Impacts of sponge produced dissolved inorganic nitrogen on Caribbean coral reef seaweed communities Public Deposited

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  • March 21, 2019
  • Silbiger, Nyssa Joy
    • Affiliation: College of Arts and Sciences, Department of Marine Sciences
  • Sponges are known to excrete copious amounts of remineralized nitrogen, but it is unknown how this may potentially facilitate seaweed proliferation on Caribbean coral reefs. We used the unusually low delta15N value of sponge-produced nitrate as a natural tracer to assess whether seaweeds utilize sponge nitrate on Conch Reef in FL. Over summer and fall seasons, we examined C and N tissue characteristics of 4 seaweed species (Dictyota pulchella, D. menstrualis, Halimeda tuna and Amphiroa beauvoisii) naturally growing in the excurrent flow of 4 sponge species (Agelas schmidti, Niphates digitalis, Verongula gigantea and Xestospongia muta) versus control seaweeds growing away from the sponges. An additional experiment transplanted seaweeds into the excurrent plume of X. muta with appropriate controls. We found that Dictyota spp., the most abundant seaweeds on Conch Reef, utilized sponge effluent more efficiently than the other seaweeds. If sponges are promoting changes in seaweed biomass or community composition, this may have significant impacts on coral reef health, as seaweeds can be harmful to corals. This information will help managers better understand the implications of sponge-seaweed interactions for coral reef degradation and recovery.
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  • Lindquist, Niels
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