Natural values of the Solitary Islands Marine Park - Marine Parks ...

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Figure 37.Station Creek.5 Estuarine ecosystemsEstuaries are places where freshwater creeks and rivers meet the sea. In their naturalstate, they are productive systems supporting high levels of floral and faunal diversityand provide important nursery grounds for many species. The 15 estuaries in themarine park are either:• barrier lagoons, which have larger catchment areas, large variations in salinity, and ahigh diversity of marine and brackish water plant species, or;• intermittently closed and open lakes and lagoons (ICOLLs), which have smallercatchment areas, lower average salinity, brackish to fresh waters, a lower diversity ofmarine vegetation, and a higher diversity of brackish and fresh water vegetation.Sandon River, Wooli Wooli River, Corindi River, Moonee Creek and Coffs Creek arebarrier lagoons that, in most cases, are permanently open. Station Creek, ArrawarraCreek, Darkum Creek, Woolgoolga Lake, and Hearnes Lake are ICOLLs.The benthic macrofaunal communities in the barrier lagoons and ICOLLs are verydifferent. Significant differences between these two types are maintained throughtime, but are not as great when the ICOLLs are open. There are also macrofaunalcommunity differences between each individual estuary. These differences in andbetween estuary types are caused by catchment size, which influences environmentalconditions, with each estuary having highly individual characteristics (Hastie andSmith 2006). Nine key species, all common estuarine fauna along the coast of NSW,are consistently responsible for driving these spatial and temporal differences (Hastie2006).Within each estuary, there are also differences in macrofaunal communities movingfrom downstream to upstream in response to changes in environmental conditions(Hastie and Smith 2006).Station Creek is unique among the larger ICOLLs in the marine park. It is the mostextensive ICOLL, and it contains mostly freshwater vegetation (Figure 37). Althoughmany ICOLLs are affected by human activity due to their small size and being closedto tidal flushing for sometimes extended periods of time, the catchment of StationCreek is surrounded by Yuraygir National Park, meaning it is one of the catchmentsleast affected by human activity. This contributes to the overall high environmentalhealth of this estuarine system.The adjacent position of Yuraygir National Park hasstrongly benefited the health of estuaries in thenorthern end of the marine park. For example, withrelatively little development within its catchment,and 50% of the catchment protected, the SandonRiver was classified as near pristine during theNational Land & Water Resources Audit (GeoscienceAustralia 2007).Estuaries are important areas of productivity incoastal environments, exporting nutrients on whichother inshore marine environments rely. Estuariesprovide key nursery grounds and adult habitat formany species of marine life. More than 100 fishspecies have been recorded in marine park estuariesduring biodiversity surveys undertaken by NSWFisheries in 1995 (Gray et al 1995), and between
Estuarine ecosystems 272000 and 2002 a further survey found manyspecies only recorded in one estuary (R Williamset al unpubl. data). Some of these also occur innearshore waters. The most species-rich family wasthe Gobiidae (gobies) with 17 species. Generally,between 12 and 42 fish species were recorded ineach estuary, although this varied with season.Estuarine sediments are also rich in invertebratelife (Johnstone 1997, Sawtell 2002), with over130 species recorded in the marine park to date.Polychaetes, gastropods, bivalves, amphipodsand decapod crustaceans are the most species-rich groups. About 16 of thesespecies were in all or most estuaries surveyed (Hastie and Smith 2006, Hastie 2006).Invertebrates can increase estuarine productivity and value as nursery grounds forrecreational and commercial fish, as well as being valuable to biodiversity in their ownright.Estuaries are also key habitats for threatened bird species such as the osprey (Figure38), pied oystercatcher, and beach stone-curlew. The Corindi, Wooli Wooli and Sandonrivers are wetlands of key importance to seabirds on a statewide basis. They arenesting sites for the endangered beach stone-curlew in NSW (Smith 1991, Taffs 2006).Three highly productive estuarine vegetation communities are particularly important.These are mangrove forests, seagrass beds, and saltmarshes (Figure 39). Such estuarinevegetation is extensive in the Sandon River, Wooli River, the Corindi River System andMoonee Creek (Figure 40).5.1 SeagrassesSeagrasses are subtidal and intertidal plants found mainly in shallow waters ofprotected estuaries and bays. Like terrestrial grasses, they are anchored to thesubstrate by roots or rhizomes, have leaves with veins, reproduce using flowers andseeds, and require sunlight to grow. They areimportant contributors to coastal productivity andare particularly important in maintaining sedimentstability because the seagrass roots stabilise theunderlying sediment. They are also important inmaintaining water quality by using nutrients andstabilising sediments in shallow water.Seagrass beds are also important areas for algalproduction. Much of the seagrass and algaeproduced is not used within the area of the bedbut is exported as detritus, forming an importantcomponent of the food chain for fish andinvertebrates in adjacent coastal waters.Seagrass beds provide habitat for a diverse rangeof flora and fauna, including algal epiphytes, crabs,shrimps, fishes, hydroids, sponges, bryozoans,ascidians, amphipods, polychaetes, gastropods,bivalves and holothurians (Bell and Pollard 1989,Ferrell et al 1993, Hannan and Williams 1998, Howardand Edgar 1999).Figure 38.Osprey on nest.Figure 39.Mangrove, saltmarsh,seagrass and intertidalsandflat habitat in theCorindi River.
Page 1 and 2: Naturalvalues of theSolitary Island
Page 3: ContentsGlossary1 Introduction . .
Page 6 and 7: littorinid snails: species of mollu
Page 8 and 9: 2 Natural values of the Solitary Is
Page 10 and 11: 2 Physical environment2.1 ClimateTh
Page 16 and 17: 3 Ecosystems and habitatsBiological
Page 18 and 19: 4 Ocean ecosystemsConsolidated area
Page 20 and 21: 14 Natural values of the Solitary I
Page 38 and 39: 6 Pelagic ecosystemsOcean currents

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