title: Size matters at deep-sea hydrothermal vents: different diversity and habitat fidelity patterns of meio- and macrofauna.
abstract: Species with markedly different sizes interact when sharing the same habitat. Unravelling mechanisms that control diversity thus requires consideration of a range of size classes. We compared patterns of diversity and community structure for meio- and macrofaunal communities sampled along a gradient of environmental stress at deep-sea hydrothermal vents on the East Pacific Rise (9° 50' N) and neighboring basalt habitats. Both meio- and macrofaunal species richnesses were lowest in the high-stress vent habitat, but macrofaunal richness was highest among intermediate-stress vent habitats. Meiofaunal species richness was negatively correlated with stress, and highest on the basalt. In these deep-sea basalt habitats surrounding hydrothermal vents, meiofaunal species richness was consistently higher than that of macrofauna. Consideration of the physiological capabilities and life history traits of different-sized animals suggests that different patterns of diversity may be caused by different capabilities to deal with environmental stress in the 2 size classes. In contrast to meiofauna, adaptations of macrofauna may have evolved to allow them to maintain their physiological homeostasis in a variety of hydrothermal vent habitats and exploit this food-rich deep-sea environment in high abundances. The habitat fidelity patterns also differed: macrofaunal species occurred primarily at vents and were generally restricted to this habitat, but meiofaunal species were distributed more evenly across proximate and distant basalt habitats and were thus not restricted to vent habitats. Over evolutionary time scales these contrasting patterns are likely driven by distinct reproduction strategies and food demands inherent to fauna of different sizes.
authors.affiliation: Department of Marine Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria ; German Center for Marine Biodiversity Research (DZMB), Senckenberg am Meer, Am Südstrand 44, 26382 Wilhelmshaven, Germany ; Royal Netherlands Institute for Sea Research (NIOZ), Ecosystem Studies, Korringaweg 7, 4401 NT Yerseke, The Netherlands.
authors.forename: Sabine
authors.initials: S
authors.lastname: Gollner
authors.affiliation: Biology Department, Rhode Island College, 600 Mt. Pleasant Ave., Providence, Rhode Island 02908, USA.
authors.forename: Breea
authors.initials: B
authors.lastname: Govenar
authors.affiliation: Department of Biology, 208 Mueller Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Fisher
authors.affiliation: Department of Marine Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
authors.forename: Monika
authors.initials: M
authors.lastname: Bright
keywords: Body size; Deep sea; Diversity; Habitat fidelity; Hydrothermal vent; Macrofauna; Meiofauna; Stress