Effect of nursery habitat on density-dependent habitat selection in juvenile flatfish Ariel L. Camp a, ⁎, Clifford H. Ryer b , Benjamin Laurel b , Kelly Seals c a Dept. Biology, Hofstra University, Hempstead, NY 11549, USA b Fisheries Behavioral Ecology Program, Alaska Fisheries Science Center, NOAA Fisheries, Hatfield Marine Science Center, Newport, OR 97365, USA c The Maritime Aquarium at Norwalk, Norwalk, CT 06854, USA abstract article info Article history: Received 2 August 2010 Received in revised form 2 May 2011 Accepted 3 May 2011 Available online 2 June 2011 Keywords: Carrying capacity English sole Estuary Northern rock sole Predation risk Nursery habitats contribute significantly to adult recruitment of marine fish, but the density of juveniles that they can support depends in part on conspecific interactions among juveniles. Density-dependent habitat selection (DDHS) was compared in the laboratory using two species of age-0 yr flatfish: 1) English sole Pleuronectes vetulus, which utilizes estuarine nurseries at high densities and 2) northern rock sole Lepidopsetta polyxystra, which occurs at lower densities in coastal nurseries and is known to exhibit DDHS. The pattern of DDHS was hypothesized to be similar in both species, but to initiate at higher densities and be less responsive to predation risk in English sole. Trials were conducted over eight density treatments (0.4, 0.8, 1.5, 3.0, 6.1, 12.2, 18.6, and 23.8 fish m -2 ), both with and without predation risk, and offered fish equal access to a preferred sand habitat and a less-preferred gravel habitat. Rock sole showed typical DDHS by increasing percentage use of the gravel habitat as conspecific density increased, with DDHS initiated at about 1.5 fish m -2 . English sole showed no DDHS: there was no relationship between percentage use of gravel habitat and conspecific density. Predation risk caused rock sole to significantly decrease gravel usage across all densities, but did not significantly change habitat selection for English sole. These results suggest that each species may be behaviorally adapted to the conspecific density and predation risk of their respective nursery habitats, and correspond well with the comparatively risk-prone behaviors of English sole. The relationship between nursery habitat and density-dependent behavior may be further understood by studies integrating factors such as turbidity, food resources and ontogeny. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Many marine fish species rely on nurseries: juvenile habitats that contribute a disproportionately large number of recruits to adult populations by increasing juvenile growth, survival, or successful migration to the adult habitat (Beck et al., 2001). The importance of nursery habitats is well studied (e.g., Gillanders, 1997; Krygier and Pearcy, 1986; Rooper et al., 2004; van der Veer et al., 2000), but the factors that determine how species exploit nurseries are diverse and often unquantified. The ability to support comparatively high densities of juveniles is often considered a hallmark of nurseries (e.g. Orth and van Montfrans, 1987), but carrying capacity will depend on the resources available to juveniles, as well as their survival and density-dependent interactions (Norcross et al., 1995; Rangeley and Kramer, 1998; Rooper et al., 2003). Following ideal free distribution theory, juveniles should distrib- ute themselves between preferred (high quality) and less-preferred (low quality) habitats such that fitness is comparable between habitats (Fretwell and Lucas, 1970). Individuals are expected to move to a less-preferred habitat as the quality of preferred habitat is degraded by increased conspecific density. Such behavior is defined as negative density-dependent habitat selection (DDHS). Juvenile flatfish are a useful model system for studying DDHS behavior: pelagic juveniles settle into nurseries at comparatively high densities (Rooper et al., 2003), and the two-dimensional nature of flatfishes' habitat may increase lateral concentration and density-dependent forces (Beverton, 1995). Flatfish habitat preference depends upon sediment type, depth and temperature (Gibson, 1994; Rooper et al., 2003). Northern rock sole Lepidopsetta polyxystra (Orr and Matarese, 2000), hereafter ‘rock sole’, age-0 yr juveniles are most abundant at the shallow depths and higher temperatures of coastal embayments (Stoner et al., 2007), and prefer sand or silts (Stoner and Ottmar, 2003). In contrast, age-0 yr English sole Pleuronectes vetulus (Girard, 1854) are most abundant in estuaries (Krygier and Pearcy, 1986), with an estimated 50% of adults on the central California coast recruiting from estuaries, which comprise only 6% of the available juvenile habitat (Brown, 2006). No sediment preference data is available for English sole. Conspecific densities of each species differ between nursery habitats: rock sole have been observed at 0.25–0.60 fish m -2 (Hurst et al., 2007; Lemke and Ryer, 2006a; Stoner et al., 2007) in coastal Journal of Experimental Marine Biology and Ecology 404 (2011) 15–20 ⁎ Corresponding author at: Dept. of Ecology and Evolution, Brown University, 80 Waterman St., Box G-W, Providence, RI 02912, USA. Tel.: +1 401 863 9578; fax: +1 401 863 7544. E-mail address: ariel_camp@brown.edu (A.L. Camp). 0022-0981/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jembe.2011.05.001 Contents lists available at ScienceDirect Journal of Experimental Marine Biology and Ecology journal homepage: www.elsevier.com/locate/jembe