Seasonal variations in photosynthetic irradiance response curves of macrophytes from a Mediterranean coastal lagoon

Abstract

The main photosynthesis and respiration parameters (dark respiration rate, light saturated production rate, saturation irradiance, photosynthetic efficiency) were measured on a total of 23 macrophytes of the Thau lagoon (2 Phanerogams, 5 Chlorophyceae, 10 Rhodophyceae and 6 Phaeophyceae). Those measurements were performed in vitro under controlled conditions, close to the natural ones, and at several seasons. Concomitantly, measurements of pigment concentrations, carbon, phosphorous and nitrogen contents in tissues were performed. Seasonal intra-specific variability of photosynthetic parameters was found very high, enlightening an important acclimatation capacity. The highest photosynthetic capacities were found for Chlorophyceae (e.g. Monostroma obscurum thalli at 17 °C, 982 μmol O 2 g −1 dw h −1 and 9.1 μmol O 2 g −1 dw h −1 /μmol photons m −2 s −1 , respectively for light saturated net production rate and photosynthetic efficiency) and Phanerogams (e.g. Nanozostera noltii leaves at 25 °C, 583 μmol O 2 g −1 dw h −1 and 2.6 μmol O 2 g −1 dw h −1 /μmol photons m −2 s −1 respectively for light saturated net production rate and photosynthetic efficiency). As expected, species with a high surface/volume ratio were found to be more productive than coarsely branched thalli and thick blades shaped species. Contrary to R d (ranging 6.7-794 μmol O 2 g −1 dw h −1 , respectively for Rytiphlaea tinctoria at 7 °C and for Dasya sessilis at 25 °C) for which a positive relationship with water temperature was found whatever the species studied, the evolution of P/I curves with temperature exhibited different responses amongst the species. The results allowed to show summer nitrogen limitation for some species (Gracilaria bursa-pastoris and Ulva spp.) and to propose temperature preferences based on the photosynthetic parameters for some others (N. noltii, Zostera marina, Chaetomorpha linum).

Temporal and spatial variations in the distribution of macroalgal communities along the Yantai coast, China

“…Our study, along with previous studies (Pihl et al, 1996;Plus et al, 2005; Sousa-Dias and Melo, 2008), has shown that macroalgal communities can have higher species richness and biomass in summer than in other seasons (Table 2; Fig.5). In summer, U lva pertusa was the dominant species along the Yantai coast (Table 3).…”

“…Similarly, many studies have found that Ulva sp. biomass peaked in spring and summer (Ferreira and Ramos, 1989;Solidoro et al, 1997;Plus et al, 2005). Zhuang and Chen (2003) found similar summer peaks in Moon Bay, near Fisherman's Wharf, on the Yantai coast.…”

Antibacterial activity of marine macroalgae against fish pathogenic Vibrio species

“…No other paper on the potential use as a source of bioactive compounds of this species seems to be present in the literature. The positive results obtained in the present study could, therefore, represent a valid basis for the development of the research on C. linum, considering that this is usually a dominant species in the lagoon unattached communities in several world regions [29,30].…”

Herbicide Impact on Seagrass Communities

“…A 5‰ salinity is the smallest salinity amount compatible with seagrass development (Iversen, 1931 cited by Vermaat et al [23]; [24][25][26]), whereas seagrass communities can stand waters which are more salty than the global ocean salinity (35‰): Depending on species, seagrasses could stand a salty environment up to 42‰ [27]. Euryhaline seagrass species, i.e.…”