Mechanisms of damage to corals exposed to sedimentation

Miriam Weber, Dirk De Beer, Christian Lott, Lubos Polerecky, Katharina Kohls, Raeid M M Abed, Timothy G. Ferdelman, Katharina E. Fabricius

Research output: Contribution to journalArticle

92 Citations (Scopus)

Abstract

We investigated the mechanisms leading to rapid death of corals when exposed to runoff and resuspended sediments, postulating that the killing was microbially mediated. Microsensor measurements were conducted in mesocosm experiments and in naturally accumulated sediment on corals. In organic-rich, but not in organicpoor sediment, pH and oxygen started to decrease as soon as the sediment accumulated on the coral. Organic-rich sediments caused tissue degradation within 1 d, whereas organic-poor sediments had no effect after 6 d. In the harmful organic-rich sediment, hydrogen sulfide concentrationswere lowinitially but increased progressively because of the degradation of coral mucus and dead tissue. Dark incubations of corals showed that separate exposures to darkness, anoxia, and lowpH did not causemortality within 4 d. However, the combination of anoxia and low pH led to colony death within 24 h. When hydrogen sulfide was added after 12 h of anoxia and lowpH, colonies died after an additional 3 h.We suggest that sedimentation kills corals through microbial processes triggered by the organic matter in the sediments, namely respiration and presumably fermentation and desulfurylation of products from tissue degradation. First, increased microbial respiration results in reduced O 2 and pH, initiating tissue degradation. Subsequently, the hydrogen sulfide formed by bacterial decomposition of coral tissue and mucus diffuses to the neighboring tissues, accelerating the spread of colony mortality. Our data suggest that the organic enrichment of coastal sediments is a key process in the degradation of coral reefs exposed to terrestrial runoff.

Original languageEnglish
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number24
DOIs
Publication statusPublished - Jun 12 2012

Fingerprint

Anthozoa
Hydrogen Sulfide
Mucus
Respiration
Coral Reefs
Darkness
Fermentation
Oxygen
Mortality

Keywords

  • Acidification
  • Coastal management
  • Fertilizer input
  • Microbial activity
  • Urbanization

ASJC Scopus subject areas

  • General

Cite this

Mechanisms of damage to corals exposed to sedimentation. / Weber, Miriam; De Beer, Dirk; Lott, Christian; Polerecky, Lubos; Kohls, Katharina; Abed, Raeid M M; Ferdelman, Timothy G.; Fabricius, Katharina E.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 109, No. 24, 12.06.2012.

Research output: Contribution to journalArticle

Weber, Miriam ; De Beer, Dirk ; Lott, Christian ; Polerecky, Lubos ; Kohls, Katharina ; Abed, Raeid M M ; Ferdelman, Timothy G. ; Fabricius, Katharina E. / Mechanisms of damage to corals exposed to sedimentation. In: Proceedings of the National Academy of Sciences of the United States of America. 2012 ; Vol. 109, No. 24.
@article{0c84ca432ffc48f18e75483f0f7804c4,
title = "Mechanisms of damage to corals exposed to sedimentation",
abstract = "We investigated the mechanisms leading to rapid death of corals when exposed to runoff and resuspended sediments, postulating that the killing was microbially mediated. Microsensor measurements were conducted in mesocosm experiments and in naturally accumulated sediment on corals. In organic-rich, but not in organicpoor sediment, pH and oxygen started to decrease as soon as the sediment accumulated on the coral. Organic-rich sediments caused tissue degradation within 1 d, whereas organic-poor sediments had no effect after 6 d. In the harmful organic-rich sediment, hydrogen sulfide concentrationswere lowinitially but increased progressively because of the degradation of coral mucus and dead tissue. Dark incubations of corals showed that separate exposures to darkness, anoxia, and lowpH did not causemortality within 4 d. However, the combination of anoxia and low pH led to colony death within 24 h. When hydrogen sulfide was added after 12 h of anoxia and lowpH, colonies died after an additional 3 h.We suggest that sedimentation kills corals through microbial processes triggered by the organic matter in the sediments, namely respiration and presumably fermentation and desulfurylation of products from tissue degradation. First, increased microbial respiration results in reduced O 2 and pH, initiating tissue degradation. Subsequently, the hydrogen sulfide formed by bacterial decomposition of coral tissue and mucus diffuses to the neighboring tissues, accelerating the spread of colony mortality. Our data suggest that the organic enrichment of coastal sediments is a key process in the degradation of coral reefs exposed to terrestrial runoff.",
keywords = "Acidification, Coastal management, Fertilizer input, Microbial activity, Urbanization",
author = "Miriam Weber and {De Beer}, Dirk and Christian Lott and Lubos Polerecky and Katharina Kohls and Abed, {Raeid M M} and Ferdelman, {Timothy G.} and Fabricius, {Katharina E.}",
year = "2012",
month = "6",
day = "12",
doi = "10.1073/pnas.1100715109",
language = "English",
volume = "109",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "24",

}

TY - JOUR

T1 - Mechanisms of damage to corals exposed to sedimentation

AU - Weber, Miriam

AU - De Beer, Dirk

AU - Lott, Christian

AU - Polerecky, Lubos

AU - Kohls, Katharina

AU - Abed, Raeid M M

AU - Ferdelman, Timothy G.

AU - Fabricius, Katharina E.

PY - 2012/6/12

Y1 - 2012/6/12

N2 - We investigated the mechanisms leading to rapid death of corals when exposed to runoff and resuspended sediments, postulating that the killing was microbially mediated. Microsensor measurements were conducted in mesocosm experiments and in naturally accumulated sediment on corals. In organic-rich, but not in organicpoor sediment, pH and oxygen started to decrease as soon as the sediment accumulated on the coral. Organic-rich sediments caused tissue degradation within 1 d, whereas organic-poor sediments had no effect after 6 d. In the harmful organic-rich sediment, hydrogen sulfide concentrationswere lowinitially but increased progressively because of the degradation of coral mucus and dead tissue. Dark incubations of corals showed that separate exposures to darkness, anoxia, and lowpH did not causemortality within 4 d. However, the combination of anoxia and low pH led to colony death within 24 h. When hydrogen sulfide was added after 12 h of anoxia and lowpH, colonies died after an additional 3 h.We suggest that sedimentation kills corals through microbial processes triggered by the organic matter in the sediments, namely respiration and presumably fermentation and desulfurylation of products from tissue degradation. First, increased microbial respiration results in reduced O 2 and pH, initiating tissue degradation. Subsequently, the hydrogen sulfide formed by bacterial decomposition of coral tissue and mucus diffuses to the neighboring tissues, accelerating the spread of colony mortality. Our data suggest that the organic enrichment of coastal sediments is a key process in the degradation of coral reefs exposed to terrestrial runoff.

AB - We investigated the mechanisms leading to rapid death of corals when exposed to runoff and resuspended sediments, postulating that the killing was microbially mediated. Microsensor measurements were conducted in mesocosm experiments and in naturally accumulated sediment on corals. In organic-rich, but not in organicpoor sediment, pH and oxygen started to decrease as soon as the sediment accumulated on the coral. Organic-rich sediments caused tissue degradation within 1 d, whereas organic-poor sediments had no effect after 6 d. In the harmful organic-rich sediment, hydrogen sulfide concentrationswere lowinitially but increased progressively because of the degradation of coral mucus and dead tissue. Dark incubations of corals showed that separate exposures to darkness, anoxia, and lowpH did not causemortality within 4 d. However, the combination of anoxia and low pH led to colony death within 24 h. When hydrogen sulfide was added after 12 h of anoxia and lowpH, colonies died after an additional 3 h.We suggest that sedimentation kills corals through microbial processes triggered by the organic matter in the sediments, namely respiration and presumably fermentation and desulfurylation of products from tissue degradation. First, increased microbial respiration results in reduced O 2 and pH, initiating tissue degradation. Subsequently, the hydrogen sulfide formed by bacterial decomposition of coral tissue and mucus diffuses to the neighboring tissues, accelerating the spread of colony mortality. Our data suggest that the organic enrichment of coastal sediments is a key process in the degradation of coral reefs exposed to terrestrial runoff.

KW - Acidification

KW - Coastal management

KW - Fertilizer input

KW - Microbial activity

KW - Urbanization

UR - http://www.scopus.com/inward/record.url?scp=84862166514&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84862166514&partnerID=8YFLogxK

U2 - 10.1073/pnas.1100715109

DO - 10.1073/pnas.1100715109

M3 - Article

VL - 109

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 24

ER -