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Environmental FactorsAffecting Corals and

Coral Reefs

Environmental FactorsAffecting Corals and

Coral Reefs

Environmental FactorsCorrelated with Healthy Reef

Coral Growth

Environmental FactorsCorrelated with Healthy Reef

Coral Growth

The ElectromagneticRadiation SpectrumThe ElectromagneticRadiation Spectrum

Photosynthetically Active RadiationPhotosynthetically Active Radiation

PARPAR

Light Absorption in the OceanLight Absorption in the Ocean

• Light Intensity– decreases with depth

– 100 meter = depth limit of hermatypiccorals primarily a result of the overallreduction in light

– many studies have focused upon howchanging light intensities with depth affectthe photosynthesis of zooxanthellae ofcorals

• Light Intensity– decreases with depth

– 100 meter = depth limit of hermatypiccorals primarily a result of the overallreduction in light

– many studies have focused upon howchanging light intensities with depth affectthe photosynthesis of zooxanthellae ofcorals

Light Absorption in the OceanLight Absorption in the Ocean

• Spectral Characteristics– red wavelengths absorbed more readily by

water than blue wavelenths

– blue light penetrates deepest in the oceans

– the change in the spectral characteristicsof light with depth likely to influence plantphotosynthesis

– less work has been done to understand theinfluence of the spectral distribution of lighton zooxanthellae photosynthesis in corals

• Spectral Characteristics– red wavelengths absorbed more readily by

water than blue wavelenths

– blue light penetrates deepest in the oceans

– the change in the spectral characteristicsof light with depth likely to influence plantphotosynthesis

– less work has been done to understand theinfluence of the spectral distribution of lighton zooxanthellae photosynthesis in corals

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Light Penetration in the OceanLight Penetration in the OceanPrimary ProductivityPrimary Productivity

The rate of production oforganic matter by autotrophs

The rate of production oforganic matter by autotrophs

6CO2 + 6H2O Æ C6H12O6 + 6O26CO2 + 6H2O Æ C6H12O6 + 6O2

PhotosynthesisPhotosynthesis

Measuring PrimaryProductivity in the Ocean

Measuring PrimaryProductivity in the Ocean

• Standing Crop Estimates– weigh out total plant material

– measure concentration of chlorophyll in the water

– use satellite imagery

• Measure Actual Rates of Primary Productivity– measure oxygen production and consumption by

plants (e.g., light-dark bottle technique)

• Standing Crop Estimates– weigh out total plant material

– measure concentration of chlorophyll in the water

– use satellite imagery

• Measure Actual Rates of Primary Productivity– measure oxygen production and consumption by

plants (e.g., light-dark bottle technique)

6CO2 + 6H2O Æ C6H12O6 + 6O26CO2 + 6H2O Æ C6H12O6 + 6O2

PhotosynthesisPhotosynthesis

C6H12O6 + 6O2 Æ 6CO2 + 6H2O C6H12O6 + 6O2 Æ 6CO2 + 6H2O

Aerobic RespirationAerobic Respiration

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Light-Dark Bottle TechniqueLight-Dark Bottle Technique

LightLight DarkDark

O2 ProducedO2 Produced O2 ConsumedO2 Consumed

Using the Oxygen Light-DarkBottle Technique to Measuring

Primary Productivity

Using the Oxygen Light-DarkBottle Technique to Measuring

Primary Productivity

O2start = Starting Oxygen ConcentrationO2start = Starting Oxygen Concentration

O2end = Ending Oxygen ConcentrationO2end = Ending Oxygen Concentration

O2end - O2start = ∆O2O2end - O2start = ∆O2

Relationships Between GrossProduction, Respiration, and

Net Production

Relationships Between GrossProduction, Respiration, and

Net ProductionGross Production (GP)

The total amount of oxygen (or organic matter)produced due to photosynthesis

Gross Production (GP)The total amount of oxygen (or organic matter)

produced due to photosynthesis

Respiration (R)The total amount of oxygen (or organic matter)

consumed due to aerobic respiration

Respiration (R)The total amount of oxygen (or organic matter)

consumed due to aerobic respiration

Net Production (NP)The net amount of oxygen (or organic matter)produced (or consumed) due to the combined

effects of respiration and photosynthesis

Net Production (NP)The net amount of oxygen (or organic matter)produced (or consumed) due to the combined

effects of respiration and photosynthesis

Symbols UsedSymbols Used

∆O2 due to RESPIRATION = ∆O2R∆O2 due to RESPIRATION = ∆O2R

∆O2 due to GROSS PRODUCTION = ∆O2GP∆O2 due to GROSS PRODUCTION = ∆O2GP

∆O2 due to NET PRODUCTION = ∆O2NP∆O2 due to NET PRODUCTION = ∆O2NP

Calculating GP from NP and RCalculating GP from NP and R

∆O2GP = ∆O2NP - ∆O2R∆O2GP = ∆O2NP - ∆O2R

assumption:respiration continues at a constant rate regardless of

whether the light is on or off

assumption:respiration continues at a constant rate regardless of

whether the light is on or off

Photosynthesis as a Functionof Light Intensity

Photosynthesis as a Functionof Light Intensity

DO2time

prod

uctiv

ity r

ate

0

NP

GP

R

region of light saturation

light intensity

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Photoadaptation in CoralsPhotoadaptation in Corals

Changes in pigment concentrations andalgal densities in response to light intensity

Changes in pigment concentrations andalgal densities in response to light intensity

Colony Morphology Responsesto Irradiance

Colony Morphology Responsesto Irradiance

HemisphericalBranching Colonies

HemisphericalBranching Colonies

Plate-FormingColonies

Plate-FormingColonies

Hoover, J.P., 1998)Hoover, J.P., 1998)

Absorption ofUltraviolet

Radiation bythe Earth’s

Atmsophere

Absorption ofUltraviolet

Radiation bythe Earth’s

Atmsophere

Cosmic RaysGamma Rays

X Rays Ultra-Violet

Visable Light

InfraredRadio Waves

Visable LightX Rays

Vacuum UV UVB100 200 300 400

Shortwave UV (UVC) A b s o r b e d b y o z o n e i n E a r t h ' s a t m o s p h e r e

Middle- & Lon gwave UV (UVB & UVA)V is ib l e L ig h t & I n fr a re d

UVC UVA

Types of UV and HumanSunburn Responses

Types of UV and HumanSunburn Responses

Effects of UV on Living ThingsEffects of UV on Living Things

• damage to DNA resulting in mutations

• damage to other biological molecules– proteins: enzyme inactivation

– lipids: disruption of cell membranes andmembrane transport systems

• damage to DNA resulting in mutations

• damage to other biological molecules– proteins: enzyme inactivation

– lipids: disruption of cell membranes andmembrane transport systems

Corals and UV RadiationCorals and UV Radiation

• decreased growth and increasedreproductive output

• decreased rates of calcification

• transplantion experiments (deep coralsbrought to the surface) demonstrate coralsmay be UV-sensitive (exhibit bleaching andincreased mortality)

• coral sperm appears to be UV-sensitive (notespawning normally takes place at night)

• decreased growth and increasedreproductive output

• decreased rates of calcification

• transplantion experiments (deep coralsbrought to the surface) demonstrate coralsmay be UV-sensitive (exhibit bleaching andincreased mortality)

• coral sperm appears to be UV-sensitive (notespawning normally takes place at night)

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Ultraviolet AbsorbingCompounds in CoralsUltraviolet AbsorbingCompounds in Corals

• mycosporine-like amino acids (MAA’s)

• MAA’s apparently produced by zooxanthellae butstored in the animal tissues

• concentrations greater in shallow water corals thanin deeper ones

• transplation experiments demonstrate adaptionalchanges in pigment concentrations

• positively buoyant eggs exhibit higherconcentrations of pigments than do negativelybuoyant eggs

• mycosporine-like amino acids (MAA’s)

• MAA’s apparently produced by zooxanthellae butstored in the animal tissues

• concentrations greater in shallow water corals thanin deeper ones

• transplation experiments demonstrate adaptionalchanges in pigment concentrations

• positively buoyant eggs exhibit higherconcentrations of pigments than do negativelybuoyant eggs

Effects of UV on theCoral-Zooxanthellae

Symbiosis

Effects of UV on theCoral-Zooxanthellae

Symbiosis

EFFECTS OF UV ON THECORAL - ALGAL SYMBIOSIS

Li g htEn e rgy

Harmful UV light can be filtered by coral pigments or specialUV absorbing chemicals(S-320 compounds)

Some corals have pigmentswhich absorb UV light,exciting certainmolecules, whichin turn emit lowerfrequency light. Suchflourescence can be used forphotosynthesis

Coral pigment granule

Light is necessary for photosynthesis to occur; but certainwavelengths of light canbe harmful.

PAR

Coral Polyp

Zooxanthellae

P H O T O S Y N T H E S I S

PAR

PA R + U V

Ozone in theAtmosphereOzone in theAtmosphere

MaintainingOzone

Levels inthe

Atmosphere

MaintainingOzone

Levels inthe

Atmosphere

TemperatureTemperature• Lethal Limits

– 5 - 36oC

– physiological effects = bleaching (expulsion of zooxanthellaefrom coral tissues)

• Ecological Limits– 18 - 29oC (low limit correlates with 20o N & S latitude limit of

reef corals)

– some exceptions exist

– reasons for differences between lethal and actual limits

• secondary effects of temperature on feeding or onreproduction

• synergistic effects of other environmental factors (e.g.,UV irradiance)

• Lethal Limits– 5 - 36oC

– physiological effects = bleaching (expulsion of zooxanthellaefrom coral tissues)

• Ecological Limits– 18 - 29oC (low limit correlates with 20o N & S latitude limit of

reef corals)

– some exceptions exist

– reasons for differences between lethal and actual limits

• secondary effects of temperature on feeding or onreproduction

• synergistic effects of other environmental factors (e.g.,UV irradiance)

Global Distribution of Coral ReefsGlobal Distribution of Coral Reefs

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BleachingBleaching

Global ClimateChange

Global ClimateChange

Other FactorsOther Factors

Salinity

Sedimentation

Aerial Exposure at Low Tide

Water Motion

Inorganic Nutrients

Currents

Salinity

Sedimentation

Aerial Exposure at Low Tide

Water Motion

Inorganic Nutrients

Currents

SedimentsSediments

Nutrients and Algae GrowthNutrients and Algae Growth