In this investigation, we have tested the potential usefulness of variable fluorescence, i.e., the potential photochemical efficiency of photosystem II (F(v)/F(m)), determined with a fast repetition rate fluorometer (FRRF), as an indicator of the effect of metal pollution on natural phytoplankton assemblages. Phytoplankton populations were collected from an eutrophic embayment and exposed to di...

Acclimation of the photosynthetic apparatus to changes of irradiance, temperature and nutrient availability, involving regulation of the chlorophyll a:carbon ratio (g), is a universal feature of all phytoplankton studied to date. We derive a dynamic regulatory model that predicts the dependencies of 8 and growth rate ( U ) on irradiance, daylength, temperature and nutrient availdbilitv. Thc mod...

Urea and uraease (U-ase) activity were determined in water samples taken from the surface layers of 17 lakes of different trophic status. Urea concentrations were inversely correlated with the trophic status of the studied lakes and varied from below the detection limit to 25 micromol l(-1). Maximal potential ureolytic activity (V(max)) ranged from 0.2 to 7.0 micromol l(-1) h(-1). The highest u...

The eastern South Pacific (ESP) oxygen minimum zone (OMZ) is a permanent hydrographic feature located directly off the coasts of northern Chile and Peru. The ESP OMZ reaches from coastal waters out to thousands of kilometers offshore, and can extend from the near surface to depths greater than 700 m. Oxygen minimum zones support unique microbial assemblages and play an important role in marine ...

Intra-tidal variability in the transport of materials through the Cochin estuary was studied over successive spring and neap tides to estimate the export fluxes of nutrients and chlorophyll a into the adjoining coastal zone. The results showed that there was a substantial increase in the freshwater flow into the estuary following heavy rains (~126 mm) prior to the spring tide observations. The ...

We study the use of airborne and simulated satellite remote sensing data for classification of three water quality variables: Secchi depth, turbidity, and chlorophyll a. An extensive airborne spectrometer and ground truth data set obtained in four lake water quality measurement campaigns in southern Finland during 1996–1998 was used in the analysis. The class limits for the water quality variab...

The capabilities of the Envisat MEdium Resolution Imaging Spectrometer (MERIS) for monitoring water quality parameters of oligoto mesotrophic lakes in Austria and of Lake Garda in Italy are investigated within the project AO-164, “Environmental Research in the Eastern Alps”. From May to September 2003 field measurements and routine measurements from limnological stations are available parallel ...

In the present investigation the effect of different concentrations of zinc and cadmium chloride (ZnCl2 and CdCl2) on one of the Cyanophyta "Chroococcus minutus" isolated from ponds in Sana'a Yemen was evaluated. The two heavy metals adversely affected cell division; however the protein and glucose contents of the cells were slightly affected. They caused destruction of chlorophyll a as the res...

The study discusses a new supplementary method of masking cloud-affected pixels in satellite ocean color imageries. Pixels, typically found around cloud edge, sometimes have anomalous features either in chlorophyll a concentration or in-water reflectance estimates caused by residual error of inter-band registration correction, or more generally, by differences in the band-wise field-ofview of t...

Peridinin-Chlorophyll-α-Proteins (PCPs) are water-soluble light harvesting complexes from dinoflagellates. They have unique light-harvesting and energy transfer properties which have been studied in details in the last 15 years. This review aims to give an overview on all the main aspects of PCPs photophysics, with an emphasis on some aspects which have not been reviewed in details so far, such...