NEWS, NEWS | 07.06.2022

Les­sons from the past: how cold-wa­ter cor­als re­spond to global warm­ing

New MARUM study: Food and oxy­gen have the greatest im­pact on sur­vival

Cor­als re­act to changes in their en­vir­on­ment. This is true for trop­ical as well as cold-wa­ter cor­als and in­cludes, among oth­ers, changes in tem­per­at­ure, sa­lin­ity and pH val­ues. MARUM re­search­ers, in a study led by Dr. Rodrigo da Costa Portilho-Ramos, have now in­vest­ig­ated how warmer tem­per­at­ures oc­cur­ring as a res­ult of cli­mate change are af­fect­ing cold-wa­ter cor­als. For this pur­pose, they ex­amined in de­tail how these cor­als have re­acted to en­vir­on­mental changes over the past 20,000 years. Their study has been pub­lished in the pro­fes­sional journal PLOS Biology. MARUM is a member of the DAM 

Cold-wa­ter cor­als, and the spe­cies Lophelia pertusa in par­tic­u­lar, are the ar­chi­tects of com­plex reef struc­tures. They build the found­a­tions of im­port­ant hab­it­ats for deep-sea or­gan­isms that find pro­tec­tion as well as food within the struc­tures. Coral reefs, however, re­act very sens­it­ively to chan­ging con­di­tions. These in­clude warm­ing of the ocean wa­ters, acid­i­fic­a­tion, de­clin­ing oxy­gen con­tent, and the vari­able sup­ply of food. A change in any one of these para­met­ers, as a con­sequence of global cli­mate change, for ex­ample, can im­pact the health of the total coral reef. Ac­cord­ing to the new study, there­fore, it is im­port­ant to un­der­stand ex­actly how these eco­sys­tems re­act to en­vir­on­mental changes in or­der to be bet­ter able to pro­tect them more ef­fect­ively in the fu­ture.

First au­thor Rodrigo da Costa Portilho-Ramos of MARUM – Cen­ter for Mar­ine En­vir­on­mental Sci­ences of the Uni­versity of Bre­men, with his col­leagues, ex­amined sed­i­ments from six cold-wa­ter coral loc­a­tions in the North At­lantic and the Medi­ter­ranean in or­der to identify of the crit­ical para­met­ers that could trig­ger the mor­tal­ity and en­su­ing pro­lif­er­a­tion of cold-wa­ter cor­als. In­form­a­tion provid­ing in­sights to the en­vir­on­mental con­di­tions of the past are stored in these sed­i­ments. This fact al­lows re­search­ers to de­term­ine when and why cold-wa­ter cor­als flour­ished or not. The au­thors point out that the res­ults could also be used to show how cor­als might re­spond to fu­ture cli­matic changes. The study ana­lyzes the changes of the most im­port­ant en­vir­on­mental factors over the past 20,000 years, the period of gen­eral global warm­ing since the last gla­ci­ation, and com­pares them with the oc­cur­rence of the cold-wa­ter cor­als.

“We looked back into the past to un­der­stand how Lophelia pertusa re­acted to en­vir­on­mental changes,” says Portilho-Ramos. The cor­als van­ished from or re­turned to a re­gion mainly when the food sup­ply or the oxy­gen con­tent of the wa­ter changed. Cold-wa­ter cor­als feed on mi­cro­scop­ic­ally small plank­ton and other particles that are trans­por­ted by ocean cur­rents. The tem­per­at­ure and sa­lin­ity of the wa­ter had little ef­fect on the mor­tal­ity or pro­lif­er­a­tion of cold-wa­ter cor­als. As Portilho-Ramos points out, “we there­fore as­sume that food sup­ply and avail­ab­il­ity of oxy­gen are the primary factors that de­term­ine the life or death of cold-wa­ter cor­als.” It is not clear what kind of im­pact ocean acid­i­fic­a­tion has over the long term be­cause there is no pa­leocean­o­graphic in­dic­ator for this para­meter.

Act­ing as eco­sys­tem ‘en­gin­eers’, cold-wa­ter cor­als con­trib­ute sig­ni­fic­antly to the form­a­tion of biod­iversity hot­spots in the deep sea. With their in­flu­ence on food webs and nu­tri­ent cycles, their role as fish nurs­er­ies and their im­press­ive biod­iversity, cold-wa­ter coral reefs provide im­port­ant eco­sys­tem ser­vices. In or­der to con­tinue these ser­vices in a fu­ture un­der the in­flu­ence of cli­mate change, the res­ults of this study form an im­port­ant found­a­tion for de­vel­op­ing know­ledge-based man­age­ment strategies for such deep-sea eco­sys­tems. They also con­trib­ute sig­ni­fic­antly to the goals of the Bre­men Cluster of Ex­cel­lence, which is ded­ic­ated to the study of the ocean floor.

ORiginal Publication

Rodrigo da Costa Portilho-Ramos, Jürgen Titschack, Claudia Wienberg, Michael Georg Siccha Rojas, Yusuke Yokoyama, Dierk Hebbeln: Major environmental drivers determining life and death of cold-water corals through time. PLOS Biology 2022. DOI: https://doi.org/10.1371/journal.pbio.3001628


Further Information


Contact science

MARUM – Center for Marine Environmental Science, University of Bremen
Dr. Rodrigo da Costa Portilho-Ramos
E-Mail: rcpramos@marum.de, rcpramos@yahoo.com.br


Contact

MARUM – Center for Marine Environmental Science, University of Bremen
Public Relations and Press Office
E-Mail: medien@marum.de


Header-picture: Large colony of the cold-wa­ter coral Loph­elia pertusa col­on­ized by crin­oids and soft cor­als in 700 meters of wa­ter (Por­cu­pine Seabight, Ir­ish con­tin­ental mar­gin). Photo: MARUM – Cen­ter for Mar­ine En­vir­on­mental Sci­ences, Uni­versity of Bre­men

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