Mar Biodiv DOI 10.1007/s12526-010-0070-z ARCTIC OCEAN DIVERSITY SYNTHESIS Biodiversity of arctic marine fishes: taxonomy and zoogeography Catherine W. Mecklenburg & Peter Rask Møller & Dirk Steinke Received: 3 June 2010 /Revised: 23 September 2010 /Accepted: 1 November 2010 # Senckenberg, Gesellschaft für Naturforschung and Springer 2010 Abstract Taxonomic and distributional information on each Six families in Cottoidei with 72 species and five in fish species found in arctic marine waters is reviewed, and a Zoarcoidei with 55 species account for more than half list of families and species with commentary on distributional (52.5%) the species. This study produced CO1 sequences for records is presented. The list incorporates results from 106 of the 242 species. Sequence variability in the barcode examination of museum collections of arctic marine fishes region permits discrimination of all species. The average dating back to the 1830s. It also incorporates results from sequence variation within species was 0.3% (range 0–3.5%), DNA barcoding, used to complement morphological charac- while the average genetic distance between congeners was ters in evaluating problematic taxa and to assist in identifica- 4.7% (range 3.7–13.3%). The CO1 sequences support tion of specimens collected in recent expeditions. Barcoding taxonomic separation of some species, such as Osmerus results are depicted in a neighbor-joining tree of 880 CO1 dentex and O. mordax and Liparis bathyarcticus and L. (cytochrome c oxidase 1 gene) sequences distributed among gibbus; and synonymy of others, like Myoxocephalus 165 species from the arctic region and adjacent waters, and verrucosus in M. scorpius and Gymnelus knipowitschi in discussed in the family reviews. Using our definition of the G. hemifasciatus. They sometimes revealed the presence of arctic region, we count 242 species with documented additional species that were not entirely expected, such as an presence, if 12 species that likely are synonyms are unidentified species of Ammodytes in the western Gulf of excluded. The 242 species are distributed among 45 families. Alaska, most likely A. personatus; and an unidentified Icelus species of the I. spatula complex with populations in the western Gulf of Alaska and the northern Bering and Chukchi This article belongs to the special issue “Arctic Ocean Diversity Seas which could be a new species or a species in synonymy. ” Synthesis Reviewing distribution, we found that for 24 species the Electronic supplementary material The online version of this article patterns assigned by authors understated historical presence (doi:10.1007/s12526-010-0070-z) contains supplementary material, in the arctic region, and for 12 species they overstated which is available to authorized users presence. For instance, Hippoglossoides robustus is counted C. W. Mecklenburg (*) as an arctic–boreal species rather than predominantly boreal, Department of Ichthyology, California Academy of Sciences, and Artediellus uncinatus as predominantly arctic rather than mail: Point Stephens Research, P.O. Box 210307, Auke Bay, AK 99821, USA predominantly boreal. Species with arctic, predominantly e-mail: [email protected] arctic, or arctic–boreal distributions composed 41% of the 242 species in the region, and predominantly boreal, boreal, P. R. Møller and widely distributed species composed 59%. For some Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, continental shelf species, such as the primarily amphiboreal 2100 Copenhagen Ø, Denmark Eumesogrammus praecisus and Leptoclinus maculatus, distributions appear to reflect changes, including reentry into D. Steinke Arctic seas and reestablishment of continuous ranges, that Biodiversity Institute of Ontario, University of Guelph, 50 Stone Road East, zoogeographers believe have been going on since the end of Guelph, Ontario N1G 2W1, Canada land bridge and glacial times. Mar Biodiv Keywords Biodiversity . Arctic marine fishes . Barcoding . occurrence affecting known patterns of distribution. The Taxonomy. Zoogeography family reviews and annotated list incorporate new information gained from DNA sequencing, examination of museum collections and records, and research fishing in the Arctic Introduction Ocean and adjacent arctic waters of the North Pacific and North Atlantic during the IPY and CoML (2001–2010). The way we classify organisms demonstrates our under- standing of biodiversity at the most basic level. The Definition classification of arctic marine fishes is somewhat unsettled, with the status of several species, genera, and even higher By “arctic region” (Fig. 1) we mean the Arctic Ocean and its taxa controversial. The lack of nomenclatural stability and seas and adjacent waters of the North Atlantic and North Pacific taxonomic resolution for some species has made it difficult southward to the arctic–boreal ichthyofaunal boundary. The to interpret the historical record of fish distribution and position of the boundary is reflected in major differences in make temporal comparisons, and to identify fishes in the species composition associated with seafloor topography, such field and laboratory for modern assessments. Studies as sills and canyons, and water characteristics, such as focusing on the taxonomy and geographic distributions of temperature and salinity, that form barriers against fish move- arctic marine fishes during the International Polar Year ments. The boundary has a temporal dimension, in that it (IPY) and first Census of Marine Life (CoML) programs reflects historical patterns of distribution. Briggs (1974), in his have advanced knowledge on those aspects of diversity to comprehensive treatment of marine zoogeography for faunal the extent that a review and synthesis are required. Such a regions of the world, defined the boundaries before the synthesis is timely because it provides a critical component acceleration of climate change and retraction of the Arctic sea of the baseline for monitoring and detecting effects of ice observed in recent decades. Wherever Briggs’ (1974) climate change on biodiversity. This paper reviews advances arctic–boreal boundary has been modified it has been done to in our taxonomic knowledge of species within the context of add refinements from increased knowledge on historical each family represented in arctic marine waters and provides patterns of distribution, not in response to any observed shifts an annotated list of species with notes on new records of in species composition attributed to recent climate change. Fig. 1 Arctic marine ichthyofaunal region. See text for definition of boundary Mar Biodiv In the North Atlantic, the arctic faunal region extends south Zoarcidae, Stichaeidae) (Andriashev 1954; Dunbar 1968). to Cape Charles (52°13'N), Labrador, at the northern border Old groups are thought to have been eliminated during the of the Strait of Belle Isle (Briggs 1974, 1995). The region rapid cooling of the Middle Miocene (Savin 1977), and extends seaward at depths less than 50 m along the Canadian younger families to have invaded the Arctic mainly from the coast north approximately to Durban Island (67°05'N), along Pacific when the Bering Strait opened 3–3.5 million years the Canada–Greenland Ridge, separating Baffin Bay from ago. A few families appear to have invaded the Arctic from Davis Strait with depths less than 700 m, to near Aasiaat the Atlantic (e.g., Gadidae, Anarhichadidae). These theories (68°40'N); along southern Greenland coasts at depths less are mainly based on current species diversity in the Atlantic, than 50 m to about the middle of the Greenland–Iceland Arctic, and Pacific (Schmidt 1950;Briggs1974), but are Ridge (67°N), separating the Greenland Sea and the North largely confirmed by phylogenetic studies (Møller and Atlantic Ocean with depths less than about 630 m, across to Gravlund 2003; Roa-Varóna and Orti 2009). At the time of northern Iceland; along the Iceland–Faroe Ridge, with a this great biotic interchange (Briggs 2003), the Arctic Ocean maximum depth of 657 m, including the Faroe Trench; in the was free of ice and boreal (cold–temperate) conditions still Norwegian Sea at depths more than 500 m nearly to Bear prevailed (Golikov and Scarlato 1989). Between 3.5 million Island; and in the Barents Sea from 74–75°N nearly to years ago and the present, the Bering seaway apparently southern Novaya Zemlya and including the White Sea west closed and reopened as many as ten times (Einarsson et al. to the Murman Peninsula (Møller et al. 2005a,modified). 1967;Briggs1974, 1995, 2003). The multiple Pliocene– Studies describing fish assemblages and associated hydro- Pleistocene glacial periods are thought to be the most graphic and topographic conditions at key locations along important vicariance events in the evolution of Arctic fishes the Atlantic part of the boundary include Backus (1957)on (Berg 1934; Andriashev 1939, 1949; Anderson 1982). Labrador; Kotthaus and Krefft (1967) on the Iceland–Faroe With continued cooling during the Pliocene and Pleisto- Ridge; Haedrich and Krefft (1978) on Denmark Strait and cene (Herman and Hubkins 1980), some Arctic Ocean the Irminger Sea; Bergstad et al. (1999) on the slope of the species became extinct in the Arctic and relegated to warmer eastern Norwegian Sea; Møller and Jørgensen (2000)and waters of the Pacific and Atlantic Oceans. This event created Jørgensen et al. (2005) on Baffin Bay and Davis Strait; some amphiboreal sister species (e.g., Hippoglossus hippo- Blindheim (2004) on the