This summertime satellite image of the Gulf of Mexico depicts water clarity; areas with high sediment loads or phytoplankton (algal) blooms are less clear (more turbid). Sediment can block sunlight and deplete oxygen through diminished photosynthesis. Phytoplankton blooms also result in oxygen depletion and dead zones. Red and orange represent the most turbid water; yellow, green, and aqua are progressively less turbid but still contain enough phytoplankton to trigger oxygen depletion.