Limits...
River dolphins can act as population trend indicators in degraded freshwater systems.

Turvey ST, Risley CL, Barrett LA, Yujiang H, Ding W - PLoS ONE (2012)

Bottom Line: Whereas species may be expected to respond differently at the population level even in highly degraded ecosystems, highly vulnerable (e.g. migratory) species can therefore display very similar responses to extrinsic threats, even if they represent otherwise very different taxonomic, biological and ecological groupings.Monitoring the status of river dolphins or other megafauna therefore has the potential to provide wider information on the status of other threatened components of sympatric freshwater biotas, and so represents a potentially important monitoring tool for conservation management.We also show that interview surveys can provide robust quantitative data on relative population dynamics of different species.

View Article: PubMed Central - PubMed

Affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom. samuel.turvey@ioz.ac.uk

ABSTRACT
Conservation attention on charismatic large vertebrates such as dolphins is often supported by the suggestion that these species represent surrogates for wider biodiversity, or act as indicators of ecosystem health. However, their capacity to act as indicators of patterns or trends in regional biodiversity has rarely been tested. An extensive new dataset of >300 last-sighting records for the Yangtze River dolphin or baiji and two formerly economically important fishes, the Yangtze paddlefish and Reeves' shad, all of which are probably now extinct in the Yangtze, was collected during an interview survey of fishing communities across the middle-lower Yangtze drainage. Untransformed last-sighting date frequency distributions for these species show similar decline curves over time, and the linear gradients of transformed last-sighting date series are not significantly different from each other, demonstrating that these species experienced correlated population declines in both timing and rate of decline. Whereas species may be expected to respond differently at the population level even in highly degraded ecosystems, highly vulnerable (e.g. migratory) species can therefore display very similar responses to extrinsic threats, even if they represent otherwise very different taxonomic, biological and ecological groupings. Monitoring the status of river dolphins or other megafauna therefore has the potential to provide wider information on the status of other threatened components of sympatric freshwater biotas, and so represents a potentially important monitoring tool for conservation management. We also show that interview surveys can provide robust quantitative data on relative population dynamics of different species.

Show MeSH

Related in: MedlinePlus

Middle-lower Yangtze drainage, showing distribution of interview localities (1–27), and key spawning grounds of Yangtze paddlefish (above Chongqing) and Reeves’ shad (Ganjiang River draining into Poyang Lake).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3362568&req=5

pone-0037902-g001: Middle-lower Yangtze drainage, showing distribution of interview localities (1–27), and key spawning grounds of Yangtze paddlefish (above Chongqing) and Reeves’ shad (Ganjiang River draining into Poyang Lake).

Mentions: Interviews were conducted in 2008 in 27 fishing communities along the middle-lower Yangtze channel (1767 km stretch from Yichang downstream to the Yangtze estuary) and around two major lake systems (Dongting and Poyang Lakes) connected to the Yangtze mainstem (Figure 1; Supporting Information Table S1). Baiji, paddlefish and shad were all historically present over the entire survey area. A total of 599 informants were interviewed during the survey.


River dolphins can act as population trend indicators in degraded freshwater systems.

Turvey ST, Risley CL, Barrett LA, Yujiang H, Ding W - PLoS ONE (2012)

Middle-lower Yangtze drainage, showing distribution of interview localities (1–27), and key spawning grounds of Yangtze paddlefish (above Chongqing) and Reeves’ shad (Ganjiang River draining into Poyang Lake).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3362568&req=5

pone-0037902-g001: Middle-lower Yangtze drainage, showing distribution of interview localities (1–27), and key spawning grounds of Yangtze paddlefish (above Chongqing) and Reeves’ shad (Ganjiang River draining into Poyang Lake).
Mentions: Interviews were conducted in 2008 in 27 fishing communities along the middle-lower Yangtze channel (1767 km stretch from Yichang downstream to the Yangtze estuary) and around two major lake systems (Dongting and Poyang Lakes) connected to the Yangtze mainstem (Figure 1; Supporting Information Table S1). Baiji, paddlefish and shad were all historically present over the entire survey area. A total of 599 informants were interviewed during the survey.

Bottom Line: Whereas species may be expected to respond differently at the population level even in highly degraded ecosystems, highly vulnerable (e.g. migratory) species can therefore display very similar responses to extrinsic threats, even if they represent otherwise very different taxonomic, biological and ecological groupings.Monitoring the status of river dolphins or other megafauna therefore has the potential to provide wider information on the status of other threatened components of sympatric freshwater biotas, and so represents a potentially important monitoring tool for conservation management.We also show that interview surveys can provide robust quantitative data on relative population dynamics of different species.

View Article: PubMed Central - PubMed

Affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom. samuel.turvey@ioz.ac.uk

ABSTRACT
Conservation attention on charismatic large vertebrates such as dolphins is often supported by the suggestion that these species represent surrogates for wider biodiversity, or act as indicators of ecosystem health. However, their capacity to act as indicators of patterns or trends in regional biodiversity has rarely been tested. An extensive new dataset of >300 last-sighting records for the Yangtze River dolphin or baiji and two formerly economically important fishes, the Yangtze paddlefish and Reeves' shad, all of which are probably now extinct in the Yangtze, was collected during an interview survey of fishing communities across the middle-lower Yangtze drainage. Untransformed last-sighting date frequency distributions for these species show similar decline curves over time, and the linear gradients of transformed last-sighting date series are not significantly different from each other, demonstrating that these species experienced correlated population declines in both timing and rate of decline. Whereas species may be expected to respond differently at the population level even in highly degraded ecosystems, highly vulnerable (e.g. migratory) species can therefore display very similar responses to extrinsic threats, even if they represent otherwise very different taxonomic, biological and ecological groupings. Monitoring the status of river dolphins or other megafauna therefore has the potential to provide wider information on the status of other threatened components of sympatric freshwater biotas, and so represents a potentially important monitoring tool for conservation management. We also show that interview surveys can provide robust quantitative data on relative population dynamics of different species.

Show MeSH
Related in: MedlinePlus