Wetlands,
Biodiversity and Salt
Changes in ecosystem structure and function
August 2006
Overview
Aim
As part of the Wetlands, Biodiversity and Salt
project, a university project is examining
changes in ecosystem structure and function
in response to disturbance, using salinising
wetlands as model systems.
This work aims to investigate the impact of
salinity on ecosystem structure and function.
Belinda Cant started this PhD research project
in March 2004 and data collection will finish in
February 2007. The project has been
supervised by Dr Ralph MacNally, Dr John
Beardall (School of Biological Sciences,
Monash University) and Dr Sabine Schreiber
(DSE).
Specifically, to
• better understand the way wetlands
function; and
• examine the biodiversity within them.
Both of these will be examined at a landscape
scale.
Belinda works in the following areas of
western Victoria:
• Corangamite
• Glenelg-Hopkins
• Wimmera.
She has examined small wetlands that differ
in their salinity levels from fresh (<4000 EC)
to hypersaline (>50 000 EC).
PhD student Belinda Cant
Photo: Steve Morton
Measures of ecosystem function include
productivity and decomposition. Ecosystem
function is an important component of the
health of ecosystems, along with biodiversity.
Ecosystem function and biodiversity are often
linked. Changes in ecosystem function are
often a precursor to loss of species or changes
in the composition of species in an ecosystem.
A Victorian
Government
initiative
Methods
For part of the work, Belinda measured the
production and diversity of algae that live on
top of lake sediments because they are
present in fresh to hypersaline wetlands, and
are the main primary producers in saline
wetlands where there are no water plants.
Results
• It is expected that diversity of algae will
decrease with increases in salinity through
space and time.
• On the other hand, algal biomass
showed a humpbacked relationship with
salinity as salinity varied across space with
a peak at 100 000EC.
• In wetlands studied through time from
wetting to drying, changes in salinity
brought about by evaporation and rain
directly affected algal biomass but only in
the hypersaline wetlands.
• In medium saline wetlands, algal
biomass
increased
through
time
responding to increases in light and
temperature. Each freshwater wetland was
unique in that algal biomass changes were
inconsistent between sites and over time.
• Algae that live in wetlands are
sometimes the major primary producers
and form the basis of the food chain. While
we don’t want to see algal blooms,
wetlands need algae to function.
• Algae are one of the most salt-tolerant
groups. Decreases in algal biomass seem
to occur at 100 000 EC, which is twice the
salinity of seawater.
• We may expect to see a loss of
function in naturally saline wetlands when
they are subject to secondary salinity that
causes them to rise above 100 000 EC
Salinity history and changes in biota and
ecosystems of the Western District
Lakes Area
Another part of the PhD will develop a method
to investigate the salinity history of the area
using data from several disciplines: ecology,
paleoecology (ancient ecology), groundwater
studies and social sciences (including
interviews with landholders).
Management implications
• Both fresh and naturally saline
wetlands are at threat from increasing
salinity in areas where soils and/or water
tables are salty and where water tables
move either laterally or vertically to
intersect wetlands.
Published by the Victorian Government Department of Sustainability and Environment
Melbourne, August 2006
© The State of Victoria Department of Sustainability and Environment 2006
This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968.
Authorised by the Victorian Government, 8 Nicholson Street, East Melbourne.
ISBN 1 74152 616 7
For more information contact the DSE Customer Service Centre 136 186 or Belinda Cant on (03) 9905 5649 or belinda.cant@dse.vic.gov.au, Australian Centre for Biodiversity
Analysis, Policy and Management; School of Biological Sciences; Building 18; Monash University; VIC 3800.
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for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
www.dse.vic.gov.au