface of the sponge body that converge at the oscula, and a more disorganized skeleton than previously defined for the genus. N. sigmafera sp. nov. adds the (1) presence of sigma microscleres, (2) significantly wider/longer oxeas (>200 μm), and (3) the presence of parenchymella larvae. Sampling of conspecifics throughout several locations in the Caribbean revealed larger spicules in habitats closer to the continental shelf than those in remote island locations. Our study highlights the importance of integrating molecular and morphological systematics for the discrimination of new Neopetrosia spp. despite belonging to one of several polyphyletic groups (families, genera) within the current definition of the order Haplosclerida.

Coral reefs are commonly associated with oligotrophic, well-illuminated waters. In 2013, a healthy coral reef was discovered in one of the least expected places within the Colombian Caribbean: at the entrance of Cartagena Bay, a highly-polluted system that receives industrial and sewage waste, as well as high sediment and freshwater loads from an outlet of the Magdalena River (the longest and most populated river basin in Colombia). Here we provide the first characterization of Varadero Reef’s geomorphology and biological diversity. We also compare these characteristics with those of a nearby reference reef, Barú Reef, located in an area much less influenced by the described polluted system. Below the murky waters, we found high coral cover of 45.1% (±3.9; up to 80% in some sectors), high species diversity, including 42 species of scleractinian coral, 38 of sponge, three of lobster, and eight of sea urchin; a fish community composed of 61 species belonging to 24 families, and the typical zonation of a Caribbean fringing reef. All attributes found correspond to a reef that, according to current standards should be considered in “good condition”. Current plans to dredge part of Varadero threaten the survival of this reef. There is, therefore, an urgent need to describe the location and characteristics of Varadero as a first step towards gaining acknowledgement of its existence and garnering inherent legal and environmental protections.

Although sponges are important components of benthic ecosystems of the Caribbean Sea, their diversity remained poorly investigated in the Lesser Antilles. By organizing a training course in Martinique, we wanted both to promote taxonomy and to provide a first inventory of the sponge diversity on this island. The course was like a naturalist expedition, with a field laboratory and a classroom nearby. Early-career scientists and environmental managers were trained in sponge taxonomy. We gathered unpublished data and conducted an inventory at 13 coastal sites. We explored only shallow water habitats (0-30 m), such as mangroves, reefs or rocky bottoms and underwater caves. According to this study, the sponge fauna of Martinique is currently represented by a minimum of 191 species, 134 of which we could assign species names. One third of the remaining non-identified sponge species we consider to be new to science. Martinique appears very remarkable because of its littoral marine fauna harboring sponge aggregations with high biomass and species diversity dominating over coral species. In mangroves, sponges cover about 10% of the surface of subtidal roots. Several submarine caves are true reservoirs of hidden and insufficiently described sponge diversity. Thanks to this new collaborative effort, the Eastern Caribbean has gained a significant increase of knowledge, with sponge diversity of this area potentially representing 40% of the total in the Caribbean Sea. We thus demonstrated the importance of developing exploratory and educational research in areas historically devoid of biodiversity inventories and systematics studies. Finally, we believe in the necessity to consider not only the number of species but their distribution in space to evaluate their putative contribution to ecosystem services and our willingness to preserve them.

De la esponja marina Ágelas schmidti recolectada en la bahía de Santa Marta (Caribe Colombiano), se aisló por cromatografía en columna sobre silica gel la fracción esterólica. Los esteróles presentes en esta fracción fueron sometidos a Cromatografía Líquida de Alta Eficiencia preparativa en fase reversa y analizados por Cromatografía de Gases de Alta Resolución y Cromatografía de Gases de Alta Resolución acoplada a Espectrometría de Masas. De dieciocho esteróles separados, diecisiete fueron identificados presentando la mayoría de ellos núcleos A" y A' con cadenas laterales convencionales.

Long-term monitoring data provide a basis to recognize changes in coral reef communities and to implement appropriate management strategies. Unfortunately, coral reef dynamics have been poorly documented at any temporal scale in the Southern Caribbean. Through the "National Monitoring System of Coral Reefs in Colombia" (Spanish acronym: SIMAC), we assessed 32 permanent plots at different depth levels in six reefs areas of the Colombian Caribbean from 1998 to 2004. Temporal trends in coral and algal cover were evaluated by repeated measures ANOVA. The model included the effect of depth levels (a fixed effect), monitoring plots (a random effect) as a nested factor within depths, and time (repeated factor). We found high spatial variability in major benthic components. Overall means indicated that algae were the most abundant biotic component in nearly all areas, ranging from 30.3% at Rosario to 53.3% at San Andrés. Live coral cover varied considerably from 10.1% at Santa Marta up to 43.5% at Urabá. Coral and algae cover per se are not always accurate reef indicators and therefore they need supplementary information. Temporal analyses suggested relative stability of coral and algal cover along the study but the causes for the observed trends were rarely identified. A significant decrease (p=0.042) in coral cover was only identified for some monitoring plots in Tayrona-time x plot (depth level) interaction, and importantly, few coral species explained this trend. Significant increase (p=0.005) in algal cover was observed over time for most plots in Rosario. Temporal trajectories in algal cover were influenced by depth-significant time x depth interaction-in San Andrés (increase, p=0.004) and Urabá (decrease, p=0.027). Algae trends were mainly explained by changes in algal turfs. Monitoring programs must focus on the mechanisms mediating the changes, in particular those concerning coral recovery and reef resilience in the current context of climate change. Rev. Biol. Trop. 58 (Suppl. 1): 107-131. Epub 2010 May 01.

Las esponjas Aplysina insularis (con epitelio libre de epibiontes), y Aplysina lacunosa (con epitelio recubierto por epibiontes) fueron escogidas como modelo para estudiar algunos de los mecanismos químicos y bacterianos que podrían determinar su grado de epibiosis. A través de la técnica molecular de electroforesis en gel con gradiente desnaturalizante (DGGE), se determinó que la comunidad de epibiontes bacterianos varía entre individuos, pero en general es muy similar entre especies de esponja, sin ninguna relación con el grado de epibiosis. Para las dos especies, se detectaron diferencias en la presencia/ausencia de compuestos bromados bioactivos en las fracciones químicas del extracto crudo. Todas las fracciones químicas con compuestos bromados inhibieron el crecimiento de todas las cepas bacterianas aisladas de biopelículas asociadas a diferentes superficies (pinacodermo externo de A. insularis y A. lacunosa, pinacodermo del pseudoatrio de A. lacunosa, y una superficie inerte, la concha del bivalvo Donax sp.). Tres fracciones químicas de A. lacunosa y dos de A. insularis presentaron los niveles de actividad antibacteriana más altos. La susceptibilidad in vitro a las fracciones con compuestos bromados de las bacterias aisladas de las superficies limpias fue menor que aquellas aisladas de superficies con mayor grado de epibiosis. Asumiendo que los compuestos bromados son exudados, ellos podrían controlar el crecimiento de algunas poblaciones bacterianas in situ. Se sugiere que las sinuosidades morfológicas de la superficie de A. lacunosa restringen la exudación de compuestos bromados hacia las depresiones inhalantes, las cuales se mantienen limpias, mientras que esto permite que las crestas sean colonizadas, quizá para camuflarse. Las cepas bacterianas aisladas del pinacodermo externo y limpio de A. insularis presentaron una frecuencia alta de interacciones antagónicas in vitro con bacterias aisladas de la misma superficie, sugiriendo que las interacciones antagónicas pueden prevenir la epibiosis a través de la regulación del crecimiento bacteriano. Se discuten varios mecanismos por los cuales la epibiosis puede ser controlada.

La necesidad por obtener una utilidad tangible de los organismos marinos, ha generado un creciente interés por realizar estudios que permitan entender y por lo tanto aprovechar, sus características físicas, biológicas, químicas y ecológicas. La ecología química permite aproximarse a esto, por lo tanto, los estudios desarrollados en esta área encierran gran importancia. En el presente estudio se evaluó la actividad de los extractos orgánicos crudos de las esponjas marinas Cribrochalina vasculum y Biemna cribaria, en ensayos de antiepibiosis y disuasión de la alimentación de peces arrecifales generalistas. Estas dos especies mostraron inhibición positiva de la abundancia total, de organismos solitarios, de poliquetos e hidroides; B. cribaria inhibió adicionalmente la abundancia de cianofíceas, cobertura total y cobertura del alga parda. Así mismo, las píldoras preparadas con extracto de C. vasculum no disuadieron a los peces generalistas Stegastes partitus de alimentarse (97,5% de consumo), pero si mostraron rechazo por las píldoras con extracto de B. cribaria (37,5% de consumo). Lo que parece indicar que la esponja B. cribaria está mejor defendida químicamente contra la epibiosis y la depredación, mientras que C. vasculum parece tener un efecto atrayente sobre los peces, por lo que no mostró efectividad en este ensayo. Se propone a B. cribaria como una esponja con posibilidades en la industria de pinturas antiepibióticas, dada su mayor efectividad inhibitoria de epibiontes y su baja tasa de lixiviación. Ya que este es un primer acercamiento a la bioactividad de estas dos esponjas, surge la necesidad por continuar estudiando los aspectos ecológicos y químicos de los metabolitos que ellas producen.

Abstract  The Caribbean encrusting and excavating sponge Cliona tenuis successfully competes for space with reef corals by undermining, killing, and displacing live coral tissue at rates of up to 20 cm per year. The crude extract from this sponge, along with the more polar partitions, kills coral tissue and lowers the photosynthetic potential of coral zooxanthellae. We used a bioassay-guided fractionation of the extract to identify the compound(s) responsible. The crude extract, the aqueous partition, and compound 1, herein named clionapyrrolidine A [(−)-(5S)-2-imino-1-methylpyrrolidine-5-carboxylic acid], when incorporated into gels at close to natural volumetric concentrations, killed coral tissue when brought into forced contact with live coral for periods of 1–4 days. This is the first report of a pure chemical produced by a sponge that kills coral tissue upon direct contact. The results are consistent with the localized coral death that occurs when C. tenuis-colonized coral fragments are thrown forcibly against live coral during storms. However, healed C. tenuis fragments placed directly onto live coral were killed readily by coral defenses, and fragments placed in close proximity to coral did not have any effect on the adjacent coral tissue. Solutions of clionapyrrolidine A in sea water were only slightly toxic against live coral. Hence, the coral death naturally brought about by C. tenuis when undermining live coral does not occur through external release of allelochemicals; below-polyp mechanisms must be explored further. N-acetylhomoagmatine (2), originally isolated from Cliona celata from the Northeastern Atlantic, was also assayed for comparison purposes because of its structural similarity to siphonodictidine, a toxic compound produced by a coral excavating sponge of the genus Aka. The lack of activity of N-acetylhomoagmatine at close to natural concentrations seems to indicate that the guanidine moiety, which is also present in siphonodictidine, is not a sufficiently strong structural motif for activity against corals. [ABSTRACT FROM AUTHOR]