Posidonia australis seagrass meadows of the Manning-Hawkesbury ecoregion

Posidonia australis seagrass meadows of the Manning-Hawkesbury ecoregion is an endangered ecological community, listed under the EPBC Act of the Commonwealth of Australia on 7 May 2015

Posidonia australis

Description

The ecological community is "the assemblage of plants, animals and micro-organisms associated with seagrass meadows dominated by Posidonia australis occurring in the warm temperate Manning Shelf and Hawkesbury Shelf bioregions on the east coast of Australia." It occurs subtidal waters at depths from less than 1 m to 10m within the sheltered environments of estuaries on the coastline from Wallis Lake to Port Hacking. It is found on sand and silty mud and in these estuarine waters the salinity is close to marine levels.

The meadows of the community occur as both monospecific meadows (of P. australis) or as multispecies meadows (with, for example, P. australis together with Zostera muelleri subsp. capricorni, Halophila ovalis). The macrophyte, Ruppia, may also be found growing within the ecological community (Creese et al., 2009). The leaves of Posidonia australis provide a place for many benthic flora, including epiphytes, to grow. These epiphytes photosynthesise and their proportion within the meadows is largely dependant on the nutrients available in the water.

Fauna found within the shelter of the meadows include: protozoans, bacteria, harpacticoid copepods,ostracods, nematodes, polychaetes, bivalves, amphipods, cumaceans, holothurians, phoronids, rotifers, isopods; small decapods, gastropods, pycnogonids, echinoderms, nemerteans, hydroids, bryozoans, sponges; ascidians; serpulid polychaetes, and fish.

Threats

1. Coastal development
2. Dredging
3. Boat mooring and boating activities
4. Catchment disturbance and pollution
5. Climate change

Further reading

• J.J. Burchmore; D.A. Pollard; J.D. Bell (March 1984). "Community structure and trophic relationships of the fish fauna of an estuarine Posidonia Australis seagrass habitat in port hacking, new South Wales". Aquatic Botany. 18 (1–2): 71–87. doi:10.1016/0304-3770(84)90081-0. ISSN 0304-3770. Wikidata Q107919737.
• J. Fitzpatrick; H. Kirkman (1995). "Effects of prolonged shading stress on growth and survival of seagrass Posidonia australis in Jervis Bay, New South Wales, Australia" (PDF). Marine Ecology Progress Series: 279–289. ISSN 0171-8630. Wikidata Q107919867.
• Neil Saintilan; Kamal Hossain; Debashish Mazumder (3 February 2007). "Linkages between seagrass, mangrove and saltmarsh as fish habitat in the Botany Bay estuary, New South Wales" (PDF). Wetlands Ecology and Management. 15 (4): 277–286. doi:10.1007/S11273-006-9028-0. ISSN 0923-4861. Wikidata Q60552150.
• D.I Walker; A.J McComb (January 1992). "Seagrass degradation in Australian coastal waters". Marine Pollution Bulletin. 25 (5–8): 191–195. doi:10.1016/0025-326X(92)90224-T. ISSN 0025-326X. Wikidata Q107919934.
• Kieryn Kilminster; Kathryn McMahon; Michelle Waycott; et al. (25 April 2015). "Unravelling complexity in seagrass systems for management: Australia as a microcosm". Science of the Total Environment. 534: 97–109. doi:10.1016/J.SCITOTENV.2015.04.061. ISSN 0048-9697. PMID 25917445. Wikidata Q39136176.