Empirical evidence linking increased hydrologic stability with decreased biotic diversity within wetlands

Nielsen, Daryl L.; Podnar, Kiya; Watts, Robin; Wilson, Andrea

doi:10.1007/s10750-011-0989-5

Cited by 65 publications

(51 citation statements)

References 48 publications

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“…Similar responses have been reported in other wetland systems based on taxonomic groups including epiphytic diatoms and macroinvertebrates (Davidson et al, 2012), and planktonic microbial communities (Kobayashi et al, 2009(Kobayashi et al, , 2013. This suggests that the inundation of distinct channel, floodplain floodout and lagoon hydro-geomorphic habitats in semi-arid regions is an important driver for taxa-specific responses that contribute to localscale biodiversity (see also Nielsen et al, 2013).…”

Section: Discussionsupporting

confidence: 79%

Spatial dissimilarities in plankton structure and function during flood pulses in a semi-arid floodplain wetland system

Kobayashi¹,

Ralph

Ryder³

et al. 2014

Hydrobiologia

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Floodplain wetlands in semi-arid regions have intricate channel-floodplain networks with highly variable and unpredictable wet and dry phases related to changes in hydrology and geomorphology. We tested the hypothesis that the presence of different hydro-geomorphic habitats in those systems drives structural and functional differences in aquatic communities. To test this hypothesis, we examined the densities and species composition (structural variables), and primary productivity and respiration (functional variables) of plankton communities, and water chemistry in three spatially explicit channel, floodout and lagoon habitat types inundated by environmental water releases in the Macquarie Marshes, semi-arid Australia. Significant differences were recorded among the community-level structural and functional variables among the three habitats. Greater densities of phytoplankton, zooplankton and planktonic bacteria were observed in a hydrologically isolated floodplain lagoon. The lagoon habitat also had greater primary productivity of phytoplankton and planktonic respiration compared with the channel and floodout. Our results suggest that water release to meet environmental flow requirements can be an important driver of planktonic diversity and functional responses in semi-arid wetland systems by inundating diverse, hydro-geomorphically distinct habitats.

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Section: Discussionsupporting

confidence: 79%

Spatial dissimilarities in plankton structure and function during flood pulses in a semi-arid floodplain wetland system

Kobayashi¹,

Ralph

Ryder³

et al. 2014

Hydrobiologia

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“…This suggests that stability is determined by long-term processes allowing the community to remain functional through species turnover. Resilience may be enhanced by a higher number of viable seeds from species tolerant to both wet and dry conditions compared to those restricted to aquatic or terrestrial environments (Nielsen et al, 2013) when recovering from extreme or recurrent flooding. Toogood et al (2008) also recorded high species turnover in the 2 years following major flooding of a wet grassland, with particular increases in less flood tolerant species suggesting a recovery.…”

Section: Wet Grassland Plant Communities and Extreme Climate Impactsmentioning

confidence: 99%

Extreme climate events and wet grasslands: plant traits for ecological resilience

Brotherton

Joyce

2014

Hydrobiologia

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Extreme climate events, including floods and droughts, represent disturbances that impact plant functioning, biodiversity and ecosystem processes. Wetlands can mediate climate change impacts through their multiple ecosystem services, and wet grasslands offer a fascinating wetland case because they are adapted to regular disturbance regimes typified by inundation, cutting and/or grazing. This review identifies key concepts for a better understanding of extreme climate impacts on wet grassland plant communities, focussing upon the use of functional traits for ecological resilience. It suggests that wet grasslands are underrepresented in extreme climate event experiments, despite some field studies that show floods have significant impacts upon community composition. Mechanisms for ecological stability and resilience are linked to functional diversity through plant traits, via niche complementarity or dominance. Facilitation may be important as climate stresses increase, while modified plant behaviour may promote recovery. However, plant community responses to extreme events are complex; the challenges for wet grassland researchers include: (i) identifying thresholds, tipping points and lag effects; (ii) monitoring key community components; (iii) using effective plant trait metrics; (iv) investigating beyond conservative norms; (v) combining multiple stressors and traits and (vi) extrapolating experimental results to field conditions.

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“…Historical local reductions in shorebird populations were underway well before the time-series analysed here began, for example, through drainage of wetlands in southeastern South Australia (Taffs, 2001) and loss of intertidal habitat in Botany Bay (Pegler, 1997). More recent loss or degradation of Australia's inland wetlands Finlayson et al, 2013;Nielsen et al, 2013;van Dijk et al, 2013) and the collapse of the estuarine ecosystem of The Coorong, show clearly that such cases are still occurring (Paton et al, 2009;. Indeed, careful management of wetlands is crucial to maintain their suitability for shorebirds.…”

Section: Local Trends and Threatsmentioning

confidence: 99%

“…The consequences of over extraction and regulation of water are dire for wetland ecosystems and in this case for shorebirds and the food they eat Kingsford, 2000;Nebel et al, 2008;Nielsen et al, 2013). Second, artificial wetlands should be created and managed where possible.…”

Section: Management Recommendationsmentioning

confidence: 99%

“…First, for shorebird species that stay in Australia year round (hereafter resident species), the loss or degradation of inland wetlands in Australia Nielsen et al, 2013) has coincided with large population decreases in both resident and migratory shorebirds that use inland wetlands . The collapse of estuarine wetland ecosystems, such as those of The Coorong in South Australia, as a result of regulation of flows in the Murray-Darling Basin, has also resulted in thousands fewer shorebirds being counted in recent surveys (Wainwright & Christie, 2008;.…”

Section: Introductionmentioning

confidence: 99%

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Ecology and conservation of Australia’s shorebirds

Clemens¹

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Global biodiversity continues to decline rapidly, and addressing this situation requires an understanding of both the problems and the solutions. This understanding is urgently required for animals occupying wetlands, among the most threatened of all habitats globally. In this thesis I focus on the ecology and conservation of shorebirds, a group comprising many threatened and declining species dependent on wetlands throughout much of their annual cycle. I focus on threats operating within Australia, where wetland loss and degradation continues due to human activity. Non-migratory shorebird species that travel widely across Australia's inland wetlands have been reported as declining in eastern Australia, but a national assessment is lacking. Migratory shorebird species that visit Australia from breeding grounds overseas appear to be declining most due to factors beyond Australia's borders, but it is not clear if threats located in Australia are exacerbating these declines. I make the most of the rich data available on shorebirds in Australia to address these knowledge gaps, in the hopes of better targeting shorebird conservation actions in Australia.In chapter one I introduce the importance of conserving migratory and highly mobile species.I then review how pulses in resource availability such as those exemplified by Australia's ephemeral wetlands impact wildlife populations. I also provide an overview of shorebird conservation in Australia. These introductions provide the theoretical underpinning for the work presented later, and highlight the challenges inherent in understanding where and when highly mobile species such as shorebirds have been impacted.In chapter two I show the benefits of applying a consistent approach to setting boundaries around areas used by migratory shorebirds during the non-breeding season. One of the first steps in identifying where conservation actions are needed for highly mobile species is defining the boundaries of management units where actions can be targeted, and which define the optimal scale for monitoring. I achieved this step by using expert knowledge to define the extent of area being used by the same local population of non-breeding shorebirds. These improved boundaries were at times very different to boundaries identified originally.In chapter three I analyse available Australian shorebird count data from many areas to determine if spatial variation in shorebird trends relates to local threats. I confirm Australia wide declines in a number of shorebird species, and add a few more to the list of shorebird species showing continental scale declines. I further show that declines are often greater in the south, but find substantial interspecific variation in trends with both latitude and 3 longitude. This suggests large scale patterns in the declines are not explained by local factors.For resident shorebirds I find rates of decline greater at non-tidal wetlands threatened by inappropriate water levels, while local threats do not appear to explain rates of decline in mi...

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Empirical evidence linking increased hydrologic stability with decreased biotic diversity within wetlands

Cited by 65 publications

References 48 publications

Spatial dissimilarities in plankton structure and function during flood pulses in a semi-arid floodplain wetland system

Spatial dissimilarities in plankton structure and function during flood pulses in a semi-arid floodplain wetland system

Extreme climate events and wet grasslands: plant traits for ecological resilience

Ecology and conservation of Australia’s shorebirds

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