The Magnitude of Global Marine Species Diversity

Abstract

The most widely used metric of biodiversity is species richness, and much has been written about how many species may exist on land and in the sea [1, 2, 3]. Recent estimates of the number of extant described marine species vary from 150,000 to 274,000, and of those that may exist from 300,000 to over 10 million [4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14] (Table 1). Most of these estimates were made without the benefit of a global inventory of known marine species. The former estimates were based on experts’ polls. The latter were based on extrapolation from past rates of description of species and higher taxa, proportions of undescribed species in samples, proportions that well-known taxa may represent of regional biota, and numbers of species in samples (Table 1). Here, we report on the near completion of such an inventory. The World Register of Marine Species (WoRMS) is an open-access online database created by an editorial board of 270 taxonomists from 146 institutions in 32 countries [15]. The first goal of WoRMS has been the compilation of a list of all taxonomically accepted marine species, commonly used synonyms, and key literature sources. Beyond complete taxonomic coverage, the longer-term aim is to provide or link to data on species distributions, biology, ecology, images, and guides to their identification. An important side benefit is that it facilitates communication within and beyond the taxonomic community, which can lead to increased rates of discovery of species and synonyms and a reduced rate of creation of new synonyms (and homonyms).