Effects of UV rays on Aquatic Ecosystems

Ozone depletion causes increases in UV rays's effects on aquatic ecosystems by:

1. decreasing the abundance of phytoplankton – affects the food stock for fishes and the absorption of CO₂
2. decreasing the diversity of aquatic organisms – reduces food stock and also destroys several fish and amphibians.

Effects of UV rays on Terrestrial Ecosystems

• Damage to plant cell DNA molecules - makes plants more susceptible to pathogens and pests
• Reductions in photosynthetic capacity in the plant - results in slower growth and smaller leaves
• Causes mutations in mammalian cells and destroys membranes

Harmful effects of UV rays on people

• Skin cancer
• Premature aging (photoaging) of the skin (different from normal chronological aging)
• Cataracts and eye disorders (corneal sunburn and blindness) Immune system damage

Correlation between Ozone depletion and skin diseases

The Ultraviolet Exposure Index

INDEX VALUES EXPOSURE

0 – 2 = Minimal

3 - 4 = Low

5 - 6 = Moderate

7 - 9 = High

10 + = Very High

Factors affecting UV exposure

• Clouds cover - partly cloudy days do little to reduce UV exposure but rainy or substantially overcast days reduce UV exposures
• The time of day – peak exposure time is 12:00 noon - 1:00 p.m. UV intensity is reduced by about half at three hours before and three hours after the peak exposure time.

Factors affecting UV exposure..2

• The time of year - more UV is received in the late spring and early summer and much less is received in the late fall and early winter.
• Life style – determines a person's risk to UV exposure. Skiing, sunbathing, or swimming can lead to extremely high exposures. Use of tanning parlors also increase risk.