Editing Photic zone (section)

== Photic zone depth ==
[[File:Light Penetration Spectrum in Water 01.png|thumb|Depth of light penetration]]
The depth is, by definition, where radiation is degraded down to 1% of its surface strength.<ref>{{Cite journal|last1=Lee|first1=ZhongPing|last2=Weidemann|first2=Alan|last3=Kindle|first3=John|last4=Arnone|first4=Robert|last5=Carder|first5=Kendall L.|last6=Davis|first6=Curtiss|date=2007|title=Euphotic zone depth: Its derivation and implication to ocean-color remote sensing|journal=Journal of Geophysical Research: Oceans|volume=112|issue=C3|pages=C03009|doi=10.1029/2006JC003802|bibcode=2007JGRC..112.3009L|issn=2156-2202|url=https://scholarcommons.usf.edu/msc_facpub/11|doi-access=free}}</ref> Accordingly, its thickness depends on the extent of light [[attenuation]] in the water column. As incoming light at the surface can vary widely, this says little about the net growth of  phytoplankton. Typical euphotic depths vary from only a few centimetres in highly [[turbidity|turbid]] [[eutrophic]] lakes, to around 200 meters in the open [[ocean]]. It also varies with seasonal changes in turbidity, which can be strongly driven by [[phytoplankton]] concentrations, such that the depth of the photic zone often decreases as [[primary production]] increases. Moreover, the [[respiration rate]] is actually greater than the photosynthesis rate. The reason why phytoplankton production is so important is because it plays a prominent role when interwoven with other [[food web]]s.