Role of light and photophysiological properties on phytoplankton succession during the spring bloom in the north-western Mediterranean Sea

Abstract

This study aimed to determine the role of light on the succession of the phytoplankton community during the spring bloom in the northwestern Mediterranean Sea. To this end, three successive Lagrangian experiments were carried out between March and April 2003. The three experiments correspond to distinct phases of the bloom development (pre-bloom, bloom peak and post-bloom, respectively) and therefore to different trophic conditions. Phytoplankton (sampled on a daily scale) was grouped in size-based classes (pico and nano+micro) each of them were characterised in terms of chemotaxonomic composition, primary production and photophysiological properties. The phytoplankton community evolved with time changing in both size-class dominance and specie/group dominance within each size class. The bloom peak was characterised by highly dynamic condition (i.e. vertical mixing) and by the dominance of both small (pico) and large (nano and micro) diatoms, as a result of their capacity to photoacclimate to changing light regimes (‘physiological plasticity’). Concluding, we suggest that the physiological adaptation to light is the main factor driving the succession of the phytoplankton community during the first phases of the bloom (until the onset of thermal stratification) in the western Mediterranean Sea.

The Challenge of Ecophysiological Biodiversity for Biotechnological Applications of Marine Microalgae

“…Many diatom species grow on benthic substrates, at least during one step of their life cycle; therefore, their cultivation for biotechnological purposes needs a deeper communication between ecophysiological and process engineering researchers. Moreover, they are able to reproduce sexually [ 134 ], allowing this group frequent gene recombination processes and present high physiological flexibility [ 274 ]. Due to this relevant feature, we could easily manipulate their photophysiological responses and biochemical pathways to increase the production of targeted molecules by varying the culture conditions.…”

“…The spectral composition of light plays a key role in the ability of diatoms to finely balance light harvesting and photoprotective capacities [ 273 ]. Indeed, red radiation mixed to blue is necessary for activating the photoprotective pathway, such as the synthesis of xanthophyll pigments with an antioxidant role [ 274 , 275 ]. The spectral properties of microalgal absorption are the base for designing new models of photobioreactors and improving microalgal growth [ 276 ].…”

Biotechnological response curve of the cyanobacterium Spirulina subsalsa to light energy gradient

“…The cellular level of secondary metabolites depends thus on both cell and environment constraints, i.e., on the organismal fitness within its environment and its variations. It is noteworthy that light is one of the main ecological axes for photosynthetic organisms in the marine environment [ 11 , 12 ]. Microalgal cells inhabiting the pelagic system and, therefore, moving up and down along water column, experience changes in photon flux density (PFD) and spectral variations [ 12 ].…”

Habitat-specific differences in adaptation to light in freshwater diatoms

“…Many studies have focused on the role of environmental factors such as light (Marra and Heinemann 1982), turbulence (Thomas and Gibson 1990), and nutrients (Ferris and Lehman 2007;Sommer 1986) in the dynamics of diatom populations in aquatic ecosystems. Light intensity has been shown to be the main factor controlling the timing of the first occurrence of spring diatom blooms (e.g., Znachor et al 2013;Letelier et al 2004) and driving phytoplankton succession during the initial phase of the spring bloom in the north-western Mediterranean Sea (Brunet et al 2013). Phytoplankton composition is highly related to the light regime of aquatic habitats (Robinson and Rushforth 1987).…”