No abstract

During a survey done on the mineral springs in the French Massif Central region, a new Chamaepinnularia species (Bacillariophyceae) was found and is hereby described: Chamaepinnularia salina Beauger, C.E.Wetzel, Allain & Ector sp. nov. This new small species, with valves linear with almost parallel margins, is formally described using light and scanning electron microscopy. The central area is rectangular, forming a rather broad fascia and the raphe is straight, filiform located on an elevated sternum. Virgae between striae are developed. The ecological preferences of Chamaepinnularia salina are presented. This species is mainly in mineral springs with Na-K-HCO3 water type.

Although a strong link between viruses and prokaryotes is commonly known to exist in aquatic systems, few studies have investigated their relationship in spring waters. In the French Massif Central, certain springs are known to exhibit varying levels of naturally occurring radioactivity. Therefore, the aim of this study was to examine the standing stock of viruses together with prokaryotes, and determine the potential environmental factors influencing them in springs characterized by contrasted radioactivity gradient. Among the investigated 15 spring habitats, flow cytometry analyses indicated that both viral (VA) and prokaryotic abundances (PA) varied by an order of magnitude accompanied by virus-toprokaryote ratio ranging between 8 and 144.2. Significant differences in VA was evident among springs where low abundances (mean ± SD: 21.3 ± 7.0 x 10 7 VLP l -1 ) corresponded to high (mean ± SD: 1911 ± 814.0 nGy.h -1 ) gamma (γ) dose radiation ( 222 Rn) and vice versa.Adverse effect of water radioactivity ( 222 Rn) on VA could perhaps corroborate our hypothesis of drastic effect of ionizing radiations on viruses, which might explain for lack of significant relationship between PA and VA. In such a scenario of prevailing low VA, the adopted phage life strategies could define their existence in these specialized ecosystems.