Defensive synergy : the antipredatory role of glass spicules in Caribbean demosponges
- UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
- Adam C. Jones (Creator)
- Institution
- The University of North Carolina Wilmington (UNCW )
- Web Site: http://library.uncw.edu/
- Advisor
- Stephen Kinsey
Abstract: Many sponge species produce secondary metabolites that deter predation. Sponges also
contain siliceous spicules, but previous studies have provided little evidence that spicules offer
any defense against generalist fish predators. However, feeding assays in past investigations
tested sponge skeletal elements in isolation, and did not consider whether they may enhance
chemical defenses. To determine whether the two components have an additive, antagonistic, or
synergistic interaction, crude organic extracts and spicules from 8 Caribbean sponge species
were isolated and tested in laboratory assays. The sponges used included one chemically
defended reef sponge (Agelas clathrodes) and seven sponges known to be intermediately
deterrent. These included six reef species (Calyx podotypa, Cinachyra alloclada, Cribrochalina
vasculum, Niphates digitalis, Rhaphidophlus juniperinus, and Xestospongia muta) and one
mangrove species (Tedania ignis). Extracts and spicules were used in various concentrations,
both individually and in combination, in laboratory feeding assays with the bluehead wrasse,
Thalassoma bifasciatum. A SAS based GENMOD procedure based on an isobolographic
analysis model was used for statistical comparisons. Four sponges (A. clathrodes, C. alloclada,
R. juniperinus, and X. muta) showed evidence of synergisms. Of these species, synergy in C.
alloclada, R. juniperinus, and X. muta was caused by approximate natural concentrations of
extracts and spicules. Extracts of A. clathrodes were deterrent, but combination assays required
unnatural reductions in extract concentrations and increases in spicule concentrations to show the
synergistic effect. Contrary to previous findings, spicules from Cribrochalina vasculum and X.
muta were deterrent at natural concentrations. These results indicate that, for some sponges,
structural elements may serve to enhance chemical defenses against consumers.
Defensive synergy : the antipredatory role of glass spicules in Caribbean demosponges
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Created on 1/1/2009
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Additional Information
- Publication
- Thesis
- A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment Of the Requirements for the Degree of Master of Science
- Language: English
- Date: 2009
- Keywords
- Demospongiae--Animal defenses, Sponges--Caribbean Area, Sponges--Defenses
- Subjects
- Demospongiae -- Animal defenses
- Sponges -- Defenses
- Sponges -- Caribbean Area