Effects of chronic bottom trawling disturbance on benthic biomass, production and size spectra in different habitats A.M. Queirós ⁎ , J.G. Hiddink 1 , M.J. Kaiser 1 , H. Hinz 1 School of Ocean Sciences, University of Wales-Bangor, Menai Bridge, Anglesey, LL59 5AB, United Kingdom Received 1 June 2005; received in revised form 20 February 2006; accepted 1 March 2006 Abstract Bottom trawling has widespread impacts on benthic communities and habitats. It is argued that the impact of chronic bottom trawling on benthic infauna depends on the natural disturbance levels to which benthic communities are adapted. We analysed biomass, production and size structure of two communities from a muddy and a sandy habitat, in relation to quantified gradients of trawling disturbance on real fishing grounds. We used an allometric relationship between body mass and individual production to biomass ratio to estimate community production. Chronic trawling had a negative impact on the biomass and production of benthic communities in the muddy habitat, while no impact was identified on benthic communities from the sandy habitat. These differences are the result of differences in size structure within the two communities that occur in response to increasing trawling disturbance. © 2006 Elsevier B.V. All rights reserved. Keywords: Bottom trawling; Infauna; Secondary production; Size spectrum 1. Introduction Bottom trawling has global impacts on benthic communities and habitats and is relatively non-selective (Kaiser and Spencer, 1996; Rijnsdorp et al., 1998; Bergman and van Santbrink, 2000). Benthic invertebrate bycatches can account for up to 90% of commercial catches that include undersized target species and non- marketable species (Bergmann and Moore, 2001; Bergmann et al., 2002; Lindeboom and de Groot, 1998). This disturbance affects the diversity, abundance, size structure and the production of benthic communities (Bergman and Hup, 1992; Kaiser and Spencer, 1996; Ball et al., 2000a,b; Bergman and van Santbrink, 2000; Collie et al., 2000; Frid et al., 2000; Bergmann and Moore, 2001; Jennings et al., 2001, 2002; Duplisea et al., 2002; Hermsen et al., 2003). With the increasing recognition of the need to adopt an ecosystem-based approach to fisheries management (Pikitch et al., 2004), it is imperative that the impact of bottom trawling on benthic communities is evaluated at the scale of com- mercial fisheries, to test the findings of small-scale manipulative studies (Jennings et al., 1999; Kaiser et al., 2000; Collie et al., 2000). The mortality of benthic invertebrates that are re- moved as trawl bycatch is high (Kaiser and Spencer, 1995; Ramsay et al., 1997) but the mortality rates caused Journal of Experimental Marine Biology and Ecology 335 (2006) 91 – 103 www.elsevier.com/locate/jembe ⁎ Corresponding author. Tel.: +44 1248 388 532. E-mail address: anamqueiroz@yahoo.com (A.M. Queirós). 1 Tel.: +44 1248 382 864. 0022-0981/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jembe.2006.03.001