Hydrothermal Vents: Oases at Depth

Abstract

The deep ocean, often called the abyss, covers 66% of the planet. Schematically, it is the marine zone where there is not enough light to allow plants to grow. In fact, the lightened part of the ocean is shallow and does not exceed a few hundred meters; the rest of the ocean can reach much greater depths (11 km in the Mariana Trench) and is in complete darkness except for slight glows of bioluminescence. In the absence of local organic production, the organisms living at depth subsist due to organic matter produced in surface waters. This organic matter, in the form of decomposed matter, feces and molts, is clumped together by secretions from gelatinous organisms, sediments at depth and is degraded under the action of heterotrophic microbial communities, or is being recycled by pelagic organisms. Stratification of the water column, depth, surface production and seasonal variations as well as distance from continental shelves directly affect the flow of organic matter that reaches deep sediments. Generally speaking, the further we move away from the coast, the greater the depth, the lower the organic input and consequently, the lower the benthic biomass. Production in the abyssis approximately a hundredth of the primary production at the surface and benthic biomass expressed in fresh weight rarely exceeds 2 g/m 2. Only some populations of filter-feeding Chapter written by Jozée SARRAZIN and Daniel DESBRUYÈRES.

Nannochlropsis gaditana Cultivation Using Cheese Whey as Substrate for Biomass Production

“…The comparison between the control medium and the vitamin-enriched media shows that they do not have a major influence on the growth of Nannochloropsis gaditana, these observations are consistent with the work of De La Noue (1989). Monaco and Prouzet (2014) showed that for the growth of microalgae, the essential macronutrients are carbon, nitrogen, phosphorus. However, micronutrients include iron, cobalt, zinc, manganese and magnesium, which are essential for certain key enzymatic activities and other intracellular functions.…”

A step in the deep evolution of Alvinellidae (Annelida: Polychaeta): a phylogenomic comparative approach based on transcriptomes

“…After the discovery of hydrothermal vents and their associated communities on the Galapagos rift in the late 1970s, the Pompeii worm Alvinella pompajena Desbruyères and Laubier (1980), was one of the first emblematic species collected from the vent chimney environment following the sampling of a "black smoker" chimney at 21°N on the East Pacific Rise (EPR) (Monaco and Prouzet, 2015). Two morphological types living in close association (syntopy), initially viewed as ontogenic forms, were later found to represent two distinct species, A. pompejana and Alvinella caudata Desbruyères and Laubier (1986) (Jollivet and Hourdez, 2021).…”

“…Discovered in the late 1970s, hydrothermal vents represent extreme environments with particularly intriguing ecosystems. These habitats, associated with submarine volcanism resulting from the geological activity of oceanic ridges and back-arc basins, offer a large quantity of reduced compounds and energy on which mainly chemosynthetic and highly specialized communities are based (Monaco and Prouzet, 2015). Hydrothermal vents are unstable environments, both in time and space.…”