Posted on Authorea 17 Mar 2020 | CC BY 4.0 | https://doi.org/10.22541/au.158447740.08658165 | This a preprint and has not been peer reviewed. Data may be preliminary. nwre aes eepoeti ycmaigdvriyadsz in size and diversity comparing by this of littoral explore northern limits We in 2018). previous longevity) waters. al. perennial their advection et with warmer of Weslawski (associated increasing in 2007, North size the al body species et larger to Fleisher boreal a marus due 2006, that brings mainly hypothesize al. that we et 2005), Here, 2012) Beuchel (ACIA 2005, fast al al. et very et (Berge warming (Walczowski distribution cold-water is waters of Arctic size Atlantic 1999). large the Peck of 1975). the & Steele of for (Chapelle & responsible sector Steele gigantism” are Atlantic in egg “polar levels review oxygen as time, model the also known incubation (see best but phenomenon Egg temperature temperatures a the to low Crustacea, increments. be related only grow the inversely to not juveniles are demarcating addition, likely and size In clearly are stage, female larval moults hand, gammarid no successive and linear other have which size the Peracaridans among the in with pattern changes. on groups but size life, size two crustaceans, 2000), temperature-related blurred – throughout Peracaridan bivalves of The al. and studies worms assess. 2020). for et polychaete taxon to (Beaugrand al. of difficult et dominance Copepoda Sible is the (Mazurkiewicz & pelagic to communities growth (Atkinson in due benthic communities cause is demonstrated in to in benthos been universal likely soft-bottom species is yet already smaller warming not has towards global is Species to pattern selection it due a or increase organism. Such size, temperature an terrestrial individual the on 1997). why of average documented poikilotherms, is well in size That was In change regions that the 1996). 2000). organism, a warmer hence, an 1998, al. towards of and et (Gaston size diversity cold (Siemann the Nearctic rates, the insects with from and growth correlated for Palearctic negatively increasing and usually the responsible richness is metabolism in diversity indirectly species least controls and at show directly directly taxa, patterns temperature of both usual majority factor The the key among a fauna. as marine regarded of widely is Temperature hitherto coasts northern on seas appear Arctic Introduction may European species the Gammarus of species. shrinking warming two more the most ongoing that of at The so (3 example or population species species. good one the boreal smaller a just of mm of of are by cohorts 30 limits gammarids adults occupied annual to Littoral distribution the the waters warmer the replace species years). in large functionally extend 5 In mm may groups) > diversity. 5 size to species (from annual months 14 maturity size-related 5 6 (from reaching and species to < temperature on temperatures several (from and animals increasing to lifespan the time of one of incubation in effect From size egg size and between the ones) Atlantic. relationship in coldest North inverse trends the the evident, consequent in an of and is days) coasts There 120 the > region. along to single occur a Gammaridea in marine coexist littoral can of species thirty Over Abstract 2020 5, May 2 1 ? litoral We˛s Arctic Jan the of of diversity Warming species the increasing follow and crustaceans size body shrinking Will oihAaeyo cecsIsiueo Oceanology of Institute Sciences of Academy Polish PAS Oceanology of Institute ouain eue h osblt fsbigseisocrigsmarcly sosre tpresent at observed as sympatrically, occurring species sibling of possibility the reduces populations l awski 1 onaLegezynska Joanna , 1 n ai ldrk-Kowalczuk Wlodarska- Maria and , 1 Gammarus ouain inhabiting populations 2 Gam- Posted on Authorea 17 Mar 2020 | CC BY 4.0 | https://doi.org/10.22541/au.158447740.08658165 | This a preprint and has not been peer reviewed. Data may be preliminary. 99,ado s,said n el nSabr Wsasi&Klnk 99 yesne l 94.The 1994). al. et al. Lydersen et 1989, (MacNeil Kulinski Baltic & (Weslawski hide the Svalbard can in on they fish seals which coastal under and of crevices seabirds constituent or the fish, dietary stones of is preferred and a dynamics i.e. 1999), are water microhabitat, Gammarids suitable the is there predators. factor as from limiting supersaturated, only oxygen even The The or 1999). salinity. 1993). these high, Peck al. always of & et size is Weslawski highest. (Chapelle plentiful; waters the are controlling saturation coastal microorganisms factors in oxygen and Other concentration meiofauna and/or detritus, 1995). (plant food in littoral al. of the observed et quality (as Koszteyn and – only of availability Adults hyperids temperature the pelagic by or are governed 2000 invertebrates probably al. of is et generations period Irigoien summer incubation contrast, egg by the Baltic, southern 2 or < salinus Sea temperatures Black time round the incubation year genus egg In at the the waters, in is in Arctic phenomenon poikilotherms specifically Incubation – in critical as times 2011). the size. many well first studied less, large al. as been or the a et has crustaceans, year attaining in temperature and ambient a ultimately maturity to fish within years, time reach two like completed this not of or be relationship one may to The next 1). individual is (Table the cycle water for life cold continuously the A grow If will 3). but (Fig. life, lengths its greater of intervals). year ( to mm species grows (2 same and groups one frequency the size longer of length 20 of twenty cohort summer plus populations to a The different temperatures up very has same gives summer intervals). two Arctic spring) the mm in the in (2 of growth in release groups (Baltic) The species juvenile size population mm) five and water (40 to and cohort large temperate winter corresponds lifespan the the that the to of two Arctic, mm) of related of 6-15 the death is population (length to the Arctic age and (after Compared the mm summer 2). of in 52 samples species to (Fig. summer intervals) 4 the mm from in (2 ranges frequencies maturity Length sibling at 1). sympatric size (Fig. Their temperature ambient 1). (Table Atlantic North Dikerogammarus the from from Pontogammarus, species (sea) marus, sibling region thirty the least for At assessed (2001). was Costello species discussion and sympatric Bellan-Santini and after the Results checked of were poikilotherms occurrence names marine for The species value cited, critical 1990). a literature as manuscript taken al. unpublished was et region an geographic of (Golikov the form 1983). Gda´nsk for (Wolska the temperature of different in minimal Internet. University presented Summer the the the were on at Formalin-preserved for author available thesis first spines. currently temperatures MSc the data excluding The The by an meteorological telson, algae. collected paper. – or and of materials filter references stones the tip cited on of under the the Some blotted from to from depth, been obtained head m having were the 0-1 localities after of at wet-weighed tip shore, were the the specimens on from hand-net measured a were with animals littoral collected 54 sampled were Sea, who Gda´nsk They (Baltic author, of first 1982. Gulf the of the archive in unpublished 2000). the species al. from et comes material (Irigoien original temperature The ambient pelagic the in on methods observed depending and been year, Material already tend per has seas will phenomenon temperate increase a in temperature Such three – the Subarctic. to species as the same change, the in to where cycles likely Crustacea, life are gammarid distribution 81 shorten of to to patterns 45 present-day from that latitudes across expect coasts Atlantic North rocky nuaeeg ttmeaue 20 > temperatures at eggs incubate Gammaru Gammarus Gammarus pce aeaeut odrsucs ihlvlo xgnada prpit ag of range appropriate an and oxygen of level high a resources, food adequate have species s pce r mioe Tvtoa17)adfo viaiiyi o iiigfco in factor limiting a not is availability food and 1975) (Tzvetkova omnivores are species amrssetosus Gammarus pce niaeta hr r he nulchrs rfute iegroups size fourteen or cohorts, annual three are there that indicate species ° n 4 and C Gammarus aau finmarchicus Calanus ° epciey ssmlr lhuhtecl ae ouainlives population water cold the although similar, is respectively) C ° nls hn2 as(az˙esi17) h blt oshorten to ability The (Ja˙zd˙zewski 1970). days 20 than less in C t. cu nteitria fbt h atr n western and eastern the both of intertidal the in occur etc.) ° )adHrsn jr Sabr rhplg,77 Archipelago, (Svalbard fjord Hornsund and N) or n te pce rmcoeyrltdgnr ( genera related closely from species other and ° Sel tee17,Wsasi&Lege˙zy´nska & 2002). Weslawski 1974, Steele & (Steele C .wilkitzkii G. 2 ° n ae eprtrsfo 18t 25 to -1.8 from temperatures water and N a rdc rmoegnrto ncl water cold in generation one from produce may – Gammarus at 2 n oedy ncl,Subarctic cold, in days more and 120 lasts .oceanicus G. Sel n tee17,Whiteley 1975, Steele and (Steele amrsinaequicauda Gammarus rmteBli n Arctic, and Baltic the from Calanus Marinogam- ° oeos– copepods )i 1979- in N) Gammarus and ° .We C. G. Posted on Authorea 17 Mar 2020 | CC BY 4.0 | https://doi.org/10.22541/au.158447740.08658165 | This a preprint and has not been peer reviewed. Data may be preliminary. rprto fti ulcto a upre yfnsfo h vladMloenSPPoet-RSNo. RIS - Project SIP Miljovern Svalbard the from funds by supported was areas publication in this of competition species Preparation where sympatric northwards, rises. two of species these temperature From number boreal the small. low as the are Acknowledgements reduced shift the animals be may the is will change where grow other species climate species species large such The that known of from infer all number size. temperatures, can high warmer the we smaller at and observations a occur, animal: species at adult large an maturity where of reach size and the and faster of lifespan not to littoral effect in temperature structure documented direct size of well favourable a are the phenomena be two of summary, will but which In there) This size, living smaller of species. a capable southern at already competitors. by cycle are of colonization increasing life species with area’s their eurytopic that complete (those the speculate temperature will may for five we gammarids opportunities to temperature, littoral the create ambient three Arctic, to In will of the related data. occurrence closely in few so actual temperatures very is coastal the are gammarids of there occur, observations). size as species own the (Ja˙zd˙zewski assess, introduced) 1970, As confirmed to (man was difficult alien spot is occur- four one diversity co- in plus alpha The species sample, local diversity). one 9 (gamma of scale where published scale regional Baltic, (up to small the co-exist considering a according can is on two, 1). species here rence Table to more discussed Sea, – and occurrence Mediterranean groups limited sympatric the size The is like All fewer size species region are 2010). units: a true there al. ecological small, in of et separate Weslawski are fourteen number as (see species to the act where behaviour that and areas and groups In occupied food size observations. mobility, is many in space are differences available there to the large, lead is gammarids species 2019). in the a variations al. as when recently, et littoral, co-exist (Grabowski the species retreat In two glacial the cold-water the Spitsbergen, after local On area the 1974). the where Steele colonising metres, Svalbard, & twelve (Steele and to down Canada lower three is from together range occur tidal species large two setosus where regions of wilkitzkii c-soitdseisand species ice-associated pnsivreyt hi ieadlf egh(al ,Fg ) nteAci,weetetolre cold-water large, two the where Arctic, corre- the species In of 1). number Fig. the 1, (Table and length limited, life more stenothermic and ( spatially size species cold are their with gammarids to littoral inversely zone the sponds narrow however, a fact, into actual temperature In divided occurrence, and be their limiting range salinity would factor temperature ( coast only to the the Atlantic were tolerance in North temperature If occur the wide distribution. species geographical very different wide very many a potentially intertidal, display Atlantic 0 gammarids North between the littoral littoral In in marine colonisation 1975). (Tzvetkova species 2013). of new al. majority the et for Kotta The factor 2008, critical al. a et as (Piscart described conceal was amphipods can competition and mm) selection 5 Niche length 000/m (mean the 10 ones exceed colonizing small can successfully 2000 species or from large, cm mm) species by (300-500/m 20 400 microhabitat eurytopic localities length this stone boreal, of (mean a preventing occupation specimens under the factor large themselves is likely 300 It animals Ca the 1994). of (Weslawski is hundreds North. them some that of when species one filled beneath quickly local hide are to shelter, trying adequate providing are stones, loose among interstices amrswilkitzkii Gammarus scnrne ihteboreal the with confronted is .wilkitzkii G. ek h aesetra t itrlcnee Wsasi19,Plemn19) nte example Another 1997). Polterman 1994, (Weslawski congener littoral its as shelter same the seeks ° nwne o>20 > to winter in C and 2 Wsasi19)adfrtmeaests hr h ubro ml gammarid small of number the where sites, temperate for and 1994) (Weslawski ) and .setosus G. .setosus G. .setosus G. 2 Tvtoa1975). (Tzvetkova ° nsme.Cneunl,ms fteseislse nTbe1 aea have 1, Table in listed species the of most Consequently, summer. in C 2 nae;ti orsod ihteaeaedniisrpre o Arctic for reported densities average the with corresponds this area; in oocr hr sams osmarcocrec,as occurrence, sympatric no almost is there co-occur, ) .oceanicus G. saltoa pce.Hwvr hnteiemlsi osa waters, coastal in melts ice the when However, species. littoral a is ,wt h eto h raspotn h te,ertpcspecies. eurytopic other, the supporting area the of rest the with ), .setosus G. nNwonln,tecat fwihhv nextensive an have which of coasts the Newfoundland, On . a eoddhge po h hr and shore the on up higher recorded was 3 Gammarus pce.Oei h ietrelationship direct the is One species. Gammarus .wilkitzkii G. .oceanicus G. .oceanicus G. species san is G. G. is Posted on Authorea 17 Mar 2020 | CC BY 4.0 | https://doi.org/10.22541/au.158447740.08658165 | This a preprint and has not been peer reviewed. Data may be preliminary. ..(09.Cnrsigmlclrdvriyaddmgah atrsi w netdlapio crus- amphipod intertidal two in patterns Arctic. demography High and of diversity Atlantification reflect molecular taceans Contrasting (2019). J.M. marine Jab to M., approaches Grabowski Theoretical (1990). O.A. Scarlato N.N., Maximovich biogeography. M.A., Dolgolenko biodiversity. A.N., Golikov of patterns Global transformation. (2000). and K.J. extinction Gaston speciation, of products Soc. Royal distributions: Trans. size range Pr. Species- Cycle. (1998). Life K.J. Gaston and Ecology Amphipod, I. Marsh Distribution Salt its The 123-134. of (1977). Limit Croker, Northern A. R. Virginia, M.F., of River, Gable history York habitats, Life estuarine (1986). temperate warm Diaz. in J. ( R. pipefish Ocean). snake T.J., (Arctic Atlantic Fredette Svalbard (2007). to range D. distribution Piepenburg northward in & its species M., new Schaber – D., gammarids Fleischer Ponto-Caspian Sea), (2013). Baltic Gda´nsk A. (Southern of Szaniawska, Gulf availability. the oxygen H. Kendzierska, by dictated gigantism A. Dobrzycka-Krahel, Polar (1999). L.S. Peck Region, Atlantic G., Middle Chapelle the from Amphipoda) (Crustacea: Gammarus Science of (1980–2003). com- Chesapeake records variability New macrobenthic climate (1969). bottom to E.L. rocky Bousfield relation of in patterns Svalbard) Systems (Kongsfjorden, Long-term Marine fjord of (2006). Arctic Journal M.L. an Carroll in structure & munity B., enable Gulliksen oscillations F., temperature Beuchel Ocean (2005). D. their Slagstad to & Series, guides mussels B., of Gulliksen blue bibliography F., of a Nilsen reappearance and G., Europe Johnsen in J., species Berge marine the Naturels of Patrimoines check-list Collection a identification. Amphipoda. species: marine (2001). Biscay. of M.J. of register AC- Costello, Bay & and D., Sea relation Bellan-Santini, in page Celtic plankton of Channel, fluctuations English term web long the and sense Series in seasonal Making Spatial features hydroclimatic (2000). ? project PC environments to Reid colder F., in Ibanez the G., bigger UniversityBeaugrand usually Cambridge organisms puzzle. are through Assessment. history Why life Impact (1997). of R.M. 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Nauk Akademii Institut Zoologicheskii 1–1029. pp. 0 423–480. 20, amrsoceanicus Gammarus setosus Gammarus ilgclReviews Biological amrslawrencianus Gammarus nteEgihChanel. English the in ad ouain nErpa-rtcSeas. European-Arctic in populations Mandt etn 99(rsae:Gmaia)i rtay France. Brittany, in Gammaridae) (Crustacea: 1939 Sexton, 4 375–395. 74, Dementieva. Segerstr˚ale. inlg n Oceanography and Limnology osed Can. Bousfield. aainJunlo Zoology of Journal Canadian aainJunlo Zoology of Journal Canadian l aainJunlo Zoology of Journal Canadian drk-oacu .(00.Lttdnlcnitnyof consistency Latitudinal (2020). M. odarska-Kowalczuk amrstigrinus Gammarus Gammarus Gammarus Gammarus Gammarus Gammarus cioamrsKaradagiensis Echinogammarus 5 eihezmPolarforschung zum Berichte J. ol 8 1261-1267. 48: Zool. eti Zoologii, Vestnik aieBooia Journal Biological Marine oa Biology Polar Cutca mhpd)i h north-western the in Amphipoda) (Crustacea, north-western the in Amphipoda) (Crustacea, north-western the in Amphipoda) (Crustacea, north-western the ln Amphipoda) (Crustacea, Cutca mhpd)I h Northwestern The In Amphipoda) (Crustacea, aainJunlo Zoology of Journal Canadian 5 44-54 45, etn 99ascae ihisniche its with associated 1939 Sexton, 3 1116–1126. 53, 5 85-92 15, 8 659–671. 48, 32:23-26 43(2): 0 801–813. 50, Gammarus hmsoabyssorum Themisto qai Invasions Aquatic AWI p .(Amphipoda, N. Sp. o3 22-26. 3: No 1 peeieiFaune Opredeliteli p.(Crustacea: spp. 2 1115–1120. 52, Zoological . Calanus Boeck (4), 3 Posted on Authorea 17 Mar 2020 | CC BY 4.0 | https://doi.org/10.22541/au.158447740.08658165 | This a preprint and has not been peer reviewed. Data may be preliminary. amrsdieiBufil,16 t.81, 015Bufil 1969 Bousfield 1975 Steele and 1985 Steele Greze 1975, Tzvetkova 1979, Lincoln 1970, Jazdzewski 1979 Lincoln Bousfield 30 1979 Lincoln 1975 Steele 5 and Steele https://www.marlin.ac.uk/species/detail/1776 2017, 9 Zettler 1985 and 30 Greze 6 Zettler to 1979, 15 Lincoln 1 1975, Tzvetkova 1951, 14 Gurjavova 1 5 1 1 1985 20 Greze 1975 10 2016 Steele 2017, 1 2009, 1979 and Zettler 25 Grintsov Lincoln Steele and https://nas.er.usgs.gov/queries/greatlakes/FactSheet.aspx?SpeciesID=23 1979, Zettler 20 16 Lincoln 1979, 0,5 1975, Lincoln Tzvetkova 1975, 1951, Tzvetkova Gurjavova 1951, http://www.iop.krakow.pl/gatunkiobce/ Gurjavova 25 2017, Zettler&Zettler 2016 5 2013, Grintsov 15 11 al. 15 116 2017 et to Zettler Dobrzycka-Krahel 15 10 and 30 14 Zettler to 20 15 1979, 12,5 15 10 Lincoln 1975, Tzvetkova 15 1 1951, Gurjavova http://www.iop.krakow.pl/gatunkiobce/ 20 2017, 2017 Zettler&Zettler Zettler 0,5 22 1 2013, 5 nad al. Zettler et Dobrzycka-Krahel 10 30 10 20 to 15 10 8 http://www.iop.krakow.pl/gatunkiobce/ 10 20 2017, 9 Zettler&Zettler 10 20 2013, 9 20 25 al. 6 et 0,5 13 1 Dobrzycka-Krahel 8 1 1 0,5 8 10 14 1 10 3 1985 10 15 Greze 6 15 15 6 Baltic 15 North, 1 20 Atl. 25 W 9 1 20 20 2 Black 8 10 6 Mediterr. 6 5 Atl. 25 15 15 E 5 North, 15 Atl. 5 10 10 15 W 1 14 20. 1 4 9 10 mm 25 6 15 1852 Lilljeborg, 15 duebeni Gammarus 5 10 1969 1 10 14 11 Bousfield, Medit. 20 Black, daiberi 9. Atl. mm Gammarus 1966 W Stock, North, 15 crinicornis 8 5 Gammarus 1966 4 21 Stock, 1 30 crinicornis 6 Gammarus North 1913 20 10 Sexton, 10 chevreuxi Gammarus Atl. 1873 W Smith, North, annulatus Atl. Gammarus W 1931) 6 North, (Martynov, eggs 10 20 aequicauda Gammarus 7 8 22 1938) 15 (Reid, sympatric North stoerensis Echinogammarus 1940) (Reid, 1940) planicrurus Spooner, Echinogammarus life Black & (Sexton 15 20 Black pirloti Echinogammarus Baltic 1938) 10 (Dahl, 5 obtusatus Echinogammarus max. Mediterr. 1815) (Leach, marinus Echinogammarus 12 2009 Grintsov, White karadagiensis Echinogammarus 8 1899) Baltic min. (Stebbing, ischnus Echinogammarus 1899) (Stebbing, ischnus max. Echinogammarus 1928) (Schellenberg, 6 foxi minimal Echinogammarus 1938) Baltic (Dahl, finmarchicus Baltic Echinogammarus Black 1894) Azov, (Sowinsky, villosus Dikerogammarus 1841) (Eichwald, haemobaphes Dikerogammarus Medit. 1841) Black, (Eichwald, haemobaphes Dikerogammarus 1897 Sars, 1830) warpachowskyi Edwards, Chaetogammarus Milne (H. olivii Chaetogammarus region species/population Adjacent And region Atlantic Sea from Baltic Gammaridae The 1 From Table Amphipoda Freshwater 846 And of Pp. Marine physiology Germany the 2017). Harxheim, in Conchbooks, ( variations Territories. A. Latitudinal Zettler M.L., (2011). Zettler J. Rock & amphipods. D.H., gammarid Lunt marine S.P.S., Rastrick N.M., Whiteley phipod We˛s biomass. and distribution ganism crustaceans. Arctic in diversity We˛s Hidden play? species a can 205-216. roles many How (2010). We˛s Research We˛s density. and bution We˛s an properties: water 253–264. Atlantic in climate. marine Changes We˛s Arctic (2012). P. European Wieczorek the & in I., factor Goszczko important J., Piechura W., Walczowski l l l l wk M rg´saDj ,Lg˙ynk ,Wlzwk 21) ag xeso fabra am- boreal a of extension Macroor- Range Svalbard: of (2018). zone W Lege˙zy´nska Walczowski Intertidal Draga´nska-Deja K, J, JM, (1993). awski S. Swerpel & M., Zaja˛czkowski J., Wiktor J.M., awski (1994). J.M. amphipods. awski Arctic some of cycles Life Lege˙zy´nska (2002). & J. J.M. awski l l wk J.M., awski J.M., awski amrsoceanicus Gammarus 0 241-250. 10, uin k .(99.Ntso se nHrsn jr ra(Spitsbergen). area fjord Hornsund in fishes on Notes (1989). Kuli´nski W. Sarsia pnwk . eez´saJ,MceesaB,W B., Maciejewska Lege˙zy´nska J., A., Opanowski Gammarus 9 145–150. 79, ntewrigArctic. warming the in ora fEprmna aieBooyadEcology and Biology Marine Experimental of Journal oa Biology Polar Cutca mhpd)fo vladadFazJsfLn.Distri- Land. Josef Franz and Svalbard from Amphipoda) (Crustacea, 3 73–79. 13, 6 osdrdfml eghsme umrsa pce incubation species span summer summer length female considered clEvol Ecol CSJunlo aieScience Marine of Journal ICES 8(15):7624-7632.doi:10.1002/ece3.4281 l drk-oacu ,K˛r M. Ke˛dra M, odarska-Kowalczuk eghautwtrwtri region in water water adult length oihPlrResearch Polar Polish 0,70–77. 400, o.PlrResearch Polar Pol. 9 864–869. 69, oihPolar Polish ° ep temp. temp. C 31, 23, ° r rdy reference days nr yrs C Posted on Authorea 17 Mar 2020 | CC BY 4.0 | https://doi.org/10.22541/au.158447740.08658165 | This a preprint and has not been peer reviewed. Data may be preliminary. amrszdah etn 92Bli 01 016Graoa15,Tvtoa17,Zte n ete 2017 Zettler and Zetler 1975, http://www.iop.krakow.pl/gatunkiobce/default2436.html?nazwa=opis&id=35&je=pl, Tzvetkova 2013, 1951, Gurjanova al. et Dobrzycka-Krahel 2007, al. et Grabowski 1997 Poltermann 1975, 1970 Tzvetkova 1985 Jazdzewski Greze, 2017 2017 Zettler Zettler and and Zettler Zettler 1979, 1969,Lincoln 60 Bousfield 180 1975 to 37- Steele 30 and Steele 1975 Tzvetkova 1975, Tzvetkova 1979, 1970, Lincoln 2017 Steele 2017 Zettler and Zettler 1977 Steele and and Croker 1951, Zettler Ja˙zd˙zewski Zettler and Gurjanova 1970, Gable 6 1969, Bousfield 30 0 60 6 to 6 150 30 35- 1 5 1 1986 1 9 Diaz and Fredette 1969, 6 6 2017 Bousfield 30 Zettler 1975 and Steele Zettler and 6 Ja˙zd˙zewski 1 1970, Steele 1 1975, Tzvetkova 25 10 5 1972, 15 15 Ja˙zd˙zewski 2017 1 Steele 1970 to 1 Zettler and 12 and Steele 94 Zettler 1979, to 1979, 10 Lincoln 2 3 25 Lincoln 6 1951, Gurjavova 1 25 2017 5 1975 Zettler 60 1970, 10 150 of-the-arctic-litoral and 30- Steele to 10 Zettler 25 and 60 0 20 Steele 30 1 shrinking-body-size-and-increasing-species-diversity-of-crustaceans-follow-the-warming- 2017 Zettler 25 15 2017 and 1 5 Zettler Multispecies_fig3.docx Zettler and 1985, 20 20 15 Zettler Greze 15 6 1979, 52 1975 Tzvetkova Lincoln file 82 1951, 10 Hosted 0,5 17- Gurjanova 10 15 10 6 7 10 25 20 of-the-arctic-litoral 150 2 0 to 10 10 30 14 shrinking-body-size-and-increasing-species-diversity-of-crustaceans-follow-the-warming- 22 20 7 2 2 30 24 Multispecies-fig1.docx 10 44 10 5 24 20 file 5 Hosted 6 12 6 0,5 4 23 20 20 3 2 of-the-arctic-litoral 5 10 Baltic 13 14 12 shrinking-body-size-and-increasing-species-diversity-of-crustaceans-follow-the-warming- 10 Atl., 6 E 1 14 Multispecies_Fig2.docx 1 Baltic 15 Arcic 12 10 North 4 Baltic Baltic, 5 20 North, file Hosted 30 1 1 4 15 Black 18 15 38 1894) Sars, 5 (G.O. 10 1894) robustoides Baltic Sars, 1 Pontogammarus O. 10 Arctic 20 (G. Atl. 25 crassus E Obesogammarus 1912 10 Sexton, eggs 12 zaddachi 10 33 Gammarus 5 11 1912 Baltic Sexton, sympatric zaddachi Gammarus 1897 10 Birula, 15 Atl. 25 wilkitzkii W Gammarus life 1939 25 Sexton, tigrinus Gammarus 15 1966 5 Stock, Atl. subtypicus 10 21 W Gammarus max. 1931 Baltic Dementieva, setosus 10 Gammarus 1947 Atlantic Spooner, 12 salinus Baltic North Gammarus 1947 , min. Spooner, Atl. salinus E. Gammarus 1758) 8 (Linnaeus, 5 pulex max. Gammarus 1969 Baltic Atl., Bousfield, Black E palustris Med.., minimal Gammarus Atl., Atl. E W Segerstr˚ale, oceanicus 1947 Gammarus Segerstr˚ale, oceanicus 1947 Baltic Gammarus North, 1818 Say, White mucronatus Gammarus 1758) (Linnaeus, locusta Gammarus 1758) (Linnaeus, locusta Gammarus 1956 Bousfield, lawrencianus 1863 Gammarus region Sars, G.O. lacustris Gammarus 1966 Stock, insensibilis Gammarus 1966 Stock, inaequicauda Gammarus 1852 Lilljeborg, duebeni Gammarus region Atlantic from Gammaridae 1 Table vial at available at available at available https://authorea.com/users/303572/articles/433753-will- https://authorea.com/users/303572/articles/433753-will- https://authorea.com/users/303572/articles/433753-will- 7