Census of marine zooplankton (CMarZ): Accomplishments and prospects

Zooplankton is widely distributed from coastal to oceanic waters, and from sea surface to abyssal depths. Some of it are known to play important roles in marine ecosystems, including those in the food-chain and matter transfer, but there are also many species whose distribution and ecology are mostly unknown. The Census of Marine Zooplankton (CMarZ) is a field project of the Census of Marine Life (CoML), aiming at compiling and expanding information on the biodiversity of marine metazoan plankton, including its taxonomy, distribution, abundance/biomass, community structure, and genetic diversity. Presently 23 steering members from 14 countries and ca. 140 network-members are cooperating with CMarZ, promoted by three offices: the main project office (the University of Connecticut, USA), the Asian office (Ocean Research Institute, University of Tokyo, Japan), and the European office (Alfred-Wegener Institute for Polar and Marine Research, Germany). CMarZ covers the world oceans. Samples have been collected from various sea areas and habitats by utilizing cruises of 'ships of opportunity'. Historical collections preserved in universities, museums, etc. can also be analyzed on demand. Particular efforts have been paid to 'hot spots', areas where there have been few studies due to historical consequences and/or technical difficulties. This resulted in discoveries of more than 100 species so far unknown, of which ca. 50 species have been described as new to science, from the estuaries, coral reefs and marginal seas of Southeast Asia, the deep-waters of the tropical-subtropical Atlantic, the Arctic Sea, and so on. Genes as well as morphology provide important information in understanding the biodiversity of zooplankton. In addition to the analyses of the relationships between species and phylogeny, genetic information is used in practical identification of species, such as those in morphologically-similar species and damaged specimens. CMarZ aims at collecting gene-sequence data (mainly mtCOI) of all zooplankton species. Specimens from all over the world are currently being analyzed due to the shared efforts of the American-, Japanese-, and Chinese teams and sequences from ca. 2,000 out of ca. 7,000 known species of zooplankton have been determined. As a result, many cryptic species (species with similar morphology but regarded as different species based on their gene sequences) have been revealed in such groups as copepods, chaetognaths, and euphausiids. Special attention has been paid to the biodiversity of gelatinous plankton as major 'hotspots' in terms of taxonomic/ecological groups. This resulted in discoveries of novel cnidarian and ctenophore forms requiring establishment of new higher taxa and/or revision of the present taxonomic systems, as well as discovering many undescribed species, understanding the relationships between regional faunal differences according to geological histories and environmental factors, and discoveries of novel relationships between gelatinous plankton and other organisms by the use of newly developed observation techniques. CMarZ is also holding training courses on the methods of zooplankton research, in particular those on classification and practical identification. In Southeast Asia, by cooperation with a program of the Japan Society for the Promotion of Science (JSPS), we have held courses in five countries, with a total of ca. 120 scientists/students/technicians so far having participated. The ecological data collected by the project members have been compiled in the CMarZ Database with the metadata for each sample collection, and forwarded to OBIS (Ocean Biogeographic Information System), the comprehensive database of CoML. For the Asian Region, we are compiling the information on taxonomy, morphology, gene sequences, and ecological data provided by individual laboratories and scientists in the CMarZ-Asia Database. Data assimilation throughout the whole CMarZ project is now in progress.