Advertisement

Polar Biology

, Volume 41, Issue 4, pp 697–712 | Cite as

Composition of Harpacticoida (Crustacea, Copepoda) of the Laptev Sea in comparison with faunas of adjacent Arctic seas

  • E. Chertoprud
  • E. Abramova
  • S. Korsun
  • F. Martynov
  • L. Garlitska
Original Paper
  • 87 Downloads

Abstract

The invertebrate fauna of the Laptev Sea is one of the least investigated in the Arctic. In particular, little is known about the Harpacticoida (Copepoda, Crustacea)—one of the main components of marine meiofauna. Major objectives of our study were (1) to describe harpacticoid composition obtained from three sublittoral stations, (2) to compile the check-list of the Laptev Sea harpacticoids, and (3) to perform a comparative analysis of the Laptev Sea harpacticoid fauna with faunas of other Arctic seas. Of 38 species found in our material, 25 are new for the sea, and four species are likely new to science. A total list for the Laptev Sea includes 76 species from 18 families. Interstitial and phytal forms are poorly represented, due to the rarity of suitable biotopes and/or undersampling. The majority of the provisional endemics were found in the bathyal and abyssal zones of the sea, while widely distributed species, except for the plankton, belong to the fauna of the soft sediments of the littoral zone. Comparative analysis of harpacticoids from the Arctic region (the Laptev, White, Barents, Kara, East Siberian and Beaufort Seas and the Greenland area) shows the considerable distinction between the Eastern (Siberian) and Western sub-regions. Further investigations are necessary to reveal a more detailed pattern in Harpacticoida distribution and to evaluate possible vectors of dispersal and biogeographic relationships in the high Arctic.

Keywords

Laptev Sea Harpacticoida Species richness Life forms Ranges Biogeography 

Notes

Acknowledgements

The Transdrift-XXII expedition in the Laptev Sea and the sampling and analysis of the main factors on stations were supported by the BMBF-Project Laptev Sea System (03G0833). The study of the taxonomy of the Harpacticoida was supported by the program “Scientific bases for the creation of a national depository bank of living systems” of the RSF (No 14-50-00029). The study of the ecology and biogeography of the Harpacticoida and statistical analysis were supported by the RFBR Grant (17-04-00337-a). The study of harpacticoids species in the area around the Lena River Delta were supported by the RFBR Grant (17-04-0027-a). Drafting of the Arctic crustaceans database was supported by the RFBR Grant (15-04-02245-a). The authors are very grateful to three unknown reviewers for their complete and helpful reviews.

References

  1. Abramova EN (1999) Composition, abundance and population structure of spring-time zooplankton in the shelf zone of Laptev Sea. In: Kassens H, Bauch HA, Dmitrenko I, Eicken H, Hubberten H-W, Melles M, Thiede J, Timokhov L (eds) Land-Ocean systems in the Siberian Arctic: dynamics and history. Springer, Berlin, pp 161–168CrossRefGoogle Scholar
  2. Abramova E, Tuschling K (2005) A 12-year study of the seasonal and interannual dynamics of mesozooplankton in the Laptev Sea: significance of salinity regime and life cycle patterns. Glob Planet Change 481:141–164.  https://doi.org/10.1016/j.gloplacha.2004.12.010 CrossRefGoogle Scholar
  3. Alabyan AM, Chalov RS, Korotaev VN, Sidorchuk AY, Zaitsev AA (1995) Natural and technogenic water and sediment supply to the Laptev Sea. In: Kassens H, Piepenburg D, Thiede J, Timokhov L, Hubberten HW, Priamikov SM (eds), Russian-German cooperation: Laptev Sea system. Ber Polarforsch 176:65–271Google Scholar
  4. Anisimova N, Deubel H, Potin S, Rachor E (1997) Zoobenhos. In: Rachor E (ed) Scientific cruise report of the Arctic expedition ARK-XI of RV “Polarstern” in 1995. Ber Polarforsch 226:103–110Google Scholar
  5. Azovsky AI, Garlitska LA, Chertoprud ES (2012) Broad-scale patterns in local diversity of marine benthic harpacticoids (Crustacea). Mar Ecol Prog Ser 460:63–77.  https://doi.org/10.3354/meps09756 CrossRefGoogle Scholar
  6. Azovsky AI, Garlitska LA, Chertoprud ES (2016) Multi-scale taxonomic diversity of marine harpacticoids: does it differ at high and low latitudes? Mar Biol 163:94.  https://doi.org/10.1007/s00227-016-2876-0 CrossRefGoogle Scholar
  7. Baskakov GA, Borodachev VE, Dvorkin EN, Mustafin NV, Yanes AV (1987) Hydrological and ice conditions of the arctic shelf zone. Biological Resources of the Arctic and Antarctic. Nauka, Moscow, pp 15–47 (in Russian) Google Scholar
  8. Becker K-H, Noodt W, Schriever G (1979) Eindonomy and Taxonomy of abyssal Harpacticoidea (Crustacea, Copepoda) Part III. 13 new species deep-sea Copepoda Harpacticoidea belonging to the Canuellidae, Cerviniidae, Tisbidae, Thalestridae. Diosaccidae and Ameiridae. Meteor Forschungsergeb 31:38–62Google Scholar
  9. Bodin P (1968) Copépodes harpacticoïdes des étages bathyal et abyssal du Golfe de Gascogne. Mem Mus Natl Hist Nat Paris Ser A 55:1–107Google Scholar
  10. Bodin P (1997) Catalogue of the new marine Harpacticoid Copepods (1997 Edition). Doc Travail l’Inst R Sc Nat Belg 89:1–304Google Scholar
  11. Boxshall GA, Halsey SH (2004) An introduction to copepod diversity. Ray Society, LondonGoogle Scholar
  12. Briggs JC, Bowen BW (2012) A realignment of marine biogeographic provinces with particular reference to fish distribution. J Biogeor 39:2–30.  https://doi.org/10.1111/j.1365-2699.2011.02613.x Google Scholar
  13. Briggs JC, Bowen BW (2013) Marine shelf habitat: biogeography and evolution. J Biogeogr 40:1023–1035.  https://doi.org/10.1111/jbi.12082 CrossRefGoogle Scholar
  14. Chertoprud ES, Garlitska LA (2007) A comparative analysis of the Harpacticoida (Copepoda) faunas from the northern and southern seas of Russia. Oceanol 47:814–823.  https://doi.org/10.1134/S0001437007060069 CrossRefGoogle Scholar
  15. Chertoprud ES, Chertoprud MV, Kondar DV, Kornev PN, Udalov AA (2006) Harpacticoida taxocen diversity in the silt-sand intertidal zone of Kandalaksha Bay of the White Sea. Oceanol 46:492–500.  https://doi.org/10.1134/S0001437006040060 CrossRefGoogle Scholar
  16. Chertoprud ES, Garlitska LA, Azovsky AI (2010) Large-scale patterns in marine benthic harpacticoid diversity and distribution. Mar Biodiv 40:301–315.  https://doi.org/10.1007/s12526-010-0054-z CrossRefGoogle Scholar
  17. Chertoprud ES, Frenkel SE, Novichkova AA, Vodop’yanov SS (2014) Harpacticoida (Copepoda) fauna and the taxocenes structure of brackish lagoons and estuaries of the Russian Far East. Oceanol 54:739–751.  https://doi.org/10.1134/S0001437014060034 CrossRefGoogle Scholar
  18. Chertoprud ES, Frenkel SE, Kim K, Lee W (2015) Harpacticoida (Copepoda) of the northern East Sea (the Sea of Japan) and the southern Sea of Okhotsk: diversity, taxocenes, and biogeographical aspects. J Nat Hist 49(45–48):2869–2890.  https://doi.org/10.1080/00222933.2015.1056268 CrossRefGoogle Scholar
  19. Clarke KR, Gorley RN (2001) Primer, user manual/tutorial, 5th edn. PRIMER-E, PlymouthGoogle Scholar
  20. Clément M, Moore CG (1995) A revision of the genus Halectinosoma (Harpacticoida: Ectinosomatidae): a reappraisal of H. sarsi (Boeck) and related species. Zool J Linn Soc Lond 114:247–306.  https://doi.org/10.1111/j.1096-3642.1995.tb00118.x CrossRefGoogle Scholar
  21. Clément M, Moore CG (2000) A revision of the genus Halectinosoma (Copepoda: Harpacticoida: Ectinosomatidae): the H. herdmani (Scott & Scott) group of species. Zool J Linn Soc Lond 128:237–267.  https://doi.org/10.1111/j.1096-3642.2000.tb00163.x CrossRefGoogle Scholar
  22. Corgosinho PH, Martínez AP (2010) Ameiridae Boeck and Argestidae Por revisited, with establishment of Parameiropsidae, a new family of Harpacticoida (Crustacea, Copepoda) from deep-sea sediments. Helgol Mar Res 64:223–255.  https://doi.org/10.1007/s10152-009-0185-4 CrossRefGoogle Scholar
  23. Costello MJ, Emblow C, White R (2001) European Register of Marine Species: a check-list of marine species in Europe and a bibliography of guides to their identification. SPN 50:1–463Google Scholar
  24. Coull BC (1973) Meiobenthic Harpacticoida (Crustacea, Copepoda) from the deep sea off North Carolina I. The genera Hemimesochra Sars, Paranannopus Lang, and Cylindronannopus n. g. Trans Am Microsc Soc 92:185–198.  https://doi.org/10.2307/3224915 CrossRefGoogle Scholar
  25. Derjugin KM (1993) Benthos of the Lena River estuary. Issled Morei SSSR 15:63–66 (in Russian) Google Scholar
  26. Dmitrenko I, Golovin P, Gribanov V, Kassens H (1999) Oceanographic causes for transarctic ice transport of river discharge. In: Kassens H, Bauch HA, Dmitrenko I, Eicken H, Hubberten H-W, Melles M, Thiede J, Timokhov L (eds) Land-ocean systems in the Siberian Arctic: dynamics and history. Springer, Berlin, pp 73–92CrossRefGoogle Scholar
  27. Easton EE, Thistle D, Spears T (2010) Species boundaries in Zausodes-complex species (Copepoda: Harpacticoida: Harpacticidae) from the north-eastern Gulf of Mexico. Invert Syst 24:258–270.  https://doi.org/10.1071/IS09038 CrossRefGoogle Scholar
  28. Finlay BJ, Fenchel T (2004) Cosmopolitan metapopulation of free-living microbial eucariotes. Protist 155:237–244.  https://doi.org/10.1078/143446104774199619 CrossRefPubMedGoogle Scholar
  29. Garlitska LA, Azovsky AI (2016) Benthic harpacticoid copepods of the Yenisei Gulf and the adjacent shallow waters of the Kara Sea. J Nat Hist 50:2941–2959.  https://doi.org/10.1080/00222933.2016.1219410 CrossRefGoogle Scholar
  30. Garlitska L, Neretina T, Schepetov D, Mugue N, De Troch M, Baguley JG, Azovsky A (2012) Cryptic diversity of the ‘cosmopolitan’ harpacticoid copepod Nannopus palustris: genetic and morphological evidence. Mol Ecol 21:5336–5347.  https://doi.org/10.1111/mec.12016 CrossRefPubMedGoogle Scholar
  31. Gee JM, Huys R (1994) Paranannopidae (Copepoda: harpacticoida) from sublittoral soft sediments in Spitsbergen. J Nat Hist 28:1007–1046.  https://doi.org/10.1080/00222939400770541 CrossRefGoogle Scholar
  32. George KH (2006) New Ancorabolinae Sars, 1909 (Copepoda: Harpacticoida: Ancorabolidae) of the Atlantic and the Pacific Ocean. The taxa Ceratonotus Sars, and Dendropsyllus Conroy-Dalton. Meiofauna Mar 15:87–122Google Scholar
  33. Gheerardyn H, De Troch M, Vincx M, Vanreusel A (2009) Harpacticoida (Crustacea: Copepoda) associated with cold-water coral substrates in the Porcupine Seabight (NE Atlantic): species composition, diversity and reflections on the origin of the fauna. Sci Mar (Barc) 73:747–760.  https://doi.org/10.3989/scimar.2009.73n4747 CrossRefGoogle Scholar
  34. Giere O (2009) Meiobenthology. The microscopic motile fauna of aquatic sediments (2nd ed). Springer, BerlinGoogle Scholar
  35. Golikov AN, Scarlato OA, Averincev VG, Menshutkina TV, Novikov OK, Sheremetevsky AM (1990) Ecosystems of the New Siberian shoals, their distribution and functioning. In: Golikov NA (ed) Ecosystem of the New Siberian shoals and the fauna of the Laptev Sea and adjacent waters. Explor Fauna of the Seas 37:4–79 (in Russian)Google Scholar
  36. Gorbunov GP (1946) Bottom fauna of the Novosiberian shallow waters and the central part of the Arctic Ocean. Tr Dreifuyuschei Exsp Glavsevmorputi na Ledokol’nom Parokhode “G. Sedov” 1937–1940 gg. 3:30–138 (in Russian)Google Scholar
  37. Gukov AY (1989) Bottom biocenoses of the Buor-Khaya Bay of the Laptev Sea. Oceanol 29:316–317Google Scholar
  38. Gukov AY (1991) The bottom fauna of the Yansky Bay of the Laptev Sea. Oceanol 31:454–456Google Scholar
  39. Gukov AY (1992) The study of the Anabar Bay of the Laptev Sea. Oceanol 32:506–509Google Scholar
  40. Gukov AY (1994a) Distribution of bottom biocenoses in the straits of New Siberian Islands. Scientific results of the expedition LAPEX-93. Nauka, S-Petersburg, pp 319–325 (in Russian)Google Scholar
  41. Gukov AY (1994b) The growth and production of populations of common species of bivalves in Tiksi Bay of the Laptev Sea. Oceanol 34:259–261Google Scholar
  42. Gukov AY (1996) Benthic biocenoses of marine aquatory of the reserve « Lena-Delta». Biol Morya-Vlad 22:267–270Google Scholar
  43. Gukov AY (1999) Ecosystem of the Siberian Polynya. Nauchniy Mir, Moscow (in Russian)Google Scholar
  44. Gur’ianova EF (1964) Zoogeographical zoning of the benthic fauna of the World Ocean (benthic fauna of the continental shelf). In: Monin AS (ed) Physiographic Atlas of the World. AS USSR, Moskow, map 68BGoogle Scholar
  45. Hicks GRF, Coull BC (1983) The ecology of marine meiobenthic harpacticoid copepods. Oceanogr Mar Biol 21:67–175Google Scholar
  46. Hölemann JA, Schirmacher M, Prange A (1999) Transport and distribution of trace elements in the Laptev Sea: first results of the TRANSDRIFT expeditions. Ber Polarforsch 176:297–302Google Scholar
  47. Huys R (2009) Unresolved cases of type fixation, synonymy and homonymy in Harpacticoid Copepod Nomenclature (crustacea: Copepoda). Zootaxa 2183:1–99Google Scholar
  48. Ingole BS, Ansari ZA, Parulekar AH (1990) Benthic harpacticoid copepod community of Saphale salt marsh along the west coast of India. Indian J Mar Sci 19:217–220Google Scholar
  49. Ivanov VV (1976) Freshwater balance of the Arctic Ocean. Trudy Arkticheskogo i Antarkticheskogo NII 323:38–147 (in Russian) Google Scholar
  50. Jirkov IA (2017) Biogeography. Common and ecpecial: lands, seas and continental water bodies. KMK Scientific Press, Moscow (in Russian)Google Scholar
  51. Kihara TC, Martínez Arbizu P (2012) Three new species of Cerviniella Smirnov, 1946 (Copepoda: Harpacticoida) from the Arctic. Zootaxa 3345:1–33.  https://doi.org/10.5281/zenodo.281475 Google Scholar
  52. Klenova MV (1962) Sediments of the Arctic basin based on the drift of R/V G. “Sedov”. AS USSR, Moscow (in Russian)Google Scholar
  53. Kornev PN, Chertoprud ES (2008) The copepod crustacean order Harpacticoida of the White Sea: Morphology, Systematics, Ecology. KMK Scientific Press, Moscow (in Russian)Google Scholar
  54. Kosobokova KN, Hanssen H, Hirche HJ, Knickmeier K (1998) Composition and distribution of zooplankton in the Laptev Sea and adjacent Nansen Basin during summer 1993. Polar Biol 19:63–76.  https://doi.org/10.1007/s003000050216 CrossRefGoogle Scholar
  55. Lang K (1944) Monographie der Harpacticiden (Vorlaufige Mitteilung). Almqvist and Wiksells Boktryckeri Ab, UppsalaGoogle Scholar
  56. Lang K (1948) Monographie der Harpacticiden. Håkan Ohlsson, LundGoogle Scholar
  57. Lindemann F (1994) Sonographische und sedimentologische Untersuchungen in der Laptev-See, sibirische Arktis. Diploma Thesis, Christian Albrechts University, KielGoogle Scholar
  58. Magurran AE (2004) Measuring biological diversity. Blackwell, OxfordGoogle Scholar
  59. Martínez Arbizu P (1994) Meiofauna. In: Fütterer K (ed) The expedition ARCTIC´93 leg ARK-IX/4 of RV Polarstern 1993. Rep Polar Res, Bremerhaven 149:94–97Google Scholar
  60. Maximova OV (2016) Macrophytobenthos of the Kara Sea. Kera Sea. Ecological Atlas. Arcticheskiy Nauchniy Zentr, Moscow, pp 88–95 (in Russian)Google Scholar
  61. Mokievsky VO (2009) Ecology of marine Meibenthos. KMK Scientific Press, Moscow (in Russian)Google Scholar
  62. Moore CG, O'Reilly MG (1994) A description of Haloschizopera bulbifera (Sars) and three similar new species of harpacticoid copepod. J Nat Hist 28:53–74Google Scholar
  63. Murray KG, Winnett-Murray K, Hertel L (2002) Species diversity, island biogeography, and the design of nature reserves. In: Donnell MAO’ (ed) Tested studies for laboratory teaching. ABLE, Oklahoma, 23:125–143Google Scholar
  64. Nesis KN (1982) Zoogeography of the World Ocean: a comparison of the zonality of the pelagic zone and regional shelf division (on cephalopod mollusks). Marine biogeography. Subject matter, methods and principles of zoning. Nauka, Moscow, pp 114–134 (in Russian)Google Scholar
  65. Pavlov VK, Pavlov PV (1999) Features of seasonal and interannual variability of the sea level and water circulation in the Laptev Sea. In: Kassens H, Bauch HA, Dmitrenko I, Eicken H, Hubberten H-W, Melles M, Thiede J, Timokhov L (eds) Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer, Berlin, pp 3–16CrossRefGoogle Scholar
  66. Pesce GL (2007) Harpacticoida. Copepod Web Portal (cited 2004 Apr 30). Available from: http://www.luciopesce.net/copepods/arpa.htm
  67. Petryashov VV, Sirenko BI, Rachor E, Hinz K (1994) Distribution of the macrobenthos in the Laptev Sea from materials of the expeditions of RV “Ivan Kireev” and ice-breaker RV “Polarstern” in 1993. Sci Res Exp LAPEX-93. Nauka, S-Petersburg, pp 277–288 (in Russian)Google Scholar
  68. Petryashov VV, Sirenko BI, Golikov AV, Novozhilov AV, Rachor E, Piepenburg D, Schmid M (1999) Macrobenthos distribution in the Laptev Sea in relation to hydrology. In: Kassens H, Bauch HA, Dmitrenko I, Eicken H, Hubberten H-W, Melles M, Thiede J, Timokhov L (eds) Land-Ocean systems in the Siberian Arctic: dynamics and history. Springer, Berlin, pp 169–180CrossRefGoogle Scholar
  69. Pielou EC (1966) Shannon’s formula as a measure for species diversity: its use and disuse. Am Nat 100:463–465CrossRefGoogle Scholar
  70. Piepenburg D, Schmid M (1997) A photographic survey of the epibenthic megafauna of the Arctic Laptev Sea shelf: distribution, abundance, and estimates of biomass and organic carbon demand. Mar Ecol Prog Ser 147:63–75.  https://doi.org/10.3354/meps147063 CrossRefGoogle Scholar
  71. Pivovarov S, Hölemann JA, Kassens H, Piepenburg D, Schmid MK (2004) Laptev and East Siberian Seas. In: Robinson AR, Brink KH (eds) The Global Coastal Ocean: Interdisciplinary Regional Studies and Syntheses, Part A. The Sea 14:1107–1133Google Scholar
  72. Rachor E, Hinz K, Sirenko B (1994) Macrofauna. In: Fütterer DK (ed) The expedition Arctic’ 93, leg ARK-IX/4, of “Polarstern” 1993. Ber Polarforsch 149:7–106Google Scholar
  73. Ribnikov PV (2001) Harpacticoida. In: Sirenko AN (ed) List of free living species of invertebrates of Eurasian Arctic Seas. Nauka, St-Peterburg, pp 56–78Google Scholar
  74. Schmid MK, Piepenburg D, Golikov AA, Juterzenka K, Petryashov VV, Spindler M (2006) Trophic pathways and carbon flux patterns in the Laptev Sea. Prog Oceanogr 71:314–330.  https://doi.org/10.1016/j.pocean.2006.09.002 CrossRefGoogle Scholar
  75. Shannon CE, Weaver W (1963) The mathematical theory of communication. University of Illinois Press, UrbanaGoogle Scholar
  76. Sirenko AN, Piepenburg D (1994) Current knowledge on biodiversity and benthic zonation patterns of Eurasian Arctic shelf seas, with special reference to the Laptev Sea. In: Kassens H (ed) Russian-German Cooperation in the Siberian Shelf Seas: Geo-System Laptev Sea. Ber Polarforsch 144: 69–77Google Scholar
  77. Smirnov SS (1946) New species of Copepoda-Harpacticoida of the northern Arctic Ocean. Tr Dreifuyuschei Exsp Glavsevmorputi na Ledokol’nom Parokhode “G. Sedov” 1937–1940 gg. 3:231–263 (in Russian)Google Scholar
  78. Soviet Arctic. Seas and Islands of the Arctic Ocean (1970) Nauka, Moscow (in Russian)Google Scholar
  79. Steele M, Ermold V (2015) Loitering of the retreating sea ice edge in the Arctic Seas. Geogr Res 120:7699–7721.  https://doi.org/10.1002/2015JC011182 Google Scholar
  80. Vinogradova KL (1999) Distribution of macrophyte algae in the Arctic seas of Russia. Novosti Sist Nizsh Rast 33:14–24 (in Russian) Google Scholar
  81. Weather Underground web portal (2017) (cited 2017 Mar 10). Available from: https://www.wunderground.com
  82. Wells JBJ (2007) An annotated checklist and keys to the species of Copepoda Harpacticoida (Crustacea). Zootaxa 1568:1–872Google Scholar
  83. Werner I, Martínez Arbizu P (1999) The sub-ice fauna of the Laptev Sea and the adjacent Arctic Ocean in summer 1995. Polar Biol 21:71–79.  https://doi.org/10.1007/s003000050336 CrossRefGoogle Scholar
  84. Wilce RT, Dunton KH (2014) The Boulder Patch (North Alaska, Beaufort Sea) and its Benthic Algal Flora. Arctic 67: 43–56. doi;  https://doi.org/10.14430/arctic4360
  85. Willen E (1996) Pseudomesochra T. Scott 1902 as a Member of the Paranannopidae Por, 1986 (Copepoda, Harpacticoida) with a description of three new species. Senckenberg Mar 28:81–109.  https://doi.org/10.1007/bf03042824
  86. Zinova AD (1956) Algae of the Arctic Ocean. Trudy Bot Inst Akad Nauk SSSR 2:39–51 (in Russian) Google Scholar
  87. Zinova AD, Petrov JE (1970) Ways of forming the flora of marine macroscopic algae in the Arctic basin. In: The Arctic Ocean and its coast in the Cenozoic, Gidrometeoisdat, Leningrad, pp 162–165 (in Russian) Google Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2017

Authors and Affiliations

  • E. Chertoprud
    • 1
    • 2
  • E. Abramova
    • 3
  • S. Korsun
    • 4
    • 5
  • F. Martynov
    • 6
  • L. Garlitska
    • 5
  1. 1.Biological FacultyM.V. Lomonosov Moscow State UniversityMoscowRussia
  2. 2.Laboratory of SynecologyA.N. Severtsov Institute of Ecology and EvolutionMoscowRussia
  3. 3.Lena Delta Nature ReserveTiksiRussia
  4. 4.Biological FacultySt. Petersburg State UniversitySt. PetersburgRussia
  5. 5.Shirshov Institute of OceanologyMoscowRussia
  6. 6.Otto-Schmidt-Labor for Polar and Marine ScienceArctic and Antarctic Research InstituteSt. PetersburgRussia

Personalised recommendations