This study examined the ability of a Mediterranean demosponge Chondrosia reniformis to oxidize exogenous ammonium, simulating N-rich conditions that occur near finfish farms. We hypothesized that as the concentration of ammonium increases in the surrounding seawater, nitrification mediated by microbes associated with C. reniformis will lead to enhancement of ammonium uptake, nitrate excretion and oxygen consumption by the sponge holobiont. To test this hypothesis, we conducted laboratory experiments with C. reniformis explants exposed to ammonium enrichments (300–6667 nM) and to ambient seawater (45–1511 nM ammonium). We analyzed inhaled (IN) and exhaled (EX) water samples for dissolved oxygen, ammonium, nitrates and retention of picoplankton cells. We observed ammonium uptake in nearly half the cases and excretion of nitrate in most experimental outcomes. Yet, the consumption of ammonium and oxygen, as well as the excretion of nitrate by C. reniformis were not related to the concentration of inhaled ammonium, which suggests that the nitrification activity of sponge-associated microbes is not necessarily related to the concentration of ammonium in the surrounding seawater. Further research is required to reveal the sources of nitrate released from sponges and the fate of this nitrate in natural and manipulated ecosystems.
Bibliographical noteFunding Information:
We are grateful to the Leon H. Charney School of Marine Sciences and the Leon Recanati Institute of Maritime Studies, University of Haifa; Ramot Yam regional school and Ruppin Academic Center, Mikhmoret Israel. We thank the following people for their help in various ways: Gitai Yahel, Reuben Rosenblat, Rafi Yavetz, David Halfon, Zeev Glauber, Arik Weinberger, Gal Bogolowsky, Zafrir Kuplik, Tal Shomrat, Dori Edelist, Udi Arkin, Laura Cohen, Dina Zvieli, JJ Gottlieb, Mia Elasar, Dafna Israel, and Tanya Ukrainsky. Funding. The research was partially funded by the EU FP7 grant to DA Increasing Industrial Resource Efficiency in European Mariculture (IDREEM, project number 30857, web-site: www.idreem.eu). Financial support to PN was provided by the Hatter Fellowship for Maritime Studies, the Department of Maritime Civilizations, University of Haifa; by the Rotary Branch in Haifa, by the Rieger Foundation and by the Lev Lemaan Israel Fund. Fieldwork and sponge maintenance equipment were supported by Ramot Yam regional school and Ruppin Academic College in Mikhmoret, Israel; and by the Lev Yam Fish Mariculture Ltd. Israel. Laboratory analyses of flow cytometry were supported by the LSE Infrastructure Unit, Technion, Israel; the analyses of Nitrite and Nitrate were supported by the Inter University Institute of Marine Sciences, Eilat, Israel.
The research was partially funded by the EU FP7 grant to DA Increasing Industrial Resource Efficiency in European Mariculture (IDREEM, project number 30857, web-site: www.idreem.eu). Financial support to PN was provided by the Hatter Fellowship for Maritime Studies, the Department of Maritime Civilizations, University of Haifa; by the Rotary Branch
© Copyright © 2021 Nemoy, Spanier and Angel.
- marine ecology
- nutrient fluxes
ASJC Scopus subject areas
- Global and Planetary Change
- Aquatic Science
- Water Science and Technology
- Environmental Science (miscellaneous)
- Ocean Engineering