Most life in the oceans depends on sunlight that autotrophs are able to capture through pigments to photosynthesize and produce food. Different pigments absorb different wavelengths of light, allowing autotrophs to live at varying depths where certain wavelengths penetrate deepest. The rate of photosynthesis must exceed the rate of respiration for phytoplankton to survive, setting a compensation depth above which they can thrive. Coastal waters often have higher turbidity than the open ocean due to sediment and inputs that cloud the water and limit sunlight penetration.