Create or restore waterways

Overall effectiveness category Awaiting assessment
Number of studies: 2
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Background information and definitions

Streams may be drained or redirected during the development of agriculture or expansion of urban areas or other land uses. Many waterways have been cleared of submerged wood (‘desnagging’) for recreational purposes (e.g. fishing) or to allow boat access or protect against perceived flooding risks.

River restoration projects often include returning large woody material into streams and rivers (‘resnagging’), to slow down river flow, provide shelter for native fishes and increase basking areas for reptiles, especially freshwater turtles (Bodie 2001). Other restoration activities may include planting new or managing existing vegetation to provide appropriate shading levels for reptiles, and redirecting water flows.

For studies discussing wetlands and pond creation and restoration, see Create or restore wetlands and Create or restore ponds.

^{Bodie J.R. (2001) Stream and riparian management for freshwater turtles. Journal of Environmental Management, 62,443–444.}

Study locations

Key messages

Two studies evaluated the effects of creating or restoring waterways on reptile populations. Both studies were in the USA.

COMMUNITY RESPONSE (1 STUDY)

Community composition (1 study): One site comparison study in the USA found that restored and pristine streams had similar turtle community composition.

POPULATION RESPONSE (2 STUDIES)

Abundance (2 studies): One site comparison study in the USA found that restored and pristine streams had a similar abundance of turtles. One replicated, site comparison study in the USA found that creating new waterways by redirecting flows during forest restoration had mixed effects of reptile abundance.

BEHAVIOUR (0 STUDIES)

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A site comparison study in 2009 in 12 streams in North Carolina, USA (Dudley et al. 2015) found that restored streams had similar overall turtle abundance and community composition to pristine stream habitats. Turtle abundance was statistically similar in restored streams (9 turtles/site) compared to pristine streams (4 turtles/site). Overall, turtle communities were statistically similar between restored and pristine streams, although turtle community composition was correlated with habitat characteristics (water quality and habitat structure) that were significantly different between restored and pristine streams (see original paper for details, including abundances of the eight turtle species captured). Turtle abundance and species richness was compared in six restored and six natural, undegraded streams by trapping turtles using hoop nets in May–July 2009 (12 total trap nights/site). Restored streams were in their second to fifth growing season after restoration and shared similar characteristics (see original paper for details of restoration approach). Pristine streams were selected based on biological integrity and proximity to restored streams. Captured turtles were weighed, individually marked (or assessed for distinguishing scars) and released.
Study and other actions tested
Referenced paper
Dudley M.P., Ho M. & Richardson C.J. (2015) Riparian habitat dissimilarities in restored and reference streams are associated with differences in turtle communities in the southeastern Piedmont. Wetlands, 35, 147-157.
A replicated, site comparison study in 2012–2014 in saltcedar Tamarix ramosissima-cottonwood Populus fremontii forest along a river in Utah, Arizona and Nevada, USA (Mosher & Bateman 2016) found that the impact of redirecting water flows as part of forest restoration, along with mechanical tree removal, herbicide treatment and replanting native species, on overall lizard abundance was mixed. Trapping surveys indicated that overall lizard abundance was similar in restored stands (127–171 lizards/site/100 trap nights) compared to unrestored stands (62–74), whereas visual encounter surveys found that overall reptile abundance was greater at restored sites (results reported as statistical results). See original paper for the effects of restoration on individual species. In winter–spring 2012–2013, restoration of saltcedar-cottonwood/willow Salix spp stands was carried out along the Virgin River, including: introducing/redirecting water flows by trenching, mechanically removing 50% of saltcedar and Russian olive Elaegnus angustifolia, spraying stumps with herbicide and transplanting native plants. Saltcedar in Utah was subject to biocontrol by northern tamarisk beetles Diorhabda carinulata from 2006 (see original paper for details). Reptiles were monitored in two restored and six unrestored stands in May–July 2013–2014 using drift fences with pitfall and funnel traps (1,060 total trap days) and visual encounter surveys (3 transects/site, see original paper for details).
Study and other actions tested
Referenced paper
Mosher K.R. & Bateman H.L. (2016) The effects of riparian restoration following saltcedar (Tamarix spp.) biocontrol on habitat and herpetofauna along a desert stream. Restoration Ecology, 24, 71-80.

Please cite as:

Sainsbury K.A., Morgan W.H., Watson M., Rotem G., Bouskila A., Smith R.K. & Sutherland W.J. (2021) Reptile Conservation: Global Evidence for the Effects of Interventions for reptiles. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

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This Action forms part of the Action Synopsis:

Reptile Conservation

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