Jean-Michel Brylinski

Temporal variability of the vertical stratification of a front in a tidal Region of Freshwater Influence (ROFI) system

Abstract In the Dover strait, the ROFI along the French coast is delimited by a front. The variability of the vertical stratification of this front, studied with field data and model, is tidally dependent. The destratification always occurs at low water, when the current speed is strong, and the depth the lowest. Stratification occurs under the combined effects of a density gradient and the lateral component (seaward) of the tidal current. The duration of the stratification is a function of the tidal amplitude.

No feeding on Phaeocystis sp. as solitary cells (post-bloom period) by the copepod Temora longicornis in the coastal waters of the English Channel

A Phaeocystis sp. (Prymnesiophyceae) bloom regularly occurs in April–May in the Eastern English Channel. In the literature, views are divided about the in situ appetence of copepods for this alga. In a study carried out in the coastal waters off the bay of Somme, at the end of the bloom, from 29 of April to 1 of May 1996, HPLC pigment analysis on both gut algal pigments and algal pigments from the water column shows that Temora longicornis adults did not feed on single cells of Phaeocystis sp. Alternatively, T. longicornis ingested diatoms and the gut content was correlated with the diatom biomass in the water. More, T. longicornis fed selectively on Dinophyceae and Cryptophyceae, which were scarcely present in the food environment. An inverse relationship was found between the concentration of Phaeocystis sp. in seawater and both gut content and abundance of young stages (CI–CIII copepodites) of T. longicornis. These results suggest an unfavourable impact of Phaeocystis sp. post-bloom on both feeding activity and distribution of T. longicornis.

An optimised protocol to prepare Phaeocystis globosa morphotypes for scanning electron microscopy observation

A preparation protocol for scanning electron microscopy (SEM) was adapted and tested to the observation of Phaeocystis globosa morphotypes. For extra colonial cells, critical point drying (CPD) gave satisfactory results while for intra colonial cells, preservation with Lugols iodine and/or glutaraldehyde followed by air-drying appeared as the most suitable method.

Expansion of the North Pacific copepod Eurytemora pacifica Sato, 1913 (Copepoda: Calanoida: Temoridae) along the Atlantic coast of France

The North Pacific copepod Eurytemora pacifica Sato, 1913 was fortuitously found in a sea water tank of the Marinarium of Concarneau (Southern Brittany, France). The presence of ovigerous females in this tank as well as in some nearby ecosystems confirms the successful introduction of this species along the Atlantic coast of France. Morphology was examined using scanning electron microscopy and confirmed the species identity. The presence of two types of females resulting from cyclomorphosis was confirmed, as well as the production of two types of eggs. The French Atlantic coasts seem to be the only area in the world where the species has been reported as a non-indigenous