Environmental Factors Affecting Corals and Coral Reefs
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Environmental Factors Affecting Corals and Coral Reefs. Environmental Factors Correlated with Healthy Reef Coral Growth. Warm tropical water Normal seawater salinity Appropriate solar radiation Low organic nutrients (oligotrophic) Low turbidity Low sedimentation Vigorous water motion.

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Environmental Factors Affecting Corals and Coral Reefs

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Environmental factors affecting corals and coral reefs

Environmental Factors Affecting Corals and Coral Reefs


Environmental factors affecting corals and coral reefs

Environmental Factors Correlated

with Healthy Reef Coral Growth

  • Warm tropical water

  • Normal seawater salinity

  • Appropriate solar radiation

  • Low organic nutrients (oligotrophic)

  • Low turbidity

  • Low sedimentation

  • Vigorous water motion


The electromagnetic radiation spectrum

The Electromagnetic Radiation Spectrum

Only green and blue wavelengths pass through water a great distance.


P hotosynthetically a ctive r adiation

Photosynthetically Active Radiation

PAR

(i.e., visible light)


Environmental factors affecting corals and coral reefs

Primary Production Limitations

  • light

  • water

  • nutrients

Photosynthesis

Photic Zone

No Photosynthesis

Aphotic Zone


Environmental factors affecting corals and coral reefs

Light Absorption in the Ocean

Light Intensity

  • decreases with depth

  • 100 meter = depth limit of hermatypic corals primarily a result of the overall reduction in light

  • many studies have focused upon how changing light intensities with depth affect the photosynthesis of zooxanthellae of corals


Light penetration in the ocean

Light Penetration in the Ocean


Environmental factors affecting corals and coral reefs

Primary Productivity

The rate of production of organic matter by autotrophs


Environmental factors affecting corals and coral reefs

Primary Productivity

Photosynthesis

  • Involves the use of light energy in the conversion of inorganic carbon into organic carbon.


Photosynthesis

Photosynthesis

6H2O + 6CO2 + light  C6H12O6 + 6O2


Environmental factors affecting corals and coral reefs

Primary Producers

Common Name

Blue-green algae (cyanobacteria)

Red algae

Brown algae

Green algae

Coccolithophorids

Dinoflagellates

Diatoms

Seagrass


Environmental factors affecting corals and coral reefs

Primary Productivity

Chemosynthesis

  • Involves the use of energy released by the catalysis of certain inorganic reaction to convert inorganic carbon into organic carbon.


Cellular respiration

Cellular Respiration

C6H12O6 + 6O2 6H2O + 6CO2 + energy


Environmental factors affecting corals and coral reefs

R=P


Environmental factors affecting corals and coral reefs

Measuring Primary Productivity 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)


Environmental factors affecting corals and coral reefs

Table 1. Average net primary production and biomass of aquatic habitats. Data from R.H. Whittaker and G.E. Likens, Human Ecol. 1: 357-369 (1973).


Environmental factors affecting corals and coral reefs

Primary Productivity

Gross Primary Productivity (GP)

  • The rate of production of organic matter from inorganic materials by autotrophic organisms

    Respiration (R)

  • The rate of consumption of organic matter (conversion to inorganic matter) by organisms.

    Net Primary Productivity (NP)

  • The net rate of organic matter produced as a consequence of both GP and R.


Environmental factors affecting corals and coral reefs

Primary Productivity

NP = GP + R

Note that R is a negative value because it results in the reduction of organic matter.


Environmental factors affecting corals and coral reefs

Plankton Sampling


Environmental factors affecting corals and coral reefs

Plankton Size

  • Picoplankton (.2-2 µm)

  • Nanoplankton (2 - 20 µm)

  • Microplankton (20-200 µm)

  • Macroplankton (200-2,000 µm)

  • Megaplankton (> 2,000 µm)

microplankton

picoplankton

nanplankton


Environmental factors affecting corals and coral reefs

Plankton Sampling

Mesh

5 in

Collecting bottle

Avoidance ability- this is a function of reactive distance, radius of net, speed of tow, burst of speed of larvae

To reduce net clogging:

  • pick correct mesh size

  • use longer net

  • tow at slower speeds

  • tow for shorter time

  • change configuration of net

  • Picoplankton .2-3um

  • Nanoplankton 2-20um

  • Microplankton 20-200um


Environmental factors affecting corals and coral reefs

Rates of primary production regulated by LIMITING FACTORS:

  • major limiting factors in ocean (inorganic nutrients, light) differ from those on land (moisture, temp, inorganic nutrients, light)

  • primary production measured via change in O2 concentrations in “light” and “dark bottles”


Environmental factors affecting corals and coral reefs

Phytoplankton

Zooplankton


Environmental factors affecting corals and coral reefs

zooplankton

phytoplankton

decomposition

Light & Dark Experiments

Photosynthesis:

light + 6CO2 + 6H2O C6H12O6 + 6O2

Respiration:

C6H12O6 + 6O2

6CO2 + H2O + ATP


Environmental factors affecting corals and coral reefs

light bottle

photosynthesis

+ respiration

dark bottle

respiration

weight


Environmental factors affecting corals and coral reefs

Sources of Error

  • Respiration rates are not equal between light and dark bottles.

  • The glass wall of the light bottle filters light.

  • The bottle may not be representative of the water as a whole.


Environmental factors affecting corals and coral reefs

Photoadaptation in Corals

Changes in pigment concentrations and algal densities in response to light intensity

A coral (Acanthastrea) under high magnification. Focus stack. Fluorescent pigments emphasized with full-spectrum lights


Environmental factors affecting corals and coral reefs

Colony Morphology Responses to Irradiance

Hemispherical Branching Colonies

Plate-Forming Colonies


Environmental factors affecting corals and coral reefs

Absorption of Ultraviolet Radiation by the Earth’s Atmosphere


Environmental factors affecting corals and coral reefs

Types of UV and Human Sunburn Responses


Environmental factors affecting corals and coral reefs

Effects of UV on Living Things

  • damage to DNA resulting in mutations

  • damage to other biological molecules

    • proteins: enzyme inactivation

    • lipids: disruption of cell membranes and membrane transport systems


Environmental factors affecting corals and coral reefs

Corals and UV Radiation

  • decreased growth

  • decreased rates of calcification

  • transplantation experiments (deep corals brought to the surface) demonstrate corals may be UV-sensitive (exhibit bleaching and increased mortality)

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


Environmental factors affecting corals and coral reefs

Ultraviolet Absorbing Compounds in Corals

  • mycosporine-like amino acids (MAA’s)

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

  • concentrations greater in shallow water corals than in deeper ones

  • transplantation experiments demonstrate adaptational changes in pigment concentrations

  • positively buoyant eggs exhibit higher concentrations of pigments than do negatively buoyant eggs


Effects of uv on the coral zooxanthellae symbiosis

Effects of UV on the Coral-Zooxanthellae Symbiosis

PAR + UV

MAAs

PAR

PAR

Coral pigment

Photosynthesis


Environmental factors affecting corals and coral reefs

Ozone in the Atmosphere


Environmental factors affecting corals and coral reefs

The hole in the ozone

Oct. 1979

Sep. 2013


Temperature

Temperature

  • Lethal Limits

    • <17 and > 33oC for extended periods of time

    • physiological effects = bleaching (expulsion of zooxanthellae from coral tissues)

  • Ecological Limits

    • 18 - 32oC (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 on reproduction

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


Environmental factors affecting corals and coral reefs

Global Distribution of Coral Reefs


Environmental factors affecting corals and coral reefs

Bleaching


Environmental factors affecting corals and coral reefs

Bleaching


Environmental factors affecting corals and coral reefs

Global Climate Change


Environmental factors affecting corals and coral reefs

Other Factors

  • Salinity

  • Sedimentation

  • Aerial Exposure at Low Tide

  • Water Motion

  • Inorganic Nutrients

  • Currents


Environmental factors affecting corals and coral reefs

Sediments


Environmental factors affecting corals and coral reefs

Nutrients and Algae Growth


Environmental factors affecting corals and coral reefs

Acid Rain in Marine Environment

  • reduces ability of marine organisms to utilize calcium carbonate

  • Coral calcification rate reduced 15-20%

  • Skeletal density decreased, branches thinner


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