A Taxonomic Baseline to Monitor Retreating Arctic Biota: The Marine Invertebrate Collection of the Icelandic Institute of Natural History (IINH)

Abstract

The IINH collection comprises ~5.3 million specimens of marine invertebrates, collected within 758,000 km² of the 200-mile Exclusive Economic Zone (EEZ) of Iceland, which is a significant part of the greater Arctic-Boreal biogeographic boundary in the northern Atlantic. The oldest collected specimen is from 1871, but most of the specimens (4.7 million) were collected during the BIOICE project between 1991 and 2004. The program objective is to build a museum collection, reflecting the geographical distribution and morphological variation of benthic species. Over 1,390 zoological samples were collected following a stratified random sampling plan with 579 stations at a depth range of 20 to 3,000 m, and temperatures from −1°C to over +9°C. The material is sorted to about 50 higher taxonomic groups, and 3,007 benthic species, of which fifty-one are new to science. The collection offers a baseline to monitor changing biodiversity at the Arctic-Boreal boundary, with rising temperature, salinity, and acidification.

Keywords

museum database case study collections animal specimens natural history biography diversity research in collections

Introduction

The oceans off Iceland are divided between two worlds: the cold northern seas of the Arctic and the temperate waters of the North Atlantic. This division of the marine realm off Iceland is a part of a larger biogeographic boundary between the northern Arctic and the southern Boreal regions, each characterized by different species composition (Briggs 1974; Ekman 1953). Ongoing warming of the world oceans in recent times is pushing this boundary further north, with consequent changes in species composition in affected areas. Carefully curated museum collections, holding voucher specimens of identified species or higher taxa, along with detailed information on sampling locations, are essential to establish a baseline for subsequent monitoring of changes in species distributions and other aspects of biodiversity at this boundary.

The Icelandic Institute of Natural History maintains the largest scientific collection of marine invertebrates from Icelandic waters. The oldest collected item is from the year 1871, and ever since, museum specimens have been intermittently acquired through various independent studies. At the beginning of the 1990s the collection provided valuable, but somewhat incoherent information on many of the local taxonomic groups. The size of the collection at this time, was about 566,000 specimens of 1,785 marine species, collected at roughly 8,500 sampling locations, mainly from the sea floor. This material mostly originated from close to the shores, and within restricted and discontinuous areas on the continental shelf at water depths less than 500 m. The specimens were obtained by varying sampling methods, sometimes emphasizing analysis of disparate taxonomic groups, serving the research objectives of different studies; species identifications were sometimes obscured by use of synonyms. However, knowledge of commercially important fish stocks and their food sources were, and still are, thoroughly investigated and monitored by the Marine Institute in Iceland. Conversely, knowledge of distributions and diversity of non-commercial benthic species was rather fragmentary, especially over large areas of the deep-sea basins that surround the continental shelf of Iceland.

The BIOICE Project

The knowledge gap on species diversity contributed to the decision in 1992 by the Icelandic government to initiate the BIOICE project, a comprehensive inventory of benthic invertebrates within the 200-mile Exclusive Economic Zone (EEZ) of Iceland (BIOICE 2005). The main objectives were to record distribution and abundance of species and develop a museum collection that reflected morphological variation of the species. The intention was also to establish a background information to evaluate how long-term environmental changes will affect patterns of species distributions and diversity on the sea floor. To meet these objectives, the sampling stations of BIOICE were positioned beforehand, using a stratified random sampling scheme to ensure representative a sampling of the area as possible, with respect to: (1) mean annual bottom water temperature and salinity, (2) standard deviation of temperature and salinity, (3) bottom slope, (4) water depth, and (5) bottom type; rock, gravel, sand, or mud (Steingrímsson, Guðmundsson, and Helgason 2020).

The general aspect of how marine diversity is distributed in the world oceans contributed to the decision to focus sampling on the sea floor. Among the most fundamental questions in science is how many species inhabit the Earth. However, the answer is enigmatic because direct quantifications are fragmentary and because indirect estimates rely on very controversial assumptions. In one study, the estimated number of all known and unknown eukaryotic species on Earth ~7.8 million, of which ~2.2 million are marine, that is, about one quarter of the land species (Mora et al. 2011). However, number of species number alone is only one aspect of diversity. Animal species on land belong to fifteen phyla, and perhaps over 80 percent are insects (Stork 2018). An estimate of the number of described marine animal species on the other hand is merely 180,000 (Bouchet 2006, extracted from his Table 2.1), but they belong to about thirty-five phyla, and the most diverse group, the Arthropods comprise merely 20 percent of marine species, followed closely by Mollusca and Nematoda (Briggs 1994). Since there are more than twice as many marine phyla as those on land, the expected morphologic diversity in the oceans is, in this sense, more than double that on land. Furthermore, most marine animal species live on the sea floor, since only about 7,000 species of fifteen phyla spend all their lives in the water column, as holozooplankton (Bucklin et al. 2010). Sampling of the water column as part of the BIOICE project was therefore omitted, partly because it has relatively low diversity and the sampling cost is high. In addition, marine plankton in Icelandic waters has been thoroughly investigated with ongoing annual monitoring surveys by the Marine Research Institute in Iceland, dating back to the latter half of the twentieth century (Gislason and Astthorsson 2004; Gislason et al. 2016).

Sampling of the BIOICE program started in 1991 and was completed in 2004, after nineteen sampling expeditions on three research vessels: eight cruises with Bjarni Sæmundsson (Marine Research Institute, Reykjavík); six cruises with Håkon Mosby (University of Bergen, Norway); and one cruise with Magnus Heinason (Marine Research Institute of the Faroe Islands). The result was 1,031 zoological samples, collected at 579 stations, spanning a depth range from 20 to 3,000 m water depth, and water temperature from −1°C to over 9°C. At each station different kinds of sampling gears were used to sample species that are living buried in the sediment, on top of soft or hard substrates, and another type to sample large surface dwelling megafauna (detritus sledge, RP-sledge, triangle dredge, and Agassiz trawl, respectively) (Steingrímsson, Guðmundsson, and Helgason 2020).

The Collection of Marine Invertebrates at Icelandic Institute of Natural History (IINH)

The large number of collected zoological samples during the BIOICE project, with high taxonomic diversity, presented an arduous challenge. Nearly all samples contained large amounts of sediments and picking out and cleaning the specimens required considerable work. Further, specimens had to be sorted into major taxonomic groups, before these could be studied by scientists, each specializing in one or two animal groups. This called for establishment of a special laboratory, the Sangerdi Marine Laboratory, and hiring of seven full time para-taxonomist on an annual basis (BIOICE 2005; Gudmundsson, Ottósson, and Helgason 2014). Sample processing started after the first cruise in 1991 and was completed in 2012. This resulted in nearly 4.7 million picked specimens that were sorted to fifty-one of the highest taxonomic groups. The number of specimens that belong to each group follows a well-known hollow curve distribution, such that over 70 percent of the specimens belong to only six groups. The remaining 30 percent of the specimens belong to forty-five taxonomic groups, of which less than 1 percent of the picked specimens belong to thirty-five groups (Figure 1). This is a well-known universal trend, sometimes referred to as the “commonness of rarity” (Magurran and McGill 2010).

Figure 1.

Proportional (%) distribution of 4,730,000 BIOICE specimens among fifty-one taxonomic groups, ranked by decreasing frequency. Specimens picked from the BIOICE samples were initially counted and sorted in to the taxa listed in this graph. The phylum Mollusca mentioned in the text, is divided into seven sub-taxa (marked with red dots) and the phylum Arthropoda is divided into twelve sub-taxa (marked with green squares). The smaller subgraph arranges the same data of the taxonomic groups into four frequency bins, demonstrating the commonness of rarity; thirty-five groups are represented with less than one percent each of the picked specimens and 36% percent of the specimens belong to only two taxa.

Information on specimens in the collection is digitized and maintained in a relational database, comprising several interconnected tables, each one holding a different set of information, like environmental parameters at the sampling stations, taxonomic level of identification, number of specimens in samples, specimen condition, method of preservation, registration numbers, etc. (Gudmundsson, Ottósson, and Helgason 2014). Accepted species names and synonyms of identified voucher specimens, are updated with reference to the website World Register of Marine Species (WoRMS Editorial Board 2022). The number of species, excluding synonyms, that are now registered in the database is 3,425; comprising 3,007 invertebrates, 365 fish species, and 53 putative invertebrate species that have not been formally described and named. Several hundred of these species were previously unknown in Icelandic waters and fifty-one species have been formally described as new to science. From 1991 to present, about 170 scientists have identified to species or genus level about one third of the material, and the collection has been consulted in nearly 400 scientific publications. Identification of four groups is almost complete (bryozoans, gastropods, bivalves, and anthozoans), thirty-nine are partially studied, and twelve have received very little attention. For some of the groups, distribution maps, collection specimens, and descriptions of species are searchable on the IINH web page (https://www.ni.is/en/research/taxonomy), and a fuller version is to be released on the webpage of Landmælingar Íslands (https://atlas.lmi.is/mapview/?application=haf).

Together, the collection and the database provide a valuable tool in exploring various aspects of species diversity and to map distributions of species in relation to varying environmental conditions within the 200-mile EEZ. Distribution of some species is confined to rather limited temperature and depth ranges, and these are projected to be sensitive to environmental changes. An example is four species of Foraminifera, each confined to a restricted sector of the Greenland Scotland Ridge (GSR) (Figure 2).

Figure 2.

Distribution of four common benthic species of Pyrgo (Foraminifera) in Icelandic waters, each occurring at restricted parts of the Greenland-Scotland Ridge (GSR) with different combination of water depth and temperature. The combined occurrence of these four species represents about 75 percent of the sampling stations of the BIOICE project, but nevertheless show the geographic extent of the sampling area.

However, most species have wider tolerance limits for environmental parameters, and their distributional ranges overlap to a varying degree. This variation reveals a consistent diversity pattern at the GSR. The number of species is highest in the shallow temperate waters on the southern side of the GSR and is over 2.5 times the species richness of the cold deep-sea habitats of the Arctic (Figure 3). Although the Arctic benthos includes relatively few species, about 50 percent are endemic, that is, are only found in the Arctic environment, and are currently under increased pressure because of ocean warming and various human activities (Bluhm, Ambrose, et al. 2011; Bluhm, Gebruk, et al. 2011; Vinogradova 1997).

Figure 3.

Schematic cross section of GSR with four main distributional zones, based on water depth and temperature preferences of about 3,000 benthic invertebrate species. Species diversity is lowest in the Arctic environment north of the GSR and highest in temperate Boreal waters at the southern side. Note that many of the species occur in two or more of these divisions; hence the sum of percentages is over 100.

The Environmental Settings in Icelandic Waters

The biological diversity pattern in Icelandic waters is strongly influenced by the complex nature of the physical environment. The topographic and hydrographic settings within the Icelandic 200-mile EEZ, falls within the greater environmental conditions that form the Arctic-Boreal biogeographic boundary in the North-Atlantic. The EEZ is close to 758,000 km² and extends between about 59° and 69°N latitude, with the Arctic Circle crossing at 66°33′N. Iceland and the surrounding shelve, is the highest peak of the Greenland-Scotland Ridge (GSR), a submarine mountain range, that runs from east to west from Scotland to Greenland . It rises from adjacent deep-sea basins from 3,000 m depth, up to about 500 to 600 m below the sea surface, except for deeper trenches in the Denmark strait and the Faroe-Shetland Trough (Figure 4). The GSR is a major topographic barrier that separates water masses with strong temperature contrasts (Astthorsson, Gislason, and Jonsson 2007). North of the ridge, at greater depths than 500 to 800 m lies a cold-water mass, with a mean annual near bottom water temperature of −1°C, whereas at similar depths on the south side of the GSR it ranges between 2°C and 3°C. In shallower waters of the Icelandic shelve, from shoreline to about 500 to 800 m, the annual mean near bottom water temperature difference is more pronounced. South and west off Iceland the temperature ranges from >9°C to 4°C, and off the northern and eastern shore it is about 4°C to 2°C (Jochumsen, Schnurr, and Quadfasel 2016).

Figure 4.

Simplified scheme of the main ocean currents that affect near bottom water temperature in the vicinity of Iceland. Surface currents that affect the continental shelf and slopes are symbolized with dotted lines: the cold East Icelandic Current (EIC) and the cold East Greenland Current (EGC), jointly form the Polar Front north off Iceland; the warmer Irminger Current (IC), is a branch of the North Atlantic Current (NAC). Unbroken blue lines, affecting deeper bottom waters (>500 m): the Cold Overflow Bottom Water currents (COBW), the North Icelandic Jet (NIJ), and the Icelandic-Faroe Slope Jet (IFSJ). Compiled after (Jochumsen et al. 2017; Logemann et al. 2013; Semper et al. 2019; Símonarson, Eiríksson, and Knudsen 2021; Valdimarsson, Astthorsson, and Palsson 2012) (Reproduced from [Guðmundsson, Cedhagen, and Andersen 2022], their Figure 23).

The temperature differences in near bottom waters are strongly shaped by sea currents, both in deep waters (>500 m) and especially in the shallower waters (<500 m) of the shelf. The cold (−1°C) deep waters north of the GSR, are a source of a southward flowing currents, mainly passing through the deepest sills of the GSR: that is, in the Faroe-Shetland Trough and in the Denmark Strait, between Iceland and Greenland (Figure 4). The cold overflow bottom current in the Faroe-Shetland Trough, turns westward along the southern slopes of the GSR, at about the 1,000 m depth contour, and reaches the continental slopes east off Greenland where it joins the overflow branch that falls through the Denmark Strait (Dickson, Gmitrowicz, and Watson 1990; B. Hansen and Østerhus 2000; Hansen, Turrell, and Østerhus 2001). These cold currents create slightly more variable and cooler environment along their course. The recently discovered North Icelandic Jet bottom water current (NIJ), centered at the 650 m isobath at the continental slope north off Iceland, is a significant source of dense water to the overflow plume passing through Denmark Strait, and likewise the Iceland-Faroe Slope Jet (IFSJ) adds to the overflow between Iceland and Faroe Islands and also in the Faroe-Shetland Trough (Jochumsen et al. 2017; Semper et al. 2019).

The near bottom water temperature of the Icelandic shelf, and to some extent the upper parts of the GSR slopes, is strongly influenced by surface currents, especially the warmer Irminger Current and the cold East Iceland Current, which is a branch of the East Greenland Current (Figure 4) (Logemann et al. 2013; Valdimarsson, Astthorsson, and Palsson 2012). On the shelf, the annual mean bottom water temperature is highest south and southwest off Iceland (>8°C), where the Irminger Current enters the Icelandic shelf. It gradually cools as it flows westward in a clockwise direction around Iceland until it meets the cool East Iceland current (2°C–3°C) that bathes the northeast and eastern shelve off Iceland (Eiríksson et al. 2000, 2011; Hansen 1985; Hansen and Østerhus 2000; Jochumsen, Schnurr, and Quadfasel 2016; Malmberg 1985; Mackensen 1987; Malmberg and Désert 1999; Stefansson 1962; Stefansson and Jónsdóttir 1974).

The transitional zone where the Irminger current meets the East Iceland and the East Greenland currents, known as the Polar Front (Figure 4), has fluctuated for the past 6,000 years (Astthorsson, Gislason, and Jonsson 2007; Eiríksson et al. 2000; Símonarson, Eiríksson, and Knudsen 2021). The Icelandic marine ecosystem is highly sensitive to climate variations as demonstrated by changes in abundance and distribution of many species during the warm period in the 1930s, the cold period in the late 1960s, and ocean warming of the last decades (Astthorsson et al. 2012; Astthorsson, Gislason, and Jonsson 2007). The strength of the cold East Iceland Current has diminished, and the Arctic-Boreal boundary in Icelandic waters, has shifted further north with cold affinity species retreating north and the more temperate species following behind. Increased atmospheric CO₂ induces ocean acidification, which is corrosive to the aragonite form of calcium carbonate, the building material of many shell bearing species, like corals and some gastropods, and lowers survival rates, especially in the deep-sea cold waters north off Iceland (Egilsdottir, McGinty, and Gudmundsson 2019; Lörz et al. 2021).

The broad taxonomic spectrum of marine invertebrates deposited in the IINH, provides a unique reference point to assess long term changes in the marine life on the sea floor. The collection can also provide a valuable context of geologic changes of the local fauna. The richly fossiliferous sediments of the Tjörnes Peninsula in Northern Iceland have played an integral part in unraveling the complex climatic history of the Arctic and the North Atlantic Oceans for the past 6 million years (Eiríksson and Símonarson 2021). The IINH holds over 7,000 specimens of fossil marine invertebrates, mostly molluscs, from the Tjörnes sediments of Pliocene and Pleistocene age, and many more are kept in several foreign museums and university collections. Continued research based on the IINH collection of marine animals, will undoubtedly further our taxonomic understanding of the local fauna and species habitats; a basis to gain insight on the impact of past and future climatic changes on the succession of the marine biota in Icelandic waters.

Footnotes

Acknowledgements

This paper draws upon the collective work of all the taxonomists that have participated or continue to actively participate in the BIOICE project, too numerous mention here. We are though all especially indebted to Björn Darri Sigurðsson for his excellent programming of the collection database, the very foundation of all cognitive synthesis on various aspects of species diversity. I owe special thanks to my colleague Kristján Jónasson for compiling the data summary on the fossil collection at the IINH. I am also greatly indebted to Svetlana Nikolaeva and an anonymous reviewer for very constructive and helpful comments.

Declaration of Conflicting Interests

The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Gudmundur Gudmundsson

Author Biography

Gudmundur Gudmundsson is a curator of marine invertebrates at the Icelandic Institute of Natural History. Current projects are focused on organizing taxonomic revision of benthic marine invertebrates in Icelandic waters, and digitizing relevant information for public access on the wed, in cooperation with the Marine and Freshwater Institute in Iceland.

References

Astthorsson

Olafur S.

Gislason

Astthor

Jonsson

Steingrimur

. 2007. “Climate Variability and the Icelandic Marine Ecosystem.” Deep Sea Research Part II: Topical Studies in Oceanography, Effects of Climate Variability on Sub-Arctic Marine Ecosystems 54 (23): 2456–77. doi:10.1016/j.dsr2.2007.07.030.

Astthorsson

Olafur S.

Valdimarsson

Héðinn

Gudmundsdottir

Asta

Óskarsson

Guðmundur J.

2012. “Climate-Related Variations in the Occurrence and Distribution of Mackerel (Scomber Scombrus) in Icelandic Waters.” ICES Journal of Marine Science 69 (7): 1289–97. doi:10.1093/icesjms/fss084.

BIOICE. 2005. Benthic Invertebrates in Icelandic Waters: The Bioice Project 2005. (In Icelandic with English summary). Reykjavik, Iceland: The BIOICE Committee.

Bluhm

Bodil A.

Ambrose

William G.

Bergmann

Melanie

Clough

Lisa M.

Gebruk

Andrey V.

Hasemann

Christiane

Iken

Katrin

, et al. 2011. “Diversity of the Arctic Deep-Sea Benthos.” Marine Biodiversity 41 (1): 87–107. doi:10.1007/s12526-010-0078-4.

Bluhm

Bodil A.

Gebruk

Andrey

Gradinger

Rolf

Hopcroft

Russell

Huettmann

Falk

Kosobokova

Ksenia

Sirenko

Boris

, et al. 2011. “Arctic Marine Biodiversity: An Update of Species Richness and Examples of Biodiversity Change.” Oceanography 24 (3): 232–48. doi:10.5670/oceanog.2011.75.

Bouchet

Philippe

. 2006. “The Magnitude of Marine Biodiversity.” In The Exploration of Marine Biodiversity: Scientific and Technological Challenges, edited by Duarte

C. M.

, 31–64. Bilbao, Spain: Fundación BBVA.

Briggs

John C.

1974. Marine Zoogeography. McGraw-Hill Series in Population Biology. New York, NY: McGraw-Hill.

Briggs

John C.

1994. “Species Diversity: Land and Sea Compared.” Systematic Biology 43 (1): 130–35. doi:10.2307/2413586.

Bucklin

Ann

Nishida

Shuhei

Schnack-Schiel

Sigrid

Wiebe

Peter H.

Lindsay

Dhugal

Machida

Ryuji J.

Copley

Nancy J.

2010. “A Census of Zooplankton of the Global Ocean.” In Life in the World’s Oceans, ed. McIntyre

Alasdair D.

(Oxford, UK: Blackwell Publishing Ltd), 247–65. https://www.academia.edu/3129320/A_census_of_zooplankton_of_the_global_ocean

10.

Dickson

R. R.

Gmitrowicz

E. M.

Watson

A. J.

1990. “Deep-Water Renewal in the Northern North Atlantic.” Nature 344 (6269): 848–50. doi:10.1038/344848a0.

11.

Egilsdottir

Hronn

McGinty

Niall

Gudmundsson

Gudmundur

. 2019. “Relating Depth and Diversity of Bivalvia and Gastropoda in Two Contrasting Sub-Arctic Marine Regions.” Frontiers in Marine Science 6 (March): 129. doi:10.3389/fmars.2019.00129.

12.

Eiríksson

Jon

Knudsen

Karen Luise

Haflidason

Haflidi

Henriksen

Peter

. 2000. “Late-Glacial and Holocene Palaeoceanography of the North Icelandic Shelf.” Journal of Quaternary Science 15: 23–42.

13.

Eiríksson

Jón

Knudsen

Karen Luise

Larsen

Gudrún

Olsen

Jesper

Heinemeier

Jan

Bára Bartels-Jónsdóttir

Helga

Jiang

Hui

, et al. 2011. “Coupling of Palaeoceanographic Shifts and Changes in Marine Reservoir Ages Off North Iceland Through the Last Millennium.” Palaeogeography, Palaeoclimatology, Palaeoecology 302 (1–2): 95–108. doi:10.1016/j.palaeo.2010.06.002.

14.

Eiríksson

Jón

Símonarson

Leifur A.

, eds. 2021. Pacific - Atlantic Mollusc Migration Pliocene Inter-Ocean Gateway Archives on Tjörnes, North Iceland. Topics in Geobiology 52. Cham: Springer International Publishing. https://link-springer-com.web.bisu.edu.cn/10.1007/978-3-030-59663-7

15.

Ekman

Sven.

1953. Zoogeography of the Sea. London: Sidgwick and Jackson. https://archive.org/details/in.ernet.dli.2015.74439/page/n15/mode/2up.

16.

Gislason

Astthor

Astthorsson

Olafur S.

2004. “Distribution Patterns of Zooplankton Communities Around Iceland in Spring.” Sarsia 89 (6): 467–77. doi:10.1080/00364820410009256.

17.

Gislason

Astthor

Valdimarsson

Hedinn

Gudmundsson

Kristinn

Olafsdottir

Solveig

. 2016. “Environmental Conditions in Icelandic Waters 2015”. Marine and Freshwater Reserach in Iceland: 46. ISSN 2298-9137. https://www.hafogvatn.is/static/research/files/hafogvatn2016-001_loka.pdf

18.

Guðmundsson

Guðmundur

Cedhagen

Tomas

Andersen

Tom

. 2022. “Taxonomy and Distribution of Recent Species of the Subfamily Nodosariinae (Foraminifera) in Icelandic Waters.” European Journal of Taxonomy 824: 1–74. doi:10.5852/ejt.2022.824.1827.

19.

Gudmundsson

Gudmundur

Ottósson

Jón Gunnar

Helgason

Guðmundur Víðir

. 2014. Botndýr á Íslandsmiðum (BIOICE). (In Icelandic). Vol. Ní-14004. Gardabær, Iceland: Náttúrufræðistofnun Íslands Ní-14004. http://utgafa.ni.is/skyrslur/2014/NI-14004.pdf.

20.

Hansen

Østerhus

2000. “North Atlantic–Nordic Seas Exchanges.” Progress in Oceanography 45 (2): 109–208. doi:10.1016/S0079-6611(99)00052-X.

21.

Hansen

Bogi

. 1985. “The Circulation of the Northern Part of the Northeast Atlantic.” Journal of the Marine Research Institute 9: 110–26. https://www.hafogvatn.is/static/research/files/rit_fisk_1985_ix_14.pdf

22.

Hansen

Bogi

Turrell

William R.

Østerhus

Svein

. 2001. “Decreasing Overflow From the Nordic Seas Into the Atlantic Ocean Through the Faroe Bank Channel Since 1950.” Nature 411 (6840): 927–30. doi:10.1038/35082034.

23.

Jochumsen

Kerstin

Moritz

Martin

Nunes

Nuno

Quadfasel

Detlef

Larsen

Karin M. H.

Hansen

Bogi

Valdimarsson

Hedinn

, et al. 2017. “Revised Transport Estimates of the Denmark Strait Overflow.” Journal of Geophysical Research: Oceans 122 (4): 3434–50. doi:10.1002/2017JC012803.

24.

Jochumsen

Kerstin

Schnurr

Sarah M.

Quadfasel

Detlef

. 2016. “Bottom Temperature and Salinity Distribution and Its Variability Around Iceland.” Deep Sea Research Part I: Oceanographic Research Papers 111: 79–90. doi:10.1016/j.dsr.2016.02.009.

25.

Logemann

Ólafsson

Snorrason

Á.

Valdimarsson

Marteinsdóttir

2013. “The Circulation of Icelandic Waters: A Modelling Study.” Ocean Science 9 (5): 931–55. doi:10.5194/os-9-931-2013.

26.

Lörz

Anne-Nina

Kaiser

Stefanie

Oldeland

Jens

Stolter

Caroline

Kürzel

Karlotta

Brix

Saskia

. 2021. “Biogeography, Diversity and Environmental Relationships of Shelf and Deep-Sea Benthic Amphipoda around Iceland.” PeerJ 9: e11898. doi:10.7717/peerj.11898.

27.

Mackensen

Andreas

. 1987. “Benthische Foraminiferen auf dem Island-Schottland Rücken: Umwelt-Anzeiger an der Grenze zweier ozeanischer Räume.” Paläontologische Zeitschrift 61 (3): 149–79. doi:10.1007/BF02985902.

28.

Magurran

Anne E.

McGill

Brian J.

, eds. 2010. Biological Diversity: Frontiers in Measurement and Assessment. Oxford, NY: Oxford University Press.

29.

Malmberg

Svend-Aage

. 1985. “The Water Masses Between Iceland and Greenland.” Journal of the Marine Research Institute 9: 127–40. https://www.hafogvatn.is/static/research/files/rit_fisk_1985_ix_15.pdf

30.

Malmberg

Svend-Aage

Désert

Julie

. 1999. “Hydrographic Conditions in North Icelandic Waters and Annual Air Temperature in Iceland.” ICES/CM Theme Session. Nordic Seas Exchange, Stockholm, Sweden, 1–21. http://www.ices.dk/sites/pub/CM%20Doccuments/1999/L/L1499.pdf

31.

Mora

Camilo

Tittensor

Derek P.

Adl

Sina

Simpson

Alastair G. B.

Worm

Boris

. 2011. “How Many Species Are There on Earth and in the Ocean?” PLoS Biology 9 (8): e1001127. doi:10.1371/journal.pbio.1001127.

32.

Semper

Stefanie

Våge

Kjetil

Pickart

Robert S.

Valdimarsson

Héðinn

Torres

Daniel J.

Jónsson

Steingrímur

. 2019. “The Emergence of the North Icelandic Jet and Its Evolution From Northeast Iceland to Denmark Strait.” Journal of Physical Oceanography 49 (10): 2499–2521. doi:10.1175/JPO-D-19-0088.1.

33.

Símonarson

Leifur A.

Eiríksson

Jón

Knudsen

Karen Luise

. 2021. “The Marine Realm Around Iceland: A Review of Biological Research.” In Pacific - Atlantic Mollusc Migration: Pliocene Inter-Ocean Gateway Archives on Tjörnes, North Iceland., edited by Eiríksson

Jón

Símonarson

Leifur A.

, 52, 13–35. Topics in Geobiology. Cham: Springer International Publishing. doi:10.1007/978-3-030-59663-7_2.

34.

Stefansson

Unnsteinn

. 1962. “North Icelandic Waters.” Journal of the Marine Research Institute 3: 1–268. https://www.hafogvatn.is/is/midlun/utgafa/rit-fiskideildar/north-icelandic-waters

35.

Stefansson

Unnsteinn

Jónsdóttir

Sigþrúður

. 1974. “Near-Bottom Temperature Around Iceland.” Journal of the Marine Research Institute 3: 1–73. https://www.hafogvatn.is/is/midlun/utgafa/rit-fiskideildar/north-icelandic-waters

36.

Steingrímsson

Sigmar A.

Guðmundsson

Guðmundur

Helgason

Gudmundur V.

2020. “The BIOICE Station and Sample List: Revised Compilation, March 2020.” Zenodo. doi:10.5281/zenodo.3728257.

37.

Stork

Nigel E.

2018. “How Many Species of Insects and Other Terrestrial Arthropods Are There on Earth?” Annual Review of Entomology 63: 31–45. doi:10.1146/annurev-ento-020117-043348.

38.

Valdimarsson

Héðinn

Astthorsson

Olafur S.

Palsson

Jonbjorn

. 2012. “Hydrographic Variability in Icelandic Waters During Recent Decades and Related Changes in Distribution of Some Fish Species.” ICES Journal of Marine Science 69 (5): 816–25. doi:10.1093/icesjms/fss027.

39.

Vinogradova

N. G.

1997. “Zoogeography of the Abyssal and Hadal Zones.” Advances in Marine Biology 32: 325–87. doi:10.1016/S0065-2881(08)60019-X.

40.

WoRMS Editorial Board. 2022. “World Register of Marine Species”. VLIZ. https://Www.Marinespecies.Org at VLIZ. doi:10.14284/170.