Linking Habitat Use and Trophic Ecology of Spotted Seatrout (Cynoscion nebulosus) on a Restored Oyster Reef in a Subtropical Estuary Thomas C. TinHan 1 & John A. Mohan 1 & Mark Dumesnil 2 & Bryan M. DeAngelis 3 & R. J. David Wells 1,4 Received: 11 December 2017 /Revised: 28 February 2018 /Accepted: 2 March 2018 # Coastal and Estuarine Research Federation 2018 Abstract Predicting population- and ecosystem-level benefits of habitat restoration minimally requires an understanding of the link between the trophic ecology of a species and their use of a habitat. This study combined novel, non-lethal natural tracers of trophic ecology with acoustic tagging techniques to examine spatial and temporal patterns of habitat use of spotted seatrout Cynoscion nebulosus on Half Moon Reef (HMR), a recently restored oyster reef in Matagorda Bay, Texas. Forty-one spotted seatrout (408 ± 25 mm total length) were captured at HMR, surgically implanted with acoustic transmitters, and monitored by an array of underwater listening stations from December 2015 to August 2016. Patterns of presence-absence on HMR were strongly influenced by water temperature, and to a lesser extent, salinity and tidal height. Overall, spotted seatrout residency to HMR was low, with fish being present on the reef 24% of days. When present, individual fish exhibited strong site-attachment to small portions of the reef. Residency to HMR increased significantly with size, while scale stable isotope analysis revealed fish exhibiting high residency to HMR occupied significantly smaller isotopic niches. If indeed smaller fish with decreased residency rely upon a wider range of prey items across multiple habitats than larger, more resident individuals, restored oyster reef habitat may be expected to primarily benefit larger spotted seatrout. Keywords Gulf of Mexico . Acoustic telemetry . Stable isotope analysis . Environmental drivers . Residency Introduction Oyster reefs play an important role in the function and resilience of estuarine and coastal ecosystems. Oyster reef habitat can provide a range of ecosystem services, from increased species diversity and trophic interactions via high habitat complexity to localized improvements in water quality driven by oyster filtra- tion (Coen and Luckenbach 2000; Peterson and Lipcius 2003; Grabowski and Peterson 2007; Beck et al. 2011). However, a combination of anthropogenic alterations to coastal habitat and overexploitation through commercial oyster fisheries have re- duced oyster reef coverage in coastal ecosystems (Beck et al. 2011; Wilberg et al. 2011; zu Ermgassen et al. 2012). Restoration of oyster reef habitat has been prescribed as a means of both mitigating coastal habitat loss and enhancing local fish- eries (Peterson et al. 2003; zu Ermgassen et al. 2016). Several studies have highlighted the importance of oyster reef habitat during the early life history of estuarine fauna, particularly tele- ost fishes (Lenihan et al. 2001; Peterson et al. 2003; Stunz et al. 2010; zu Ermgassen et al. 2016). However, individuals may undergo ontogenetic shifts, expanding their movements to in- clude a suite of habitats, presumably in response to size-specific shifts in resource requirements and risk of predation (Pittman et al. 2004; Bowler and Benton 2005). Effective implementation of restored oyster reef habitat requires an improved understand- ing of the relative importance of oyster reefs to adult fishes potentially using multiple habitats. Spotted seatrout (Cynoscion nebulosus) is an estuarine- dependent species occurring from the Gulf of Mexico (GoM) to the northwest Atlantic (Bortone 2003). Previous studies have Communicated by Mark S. Peterson * Thomas C. TinHan tinhan@tamu.edu 1 Department of Marine Biology, Texas A&M University at Galveston, 1001 Texas Clipper Road, Galveston, TX 77553, USA 2 The Nature Conservancy, Texas Coastal Office, 205 N. Carrizo St., Corpus Christi, TX 78401, USA 3 The Nature Conservancy, North America Oceans and Coasts, URI Bay Campus, Narragansett, RI 02882, USA 4 Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843, USA Estuaries and Coasts https://doi.org/10.1007/s12237-018-0391-x