Study the effect of environmental factors on asexual development in salps – DEVOBLOOM

Salps are a group of gelatinous zooplankton present throughout the world's oceans (except the Arctic). Due to their complex life-cycle characterized by a very active phase of asexual proliferation (budding), salp populations seasonally grow exponentially and form very dense blooms that can cover several thousand Km2 of the ocean. Given the magnitude of these blooms, salps play a central role in oceanic trophic webs and global biogeochemical cycles. However, their biology has been surprisingly neglected in the last century.
Salp blooms are deeply influenced by sea surface temperature and by food availability and are therefore sensitive to perturbations of the environment. In addition, the direct link between asexual budding and blooms makes salps a rare model to explore the direct effect of environmental inputs on the developmental dynamics, and up to the level of population demography. The present project combines developmental biology and ecological approaches to explore the links between environmental factors and asexual budding in two species of Mediterranean salps, Thalia democratica and Salpa fusiformis. We will first couple state of the art morphological and proliferation dynamics descriptions of the budding organ (stolon) with single-cell RNA sequencing to characterize the cells implicated in budding and investigate their spatio-temporal differentiation trajectories. In parallel we will study in laboratory-controlled conditions how variations of temperature and food concentration impact the budding mechanisms at the individidual, cellular and gene expression levels. These data will help to reinforce our current understanding of Mediterranean salps demography.