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The threat of climate change to coral reefs

Elmlund, Linn (2009) In Lunds universitets Naturgeografiska institution - Seminarieuppsatser
Dept of Physical Geography and Ecosystem Science
Abstract (Swedish)
Korallrev är “den marina världens regnskogar” och de är ett av världens mest artrika
och produktiva ekosystem. Korallreven är av stor betydelse för befolkningen i
tropiska havsområden. Varmvattenkoraller utsätts idag för storskaliga nedbrytningar
och det största hotet mot deras existens anses vara klimatförändringar. Antropogena
utsläpp av koldioxid i atmosfären har inneburit en ökning av jordens medeltemperatur
vilket även innebär ökad ytvattentemperatur. Koraller är mycket känsliga för
förändringar i den fysiska miljön. Korallblekning är en process som uppstår när
ytvattentemperaturen ökar och är ett stort hot mot koraller. Blekning innebär att
koralldjuret stöter bort sin symbiotiska alg den är beroende av för överlevnad. De
... (More)
Korallrev är “den marina världens regnskogar” och de är ett av världens mest artrika
och produktiva ekosystem. Korallreven är av stor betydelse för befolkningen i
tropiska havsområden. Varmvattenkoraller utsätts idag för storskaliga nedbrytningar
och det största hotet mot deras existens anses vara klimatförändringar. Antropogena
utsläpp av koldioxid i atmosfären har inneburit en ökning av jordens medeltemperatur
vilket även innebär ökad ytvattentemperatur. Koraller är mycket känsliga för
förändringar i den fysiska miljön. Korallblekning är en process som uppstår när
ytvattentemperaturen ökar och är ett stort hot mot koraller. Blekning innebär att
koralldjuret stöter bort sin symbiotiska alg den är beroende av för överlevnad. De
biologiska funktionerna påverkas och korallen kan dö. Flera olika episoder av
massblekning de senaste årtiondena har resulterat i stora förluster av korallrev världen
över. Det andra stora klimathotet är försurning i haven. Detta beror på att haven
absorberar koldioxid från atmosfären. 25 % av antropogena utsläpp mellan år 2000-
2006 togs upp av haven, vilket har lett till en pH- sänkning i haven. Detta innebär
också att karbonatjoner, som koraller är beroende av för att bilda sitt skelett, i
ytvattnet minskar. Försurningen i haven har redan lett till en minskad tillväxt hos
korallrev och kalkavlagringen är även viktig för hela ekosystemets funktion eftersom
många arter är beroende av korallrevens skyddande skelett.
Klimatmodeller och uppskattningar visar att det i framtiden är mycket troligt att
blekning av koraller kommer öka i frekvens och svårighetsgrad eftersom
temperaturökningen fortsätter. Koldioxidkoncentrationen i atmosfären ökar konstant,
vilket innebär en fortsatt försurning som försvårar korallers tillväxt. Om
klimatförändringen pågår i denna takt är det mycket troligt att blekning och
försurning i kombination med andra hot, som till exempel föroreningar och
utfiskning, på sikt hotar korallrevens existens som vi känner till dem idag. Korallerna
kan komma att ersättas av andra organismer som snabbväxande alger. Det är därför
viktigt att implementera hållbara skötselstrategier. Att minska stressfaktorer som
utfiskning och föroreningar hjälper till att öka korallernas kapacitet att bättre klara av
klimatförändringar, vilket kallas ekologisk resiliens. Investeringar i fortsatt forskning
i klimatproblematiken och hur korallreven påverkas av denna, utökat samarbete samt
förbättrade skötselstrategier skulle öka korallrevens chans att överleva. (Less)
Abstract
Coral reefs are the “rainforests” of the oceans, containing the highest diversity of
marine organisms. They are highly productive and of great value for populations in
tropical coastal areas. All around the world, warm-water coral reefs have experienced
large-scale degradation. The greatest threat to their long-term sustainability is climate
change and there is increasing evidence that global climate change is having direct
impacts on coral reefs. These ecosystems are very sensitive to changes in their
physical environment. That is why coral bleaching, resulting from climate-induced
elevated sea surface temperatures, is a major threat. Bleaching is the loss by the coral
animal of their symbiotic algae, affecting biological... (More)
Coral reefs are the “rainforests” of the oceans, containing the highest diversity of
marine organisms. They are highly productive and of great value for populations in
tropical coastal areas. All around the world, warm-water coral reefs have experienced
large-scale degradation. The greatest threat to their long-term sustainability is climate
change and there is increasing evidence that global climate change is having direct
impacts on coral reefs. These ecosystems are very sensitive to changes in their
physical environment. That is why coral bleaching, resulting from climate-induced
elevated sea surface temperatures, is a major threat. Bleaching is the loss by the coral
animal of their symbiotic algae, affecting biological functions and possibly leading to
coral mortality. Mass bleaching events have resulted in catastrophic loss of coral
cover in many areas. The number of bleaching records worldwide has clearly
increased during the last decades. The other serious threat of climate change is ocean
acidification. The oceans absorbed 25% of the atmospheric carbon dioxide derived
from human activities between the years of 2000-2006, leading to a decrease in
seawater pH and a reduction of available carbonate in seawater. Corals depend upon
carbonate ions for skeletal growth and the present decline has lead to reduced
calcification of corals, resulting in decreased growth and skeletal density.
Calcification is an important determinant of the health of reef ecosystems since many
species depend on the structure provided by the coral skeletons.
Climate change models and estimations suggest that coral bleaching events will
increase in frequency and severity due to global warming. Atmospheric carbon
dioxide concentrations are increasing, making the ocean more acidic. Predictions
show that within the next 50 years, tropical coral reefs will be unable to calcify
because carbonate saturation may drop below those required to sustain coral reef
accretion. Acidification and bleaching together with direct human pressures, such as
pollution and overfishing, are very likely to drive ecosystems toward domination by
non-coral communities if climate change continues. It is therefore important to
implement conservation strategies that help coral reefs maintain their ecological
resilience. By removing other threats to coral reefs, such as direct human pressure,
coral health will improve and increase ecosystem resilience. Control of these
secondary stress factors may help coral reefs survive climate change. Investments in
further research of climate change impacts on coral reefs, more collaboration and
improved conservation strategies would help increase the coral reef’s ability to
survive. (Less)
Please use this url to cite or link to this publication:
author
Elmlund, Linn
supervisor
organization
year
type
M2 - Bachelor Degree
subject
keywords
acidification, bleaching, coral reefs, climate change, geography, physical geography, ecological resilience, conservation
publication/series
Lunds universitets Naturgeografiska institution - Seminarieuppsatser
report number
165
language
English
id
1883018
date added to LUP
2011-03-31 10:48:59
date last changed
2011-12-19 11:34:28
@misc{1883018,
  abstract     = {Coral reefs are the “rainforests” of the oceans, containing the highest diversity of
marine organisms. They are highly productive and of great value for populations in
tropical coastal areas. All around the world, warm-water coral reefs have experienced
large-scale degradation. The greatest threat to their long-term sustainability is climate
change and there is increasing evidence that global climate change is having direct
impacts on coral reefs. These ecosystems are very sensitive to changes in their
physical environment. That is why coral bleaching, resulting from climate-induced
elevated sea surface temperatures, is a major threat. Bleaching is the loss by the coral
animal of their symbiotic algae, affecting biological functions and possibly leading to
coral mortality. Mass bleaching events have resulted in catastrophic loss of coral
cover in many areas. The number of bleaching records worldwide has clearly
increased during the last decades. The other serious threat of climate change is ocean
acidification. The oceans absorbed 25% of the atmospheric carbon dioxide derived
from human activities between the years of 2000-2006, leading to a decrease in
seawater pH and a reduction of available carbonate in seawater. Corals depend upon
carbonate ions for skeletal growth and the present decline has lead to reduced
calcification of corals, resulting in decreased growth and skeletal density.
Calcification is an important determinant of the health of reef ecosystems since many
species depend on the structure provided by the coral skeletons.
Climate change models and estimations suggest that coral bleaching events will
increase in frequency and severity due to global warming. Atmospheric carbon
dioxide concentrations are increasing, making the ocean more acidic. Predictions
show that within the next 50 years, tropical coral reefs will be unable to calcify
because carbonate saturation may drop below those required to sustain coral reef
accretion. Acidification and bleaching together with direct human pressures, such as
pollution and overfishing, are very likely to drive ecosystems toward domination by
non-coral communities if climate change continues. It is therefore important to
implement conservation strategies that help coral reefs maintain their ecological
resilience. By removing other threats to coral reefs, such as direct human pressure,
coral health will improve and increase ecosystem resilience. Control of these
secondary stress factors may help coral reefs survive climate change. Investments in
further research of climate change impacts on coral reefs, more collaboration and
improved conservation strategies would help increase the coral reef’s ability to
survive.},
  author       = {Elmlund, Linn},
  keyword      = {acidification,bleaching,coral reefs,climate change,geography,physical geography,ecological resilience,conservation},
  language     = {eng},
  note         = {Student Paper},
  series       = {Lunds universitets Naturgeografiska institution - Seminarieuppsatser},
  title        = {The threat of climate change to coral reefs},
  year         = {2009},
}