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  • chapter 1: literature review 5

    1 literature review

    1.1 Background to the study

    A primary driving force behind this project is the recognition that Australian coastal saltmarsh has suffered from long-term neglect by researchers, natural resource managers and the wider community. The two main plant communities on the seaward side of coastal saltmarsh – seagrasses and mangroves – have been subject to intensive study over the past three decades, and there is now an extensive literature on the ecology and management of these wetland types in Australia (e.g. MacNae 1966; Lear & Turner 1977; Clough 1982; Hutchings & Recher 1982; Hutchings & Saenger 1987; Larkum et al. 1989; Robertson & Alongi 1992; Claridge & Burnett 1993; Harty 1997; Pollard et al. 2003; chapters in Green & Short 2003; Duke 2006; Carruthers et al. 2007; Alongi 2009; Paling et al. 2009).

    Australian saltmarshes have not benefited from a comparable investment in research or management. Indeed, until the publication this year of Australian Saltmarsh Ecology (edited by Saintilan 2009), some chapters in Coastal Wetlands: An Integrated Ecosystem Approach (edited by Perillo et al. 2009) and one chapter in Human Impacts on Salt Marshes (edited by Silliman et al. 2009), the most recent text with substantive sections on Australian coastal saltmarsh is 20 years old: Adam’s (1990) Saltmarsh Ecology. The presence of separate entries for mangroves (Bridgewater 1999) and seagrasses (Walker 1999) – but not for saltmarsh – in the introductory volume of Flora of Australia (Orchard 1999) may say something about the overall neglect of coastal saltmarsh by even experienced ecologists and those charged with managing coastal vegetation.

    From at least two perspectives the neglect of coastal saltmarsh is paradoxical. First, coastal saltmarsh in the Northern Hemisphere has been the subject of intensive research for decades (e.g. Teal & Teal 1969; Ranwell 1972; Chapman 1974; Long & Mason 1983; Kennish 1990; French 1997; Weinstein & Kreeger 2000; Doody 2008; Perillo et al. 2009; Silliman et al. 2009; Weis & Butler 2009). Second, a number of early botanical studies in Australia were undertaken on mangroves and coastal saltmarsh: Hamilton (1919) and Collins (1921), for example, studied saltmarsh and mangrove vegetation in the Sydney region; Pidgeon (1940) reported on spatial zonation (which she interpreted as successional patterns) in mangroves and saltmarshes along the central coast of New South Wales; Patton (1942) reported on Victorian saltmarshes; and Curtis & Somerville (1947) described coastal saltmarshes in Tasmania.

    This impressive early start was not maintained in subsequent decades. The most detailed studies of any Australian saltmarsh were undertaken 40 years ago, by Clarke & Hannon (1967, 1969, 1970, 1971). The most detailed studies of Victorian saltmarshes – Bridgewater (1975, 1982) – are nearly as old. Rather than embracing the more useful ecological orientation taken by Clarke & Hannon, they were concerned mostly with phytosociological classification and, for many potential users, have produced not-entirely- satisfying results. The most detailed identification guide to Victoria coastal saltmarshes is the booklet by Bridgewater et al. (1981), and it is not only dated but suffers from restricted availability. In fact, many of the studies undertaken on Victorian mangroves and coastal saltmarsh are available only in the ‘grey’ literature, as government or consultants’ reports or as unpublished student theses. In this aspect the literature on mangroves and coastal saltmarsh differs little from that on other types of Australian wetlands, which also suffer from poor availability and a lack of peer review (Boon & Brock 1994). An illustration of the importance of unpublished reports is provided by the review by Ross (2000) of the mangroves and coastal saltmarsh of Western Port. Of the 88 reports cited, about one half were in the ‘grey’ literature.

  • mangroves and coastal saltmarsh of victoria: distribution, condition, threats and management6

    Nevertheless, there are encouraging signs that the neglect of Australian coastal saltmarsh and other estuarine wetlands is coming to an end. The past few years have seen the publication of handbooks that allow the identification of saltmarsh plants in Queensland ( Johns 2006) and western Victoria (Allen 2007). A new identification guide to saltmarsh vegetation in south-eastern Australia, edited by Geoff Sainty et al. and published by Sainty & Associates, is expected to be released in 2011. A good start has been made into resolving the taxonomic issues associated with problematic plant species (e.g. Shepherd et al. 2005; Shepherd & Wilson 2007; Adams et al. 2008; Wilson 2008). Duke (2006) has recently produced a delightful field manual on mangroves (Australia’s Mangroves), which expands on the earlier field guide by Lovelock (1993). Australian Saltmarsh Ecology has just been published (edited by Saintilan 2009), and Laegdsgaard (2006) has published her review of the status and threats to coastal saltmarsh, mostly from the perspective of New South Wales systems. A wider perspective on anthropogenic threats to coastal saltmarsh in Australia and New Zealand was prepared by Thomsen et al. (2009). The biogeography of Australian saltmarsh vegetation has been re-examined by Saintilan (2009a,b). Two of the recent books on estuarine and coastal vegetation (Coastal Wetlands: An Integrated Ecosystem Approach: Perillo et al. 2009; and Human Impacts on Salt Marshes: Silliman et al. 2009) contain a number of chapters written by Australian authors or covering Australian systems (e.g. Adam 2009b; Alongi 2009; Paling et al. 2009; Thomsen et al. 2009).

    Comprehensive statewide mapping and inventory studies have been completed recently, or are nearing completion, for coastal and estuarine systems in Queensland (Queensland EPA 2005, 2009c), South Australia (Canty et al. 2006) and New South Wales (Williams et al. 2006). A suite of regional studies has addressed aspects of particular mangrove or saltmarsh systems in south-eastern Australia (e.g. Clarke 1993, 2003; Kessler 2006; Kelleway et al. 2007; Jugovic 1985, 2008; Pacific Wetlands 2008; Horlock & Houtgraaf 2008). Condition-assessment protocols have been developed for aspects of Victorian estuaries (Arundel et al. 2009) and, in at least one case, a method specifically tailored to assess saltmarsh condition (Kessler 2006).

    The first component of our project – the preparation of a comprehensive literature review – aims to bring together these disparate streams of information and, where appropriate, place them within the wider context of coastal wetlands in south-eastern Australia. In addition to the reference sources provided in monographs or edited books (e.g. Ranwell 1972; Long & Mason 1983; Adam 1990; Weinstein & Kreeger 2000; Doody 2008; Saintilan 2009; Perillo et al. 2009; Silliman et al. 2009; Weis & Butler 2009), we surveyed the available literature in recent scientific journals: over 300 articles published after 2000 were retrieved using the keywords ‘salt+marsh’ in Web of Science. We examined also the university archives for student theses, which were particularly helpful for studies on *Spartina in Victoria.

    To complement these formal sources of information, the project was discussed with many saltmarsh researchers and those charged with managing coastal areas: Paul Adam (University of New South Wales, Sydney), Geoff Wescott (Deakin University, Melbourne), Janine McBurnie (Deakin University, Melbourne), Rae Moran (Department of Sustainability and Environment, Melbourne), Mike Ronan (Queensland Environment Protection Authority, Brisbane), Neil Saintilan (New South Wales Department of Environment and Climate Change, Sydney), Jeff Shimeta (RMIT University, Melbourne), Mike Vanderzee (Victoria Department of Sustainability and Environment, Melbourne), Rob Williams (Aquatic Ecosystems Research Unit, Cronulla Fisheries Centre, Sydney), Debra Canty (South Australian Department of Environment and Heritage, Adelaide), David Carew (Melbourne Water, Melbourne), Greg Hunt (Western Port Greenhouse Alliance) and Steffan Howe and Leslie Leunig (Parks Victoria, Melbourne and Foster, respectively). Glenn Ehmke (Birds Australia) kindly contributed text and images for the habitat-value of coastal saltmarsh for birds, especially for Orange-bellied Parrot Neophema chrysogaster.

  • chapter 1: literature review 7

    1.2 What are mangroves and coastal saltmarsh?

    mangroves – a definition

    Woodroffe & Davies (2009, page 66) defined mangroves as ‘trees, shrubs, or palms, exceeding 0.5 m in height that occur in the upper intertidal zone’. Duke (2006, page 12) adopted a similar definition with regard vegetation structure but was more prescriptive about tidal position: he indicated that mangroves normally grew ‘…above mean sea level in the intertidal zone of marine coastal environments and estuarine margins’.

    In Victoria, vegetation is classified and described in terms of Ecological Vegetation Classes, or EVCs. Ecological Vegetation Classes are defined as one or a number of floristic and structural types that appear to be associated with a recognisable environmental niche and which can be characterised by their adaptive responses to ecological processes that operate at the landscape scale. The EVC approach to vegetation classification therefore uses floristic and structural criteria, combined with geographic information on niches and distributions (Department of Natural Resources and Environment 2002b).

    Only one mangrove species, Avicennia marina