ORIGINAL PAPER Nursery ground value of an endangered wetland to juvenile shrimps Marcus Sheaves Æ Ka ´ tya Abrantes Æ Ross Johnston Received: 11 August 2006 / Accepted: 21 December 2006 / Published online: 2 February 2007 Ó Springer Science+Business Media B.V. 2007 Abstract Although urban development impacts wetlands around the world, until now there have been no studies of its effects on coastal wetlands in tropical regions of developed countries such as Australia. In fact the ecological value of such wetlands is poorly understood. This study pro- vides an initial step in evaluating the ecological value of urbanised, tropical coastal wetlands by determining (a) the extent to which a remnant wetland, in a highly urbanised estuary in northern Australia, is used by juvenile commercial penaeid shrimps, and (b) the extent to which the shrimps rely on food chains based on wetland plants versus marine based food chains. Juvenile penae- ids were abundant in the 11 wetland pools sampled. Catches included 5 commercial penaeids with two species, Fenneropenaeus merguiensis and Metapenaeus bennetae, comprising half the catch. Densities in the wetland pools were usually substantially higher than in adjacent estuarine habitats. Stable isotope analysis indicated that much of the nutrition of juvenile shrimps was supplied by marine primary producers (phyto- plankton, epiphytic and epilithic algae, micro- phytobenthos, green filamentous algae) however the locally abundant saltmarsh grass Sporobolus virginicus was also a major contributor. In con- trast, there was little indication of nutritional support from mangrove carbon. The lack of importance of mangrove carbon is surprising because the catches of F. merguiensis are often closely linked to the area or extent of mangroves, suggesting that aspects of mangrove systems other than the supply of mangrove carbon may deter- mine the distribution of juvenile F. merguiensis. Keywords Food chain Á Penaeid shrimps Á Stable isotopes Á Urban wetlands Introduction Littoral wetlands occur adjacent to marine coasts and estuaries throughout the world, and function as links between terrestrial and marine ecosys- tems (Levin et al. 2001). These wetlands comprise temporarily flooded lowlands, ‘‘swampy’’ palus- trine habitats (Kingsford and Norman 2002), and permanent and semi-permanent pools, lakes and lagoons (Allanson and Whitfield 1983). Littoral wetlands have vibrant and diverse flora and fauna, and are crucial habitats for fish (Noble et al. 2004; Brown et al. 2005), birds (Kingsford and Norman 2002, Noble et al. 2004) and inver- tebrates (Castellanos and Rozas 2001). They often provide a crucial nursery grounds function M. Sheaves (&) Á K. Abrantes Á R. Johnston School of Marine and Tropical Ecology, James Cook University, Townsville, QLD 4811, Australia e-mail: marcus.sheaves@jcu.edu.au 123 Wetlands Ecol Manage (2007) 15:311–327 DOI 10.1007/s11273-006-9031-5