Editing Sponge (section)

=== Sponge loop ===
[[File:Sponge loop pathway.png|thumb|upright=1.8|right|Sponge loop hypothesis. Steps of the sponge loop pathway: (1)&nbsp;corals and algae release exudates as [[dissolved organic matter]] (DOM), (2)&nbsp;sponges take up DOM, (3)&nbsp;sponges release detrital [[particulate organic matter]] (POM), (4)&nbsp;sponge detritus (POM) is taken up by sponge-associated and free-living [[detritivore]]s.<ref name="Rix_2018">{{cite journal |last1=Rix |first1=L. |last2=de Goeij |first2=J.M. |last3=van Oevelen |first3=D. |last4=Struck |first4=U. |last5=Al-Horani |first5=F.A. |last6=Wild |first6=C. |last7=Naumann |first7=M.S. |title=Reef sponges facilitate the transfer of coral-derived organic matter to their associated fauna via the sponge loop |journal=Marine Ecology Progress Series |volume=589 |date=23 February 2018 |issn=0171-8630 |doi=10.3354/meps12443 |pages=85–96|bibcode=2018MEPS..589...85R }} [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License] {{Webarchive|url=https://web.archive.org/web/20171016050101/https://creativecommons.org/licenses/by/4.0/ |date=2017-10-16 }}</ref><ref name="Rix_2017"/><ref name="pmid24092742">{{cite journal |last1=de Goeij |first1=Jasper M. |last2=van Oevelen |first2=Dick |last3=Vermeij |first3=Mark J. A. |last4=Osinga |first4=Ronald |last5=Middelburg |first5=Jack J. |last6=de Goeij |first6=Anton F. P. M. |last7=Admiraal |first7=Wim |title=Surviving in a Marine Desert: The Sponge Loop Retains Resources Within Coral Reefs |journal=Science |volume=342 |issue=6154 |date=4 October 2013 |issn=0036-8075 |doi=10.1126/science.1241981 |pages=108–110|pmid=24092742 |bibcode=2013Sci...342..108D }}</ref>]]

Most sponges are [[detritivore]]s which filter [[Particulate organic matter|organic debris particles]] and [[Marine microorganisms|microscopic life forms]] from ocean water. In particular, sponges occupy an important role as detritivores in [[coral reef food web]]s by recycling detritus to higher [[trophic level]]s.<ref name="Rix_2018"/>

The hypothesis has been made that coral reef sponges facilitate the transfer of coral-derived organic matter to their associated detritivores via the production of sponge detritus, as shown in the diagram. Several sponge species are able to convert coral-derived DOM into sponge detritus,<ref>Rix L, de Goeij JM, Mueller CE, Struck U and others (2016) "Coral mucus fuels the sponge loop in warm- and coldwater coral reef ecosystems". ''Sci Rep'', '''6''': 18715.</ref><ref name="Rix_2017">{{cite journal |last1=Rix |first1=Laura |last2=de Goeij |first2=Jasper M. |last3=van Oevelen |first3=Dick |last4=Struck |first4=Ulrich |last5=Al-Horani |first5=Fuad A. |last6=Wild |first6=Christian |last7=Naumann |first7=Malik S. |date=March 2017 |title=Differential recycling of coral and algal dissolved organic matter via the sponge loop |journal=Functional Ecology |volume=31 |issue=3 |pages=778−789 |doi=10.1111/1365-2435.12758 |bibcode=2017FuEco..31..778R }}</ref> and transfer organic matter produced by corals further up the reef food web. Corals release organic matter as both dissolved and particulate mucus,<ref>{{cite journal |last= Crossland |first=C.J. |date=July 1987 |title=In situ release of mucus and DOC-lipid from the corals Acropora variabilis and Stylophora pistillata in different light regimes. |journal=Coral Reefs |volume=6 |issue=1 |pages=35−42 |doi=10.1007/BF00302210 |bibcode=1987CorRe...6...35C }}</ref><ref name="Wild_2004">{{cite journal |last1=Wild |first1=Christian |last2=Huettel |first2=Markus |last3=Klueter |first3=Anke |last4=Kremb |first4=Stephan G. |last5=Rasheed |first5=Mohammed Y. M. |last6=Jørgensen |first6=Bo B. |title=Coral mucus functions as an energy carrier and particle trap in the reef ecosystem |journal=Nature |volume=428 |issue=6978 |date=2004 |issn=0028-0836 |doi=10.1038/nature02344 |pages=66–70|pmid=14999280 |bibcode=2004Natur.428...66W }}</ref><ref>{{cite journal |last1=Tanaka |first1=Yasuaki |last2=Miyajima |first2=Toshihiro |last3=Umezawa |first3=Yu |last4=Hayashibara |first4=Takeshi |last5=Ogawa |first5=Hiroshi |last6=Koike |first6=Isao |title=Net release of dissolved organic matter by the scleractinian coral Acropora pulchra |journal=Journal of Experimental Marine Biology and Ecology |volume=377 |issue=2 |date=2009 |doi=10.1016/j.jembe.2009.06.023 |pages=101–106|bibcode=2009JEMBE.377..101T }}</ref><ref>{{cite journal |last1=Naumann |first1=M. S. |last2=Haas |first2=A. |last3=Struck |first3=U. |last4=Mayr |first4=C. |last5=el-Zibdah |first5=M. |last6=Wild |first6=C. |date=September 2010 |title=Organic matter release by dominant hermatypic corals of the Northern Red Sea. |journal=Coral Reefs |volume=29 |issue=3 |pages=649−659 |doi=10.1007/s00338-010-0612-7 |bibcode=2010CorRe..29..649N }}</ref> as well as cellular material such as expelled ''[[Symbiodinium]]''.<ref name="Hoegh-Guldberg_1987">{{cite journal |last1=Hoegh-Guldberg |first1=O. |last2=McCloskey |first2=L. R. |last3=Muscatine |first3=L. |date=April 1987 |title=Expulsion of zooxanthellae by symbiotic cnidarians from the Red Sea. |journal=Coral Reefs |volume=5 |issue=4 |pages=201−204 |doi=10.1007/BF00300964 |bibcode=1987CorRe...5..201H }}</ref><ref name="pmid11147708">{{cite journal |last1=Baghdasarian |first1=G |last2=Muscatine |first2=L |title=Preferential expulsion of dividing algal cells as a mechanism for regulating algal-cnidarian symbiosis |journal=The Biological Bulletin |volume=199 |issue=3 |date=2000 |issn=0006-3185 |doi=10.2307/1543184 |pages=278–286|jstor=1543184 |pmid=11147708 |url=https://www.biodiversitylibrary.org/part/10578 }}</ref><ref name="Rix_2018"/>

Organic matter could be transferred from corals to sponges by all these pathways, but DOM likely makes up the largest fraction, as the majority (56 to 80%) of coral mucus dissolves in the water column,<ref name="Wild_2004"/> and coral loss of fixed carbon due to expulsion of ''Symbiodinium'' is typically negligible (0.01%)<ref name="Hoegh-Guldberg_1987"/> compared with mucus release (up to ~40%).<ref>{{cite journal |last1=Crossland |first1=C. J. |last2=Barnes |first2=D. J. |last3=Borowitzka |first3=M. A. |title=Diurnal lipid and mucus production in the staghorn coral Acropora acuminata |journal=Marine Biology |volume=60 |issue=2–3 |date=1980 |issn=0025-3162 |doi=10.1007/BF00389151 |pages=81–90|bibcode=1980MarBi..60...81C }}</ref><ref name="pmid22442377">{{cite journal |last1=Tremblay |first1=Pascale |last2=Grover |first2=Renaud |last3=Maguer |first3=Jean François |last4=Legendre |first4=Louis |last5=Ferrier-Pagès |first5=Christine |title=Autotrophic carbon budget in coral tissue: a new 13C-based model of photosynthate translocation |journal=Journal of Experimental Biology |volume=215 |issue=8 |date=15 April 2012 |issn=1477-9145 |doi=10.1242/jeb.065201 |pages=1384–1393|pmid=22442377 |bibcode=2012JExpB.215.1384T }}</ref> Coral-derived organic matter could also be indirectly transferred to sponges via bacteria, which can also consume coral mucus.<ref>{{cite journal |last1=Ferrier-Pagès |first1=C |last2=Leclercq |first2=N |last3=Jaubert |first3=J |last4=Pelegrí |first4=Sp |title=Enhancement of pico- and nanoplankton growth by coral exudates |journal=Aquatic Microbial Ecology |volume=21 |date=2000 |issn=0948-3055 |doi=10.3354/ame021203 |pages=203–209}}</ref><ref>{{cite journal |last=Wild |first=C. |display-authors=etal |date=July 2010 |title=Organic matter release by Red Sea coral reef organisms—potential effects on microbial activity and in situ O<sub>2</sub> availability. |journal=Marine Ecology Progress Series |volume=411 |pages=61−71 |doi=10.3354/meps08653 |bibcode=2010MEPS..411...61W }}</ref><ref>{{cite journal |last1=Tanaka |first1=Yasuaki |last2=Ogawa |first2=Hiroshi |last3=Miyajima |first3=Toshihiro |title=Production and bacterial decomposition of dissolved organic matter in a fringing coral reef |journal=Journal of Oceanography |volume=67 |issue=4 |date=2011 |issn=0916-8370 |doi=10.1007/s10872-011-0046-z |pages=427–437|bibcode=2011JOce...67..427T }}</ref><ref name="Rix_2018"/>