Carbon Flux Through the Giant Barrel Sponge Xestospongia testudinaria in the Red Sea

Handle URI:
http://hdl.handle.net/10754/627888
Title:
Carbon Flux Through the Giant Barrel Sponge Xestospongia testudinaria in the Red Sea
Authors:
Wooster, Michael K. ( 0000-0002-6056-1796 )
Abstract:
Sponges have important ecological functions on coral reefs because they are regionally abundant, competitively dominant, and process large volumes of seawater. The sponge loop hypothesis proposes that sponges consume dissolved organic carbon (DOC) and then releases the carbon as shed cellular detritus back to the reef benthos. Within this context, we examined the carbon flux mediated by the giant barrel sponge, Xestospongia testudinaria, on reefs in the Red Sea, where sponge abundance is comparatively low relative to coral reefs elsewhere, such as the Caribbean. Seawater samples were collected from the incurrent and excurrent (In-Ex) flow of 40 sponges from inshore, mid-shelf, and offshore reefs between 18° and 22°N latitude off the coast of Saudi Arabia. Concentrations of DOC and living particulate organic carbon (LPOC) were significantly higher in incurrent (ambient) seawater on inshore reefs than mid-shelf and offshore reefs. Consistent with studies of X. muta in the Caribbean, the diet of X. testudinaria is comprised primarily of DOC; mean values of the nutritional components across all sites were 60.5% DOC, 35.7% detritus, and 3.8% LPOC. Taking into account the specific filtration rates of nutritional components and oxygen consumption of sponges across the inshore-offshore gradient, there is evidence (1) of a threshold concentration of DOC below which sponges cease to be net consumers of DOC, and (2) that sponges on offshore reefs are food-limited. Contrary to the sponge loop hypothesis, there was no evidence that X. testudinaria, returned DOC to the benthos in the form of detritus, but was, instead, a net consumer of detritus from the water column. Unlike the cryptic, interstitial sponges that were studied to advance the sponge-loop hypothesis, emergent sponges may have an alternate pathway for returning DOC to the benthos by converting it to sponge biomass rather than sponge detritus.
Advisors:
Berumen, Michael L. ( 0000-0003-2463-2742 )
Committee Member:
Moran, Xose Anxelu G. ( 0000-0002-9823-5339 ) ; Ravasi, Timothy ( 0000-0002-9950-465X )
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division
Program:
Marine Science
Issue Date:
Nov-2017
Type:
Thesis
Appears in Collections:
Theses

Full metadata record

DC FieldValue Language
dc.contributor.advisorBerumen, Michael L.en
dc.contributor.authorWooster, Michael K.en
dc.date.accessioned2018-05-16T13:30:32Z-
dc.date.available2018-05-16T13:30:32Z-
dc.date.issued2017-11-
dc.identifier.urihttp://hdl.handle.net/10754/627888-
dc.description.abstractSponges have important ecological functions on coral reefs because they are regionally abundant, competitively dominant, and process large volumes of seawater. The sponge loop hypothesis proposes that sponges consume dissolved organic carbon (DOC) and then releases the carbon as shed cellular detritus back to the reef benthos. Within this context, we examined the carbon flux mediated by the giant barrel sponge, Xestospongia testudinaria, on reefs in the Red Sea, where sponge abundance is comparatively low relative to coral reefs elsewhere, such as the Caribbean. Seawater samples were collected from the incurrent and excurrent (In-Ex) flow of 40 sponges from inshore, mid-shelf, and offshore reefs between 18° and 22°N latitude off the coast of Saudi Arabia. Concentrations of DOC and living particulate organic carbon (LPOC) were significantly higher in incurrent (ambient) seawater on inshore reefs than mid-shelf and offshore reefs. Consistent with studies of X. muta in the Caribbean, the diet of X. testudinaria is comprised primarily of DOC; mean values of the nutritional components across all sites were 60.5% DOC, 35.7% detritus, and 3.8% LPOC. Taking into account the specific filtration rates of nutritional components and oxygen consumption of sponges across the inshore-offshore gradient, there is evidence (1) of a threshold concentration of DOC below which sponges cease to be net consumers of DOC, and (2) that sponges on offshore reefs are food-limited. Contrary to the sponge loop hypothesis, there was no evidence that X. testudinaria, returned DOC to the benthos in the form of detritus, but was, instead, a net consumer of detritus from the water column. Unlike the cryptic, interstitial sponges that were studied to advance the sponge-loop hypothesis, emergent sponges may have an alternate pathway for returning DOC to the benthos by converting it to sponge biomass rather than sponge detritus.en
dc.language.isoenen
dc.subjectCarbon Fluxen
dc.subjectPoriferaen
dc.subjectFeedingen
dc.subjectLPOCen
dc.subjectDetritusen
dc.titleCarbon Flux Through the Giant Barrel Sponge Xestospongia testudinaria in the Red Seaen
dc.typeThesisen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen
dc.contributor.committeememberMoran, Xose Anxelu G.en
dc.contributor.committeememberRavasi, Timothyen
thesis.degree.disciplineMarine Scienceen
thesis.degree.nameMaster of Scienceen
dc.person.id142206en
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