Chinese giant salamanders 375
techniques, including daytime and night-time snorkeling and rock turning. Cloacal and skin swabs were taken from giant salamanders (see Tapley et al., 2017 for details), and tested for chytrid infection (Batrachochytrium dendroba- tidis) using molecular methods described by Boyle et al. (2004), and for ranaviruses following Cunningham et al. (2016). During each ecological survey, physical evidence of giant salamander exploitation (e.g. bow hooks, traps, elec- trofishing) was also recorded if detected. Ecological surveys following our standardized methods (excluding the op- portunistically surveyed Nanjiang County site) represented 2,675 person-days of passive searching and 50 cumulative person-days of active searching (Turvey et al., 2018). We recorded environmental parameters at each site.
Elevation and geographical coordinates were recorded using a GPS; water temperature, dissolved oxygen and sal- inity were measured using a Micro 800 Meter (Palintest, Gateshead, UK); pH was measured using a Micro 600 pH Meter (Palintest); and ammonia (the sum of ammonia and ammonium), nitrite, nitrate, alkalinity and dKH (car- bonate hardness) were measured with aquarium test kits (Salifert, Duiven, The Netherlands). Flow ratewasmeasured using a locally produced unbranded flow meter, and indirect measurements of turbidity were taken using a Secchi disc. Water parameters were recorded once at each site, at the start of the first daytime survey in the middle of the stream being surveyed. All parameters were recorded either in the stream (temperature, salinity, dissolved oxygen, flow rate, turbidity) or within 15 min for tests that required reagents (ammonia, nitrite, nitrate, alkalinity and hardness). Wealso conducted standardized questionnaire-based in-
terviews (Tapley et al., 2017) at the 97 selected survey sites (but not at the opportunistically surveyed site in Nanjiang County), to collect local ecological knowledge on Chinese giant salamanders, including respondent sighting experi- ence, last-sighting records and information on exploitation. All interviews were conducted in Chinese (either standard Mandarin Chinese or a local dialect), in communities situ- ated within 1 km of the surveyed rivers. Full details of inter- view methods, including respondent selection and interview protocols, are given in Tapley et al. (2017), Chen et al. (2018) and Turvey et al. (2018). As datawere not normally distributed,we used two-tailed
Mann–WhitneyUtests, with Social Science Statistics (2020), to compare each of the recorded water parameter values be- tween grouped sets of sites, as follows: (1) Sites where giant salamanders were directly detected during ecological surveys vs sites where salamanders were not detected. Because sala- manders were detected in only four of the 97 randomly selected counties, data from the opportunistically surveyed site in Nanjiang County, where a giant salamander was de- tected, were also included in this analysis, to fulfil the min- imum number of sites required for statistical analysis. This site was excluded from further analyses as it was not chosen
by our standardized site selection method. (2) Sites where giant salamanders were detected during ecological surveys and/orwheremeanreported last-sighting date (based onlast- sighting data fromall respondents in each county)was within the previous 5 years vs sites where giant salamanders were not detected and where mean reported last-sighting date was .5 years ago. We performed principal component analyses (PCA;
Hammer et al., 2001) using varimax rotation for water para- meters from three categories of sites: (1) where giant sala- manders were detected directly during ecological surveys (including the opportunistically surveyed site in Nanjiang County); (2) where giant salamanders were not detected dir- ectly, but with mean last-sighting date within the previous 5 years; and (3) sites where giant salamanders were not de- tected directly, and with mean last-sighting date .5 years ago. We examined each variable that contributed moder- ately (.0.50) to factor loadings.We also performed PCAs using varimax rotation for water parameters from sites grouped by river basin (Yellow, Yangtze, Pearl, and south- east rivers), again examining each variable that contributed moderately (.0.50) to factor loadings.
Results
We recorded water parameters at all survey sites (Table 1, Supplementary Table 1). Shallow water depth at all sites pre- cluded measurement of turbidity as the water was too clear for using a Secchi disc, and we suggest that turbidity meters are used for future studies. We detected 25 giant salaman- ders (Plate 1a) in four of the 97 selected survey counties and at the opportunistically surveyed site in Nanjiang: Liannan (Guangdong), 17 individuals; Jiangkou (Guizhou), 1; Lüeyang (Shaanxi), 5; Zhouzhi (Shaanxi), 1; Nanjiang (Sichuan), 1. Of these, 20 were captured and were swabbed for the amphibian chytrid fungus Batrachochytrium dendro- batidis and for ranaviruses. We did not detect the presence of either pathogen in any sample. Five animals that were re- corded in Liannan (Guangdong) were not accessible as they were deep within caves. Releases of farmed giant salaman- ders had occurred shortly beforehand at two sites where they were detected during ecological surveys (Liannan and Lüeyang), so a proportion or all of the giant salamanders de- tected at these two sites could have been released animals. There was no statistically significant difference between any of the water quality parameters at sites where giant sal- amanders were detected by survey teams and/or had been recently seen by local respondents, and sites where they were not detected and/or from which they had recently been extirpated (Table 2). Evidence of illegal giant salamander exploitationwas found at 26 of the 97 survey sites (illegal traps at 10 sites; bow hooks at six sites; evidence of electrofishing at six sites; evidence of poison fishing at nine sites; evidence of
Oryx, 2021, 55(3), 373–381 © The Author(s), 2021. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605320000411
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