The Experts below are selected from a list of 1236 Experts worldwide ranked by ideXlab platform
Olivia Harriott - One of the best experts on this subject based on the ideXlab platform.
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Sponge-specific bacterial symbionts in the Caribbean sponge, Chondrilla Nucula (Demospongiae, Chondrosida)
Marine Biology, 2006Co-Authors: Malcolm Hill, April Hill, Nora Lopez, Olivia HarriottAbstract:Marine sponges harbor dense and highly diverse bacterial communities, and some percentage of the microflora appears to be specialized for the sponge habitat. Bacterial diversity was examined in Chondrilla Nucula Schmidt to test the hypothesis that some subset of sponge symbiont communities is highly similar regardless of the species of host or habitat requirements of the host. C. Nucula was collected from a mangrove channel on Lower Matcumbe Key in the Florida Keys (25°53′N; 80°42′W) in August 1999. Domain-specific universal bacterial primers were used to amplify the 16S rDNA gene from genomic DNA that had been extracted from sponges and the surrounding water. An RFLP technique was used to assess diversity of sponge-associated and environmental bacterial communities. The clone library from C. Nucula contained 21 operational taxonomic units (OTUs). None of the 53 OTUs from adjacent water samples were found in the C. Nucula library indicating that a distinct community was present in the sponge. Sequence analysis indicated that C. Nucula harbors a microbial community as diverse as the microbes from other sponges in different habitats around the world. Phylogenetic analysis placed several C. Nucula clones in clades dominated by bacteria that appear to be sponge specialists (e.g., Acidobacteria, Bacteroidetes, and Cyanobacteria). Proportional representation of major bacterial taxonomic groups represented in symbiont communities was compared as a function of geographic location of sponge hosts. This study supports the hypothesis that sponges from different oceans existing in dissimilar habitats harbor closely related bacteria that are distinct from other bacterial lineages and appear specialized for residing within sponges.
Malcolm Hill - One of the best experts on this subject based on the ideXlab platform.
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Sponge-specific bacterial symbionts in the Caribbean sponge, Chondrilla Nucula (Demospongiae, Chondrosida)
Marine Biology, 2006Co-Authors: Malcolm Hill, April Hill, Nora Lopez, Olivia HarriottAbstract:Marine sponges harbor dense and highly diverse bacterial communities, and some percentage of the microflora appears to be specialized for the sponge habitat. Bacterial diversity was examined in Chondrilla Nucula Schmidt to test the hypothesis that some subset of sponge symbiont communities is highly similar regardless of the species of host or habitat requirements of the host. C. Nucula was collected from a mangrove channel on Lower Matcumbe Key in the Florida Keys (25°53′N; 80°42′W) in August 1999. Domain-specific universal bacterial primers were used to amplify the 16S rDNA gene from genomic DNA that had been extracted from sponges and the surrounding water. An RFLP technique was used to assess diversity of sponge-associated and environmental bacterial communities. The clone library from C. Nucula contained 21 operational taxonomic units (OTUs). None of the 53 OTUs from adjacent water samples were found in the C. Nucula library indicating that a distinct community was present in the sponge. Sequence analysis indicated that C. Nucula harbors a microbial community as diverse as the microbes from other sponges in different habitats around the world. Phylogenetic analysis placed several C. Nucula clones in clades dominated by bacteria that appear to be sponge specialists (e.g., Acidobacteria, Bacteroidetes, and Cyanobacteria). Proportional representation of major bacterial taxonomic groups represented in symbiont communities was compared as a function of geographic location of sponge hosts. This study supports the hypothesis that sponges from different oceans existing in dissimilar habitats harbor closely related bacteria that are distinct from other bacterial lineages and appear specialized for residing within sponges.
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Spongivory on Caribbean reefs releases corals from competition with sponges
Oecologia, 1998Co-Authors: Malcolm HillAbstract:Competition for space is an important process on tropical coral reefs. Few studies have examined the role sponges play in community structure despite the fact that many sponges are competitively superior to reef-building corals in space acquisition. Surveys conducted throughout the Florida Keys indicated that Chondrilla Nucula was involved in about 30% of all coral-sponge interactions; this sponge has also been observed in 40–50% of coral-sponge interactions on other Caribbean reefs. C. Nucula is also the top prey item of the Hawksbill turtle, and among the preferred prey of several spongivorous fish. I examined how predation influenced sponge competitive abilities (particularly those of C. Nucula), and whether this type of indirect effect had important consequences for community dynamics in the Florida Keys. Exclusion of sponge predators (primarily angelfish) resulted in increased sponge overgrowth, with a subsequent greater loss of coral cover, compared to uncaged pairwise interactions. When caged, the corals Dichocoenia stokesii and Siderastrea sideraea lost significantly greater surface area and number of polyps to the sponge C. Nucula compared to uncaged interactions. For caged interactions involving the sponge Ectyoplasia ferox, there was a trend for greater loss of S. sideraea surface area and polyps compared to uncaged interactions. Predation had a greater affect on C. Nucula than on any of the other sponges examined. Predator exclusion experiments performed with naturally occurring coral-sponge interactions demonstrated a significant decrease in total coral cover compared to uncaged controls. It is proposed that indirect effects arising from spongivory (especially consumption of C. Nucula) may have large community consequences. Species diversity on Caribbean reefs may be maintained, at least in part, by spongivores.
April Hill - One of the best experts on this subject based on the ideXlab platform.
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Sponge-specific bacterial symbionts in the Caribbean sponge, Chondrilla Nucula (Demospongiae, Chondrosida)
Marine Biology, 2006Co-Authors: Malcolm Hill, April Hill, Nora Lopez, Olivia HarriottAbstract:Marine sponges harbor dense and highly diverse bacterial communities, and some percentage of the microflora appears to be specialized for the sponge habitat. Bacterial diversity was examined in Chondrilla Nucula Schmidt to test the hypothesis that some subset of sponge symbiont communities is highly similar regardless of the species of host or habitat requirements of the host. C. Nucula was collected from a mangrove channel on Lower Matcumbe Key in the Florida Keys (25°53′N; 80°42′W) in August 1999. Domain-specific universal bacterial primers were used to amplify the 16S rDNA gene from genomic DNA that had been extracted from sponges and the surrounding water. An RFLP technique was used to assess diversity of sponge-associated and environmental bacterial communities. The clone library from C. Nucula contained 21 operational taxonomic units (OTUs). None of the 53 OTUs from adjacent water samples were found in the C. Nucula library indicating that a distinct community was present in the sponge. Sequence analysis indicated that C. Nucula harbors a microbial community as diverse as the microbes from other sponges in different habitats around the world. Phylogenetic analysis placed several C. Nucula clones in clades dominated by bacteria that appear to be sponge specialists (e.g., Acidobacteria, Bacteroidetes, and Cyanobacteria). Proportional representation of major bacterial taxonomic groups represented in symbiont communities was compared as a function of geographic location of sponge hosts. This study supports the hypothesis that sponges from different oceans existing in dissimilar habitats harbor closely related bacteria that are distinct from other bacterial lineages and appear specialized for residing within sponges.
Nora Lopez - One of the best experts on this subject based on the ideXlab platform.
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Sponge-specific bacterial symbionts in the Caribbean sponge, Chondrilla Nucula (Demospongiae, Chondrosida)
Marine Biology, 2006Co-Authors: Malcolm Hill, April Hill, Nora Lopez, Olivia HarriottAbstract:Marine sponges harbor dense and highly diverse bacterial communities, and some percentage of the microflora appears to be specialized for the sponge habitat. Bacterial diversity was examined in Chondrilla Nucula Schmidt to test the hypothesis that some subset of sponge symbiont communities is highly similar regardless of the species of host or habitat requirements of the host. C. Nucula was collected from a mangrove channel on Lower Matcumbe Key in the Florida Keys (25°53′N; 80°42′W) in August 1999. Domain-specific universal bacterial primers were used to amplify the 16S rDNA gene from genomic DNA that had been extracted from sponges and the surrounding water. An RFLP technique was used to assess diversity of sponge-associated and environmental bacterial communities. The clone library from C. Nucula contained 21 operational taxonomic units (OTUs). None of the 53 OTUs from adjacent water samples were found in the C. Nucula library indicating that a distinct community was present in the sponge. Sequence analysis indicated that C. Nucula harbors a microbial community as diverse as the microbes from other sponges in different habitats around the world. Phylogenetic analysis placed several C. Nucula clones in clades dominated by bacteria that appear to be sponge specialists (e.g., Acidobacteria, Bacteroidetes, and Cyanobacteria). Proportional representation of major bacterial taxonomic groups represented in symbiont communities was compared as a function of geographic location of sponge hosts. This study supports the hypothesis that sponges from different oceans existing in dissimilar habitats harbor closely related bacteria that are distinct from other bacterial lineages and appear specialized for residing within sponges.
Joseph R. Pawlik - One of the best experts on this subject based on the ideXlab platform.
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Variability in the chemical defense of the sponge Chondrilla Nucula against predatory reef fishes
Marine Biology, 1998Co-Authors: David C Swearingen, Joseph R. PawlikAbstract:Chondrilla Nucula is a common Caribbean demosponge that grows in a range of habitats, from coral reefs to mangrove swamps. On reefs, C. Nucula grows as a thinly encrusting sheet, while in mangrove habitats it surrounds submerged mangrove roots as fleshy, lobate clumps. Previous feeding experiments using predatory reef fish revealed a high degree of variability in the chemical defenses of C. Nucula. The present study was undertaken to determine whether a relationship exists between habitat, growth form, and chemical defense of C. Nucula. Both laboratory and field feeding-assays of crude extracts confirmed that C. Nucula possesses a chemical defense with high intercolony variability, but there was no significant variation in feeding deterrency between reef and mangrove habitats at either geographic location (Bahamas and Florida). Extracts of C. Nucula collected during September and October 1994 from the Bahamas were significantly more deterrent than those collected during August 1993, May 1994, and May 1995 from Florida, and extracts of these spring and summer Florida collections were more deterrent than extracts of C. Nucula collected in December 1994 and February 1995 in the same locations. There was no evidence that deterrent compounds were concentrated in the surface tissues of the sponge, or that chemical defense could be induced by simulated predation. Laboratory and field assays of the fractionated crude extract revealed that feeding deterrency was confined to the most polar metabolites in the extract. Field transplants were used to determine whether predation influenced the growth form of C. Nucula. Uncaged sponges transplanted from the mangrove to the reef were readily consumed by spongivorous reef fishes. Lobate mangrove sponges became thinner after being caged on the reef for 3 mo, but encrusting reef sponges did not become thicker after being caged in the mangroves for the same period of time. Reef sponges that were caged for 3 to 15 mo thickened by only a small amount (
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variability in the chemical defense of the sponge chondrilla Nucula against predatory reef fishes
Marine Biology, 1998Co-Authors: David C Swearingen, Joseph R. PawlikAbstract:Chondrilla Nucula is a common Caribbean demosponge that grows in a range of habitats, from coral reefs to mangrove swamps. On reefs, C. Nucula grows as a thinly encrusting sheet, while in mangrove habitats it surrounds submerged mangrove roots as fleshy, lobate clumps. Previous feeding experiments using predatory reef fish revealed a high degree of variability in the chemical defenses of C. Nucula. The present study was undertaken to determine whether a relationship exists between habitat, growth form, and chemical defense of C. Nucula. Both laboratory and field feeding-assays of crude extracts confirmed that C. Nucula possesses a chemical defense with high intercolony variability, but there was no significant variation in feeding deterrency between reef and mangrove habitats at either geographic location (Bahamas and Florida). Extracts of C. Nucula collected during September and October 1994 from the Bahamas were significantly more deterrent than those collected during August 1993, May 1994, and May 1995 from Florida, and extracts of these spring and summer Florida collections were more deterrent than extracts of C. Nucula collected in December 1994 and February 1995 in the same locations. There was no evidence that deterrent compounds were concentrated in the surface tissues of the sponge, or that chemical defense could be induced by simulated predation. Laboratory and field assays of the fractionated crude extract revealed that feeding deterrency was confined to the most polar metabolites in the extract. Field transplants were used to determine whether predation influenced the growth form of C. Nucula. Uncaged sponges transplanted from the mangrove to the reef were readily consumed by spongivorous reef fishes. Lobate mangrove sponges became thinner after being caged on the reef for 3 mo, but encrusting reef sponges did not become thicker after being caged in the mangroves for the same period of time. Reef sponges that were caged for 3 to 15 mo thickened by only a small amount (<1 mm) compared to uncaged and open-caged (i.e. in cages lacking tops) sponges. Simulated bite marks on both reef and mangrove sponges were repaired at a rapid rate (0.8 to 1.6 mm d−1). Fish predation has an important impact on the distribution and abundance of C. Nucula, but the thin growth form common to reef environments may be more the result of hydrodynamics than of grazing by spongivorous fishes.
