The interchangeability of autotrophic and heterotrophic nitrogen sources in Scleractinian coral symbiotic relationships: A numerical study

Gustafsson, MSM; Baird, ME; Ralph, PJ

The interchangeability of autotrophic and heterotrophic nitrogen sources in Scleractinian coral symbiotic relationships: A numerical study

Gustafsson, MSM Baird, ME

Ralph, PJ

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Publication Type:: Journal Article
Citation:: Ecological Modelling, 2013, 250 pp. 183 - 194
Issue Date:: 2013-02-10

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Field	Value	Language
dc.contributor.author	Gustafsson, MSM	en_US
dc.contributor.author	Baird, ME https://orcid.org/0000-0003-4955-2298	en_US
dc.contributor.author	Ralph, PJ https://orcid.org/0000-0002-3103-7346	en_US
dc.date.issued	2013-02-10	en_US
dc.identifier.citation	Ecological Modelling, 2013, 250 pp. 183 - 194	en_US
dc.identifier.issn	0304-3800	en_US
dc.identifier.uri	http://hdl.handle.net/10453/23426
dc.description.abstract	The success of corals in tropical oligotrophic waters depends largely on their symbiotic relationship with the dinoflagellate algae residing in their tissues. Understanding the dynamics of this symbiosis is essential to predict how corals respond to environmental stressors, such as changes in nutrients availability, water temperatures and irradiance. This study presents a numerical model of the symbiotic relationship between a heterotrophic coral (cnidarian) host and autotrophic symbiotic dinoflagellates, including the major metabolic and physical functions of the system, under non-bleaching conditions. The coral acquires nitrogen (N) through two processes, uptake of dissolved inorganic nitrogen (VDINH) and heterotrophic feeding (ZN). Numerical experiments were used to highlight the importance of these different sources of N for coral survival and growth. The model was analyzed for four external nutrient supply scenarios, using combinations of two VDINH rates (high and low) and two ZN rates (high and low), and for a range of light levels. The model outputs showed the importance of the algae symbionts to the coral host as a source of both N and C when the feeding rate was limited, with heterotrophic feeding providing only 14% of the N needed to sustain the host biomass for the low ZN+high VDINH scenario. In contrast, with no light or low light, conditions under which the symbiont population dies, the host was able to survive if ZN was high. Living inside the host the symbiont population thrived as long as there was enough light, as well as, DIN and DIC in the host tissues, independent of whether N was supplied as ZN or VDINH. Translocation and recycling of nutrient were two of the most important features of this model, emphasizing why it is essential to resolve host and symbiont in a coral model. The model highlights that the interchangeability of N sources, and the ability to exchange and recycle nutrients in the host-symbiont system, is the key to coral survival in nutrient poor environments. © 2012 Elsevier B.V.	en_US
dc.relation.ispartof	Ecological Modelling	en_US
dc.relation.isbasedon	10.1016/j.ecolmodel.2012.11.003	en_US
dc.subject.classification	Ecology	en_US
dc.title	The interchangeability of autotrophic and heterotrophic nitrogen sources in Scleractinian coral symbiotic relationships: A numerical study	en_US
dc.type	Journal Article
utslib.citation.volume	250	en_US
utslib.for	0405 Oceanography	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - C3 - Climate Change Cluster
utslib.copyright.status	closed_access
pubs.publication-status	Published	en_US
pubs.volume	250	en_US

Abstract:

The success of corals in tropical oligotrophic waters depends largely on their symbiotic relationship with the dinoflagellate algae residing in their tissues. Understanding the dynamics of this symbiosis is essential to predict how corals respond to environmental stressors, such as changes in nutrients availability, water temperatures and irradiance. This study presents a numerical model of the symbiotic relationship between a heterotrophic coral (cnidarian) host and autotrophic symbiotic dinoflagellates, including the major metabolic and physical functions of the system, under non-bleaching conditions. The coral acquires nitrogen (N) through two processes, uptake of dissolved inorganic nitrogen (VDINH) and heterotrophic feeding (ZN). Numerical experiments were used to highlight the importance of these different sources of N for coral survival and growth. The model was analyzed for four external nutrient supply scenarios, using combinations of two VDINH rates (high and low) and two ZN rates (high and low), and for a range of light levels. The model outputs showed the importance of the algae symbionts to the coral host as a source of both N and C when the feeding rate was limited, with heterotrophic feeding providing only 14% of the N needed to sustain the host biomass for the low ZN+high VDINH scenario. In contrast, with no light or low light, conditions under which the symbiont population dies, the host was able to survive if ZN was high. Living inside the host the symbiont population thrived as long as there was enough light, as well as, DIN and DIC in the host tissues, independent of whether N was supplied as ZN or VDINH. Translocation and recycling of nutrient were two of the most important features of this model, emphasizing why it is essential to resolve host and symbiont in a coral model. The model highlights that the interchangeability of N sources, and the ability to exchange and recycle nutrients in the host-symbiont system, is the key to coral survival in nutrient poor environments. © 2012 Elsevier B.V.

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