Marine Biology

, Volume 150, Issue 5, pp 929–939 | Cite as

Flexible habitat selection and interactive habitat segregation in the marine congeners Idotea baltica and Idotea emarginata (Crustacea, Isopoda)

Research Article


Habitat segregation among competing species is widespread yet very little is know how this is achieved in practice. In a case study, we examined short-term effects of conspecific and congeneric density on habitat selection in two competing marine isopod species, Idotea emarginata and Idotea baltica. Under semi-natural conditions in large outdoor cylindrical tanks (4 m high; volume 5.5 m3), animal groups of different size and composition had the choice between a set of relevant habitat samples (surface-floating seaweed, the water column, seaweed on the bottom). Habitat selection in both I. baltica and I. emarginata proved to be largely independent of conspecific density (level of intraspecific competition). In single-species treatments, both species showed a similar and stable pattern of distribution, with a clear preference for seaweed on the bottom. In mixed-species treatments (MST), however, the species were largely separated by habitat. While the distribution of I. emarginata was completely unaffected by the mere presence of interspecific competitors, habitat selection of I. baltica changed notably when I. emarginata was present. The habitat use patterns observed in MST conformed to those realized in geographical areas where the two species overlap in distribution: I. emarginata is dominant among decaying seaweed on the sea floor, and I. baltica is the dominant species among surface-floating seaweed. Our findings suggest that habitat segregation between the two species is essentially interactive, resulting from rapid decision-making of I. baltica with respect to habitat selection. The underlying mechanism is discussed. I. emarginata is highly superior to I. baltica in interference competition and rapidly eliminates the latter from one-habitat systems which do not allow I. baltica to escape from this interaction. In more natural, heterogeneous environments, however, I. baltica seems to be able to coexist with the superior competitor due to its broader habitat niche, flexibility in habitat selection, and a behavioural disposition to avoid normally preferred habitats when these are occupied by I. emarginata.


  1. Arthur WA (1982) Evolutionary consequences of interspecific competition. Adv Ecol Res 12:127–187CrossRefGoogle Scholar
  2. Boersma M, DeMeester L, Spaak P (1999) Environmental stress and local adaptation in Daphnia magna. Limnol Oceanogr 44:393–412CrossRefGoogle Scholar
  3. Bay LK, Jones GP, McCormick MI (2001) Habitat selection and aggression as determinants of spatial segregation among damselfish on a coral reef. Coral Reefs 20:289–298CrossRefGoogle Scholar
  4. Bowers MA, Thompson DB, Brown JH (1987) Spatial organization of a desert rodentcommunity: food addition and species removal. Oecologia (Berlin) 72:77–82CrossRefGoogle Scholar
  5. Branch GM (1984) Competition between marine organisms: ecological and evolutionary implications. Oceanogr Mar Biol 22:429–593Google Scholar
  6. Bremset G, Heggenes J (2001) Competitive interactions in young Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L,) in lotic environments. Nord J Freshw Res 75:127–142Google Scholar
  7. Connell JH (1983) On the prevalence and relative importance of interspecific competition: evidence from field experiments. Am Nat 122:661–696CrossRefGoogle Scholar
  8. Douglass RJ (1976) Spatial interactions and microhabitat selections of two locally sympatric voles, Microtus montanus and Microtus pennsylvanicus. Ecology 57:346–352CrossRefGoogle Scholar
  9. Ebersole JP (1995) Niche separation of two damselfish species by aggression and differential microhabitat utilization. Ecology 66:14–20CrossRefGoogle Scholar
  10. Finger TR (1982) Interactive segregation among three species of sculpins (Cottus). Copeia 3:680–694CrossRefGoogle Scholar
  11. Franke H-D, Janke M (1998) Mechanisms and consequences of intra- and interspecificinterference competition in Idotea baltica (Pallas) and Idotea emarginata (Fabricius) (Crustacea: Isopoda): a laboratory study of possible proximate causes of habitatsegregation. J Exp Mar Biol Ecol 227:1–21CrossRefGoogle Scholar
  12. Fusetani N (2004) Biofouling and antifouling. Nat Prod Rep 21:94–104PubMedCrossRefGoogle Scholar
  13. Furness RW, Todd CM (1984) Diets and feeding of fulmars Fulmaris glacialis during the breeding season: a comparison between St Kilda and Shetland colonies. Ibis 126:379–387Google Scholar
  14. Hairston NG (1980) The experimental test of an analysis of field distributions: competition in terrestrial salamanders. Ecology 61:817–826CrossRefGoogle Scholar
  15. Howard D, Harrison R (1984) Habitat segregation in ground crickets: the role of interspecific competition and habitat selection. Ecology 65:69–76CrossRefGoogle Scholar
  16. Ingólfsson A, Agnarsson I (2003) Amphipods and isopods in the rocky intertidal: dispersal and movements during high tide. Mar Biol 143:859–866CrossRefGoogle Scholar
  17. Jormalainen V, Tuomi J (1989) Sexual differences in habitat selection and activity of the colour polymorphic isopod Idotea baltica. Anim Behav 38:576–585CrossRefGoogle Scholar
  18. Jormalainen V, Tuomi J, Merilaita S (1992) Mate choice for male and female size in aquatic isopod Idotea balthica. Ann Zool Fenn 29:161–167Google Scholar
  19. Křivan V, Sirot E (2002) Habitat selection by two competing species in a two-habitatenvironment. Am Nat 160:214–234CrossRefPubMedGoogle Scholar
  20. Larson RJ (1980) Competition, habitat selection, and the bathymetric segregation of two rockfish (Sebastes) species. Ecol Monogr 50:221–239CrossRefGoogle Scholar
  21. Lawton JM, Hassell MP (1981) Asymmetrical competition in insects. Nature 289:793–795CrossRefGoogle Scholar
  22. Lürling M, Roozen F, van Donk E, Goser B (2003) Response of Daphnia to substances released from crowded congeners and conspecifics. J Plankton Res 25:967–978CrossRefGoogle Scholar
  23. Matveev V (1993) An investigation of allelopathic effects of Daphnia. Freshw Biol 29:99–105CrossRefGoogle Scholar
  24. Naylor E (1955) The ecological distribution of British species of Idotea (Isopoda). J Anim Ecol 24:270–281CrossRefGoogle Scholar
  25. Naylor E (1972) British marine isopods. Synopses of the British Fauna (New Series) No. 3. Academic Press, LondonGoogle Scholar
  26. Qian PY (1999) Larval settlement of polychaetes. Hydrobiologia 402:239–253CrossRefGoogle Scholar
  27. Robertson DR (1996) Interspecific competition controls abundance and habitat use of territorial Caribbean damselfishes. Ecology 77:885–899CrossRefGoogle Scholar
  28. Roozen F, Lürling M (2001) Behavioural response of Daphnia to olfactory cues from food, competitors and predators. J Plankton Res 23:797–808CrossRefGoogle Scholar
  29. Rosenzweig ML (1981) A theory of habitat selection. Ecology 62:327–335CrossRefGoogle Scholar
  30. Salemaa H (1979) Ecology of Idotea spp. (Isopoda) in the northern Baltic. Ophelia 18:133–150Google Scholar
  31. Schluter D (2000) Ecological character displacement in adaptive radiation. Am Nat 156:S4–S16CrossRefGoogle Scholar
  32. Schoener TW (1983) Field experiments on interspecific competition. Am Nat 122:240–285CrossRefGoogle Scholar
  33. Schoener TW (1986) Resource partitioning. In: Kikkawa J, Anderson DJ (eds) Community ecology: pattern and process. Blackwell, Oxford, pp 91–126Google Scholar
  34. Slatkin M (1984) Ecological causes of sexual dimorphism. Evolution 38:622–630CrossRefGoogle Scholar
  35. Sone S, Inoue M, Yanagisawa Y (2001) Habitat use and diet of two stream gobies of the genus Rhinogobius in south-western Shikoku, Japan. Ecol Res 16:205–219CrossRefGoogle Scholar
  36. Steinberg PD, de Nys R (2002) Chemical mediation of colonization of seaweed surfaces. J Phycol 38:621–629CrossRefGoogle Scholar
  37. Suhling F (1996) Interspecific competition and habitat selection by the riverine dragonfly Onychogomphus uncatus. Freshw Biol 35:209–217CrossRefGoogle Scholar
  38. Thiel M, Gutow L (2005a) The ecology of rafting in the marine environment. I. The floating substrata. Oceanogr Mar Biol 42:181–263CrossRefGoogle Scholar
  39. Thiel M, Gutow L (2005b) The ecology of rafting in the marine environment. II. The rafting organisms and community. Oceanogr Mar Biol 43:279–418Google Scholar
  40. Wallerstein BR, Brusca RC (1982) Fish predation: a preliminary study of its role in the zoogeography and evolution of shallow water idoteid isopods (Crustacea: Isopoda: Idoteidae). J Biogeogr 9:135–150CrossRefGoogle Scholar
  41. Werner EE, Hall DJ (1977) Competition and habitat shift in two sunfish (Centrarchidae). Ecology 60:256–264CrossRefGoogle Scholar
  42. Zar JH (1999) Biostatistical analysis, 4th edn. Prentice-Hall, Upper Saddle River, NJGoogle Scholar

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.Biologische Anstalt HelgolandFoundation Alfred Wegener Institute for Polar and Marine ResearchHelgolandGermany

Personalised recommendations