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Vernal Pools

Maryland Water Monitoring Council   Vernal/Seasonal Pool Workshop  
March 2008

Poster and supporting materials created for this workshop The poster (pdf file, large paper size) describes the design and rationale for the new research techniques developed to survey populations in large vernal pools. The project summary was written to give the volunteers who would conduct the survey an introduction to the research methodology and detailed instructions for performing the study. There are two data sheets. The "Survey Data" sheet includes general characteristics of the site, weather conditions and water quality. The "Transect Data" sheet is a two sided form used to record the count of egg masses and larvae found while following each transect across the pool. This form is computer generated to include only the observation points that are currently within the pool. (Since the size of the pool varies over time, the transects were defined to cover the maximum extent of the pool.). There is also the version of the "Transect Data sheet" with an explanation of usage that was presented along with the poster at the workshop.

Poster Abstract:

Monitoring Protocol for Larger Vernal Pool

Jeffrey D. Campbell¹, Lindsay Hollister², Elaine Friebele²

¹Center for Urban Environmental Research and Education, UMBC
²Jug Bay Wetlands Sanctuary

Unlike smaller vernal pools where most of the water surface is easily visible from the shoreline, larger pools require a different monitoring procedure. The methodology developed to study a vernal pool with maximum extent of 1.3 ha is described. The research objective is to support long term monitoring of obligate and facultative species populations. Egg mass count is of particular interest.

Egg masses are counted along randomly defined transects across the pool. Periodic dip net samples with a 1 meter sweep are taken to capture adult and larval amphibians and invertebrates. Physical properties of the pool (dimensions, pH, dissolved oxygen, temperature, salinity, turbidity) and weather (temperature, sky conditions affecting visibility) are also recorded.

            The double observer technique ^*. is used to obtain a statistical measure for errors in egg mass counting. The observers follow transects identified with ropes marked at one meter intervals with poles every five meters. Egg mass counts are recorded for each square meter. The water depth is measured at each pole. One objective of measuring depth is to quantify the anecdotal relationship between depth and spotted salamander (Ambystoma maculatum) egg masses. The measurements will also allow a depth-weighted estimate of total pool population. The size of the vernal pool is obtained by measuring the distance along the transects and by recording the dimensions with a GPS while walking around the perimeter.

^*.Grant, E.H.C., et al., “Double-observer approach to estimating egg mass abundance of pool-breeding amphibians”. Wetlands Ecology and Management, 2005. 13: p. 305 - 320

Revised: January 06, 2009
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