Seaweeds, or marine macroalgae, are macroscopic algae that grow along seashores worldwide and in many cases are key to the functioning of benthic ecosystems. Seaweeds comprise three groups, brown (Phaeophyceae), red (Rhodophyta) and green (Chlorophyta) seaweeds, which evolved independently from unicellular algal ancestors. The red and green algae are ancient, possibly emerging 1 to 1.6 billion y ago. In contrast, brown algae emerged much more recently, likely in the Early Jurassic. For many millions of years, seaweeds are the dominant primary producers of coastal marine ecosystems and therefore also the major source of energy, carbon and nutrients flowing through these ecosystems.
The long evolutionary history and independent origins of seaweeds resulted in a bewildering morphological and ecological diversity. Seaweeds range from microscopic epiphytes barely a few cells tall to the giant kelp (Macrocystis pyrifera) which grows up to 45 m in length and forms underwater forests that provide a habitat for a large variety of invertebrates, fish and marine mammals. Some species grow in the highest reaches of the intertidal area and cannot withstand to be submerged in seawater for more than half of the time (e.g., Pelvetia canaliculata). Others are adapted to extremely low light levels, growing at depths of more than 200 meters or living inside the calcium carbonate matrix of corals and molluscs (Ostreobium, Porphyra). Furthermore, not all macroalgae are multicellular. Siphonous green algae such as Caulerpa have cells that grow to a meter in length and exhibit morphological differentiation into structures that resemble the roots, stems, and leaves of land plants.
The amazing diversity of seaweeds is reflected in the ecological and morphological characteristics of the various species. Seaweed traits and functional forms have therefore long been used as a tool to answer various ecological and evolutionary questions. Traditionally, traits have been applied to create algal life-form classes or describe different reproductive strategies, which intended to reflect habitat requirements or explain various evolutionary questions. The use of traits is also popular in more applied fields such as biodiversity conservation where it has been applied to study the distribution of communities along spatial or environmental scales, the potential of communities to resist invasion, to evaluate the ecological status of coastal waters etc.

AlgaeTraits provides standardised trait information for all European seaweeds, enabling the use of trait-based approaches over broad taxonomic, spatial and temporal scales. AlgaeTraits is a thematic subregister of the World Register of Marine Species (WoRMS) which links to AlgaeBase, the most complete database on global algal taxonomic information.
AlgaeTraits is a work in progress; we are currently expanding the number of documented traits and working towards a global trait database. We kindly ask you to contact the editorial team with any errors or omissions you encounter. Any comments on the database will be critically discussed and included when valid.