A Case Study of Urban Streamside Salamander Persistence in Staten Island, NY

We monitored salamander populations in four stream segments on Staten Island, New York, from 2000 to 2012. We found three salamander species in our study. Two streams had all three species: a headwater stream (Reed’s Basket Willow) and a third-order stream (BloodrootValley). We found Eurycea bislineata and Desmognathus fuscus in all streams, although the frequency of occurrence and densities of these species differed markedly among streams. Reed’s Basket Willow had significantly greater populations of E.bislineata and D. fuscus than the other three, higher order, streams. Pseudotriton ruber was found only on two occasions each in Reed’s Basket Willow and Bloodroot Valley. We found lower population densities than that reported in other studies for both Eurycea bislineata and Desmognathus fuscus. The maximum density we recorded for E. bislineata was 14.4 individuals/m2 on one occasion in one stream and for D. fuscus 0.3 individuals/m2 on several occasions. Despite the low densities, and seasonal and yearly variability, the populations have not shown any noticeable trends in the twelve years of our study and appear stable. We measured sediment deposition and found the highest amount deposited in Reed’s Basket Willow. Because this stream also has the highest population densities, our results suggest that sediment does not always have a negative impact on streamside salamanders. We measured impervious cover in the watershed and found that it did not correspond to increased salamander densities; Reed’s Basket Willow had the highest salamander densities despite having the highest percent impervious cover. However, Reed’s had the lowest percent impervious cover in its buffer. The stream with the lowest densities was a second-order stream downstream from a dam in place for at least 80 years at the start of our study. Egbertville Ravine, which lies below a dam constructed in 2003, has not shown a declining trend in population densities, although the 2012 sampling showed a decrease that was not experienced at the other three sites. Within urban areas, local impacts such as stream order, dams and adjacent land cover may obscure effects of landscape scale factors

Conservation genetics of extremely isolated urban populations of the northern dusky salamander (Desmognathus fuscus) in New York City

Urbanization is a major cause of amphibian decline. Stream-dwelling plethodontid salamanders are particularly susceptible to urbanization due to declining water quality and hydrological changes, but few studies have examined these taxa in cities. The northern dusky salamander (Desmognathus fuscus) was once common in the New York City metropolitan area, but has substantially declined throughout the region in recent decades. We used five tetranucleotide microsatellite loci to examine population differentiation, genetic variation, and bottlenecks among five remnant urban populations of dusky salamanders in NYC. These genetic measures provide information on isolation, prevalence of inbreeding, long-term prospects for population persistence, and potential for evolutionary responses to future environmental change. All populations were genetically differentiated from each other, and the most isolated populations in Manhattan have maintained very little genetic variation (i.e. \u3c20% heterozygosity). A majority of the populations also exhibited evidence of genetic bottlenecks. These findings contrast with published estimates of high genetic variation within and lack of structure between populations of other desmognathine salamanders sampled over similar or larger spatial scales. Declines in genetic variation likely resulted from population extirpations and the degradation of stream and terrestrial paths for dispersal in NYC. Loss of genetic variability in populations isolated by human development may be an underappreciated cause and/or consequence of the decline of this species in urbanized areas of the northeast USA

Data from: Conservation genetics of extremely isolated urban populations of the Northern Dusky Salamander (Desmognathus fuscus) in New York City

Urbanization is a major cause of amphibian decline. Stream-dwelling plethodontid salamanders are particularly susceptible to urbanization due to declining water quality and hydrological changes, but few studies have examined these taxa in cities. The northern dusky salamander (Desmognathus fuscus) was once common in the New York City metropolitan area, but has substantially declined throughout the region in recent decades. We used five tetranucleotide microsatellite loci to examine population differentiation, genetic variation, and bottlenecks among five remnant urban populations of dusky salamanders in NYC. These genetic measures provide information on isolation, prevalence of inbreeding, long-term prospects for population persistence, and potential for evolutionary responses to future environmental change. All populations were genetically differentiated from each other, and the most isolated populations in Manhattan have maintained very little genetic variation (i.e. < 20% heterozygosity). A majority of the populations also exhibited evidence of genetic bottlenecks. These findings contrast with published estimates of high genetic variation within and lack of structure between populations of other desmognathine salamanders sampled over similar or larger spatial scales. Declines in genetic variation likely resulted from population extirpations and the degradation of stream and terrestrial paths for dispersal in NYC. Loss of genetic variability in populations isolated by human development may be an underappreciated cause and/or consequence of the decline of this species in urbanized areas of the northeast USA

Desmognathus.Genotypes.02Feb2012

Microsatellite genotypes in GenAlex format for five urban populations of northern dusky salamanders. Site name: HPN = North Highbridge Park; HPS = South Highbridge Park; CPW = Corson's Brook Woods; RB = Reed's Basket Willow; WR = Watchung Reservatio

duskycoords

Text file of spatial coordinates used in BAPS analysis for five northern dusky salamander populations