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Occurence of nitrification and nitrifying bacteria in encrusting sponges at the coral reefs of Curacao

Oostveen, M.M. van (2004) Occurence of nitrification and nitrifying bacteria in encrusting sponges at the coral reefs of Curacao. Master's Thesis / Essay, Biology.

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Abstract

From some open water sponges it is known that they possess nitrifying bacteria. Since in cavities an efflux of nitrate is found, these cryptic habitats can be very important as inorganic nitrogen source on coral reefs. In the present study encrusting cavity sponges as well as cavity sediment were used in enclosure experiments at the coral reefs of Curacao to investigate possible nitrate effluxes. A nitrification inhibitor was added in some experiments in order to check if nitrate production was due to nitrification processes. CARD-FISH has been used to determine the presence of nitrifying bacteria inside sponges and in the water. The sponge Halisarca caerulea showed clear nitrate effluxes (0.71 mmol m-2 d-1). For two other sponge-species (Mycale microsigmatosa and Merlia normani) no clear nitrate effluxes were found. Nitrite and nitrate fluxes were lower when a nitrification inhibitor was added, indicating nitrate releases from sponges were due to nitrification processes. In these and 5 other sponge species (Monanchora arbuscula, Clathria spp., Cliona spp., Hymeniacidon haeliophila and Diplastrella megastellata) Nitrospira and β- and γ-Proteobacteria were detected, suggesting the presence of associated nitrifying bacteria in cavity sponges. Cavity sediment also showed nitrate effluxes (0.65 mmol m-2 d-1). All together it is demonstrated that sponges (by associated nitrifying bacteria) and cavity sediment release nitrate and explain therefore nitrate effluxes of cavities. This highlights the importance of cavities as an inorganic nitrogen source on coral reefs.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Biology
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 07:31
Last Modified: 15 Feb 2018 07:31
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/9217

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