e-journal

Multiple stressors and regime shifts in shallow aquatic ecosystems in antipodean landscapes

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1. Changes in land management (land use and land cover) and water management
(including extraction of ground water and diversion of surface waters for irrigation) driven
by increases in agricultural production and urban expansion (and fundamentally by
population growth) have created multiple stressors on global freshwater ecosystems that
we can no longer ignore.
2. The development and testing of conceptual ecological models that examine the impact of
stressors on aquatic ecosystems, and recognise that responses may be nonlinear, is now
essential for identifying critical processes and predicting changes, particularly the
possibility of catastrophic regime shifts or ‘ecological surprises’.
3. Models depicting gradual ecological change and three types of regime shift (simple
thresholds, hysteresis and irreversible changes) were examined in the context of shallow
inland aquatic ecosystems (wetlands, shallow lakes and temporary river pools) in
southwestern Australia subject to multiple anthropogenic impacts (hydrological change,
eutrophication, salinisation and acidification).
4. Changes in hydrological processes, particularly the balance between groundwaterdominated
versus surface water-dominated inputs and a change from seasonal to
permanent water regimes appeared to be the major drivers influencing ecological regime
change and the impacts of eutrophication and acidification (in urban systems) and
salinisation and acidification (in agricultural systems).
5. In the absence of hydrological change, urban wetlands undergoing eutrophication and
agricultural wetlands experiencing salinisation appeared to fit threshold models. Models
encompassing alternative regimes and hysteresis appeared to be applicable where a
change from a seasonal to permanent hydrological regime had occurred.
6. Irreversible ecological change has potentially occurred in agricultural landscapes
because the external economic driver, agricultural productivity, persists independently of
the impact on aquatic ecosystems.
7. Thematic implications: multiple stressors can create multiple thresholds that may act in
a hierarchical fashion in shallow, lentic systems. The resulting regime shifts may follow
different models and trajectories of recovery. Challenges for ecosystem managers and
researchers include determining how close a system may be to critical thresholds and
which processes are essential to maintaining or restoring the system. This requires an
understanding of both external drivers and internal ecosystem dynamics, and the
interactions between them, at appropriate spatial and temporal scales.

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Informasi Detail

Judul Seri

Freshwater Biology

No. Panggil

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Penerbit

: Blackwell Publishing Ltd., 2010

Deskripsi Fisik

Freshwater Biology (2010), 55 (Suppl. 1), 5–18

Bahasa

English

ISBN/ISSN

doi:10.1111/j.1365-2

Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

55 (Suppl. 1), 5–18

Subjek

Freshwater Biology

Info Detail Spesifik

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Pernyataan Tanggungjawab

deliza

Versi lain/terkait

Lampiran Berkas

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