The Biology of Coral Reefs

Coralreefsareamongthemostbiologicallydiverseandeconomicallyvaluableecosystemsontheentireplanet,frequentlyreferredtoasthevibrantrainforestsoftheocean.Despiteoccupyinglessthanonepercentofthetotalmarineenvironment,theseincrediblycomplexstructuresprovidevitalshelter,feedinggrounds,andnurseryhabitatsforroughlyone-quarterofallknownmarinespecies.Thefoundationofthereefisbuiltbythousandsoftiny,soft-bodiedanimalscalledcoralpolyps,whicharecloselyrelatedtojellyfishandseaanemones.Theseindustriouspolypsextractdissolvedcalciumcarbonatefromthesurroundingseawatertosecreteahard,protectivelimestoneexoskeletonbeneaththem.Overthousandsofyears,thesemassivecoloniesofaccumulatedskeletonsgrowandfusetogethertoformthemassivereefstructuresweobservetoday.Thebreathtaking,brilliantcolorsofhealthycoralsarenotproducedbytheanimalsthemselves,butratherbymillionsofmicroscopic,photosyntheticalgaeknownaszooxanthellaethatlivesymbioticallywithintheirtransparenttissues.Inexchangeforasafe,sunlithome,thesealgaeprovidethecoralhostwithvitalnutritionalcompoundsproducedthroughphotosynthesis,supplyinguptoninetypercentofthecoral'senergyrequirements.Unfortunately,thesedelicateecosystemsareincrediblysensitivetoenvironmentalchanges.Whenwatertemperaturesriseduetoglobalclimatechange,thestressedpolypsexpeltheirsymbioticalgae,resultinginadevastatingphenomenonknownascoralbleaching.Withouttheiralgalpartners,thestarkwhitecoralsliterallystarvetodeath,causingtheentirevibrantecosystemtocollapseandtransformingonce-thrivingreefsintobarren,desolateunderwatergraveyards.Urgentglobalconservationeffortsareabsolutelycriticaltoprotecttheseirreplaceablemarinesanctuaries.