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Temporal changes in south east Tasmanian saltmarshes

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Prahalad, V (2009) Temporal changes in south east Tasmanian saltmarshes. Research Master thesis, University of Tasmania.

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Abstract

Coastal saltmarshes are unique and highly productive ecosystems. They form a major
part of the enclosed waterways of south east Tasmania, especially within the Pitt Water,
Pipe Clay Lagoon and Ralphs Bay areas. The Pitt Water saltmarshes are acknowledged
to be the most diverse and extensive of Tasmanian saltmarshes with extremely high
floristic and fauna! values, some recognised internationally while some remain
unstudied. A study conducted in 1975 detailed the extent and vegetation community
composition of the saltmarshes in the Pitt Water, Pipe Clay Lagoon and Ralphs Bay
areas. More than 30 years since then, the change in these important ecological
communities remained unstudied. Elsewhere in Australia and internationally, temporal
studies of saltmarshes have reported substantial changes in morphology, extent and
vegetation. This has led to several policy and management actions directed at
conserving the function and values of saltmarshes. The objective of the present study
was to investigate the spatial and temporal changes in saltmarshes mapped in 1975 to
inform policy and planning concerning their management and conservation.
Most saltmarshes have had losses in their areal extent, with nearly 17 hectares of area
(5%) lost on the seaward side primarily due to coastal erosion. The saltmarsh
shorelines have been eroding at about 6 cm to 20 cm a year, with erosion highest on the
shorelines more exposed to wind-generated waves. Nearly 6% of the saltmarsh area
had been lost due to land reclamation. While some area had been gained through
accretion and landward transgression, it was less than a quarter of the saltmarsh area
lost. Results for vegetation change show that low marsh plants, which are more adapted
to waterlogging, have replaced long lived high marsh plants as the dominant vegetation
community of the saltmarshes. A general shift of vegetation zones inland was observed,
suggesting a response to sea level rise. Extensive areas within the marsh have been
denuded of plant cover and have turned to salt pans/flats and "rotten spots" possibly
affected by an increase in tidal inundation, increases in soil salinity related to climate
change and increased nutrient inputs from irrigated land. These changes have several
implications for the conservation of both the floristic and fauna! values of saltmarshes
and their contribution to the health and productivity of the coastal waterways. This
study highlights a compelling need for strategic planning for the future conservation
and management of these important coastal ecosystems in a time of change and
contributes key information and methods to assist these efforts.

Item Type: Thesis (Research Master)
Keywords: Salt marshes, Salt marsh ecology, Coastal ecology
Copyright Holders: The Author
Copyright Information:

Copyright 2009 the Author

Additional Information:

Author advises his second name for publication purposes is Prahalad, i.e. Prahalad, Vishnu Nandagopalan. he is also know as Vishnu Prahalad Nandagopalan.

Date Deposited: 03 Feb 2015 03:05
Last Modified: 11 Mar 2016 05:53
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