Technical Reports: Methods—The Application of Temperature and Light Intensity as Intermittency Sensors in a Temporary Pond

Abstract

The aquatic and terrestrial environments associated with a temporary water body are together referred to as an aquatic-terrestrial ecosystem (Stubbington et al., 2017). One of the key features of aquatic-terrestrial ecosystems is the hydroperiod length (length of time supporting surface water) in each inundation and inversely, the length of each terrestrial phase. Hydroperiod length has been positively correlated with species richness, diversity and the length of aquatic food chains (Brooks, 2000;Schriever & Williams, 2013). The timing of inundation also affects species richness and density in aquatic environments (Kneitel, 2014). The parameters of inundation affect aquatic-terrestrial ecosystems in various means, necessitating investigation into the detection of surface water at high temporal and spatial resolutions. An array of measures exists to determine, both directly and indirectly, the hydrological state of aquatic-terrestrial ecosystems over time for the determination of hydroperiod length. Satellite data have successfully been used to detect and map the hydrological state of temporary water bodies at relatively high temporal resolution (Arledler et al., 2010;Haas et al., 2009). High-resolution aerial imagery (Gallart et al., 2016) and in situ mapping (Turner & Richter, 2011) have also been successful in detecting flow in intermittent streams, and stream gauges, depth data loggers and camera traps have been employed in monitoring temporary water bodies through space and time (Fovet et al., 2021).Numerous researchers have developed models of intermittency using loggers of environmental data, termed intermittency sensors, to monitor aquatic-terrestrial ecosystems at higher spatial and temporal resolution (Assendelft Abstract As climate change progresses, hydrological regimes of temporary and perennial water bodies are projected to change, affecting biodiversity and ecosystem functioning. Researchers have successfully employed the use of satellite imagery, camera traps and site visits to map these changes in hydrological regimes. Data loggers of conductivity have also been used in mapping hydrological regimes, but the use of data loggers of temperature and light intensity is uncommon. Using validated data of 213 days of the aquatic and terrestrial phases of a temporary pond, we show that metrics of temperature and light intensity can be used to discern hydrological state. The aquatic phase had lower measures of both parameters when compared to the terrestrial phase. This was attributed to the high specific heat of the aquatic environment and the absorption and redirection of light in water. The most powerful metrics in discerning hydrological state were diel temperature range, diel maximum temperature and light intensity standard deviation. Greater distinctive power was obtained through the use of multiple metrics of the parameters. In addition, key events such as flooding and drying were identifiable within metrics of both parameters. High-resolution temperature and light intensity data are able to aid in u...