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Light fields and optics in coastal waters
The quantitative study of underwater light fields in coastal waters and shelf seas has important applications in ecology, engineering and remote sensing. This article introduces the theoretical basis of optical measurements. Attention is paid to descriptors of light fields, optical properties of natural waters and light field modelling. For more information about the measurement of light field, see also the article Optical measurements in coastal waters.
Relevance The quantitative study of underwater light fields in coastal waters and shelf seas has important applications in ecology, engineering and remote sensing. Underwater light fields:
- play an important role in determining rates of photosynthesis by phytoplankton and macrophytes, and therefore set limits on the productivity of marine ecosystems.
- influence the range at which objects are visible under water, which is of great significance for diving and engineering operations and also for visual interactions between predators and prey species.
- determine the volume reflectance of seawater which is important for optical remote sensing.
Underwater light fields are vulnerable to human activities. Anthropogenic disturbances such as eutrophication, dredging operations and accelerated soil erosion due to the de-afforestation of river catchments can modify underwater light climates in coastal regions. Increases in turbidity produced by these activities can damage important ecosystem components such as coral reefs and sea grass beds.
