La transparence et la charge sestonique de l'�tang de Berre (c�te m�diterran�enne fran�aise)

Abstract

Water transparency and seston weight were measured in the brackish Etang de Berre and Etang de Vane (between the Rhone river and Marseilles), in nearby seawater and in four main tributaries of the Etang de Berre .The large quantities of seston conveyed by rivers, particularly the Durance diversion, strongly reduce the transparency in the brackish waters . The transparency progressively increases from freshwater to open seawater, as mineral particles sink to the bottom (about 1 .7 kg m-2 a -l on the average in brackish lakes) .Comparatively, the role played by phytoplankton in light attenuation amounts to only 5% in seawater and 10-17% in Etang de Berre .In spite of turbidity, the euphotic layer generally extends to the bottom, in both the shallow brackish waters and in the deeper seawater .

Factors affecting water clarity in Lake Ellesmere, New Zealand

“…The contraction of the euphotic zone {z^ < 0.3 m) brought about by higher inorganic suspensoid concentrations did not reduce the chl. a levels as in some other shallow lakes (e.g., Stephan & Cardoni 1983;Kim & Travers 1983). This is attributed to the predominance of scattering, with little light absorption in the water column.…”

Annual Cycles and Budget of Nutrients in Berre Lagoon (Mediterranean Sea, France)

“…The cuphotic layer (aronnd 4 to 5 n i deep) receives a very high load of particulate matter and nutrients from continental inputs (the Durance, but also two secondary rivers, Arc and Touloubrc), and shows a very high turbidity (KIM and TRAVERS, 1983). Residence time of these surface waters in t,he lagoon is estimated a t 15 days with maximum flow in the Durance, and about 30 days when the continental flow is limited to the two secondary rivers.…”