Seaweed Flora of the European North Atlantic and Mediterranean

Abstract

Algae, like most vegetables, have cells with pigments that allow them to perform the photosynthesis. These organisms have a wide geographical distribution, colonizing various sites, but always linked to the presence of water. They can be found floating in the water, on wet rocks, walls, or in association with other organisms, as in the case of lichens, in association with fungi. They are particularly abundant in lakes, rivers, and seas, occupying the euphotic region (or photic), i. e., up to lower penetration of light effective for the realization of photosynthesis of algae (up to $200\mathrm{m}$ deep). Those that live in water can be planktonic (microalgae) or benthic (macroalgae). The former are small and live suspended in water (microscopic), whereas the latter remain fixed to a substrate (usually rock), are larger in size (macroscopic), and may reach $50\mathrm{m}$ in length. Seaweeds inhabit the oceans more than $2000\mathrm{million}$ years and are used as food by people in Asia since the $17$th century. Today, seaweed is used in many countries for several purposes: directly as food, phycocolloids extraction (carrageenan, agar, and alginate) used in the pharmaceutical, cosmetic, and food industries. Algae are also used in the extraction of antiviral, antibacterial compounds, and biofertilizers. The larger or macroscopic algae, called macroalgae or seaweed, are mainly found in three of the algal taxonomic groups: Chlorophyta (green algae); Rhodophyta (red algae); and Phaeophyceae (brown algae). In this chapter, the main European seaweed flora and their biotechnological potential are listed.