Changes in rocky reef fish assemblages throughout an estuary with a restricted inlet
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PRIMARY RESEARCH PAPER
Changes in rocky reef fish assemblages throughout an estuary with a restricted inlet Jason K. Morton • William Gladstone
Received: 10 July 2013 / Revised: 17 October 2013 / Accepted: 26 October 2013 / Published online: 8 November 2013 Ó Springer Science+Business Media Dordrecht 2013
Abstract Rocky reef habitat is common in many estuaries, yet its role as a habitat for fishes is poorly understood. There is also limited understanding of how access of coastal species into estuaries and habitat quality can affect the distribution of rocky reef fishes within estuaries. This study used baited remote underwater video stations to determine spatial patterns in fish assemblages associated with rocky reef habitat throughout a barrier estuary with a permanently open but restricted inlet. Estuarine rocky reefs provided habitat for a diverse assemblage of fishes, many of which were large juveniles and subadults. In the absence of a pronounced salinity or temperature gradient, a clear transition in fish assemblages occurred from coastal waters, through the inlet channel, to the central estuary, and into the inner estuary. The inlet channel, notably its narrowness and length, limits tidal input into this estuary, which acts as a significant impediment to the dispersal of many coastal fishes, and insufficient habitat excludes many
Handling editor: M. Power J. K. Morton (&) School of Science and Mathematics, Avondale College of Higher Education, PO Box 19, Cooranbong, NSW 2265, Australia e-mail: [email protected] W. Gladstone School of the Environment, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia
coastal rocky reef species from the inner estuary. This study highlights the need to recognise estuarine rocky reefs as providing habitat for diverse fish assemblages and the role inlets play in restricting access of coastal species. Keywords Estuary mouth configuration Barrier estuaries Fish dispersal Estuarine fishes Fish habitat Larval dispersal
Introduction Estuaries are highly productive systems providing refugia, feeding areas, nursery grounds and spawning habitat for numerous fishes (Turner et al., 2004; Gillanders, 2007; Hughes et al., 2009), many of which are important commercial species (Gray et al., 1996; Roy et al., 2001). Estuarine fish assemblages include species of marine origin that are estuary residents, are passing through estuaries as migrants or are using estuaries for only a particular life history stage (Roy et al., 2001; Vorwerk et al., 2003; Kaiser et al., 2005). Many of the latter group are coastal species that use estuaries as juvenile nurseries (Hannan & Williams, 1998; Jenkins & Wheatley, 1998; Beck et al., 2001; Jelbart et al., 2007b) after being transported as larvae from coastal spawning sites (Forward et al., 1999; Trnski, 2001; Suthers et al., 2009). The high biological productivity in estuaries provides these juveniles with food, and the relatively high structural complexity and
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turbidity within many estuarine habitat
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