Chemical bioactivity of sponges along an environmental gradient in a Mediterranean cave

Abstract

SuMMarY: The bioactivity of the most abundant sponges from three communities in a Mediterranean cave was assessed by Microtox ® assay in two seasons, spring (June) and autumn (november). We quantified bioactivity as a proxy for the investment in production of biologically active substances, and we related sponge bioactivity to growth form, growth rates, and physical contacts of each species with other species. We established a threshold for classifying a species as bioactive based on a comparison between the results of the Microtox ® and the sea urchin embryo toxicity bioassay. a total of 30 species were included in the study, of which 50% were bioactive in some community or season. Significant ecological (between communities) and seasonal variation in mean bioactivity was found. When sponge bioactivity was related to sponge growth shape, it was found that the encrusting species tended to be more toxic than the non-encrusting ones. There was a negative relationship between bioactivity and sponge growth, suggesting a trade-off in energy allocation to defence and to other biological functions. Furthermore, a negative correlation was found between bioactivity and positive associations with other species. These results highlight the important role of chemically-mediated interactions in cave communities.Keywords: sponges, bioactivity, natural toxicity, Microtox ® assay, temporal variation, ecological variation, caves, western Mediterranean.reSuMen: Bioactividad química de las esponjas a lo largo de un gradiente ambiental en una cueva mediterránea. -La bioactividad de las esponjas más abundantes en tres comunidades a lo largo de una cueva mediterránea fue cuantificada por medio del bioensayo Microtox ® en dos estaciones, primavera (junio) y otoño (noviembre). La bioactividad medida se usó como una aproximación a la inversión en producción de sustancias bioactivas, y se relacionó la bioactividad de las esponjas con su morfología, tasas de crecimiento, y contactos de cada especie con otras. Se estableció un umbral para determinar si una especie es bioactiva mediante una comparación entre el test Microtox ® y el test de biotoxicidad en embriones de erizo. en total se estudiaron 30 especies, de las que un 50% fue bioactivo en alguna comunidad o estación del año. Se encontraron importantes diferencias ecológicas (entre comunidades) y estacionales en la bioactividad media. Cuando se relacionó la bioactividad con la morfología de las esponjas se encontró que las esponjas incrustantes tendían a ser más tóxicas que las de otras morfologías. Se detectó una correlación negativa entre bioactividad y crecimiento, lo que sugiere un balance entre inversión de energía en defensa y en otras funciones. Por otro lado, se encontró una correlación negativa entre bioactividad y las asociaciones positivas con otras especies. estos resultados ponen de manifiesto el importante papel de las interacciones mediadas por sustancias químicas en comunidades de cuevas.Palabras clave: bioactividad, toxicidad natural, bioensayo Microtox ® , variación t...

Spatial Variability in Secondary Metabolites of the Indo-Pacific Sponge Stylissa massa

“…Many biological or environmental factors can affect these patterns. Marine organisms can modify their levels of secondary metabolites in response to predation (e.g., Cronin and Hay, 1996a;Rohde et al, 2004), but other factors including nutrient availability, light, UV radiation, and temperature can also influence this plasticity (Uriz et al, 1995;Becerro and Paul, 2004;Turon et al, 2009). Investigations on the variability of secondary metabolites within a sponge species are scarce and controversial.…”

“…With a broad geographic distribution, S. massa is of both ecological and potential biotechnological importance on Indo-Pacific reefs. The variability of secondary metabolite production in sponges can be pronounced both on an inter-and intraspecific level (Turon et al, 1996;Betancourt-Lozano et al, 1998;Turon et al, 2009). Intraspecific production of secondary metabolites may vary among populations or even among individuals (Turon et al, 1996;Page et al, 2005).…”

Soft-bottom crustacean assemblages in Mediterranean marine caves: the cave of Cerro Gordo (Granada, Spain) as case study

“…The studies on hard-bottom assemblages suggest the processes determining spatiotemporal distribution patterns in marine caves to be highly complex, being context and scale dependent (BenedettiCechi et al 1998;Bussotti et al 2006). Thus, many other factors have been proposed to explain the distribution patterns observed (always for hard-bottom communities): physico-chemical gradients with respect to salinity, temperature, density and dissolved oxygen (Gili et al 1986;Zabala et al 1989;Harmelin 1997), diffusion-sedimentation processes (Garrabou and Flos 1995), the persistence of microlayer gradients along the walls (Gili et al 1986), variation in larval settlement and post-settlement events (Benedetti-Cechi et al 1996;Harmelin 1997;Denitto et al 2007), biotic interactions between species (Benedetti-Cechi et al 1996;Martí et al 2004bMartí et al , 2005Turon et al 2009), presence of hydrothermal springs (Benedetti-Cechi et al 1996, 1998, the depth and the exposure of the entrance (Corriero et al 2000;Bell 2002), differences in internal topography (Martí et al 2004a, b) and presence or absence of secondary openings (Zabala et al 1989). One of the main explications for the distribution of crustacean softbottom communities in the present study could be grain size.…”

Phylogeny Drives Large Scale Patterns in Australian Marine Bioactivity and Provides a New Chemical Ecology Rationale for Future Biodiscovery

“…Previous workers have sought to relate specific bioactivity to ecological function and small scale environmental gradients [47], [48] and use ecology and biology to explain intraspecific variability [33], [47], [48], [49], [50], [51], [52], [53]. However, there are no published studies that comprehensively integrate a diverse range of biodiversity and bioactivity measurements across vast bioregional and phylogenetic gradients.…”