โ Scribed by Dipl.-Phys. Lothar Paul
No coin nor oath required. For personal study only.
Technischc CniversitBt Dresden, Sektion \Viisserwewi. Dresden. Gel inan Democratic Republic Irif luen ce of' Seiche -Genera tec 1 Light Field Fluctuations on Phyt!oplankton Growth
Ley ncorcln: internal seiches, iindcrivater light intensity. eupliotic zone depth, phytoplankton growth Phytoplankton, owing to thc periodi cent and descent caused by internal seiches, is exposed to rxpoiiential fluctuations in light int,ensit>y. The increase in light intensity associated \I itli i t x ascent towards the surface is grcater than the decrease caused by its descent. A simple innthcmntiral model is used to derive relationships showing that 1 ) the mean light intensity in i i i i epiliinnion influenced by int'ernal waves is not inore than 6.1 OJ,, lower than in R stationary system and 2) in the inetna t i d hypolimnion of lakes of lo\v triinsparency (i.e. with a high extinction coefficient) internal seiches of large aniplitnde increase the mean light intensity by several orders of ningnitude. This can produce a many-fold increase in the depth of the eiiphotic zone. The niean rates of photosynthesis of phytoplankton in the nietaand hypolimnion increase particularly at the ant,inodes of the waves. Int8ernal seiches evidently niny play an important role in rausing plankton patchiness arid in the presence of pliotosvnthctir~ill~ active phyt.oplnnkton at depths far below the 1 '1 ,, light limit. Contents 1 .
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