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Structuring effects of chemicals from the sea fan Phyllogorgia dilatata on benthic communities

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ABSTRACT

Despite advances in understanding the ecological functions of secondary metabolites from marine organisms, there has been little focus on the influence of chemically-defended species at the community level. Several compounds have been isolated from the gorgonian octocoral Phyllogorgia dilatata, a conspicuous species that forms dense canopies on rocky reefs of northern Rio de Janeiro State, Brazil. Manipulative experiments were performed to study: (1) the effects of live colonies of P. dilatata (physical presence and chemistry) on recruitment of sympatric benthic organisms; (2) the allelopathic effects of its chemicals on competitors; and (3) chemotactic responses of the non-indigenous brittle star, Ophiothela mirabilis. Early establishment of benthic species was influenced on substrates around live P. dilatata colonies and some effects could be attributed to the gorgonian’s secondary metabolites.In addition, the gorgonian chemicals also exerted an allelopathic effect on the sympatric zoanthid Palythoa caribaeorum, and positive chemotaxis upon O. mirabilis. These results indicate multiple ecological roles of a chemically-defended gorgonian on settlement, sympatric competitors, and non-indigenous species.

No MeSH data available.


Total area of zoanthid P. caribaeorum tissue coverage over diffusion chambers treated with P. dilatata crude extract (triangles) and over controls (circles).(∗) = Wilcoxon test, zoanthid cover was higher for extract-treated chambers compared to controls at 42 days (T2) (Z = 2.2, p = 0.03, n = 6) and 57 days (T3) (Z = 2.2, p = 0.03, n = 6). Error bars = S.E.
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fig-8: Total area of zoanthid P. caribaeorum tissue coverage over diffusion chambers treated with P. dilatata crude extract (triangles) and over controls (circles).(∗) = Wilcoxon test, zoanthid cover was higher for extract-treated chambers compared to controls at 42 days (T2) (Z = 2.2, p = 0.03, n = 6) and 57 days (T3) (Z = 2.2, p = 0.03, n = 6). Error bars = S.E.

Mentions: At the first monitoring (T1, 16 days), there was no difference between cover of the zoanthid P. caribaeorum over diffusion chambers with and without crude extract of P. dilatata (Wilcoxon test: Z = 1.8, p = 0.074, n = 6). After 42 days (T2), coverage of P. caribaeorum on control chambers was significantly higher than for chambers with the crude extract of P. dilatata (Wilcoxon test: Z = 2.2, p < 0.05, n = 6) (Fig. 7). Although P. caribaeorum cover declined over the control chamber thereafter, cover remained significantly higher compared to the extract-treated chamber at T3 (57 days; Wilcoxon test: Z = 2.2, p < 0.05, n = 6) and zoanthid colonies were still healthy. The total area of P. caribaeorum tissue over chambers at each monitoring event is given in Fig. 8. Diffusion control gels retrieved from the field were re-extracted and thin layer chromatography (TLC) analysis revealed that overall chemical profiles were similar throughout the experiment. Although percentage mean retention was not calculated, the same procedure used in Da Gama et al. (2002) was categorically repeated in order to increase compounds preservation in gels. These authors retrieved an average of 43% of original extracts after 6 weeks. According to Henrikson & Pawlik (1995), phytagel is a resilient material, also standing periods of up to 6 weeks (42 days) with no evidence of degradation.


Structuring effects of chemicals from the sea fan Phyllogorgia dilatata on benthic communities
Total area of zoanthid P. caribaeorum tissue coverage over diffusion chambers treated with P. dilatata crude extract (triangles) and over controls (circles).(∗) = Wilcoxon test, zoanthid cover was higher for extract-treated chambers compared to controls at 42 days (T2) (Z = 2.2, p = 0.03, n = 6) and 57 days (T3) (Z = 2.2, p = 0.03, n = 6). Error bars = S.E.
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getmorefigures.php?uid=PMC5382925&req=5

fig-8: Total area of zoanthid P. caribaeorum tissue coverage over diffusion chambers treated with P. dilatata crude extract (triangles) and over controls (circles).(∗) = Wilcoxon test, zoanthid cover was higher for extract-treated chambers compared to controls at 42 days (T2) (Z = 2.2, p = 0.03, n = 6) and 57 days (T3) (Z = 2.2, p = 0.03, n = 6). Error bars = S.E.
Mentions: At the first monitoring (T1, 16 days), there was no difference between cover of the zoanthid P. caribaeorum over diffusion chambers with and without crude extract of P. dilatata (Wilcoxon test: Z = 1.8, p = 0.074, n = 6). After 42 days (T2), coverage of P. caribaeorum on control chambers was significantly higher than for chambers with the crude extract of P. dilatata (Wilcoxon test: Z = 2.2, p < 0.05, n = 6) (Fig. 7). Although P. caribaeorum cover declined over the control chamber thereafter, cover remained significantly higher compared to the extract-treated chamber at T3 (57 days; Wilcoxon test: Z = 2.2, p < 0.05, n = 6) and zoanthid colonies were still healthy. The total area of P. caribaeorum tissue over chambers at each monitoring event is given in Fig. 8. Diffusion control gels retrieved from the field were re-extracted and thin layer chromatography (TLC) analysis revealed that overall chemical profiles were similar throughout the experiment. Although percentage mean retention was not calculated, the same procedure used in Da Gama et al. (2002) was categorically repeated in order to increase compounds preservation in gels. These authors retrieved an average of 43% of original extracts after 6 weeks. According to Henrikson & Pawlik (1995), phytagel is a resilient material, also standing periods of up to 6 weeks (42 days) with no evidence of degradation.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Despite advances in understanding the ecological functions of secondary metabolites from marine organisms, there has been little focus on the influence of chemically-defended species at the community level. Several compounds have been isolated from the gorgonian octocoral Phyllogorgia dilatata, a conspicuous species that forms dense canopies on rocky reefs of northern Rio de Janeiro State, Brazil. Manipulative experiments were performed to study: (1) the effects of live colonies of P. dilatata (physical presence and chemistry) on recruitment of sympatric benthic organisms; (2) the allelopathic effects of its chemicals on competitors; and (3) chemotactic responses of the non-indigenous brittle star, Ophiothela mirabilis. Early establishment of benthic species was influenced on substrates around live P. dilatata colonies and some effects could be attributed to the gorgonian&rsquo;s secondary metabolites.In addition, the gorgonian chemicals also exerted an allelopathic effect on the sympatric zoanthid Palythoa caribaeorum, and positive chemotaxis upon O. mirabilis. These results indicate multiple ecological roles of a chemically-defended gorgonian on settlement, sympatric competitors, and non-indigenous species.

No MeSH data available.