7 documents found, page 1 of 1
Herbicide toxicity on river biofilms assessed by pulse amplitude modulated (PAM...
Tiam, Sandra Kim; Laviale, Martin; Feurtet-Mazel, Agnès; Jan, Gwilherm; Gonzalez, Patrice; Mazzella, Nicolas; Morin, SoizicThe use of Rapid light curves (RLCs) as a toxicity endpoint for river biofilms was examined in this study and compared to “classical fluorescence parameters” i.e. minimal fluorescence (F0), optimal and effective quantum yields of photosystem II (Fv/Fm and ФPSII). Measurements were performed after exposure to five concentrations of diuron (from 0.3 to 33.4 gL−1), its main degradation product (DCPMU) (from 1.0 to...
Response of intertidal benthic microalgal biofilms to a coupled light-temperatu...
Laviale, Martin; Barnett, Alexandre; Ezequiel, João; Lepetit, Bernard; Frankenbach, Silja; Méléder, Vona; Serôdio, João; Lavaud, JohannAlthough estuarine microphytobenthos (MPB) is frequently exposed to excessive light and temperature conditions, little is known on their interactive effects on MPB primary productivity. Laboratory and in situ experiments were combined to investigate the shortterm joint effects of high light (HL) and high temperature (37°C versus 27°C) on the operating efficiency of photoprotective processes [vertical migration ...
The “creme brulee” sampler: a new high-resolution method for the fast vertical ...
Laviale, Martin; Ezequiel, João; Pais, Catarina; Cartaxana, Paulo; Serôdio, JoãoThe reduced depth of the photic zone in most intertidal and shallow coastal sediments makes the characterization of its properties a considerable methodological challenge. Availablemethods for sediment sampling present insufficient resolution (ca. 2 mm) for sedimentary biofilms or require considerable post-sampling handling and operator expertise. In this study, we describe a new cryo-sampling device allowing t...
Photoacclimation state determines the photobehaviour of motile microalgae: the ...
Ezequiel, João; Laviale, Martin; Frankenbach, Silja; Cartaxana, Paulo; Serôdio, JoãoHigh productivity in intertidal microphytobenthic communities is achieved despite exposure to extreme and dynamic conditions (e.g. light, salinity, temperature). As an adaptation to this hostile environment, most of the microalgae species inhabiting fine-sediment habitats are motile, being able to migrate vertically within the uppermost layers of the sediment and actively regulating their exposure to light. In ...
Evidence for gravitactic behaviour in benthic diatoms
Frankenbach, Silja; Pais, Catarina; Martinez, Monica; Laviale, Martin; Ezequiel, João; Serôdio, JoãoVertical migration by diatoms is a well-known phenomenon, occurring in intertidal and subtidal benthic biofilms. It is partially endogenously driven, as cell movements can be observed in the absence of external stimuli such as light, temperature or water cover. Although vertical migration of diatoms under constant conditions has often been attributed to geotactic orientation, this hypothesis has never been expe...
In vivo estimation of pigment composition and optical absorption cross-section ...
Méléder, Vona; Laviale, Martin; Jesus, Bruno; Mouget, Jean Luc; Lavaud, Johann; Kazemipour, Farzaneh; Launeau, Patrick; Barillé, LaurentThe objective of the present study was to estimate in vivo pigment composition and to retrieve absorption cross-section values, a*, of photosynthetic micro-organisms using a non-invasive technique of reflectance spectrometry. To test the methodology, organisms from different taxonomical groups and different pigment composition were used (Spirulina platensis a Cyanophyta, Porphyridium cruentum a Rhodophyta, Duna...
A method for the rapid generation of nonsequential light-response curves of chl...
Serôdio, João; Ezequiel, João; Frommlet, Jörg; Laviale, Martin; Lavaud, JohannLight-response curves (LCs) of chlorophyll fluorescence are widely used in plant physiology. Most commonly, LCs are generated sequentially, exposing the same sample to a sequence of distinct actinic light intensities. These measurements are not independent, as the response to each new light level is affected by the light exposure history experienced during previous steps of the LC, an issue particularly relevan...