Amphibian occupancy, breeding and water quality of vernal pools on the Preserve have been monitored since 1931. Sampling effort has varied significantly over the dataset range, with stochastic sampling prior to 2017 and post-2017 weekly spring sampling. From 1931 - 2015, data collected at each vernal pool varied, but often included current weather conditions, water level (%), water temperature (°F), water pH and species/egg mass counts. Observations at each vernal pool occur annually between February and May. From 1931 – 1991, sampling at vernal pools and the number of vernal pools sampled each year varied. Starting in 1991, each vernal pool was observed at least two times each spring. Starting in 2016, a more rigorous protocol was adopted from the USGS Amphibian Reproductive Monitoring Initiative programme with sampling at 10 vernal pools being completed at least four times per spring season (Muths et al. 2005).The number of observers during each survey varies and is weather and logistic dependent, but with a goal of weekly sampling of each vernal pool, beginning at the onset of amphibian emergence and continuing until larvae hatch from egg masses.

In 2016, the new protocol dictated more parameters to be sampled consistently. Upon arrival at each vernal pool, initial observations performed included:

1. weather conditions: sky code, wind code, air temperature (°F) and previous day precipitation occurrence; and
2. qualitative measurements: water level (%), surface ice (%), surface vegetation (%), surface vegetation species, water odour and fairy shrimp (order Anostraca) presence.

In addition to the qualitative observations, quantitative measurements are taken of:

1. water quality: temperature (°F), pH, conductivity (µS), dissolved oxygen (%), nitrate concentration (mg/l), and turbidity (NTU); and
2. amphibian species counts: number of adults alive, dead, in amplexus; egg masses, calling frogs, spermatophores, juveniles and tadpole/larvae.

The data are recorded by hand on to standardised data sheets (Fig. 4) and later input into a machine-readable format. All parameters of amphibian species counts since 2016 were collected using the Double-Observer Dependent method (Cook and Jacobson 1979, Nichols et al. 2000). Observer A walks halfway around the pool and calls out counts to Observer B. Observer B records count made by Observer A, but also records counts that Observer A missed without informing Observer A. Observers A and B switch roles when the second half of the pool is surveyed. Prior to November 2017, water from the vernal pool was collected in a high-density polyethylene bottle and temperature was immediately recorded on-site with an analogue thermometer. The sample was then brought back to the DSRC where pH was measured. Prior to 13 December 1991, pH was measured using a Sargent-Welch analogue pH meter. Beginning 13 December 1991, pH was measured with a Fisher Accumet digital pH meter with higher resolution and probes were replaced every 6 months. In 2002, the meter was replaced with a new Fisher Accumet pH meter. Starting in February 2018, temperature and pH were collected in situ using a YSI Sonde Professional Plus hand-held multiparameter meter and additional Sonde measurements of percent dissolved oxygen, nitrate concentrations and conductivity were incorporated in the water quality measurements. Starting in March 2019, a turbidity tube was incorporated to measure turbidity.

Figure 4.  

Current format of the vernal pool monitoring data sheet for ongoing data collection. As additional data are collected, the data object in the Environmental Data Initiative repository (package identifier: edi.398) will be updated accordingly.

Prior to the publication of the dataset, historical records were checked for biological consistency. During field surveys, utmost caution was used when monitoring and sampling from the vernal pools. To avoid disturbance, wading was not done in the pools and the YSI Sonde was only submerged in areas that did not contain visible animals, egg masses, spermatophores or larvae. Starting in 2017, between each vernal pool survey, equipment and boots were disinfected with a 5% bleach solution to avoid transference of disease. The YSI Sonde was calibrated before each vernal pool survey to ensure that water quality measurements were accurate; probes were replaced as needed.

Mohonk Preserve is located in the Hudson Valley region of New York State, in Ulster County. The Preserve has land in the towns of New Paltz, Gardiner, Rochester, Marbletown and Rosendale. Main vegetation types of the Preserve are Appalachian oak-hickory forest, beech-maple mesic forest, chestnut oak forest, hemlock northern hardwood forest and grasslands/pastures (Fig. 5, Thompson and Huth 2011). The geology of this area has been influenced by the Taconic and Acadian orogenies; rocks occurring in abundance include shale, greywacke, quartz conglomerate and sandstone. Surficial geology of the Preserve includes kame deposits, lacustrine deltas, lacustrine silt & clay, bedrock and till. Bedrock geology includes Normanskill Shale and the Bloomsburg Formation (New York State Museum 1999). The coordinates below designate the bounding box surrounding the area where observations were recorded. Due to the sensitivity of the vernal pools and the amphibian species, specific locations were not revealed as part of this data package, but are available upon request from the DSRC to individuals carrying out direct research.

Figure 5.  

Vegetation cover and geography of the vernal pool data collection region in the Mohonk Preserve. Vegetation cover adapted from Thompson and Huth (2011) and New York State Museum (1999).

41.80133 and 41.738856 Latitude; -74.109075 and -74.190815 Longitude.

The described dataset, ongoing as of February 2020, includes 2,480 recorded dates, sampled across the nine amphibian species. Spotted salamanders were surveyed on the greatest number of dates, with 521 unique events and blue-spotted salamanders were surveyed the least, with 144 unique events (Fig. 6). Across all species, life stages and sampling events, a total of 151,701 individuals were recorded. All the species included in the sampling are native to this region. Three of the sampled Ambystoma species: Jefferson salamander, marbled salamander and blue-spotted salamander were listed in 2013 as species of special concern in the State of New York as defined in Section 182.2(i) of 6NYCRR Part 182. As defined by the State, species of special concern need increased consideration and monitoring, but current information does not warrant listing these species as threatened or endangered.

Figure 6.  

Pie chart showing the percent of dataset occurrence records by species. Jefferson/blue-spotted salamander complex omitted from the total, with 13 total records (0.5%).

The current taxonomic authority of the dataset is the Integrated Taxonomic Information System (ITIS) (Bisby et al. 2006). If the ITIS taxonomic classification of the monitored species changes, the dataset will be updated at that point to reflect those changes. Particularly, there has been significant debate about the appropriate genus name for green frogs, wood frogs and bullfrogs. The elevation of Lithobates as a genus name for these species has been questioned by Yuan et al. (2016) and Pauly et al. (2009). Presently, Rana is used by the vast majority of ranid systematists around the world, so we anticipate the eventual transition from Lithobates to Rana in ITIS in the near future and the subsequent updating of the data package.

This data package is released to the “public domain” under Creative Commons CC0 1.0 “No Rights Reserved” (see: https://creativecommons.org/publicdomain/zero/1.0/). It is considered professional etiquette to provide attribution of the original work, if this data package is shared in whole or by individual components. A generic citation is provided for this data package on the website https://portal.edirepository.org (herein “website”) in the summary metadata page. Communication (and collaboration) with the creators of this data package is recommended to prevent duplicate research or publication. This data package (and its components) is made available “as is” and with no warranty of accuracy or fitness for use. The creators of this data package and the website shall not be liable for any damages resulting from misinterpretation or misuse of the data package or its components. Periodic updates of this data package may be available from the website.