Characterization of exudates released by the marine diatom Skeletonema costatum exposed to copper stress: a 3D-fluorescence spectroscopy approach.

In a laboratory study, metal contamination experiments were conducted to investigate the effects of two free copper concentrations (10(-9) and 10(-8) M) on cell growth and on dissolved organic matter exudation by a marine diatom Skeletonema costatum. Throughout incubation, the growth kinetics and exudation of extracellular molecules (i.e.

Toxicity of benz(a)anthracene and fluoranthene to marine phytoplankton in culture: does cell size really matter?

The toxicity of benz(a)anthracene and fluoranthene (polycyclic aromatic hydrocarbons, PAHs) was evaluated on seven species of marine algae in culture belonging to pico-, nano-, and microphytoplankton, exposed to increasing concentrations of up to 2 mg L(-1). The short-term (24h) toxicity was assessed using chlorophyll a fluorescence transients, linked to photosynthetic parameters. The maximum quantum yield Fv/Fm was lower at the highest concentrations tested and the toxicity thresholds were species-dependent.

[Seasonal dynamics of genus Alexandrium (potentially toxic dinoflagellate) in the lagoon of Bizerte (North of Tunisia) and controls by the abiotic factors].

Some species of the genus Alexandrium are known as potential producers of saxitoxin, a neurotoxin that causes the paralytic shellfish poisoning (PSP) syndrome. Blooming of these species, especially in shellfish farms can affect the aquaculture production and harm human health. Seasonal dynamics of Alexandrium spp.

[Seasonal phytoplankton responses to N:Si:P enrichment ratio in the Bizerte Lagoon (southwestern Mediterranean)].

This study investigated the role of N, P and Si enrichments on phytoplankton in the Bizerte Lagoon (southwestern Mediterranean Sea, Tunisia) during March, June, August, October and December 2004. Polycarbonate bottles were enriched with different nutrients according to four treatments N:Si:P ratios [+NSi/-P (40:40:1), +P/-NSi (20:20:2,5), +NP/-Si (16:0:1) and +Si/-NP (16:32:1)] and incubated in situ during six days. Chl a and carbon biomass of phytoplankton varied significantly during the course of months, with the highest levels recorded in summer (4-4.