Are epiphytes a significant component of intertidal Zostera noltii beds?

Abstract

International audienceThe role of epiphytes in an intertidal Zostera noltii seagrass bed in Marennes-Oléron Bay was assessed in comparison with the other main benthic primary producers (Z. noltii, microphytobenthos) at two bathymetric levels and on a seasonal basis. Assemblage and biomass of epiphytes were studied using Scanning Electron Microscopy (SEM). Zostera noltii and its detrital matter followed a typical seasonal pattern: microphytobenthos was present in large quantities throughout the year representing 21 % of the total biomass while detrital matter, above-ground parts and below-ground parts accounted for 65, 9 and 5% respectively. Only two species of epiphytic diatoms, Cocconeis scutellum and Cocconeis placentula, were 2 observed on seagrass leaves. Epiphyte biomass was very low, representing on average less than 0.001 % of that of microphytobenthos or leaves. This low epiphyte biomass is linked with the absence of macroalgae and also with the low biovolume of Cocconeis, which formed a monolayer of cells on leaves. This can be explained by the severe conditions of the intertidal and the high leaf turn-over of Zostera noltii leaves

Seasonal variations of community production, respiration and biomass of different primary producers in an intertidal Zostera noltii bed (Western English Channel, France)

“…Seagrass leaves also represented an available substratum for bacterial colonization (Wittmann et al, 1981). In this study, the LAI of Z. noltii was relatively low compared to the range found in the literature for this species: from 0.3 to 6.6 m 2 m -2 (van Lent et al, 1991;Plus et al, 2003;Pergent-Martini et al, 2005;Lebreton et al, 2009). Nevertheless, the LAI was also higher in summer and supported a great bacterial biomass which in turn could favour the community respiration of the Z. noltii community.…”

“…A part of the detritus could be due to faecal material of epiphytic grazers, particularly during summer when grazing is normally the highest (Philippart, 1995). Temporal variations of leaf biomass showed a strong seasonal pattern, typical of temperate seagrasses (Duarte, 1989) and widely described for Z. noltii (Pérez-Lloréns & Niell, 1993;Philippart, 1995;Auby & Labourg, 1996;Vermaat & Verhagen, 1996;Sfriso & Ghetti, 1998;Pergent-Martini et al, 2005;Lebreton et al, 2009). They were explained by abiotic factors such as light (Philippart, 1995) and temperature (Marba et al, 1996).…”

“…It corresponded to both benthic microalgae and macrophyte detritus and was probably associated with a low productivity. This overall measure did not allow us to untangle which part of benthic microalgae and detritus contributed to total sediment Chlorophyll a biomass: it is important to separate and measure Chlorophyll a biomass of inert particles and the potential productive organism by sieving, as previously done by Lebreton et al (2009). Once the two components are separated, additional measurements could be done to estimate the production of each fraction.…”

Distribution of epiphytic macroalgae on the thalli of their hosts in Cuba

“…This difference might be related to the longevity of the species, which is a determining factor in the process of substrate colonization by epiphytes; in some cases, this phenomenon is more evident in the older parts of the thallus (Aguilar-Rosas & Galindo 1990). In Zostera noltii, Lebreton et al (2009) found that the number of diatoms was higher on young leaves than on old leaves.…”

Structure of epiphyton communities on Lake Baikal submerged macrophytes

“…The material was collected in Lake Baikal in August 2008-2009, Bolshiye Koty Bay (N 51º54'047, Е 105º04'083) at 3 m during the vegetative activity of submerged macrophytes. The water temperature was 16°C in Bolshiye Koty Bay and 17-20 °C at other sampling sites.…”