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Species composition and distribution are often related to water masses and the Nordic Seas are known to have one of the highest water mass diversities in the world. The combination of water masses in this area have specific hydrographic characteristics that create distinct benthic habitats. Even so, the knowledge we have on the biodiversity and distribution of benthic organisms in these regions, is limited, especially for deep-sea fauna. cumacean species are known to inhabit the cold waters in the arctic region, predominantly those from the ingroups Diastylidae Bate, 1856, Nannastacidae Bates, 1966 and Leuconidae G. O. Sars, 1878. However, distribution studies of Cumacea in the Nordic Seas are largely limited to shelf water. This leaves large numbers of species possibly undiscovered and consequently underestimate the abundance and distribution of cumaceans in these regions.
In this study, authors provide a comprehensive study of cumacean abundance and distribution within the North Atlantic to Arctic waters, using specimens collected from various international projects and expeditions, including: IceAGE (Icelandic marine Animals: Genetics and Ecology), a follow-up expedition of the BIOFAR project (Biology of the Faroe Islands) and BIOICE project (Benthic Invertebrates of Icelandic waters) as well as PASCAL (Physical feedbacks of Arctic PBL, Sea ice, Cloud and Aerosol). Occurrence records from OBIS; the Marine Area database for Norwegian waters (MAREANO); as well as specimens from the University of Bergen, supplemented the specimen collection.
Morphological and molecular identification of the collected sample specimens were performed to accurately identify the specimens to the lowest taxonomic rank. Specimen sequences were further used in phylogenetic analyses and a distribution map was created to reflect the occurrence records of Cumacea based on the new records generated by this study combined with those in OBIS (figure A). As a result, the new OBIS dataset Icelandic Cumacea (ICECU) was created for the IceAGE and PASCAL specimens.
The approach of combining morphological and molecular techniques has proven to be more advantageous than species identification based only on one of these techniques. The study recorded a total of 11 714 cumacean occurrences within the study area, consisting of 109 known species. Of these records, 6 200 originate from shelf regions; 3 900 records from shelf-break regions; and 639 records from the deep- sea. The remaining records had no available depth information. The eight ecoregions showed variation not only in the total number of species, but also in species composition from the Northern Atlantic-boreal to an Arctic community (figure B). Additionally, distribution maps of representative species from 6 cumacean families are provided. The study concluded that the Greenland-Iceland-Scotland-Ridge (GIS-Ridge) acts as a geographical barrier and that water mass types correspond well with cumacean taxa dominance.
Uhlir C, Schwentner M, Meland K, Kongsrud JA, Glenner H, Brandt A, Thiel R, Svavarsson J, Lörz A, Brix S. 2021. Adding pieces to the puzzle: insights into diversity and distribution patterns of Cumacea (Crustacea: Peracarida) from the deep North Atlantic to the Arctic Ocean. PeerJ 9:e12379.