Figure 1.
Map of general study areas within Barnegat Bay, New Jersey, USA: Sensor study area (black circle) and drone study area (gray circle). Specific site locations and names were redacted in order to protect the areas of terrapin activity.
Figure 2.
Female terrapin fitted with STAR-ODDI (DST) environmental sensor (21 g dry/13 g in water).
Figure 3.
Temperature (°C; darker shade) and depth (m; lighter shade) profile of a mature female diamondback terrapin (“BHIO”) that was fitted with DST environmental sensor on 9 July 2019, and recovered on 20 June 2020. The brumation period from early November 2019 to early April 2020 shows no movement above the surface indicating brumation as indicated within the highlighted box.
Figure 4.
Panned view of brumating terrapins (circled) leading from the sloped shoreline embankments (left) into shallow water on 7 April 2023. This image was taken by using drone technology at 1.5 – 4.6 m above the water and a water depth of < 1 m, and modified to a grayscale for better contrast and definition.
Figure 5.
Brumating terrapins found on April 11, 2023 by drone technology at 1.5 – 4.6 m above the water and a water depth of < 1 m (circled). Inset diamondback terrapin image shows the shape and definition of the carapace. This image was modified to a grayscale for better contrast and definition, which reflects similar terrapin mud burrow images by Selman and Baccigalopi (2012).
Table 1.
Environmental conditions during drone brumation surveys of the cove within Barnegat Bay - Little Egg Harbor Estuary.
| Survey 1 | Survey 2 | Survey 3 | |
|---|---|---|---|
| 5 April 2023 | 7 April 2023 | 11 April 2023 | |
| Method | drone | drone | drone |
| Water Temperature | 12.72°C | 13.78°C | 11.50°C |
| Water Depth | < 1.0 m | < 1.0 m | < 1.0 m |
| Tidal Height | 0.0067 m | 0.007 m | 0.063 m |
| Wind | SE 12.9 km/h | W 12.9 km/h | W 24.1 km/h |
| Visibility | 4.8 km | 33.8 km | 27.4 km |
Table 2.
Comparison of environmental conditions for brumation and cold water terrapin studies performed by Yearicks et al. (1981); Williard and Harden (2011); and Akins et al. (2014). All units were converted for comparison purposes.
| This Study | Yearicks et al. (1981) | Akins et al. (2014) | Williard & Harden (2011) | |
|---|---|---|---|---|
| Location | Barnegat Bay-Little Egg Harbor Estuary, New Jersey | Atlantic Coast of Cape May County, New Jersey | South Carolina (by Kiawah Island) | Mansonboro Island, North Carolina |
| Survey Type | Drone; Environmental sensor | Probing | Temperature data Loggers | Radiotelemetry & visual observation; Temperature data loggers |
| Water Depth | < 1 m | Creek bottoms at low tide = 1.5 – 2.5 m | 0.15 m | Not reported |
| Mud Depth | < 12 cm | Creek bank sides = 15 – 50 cm; Bank undercuts = <1.0 cm | 10 cm | 5 – 10 cm (intertidal zone) |
| Water Temperature | Early April: < 13.90°C | Mid to late November: 6 – 10°C | April: < 18°C | Mean weekly carapace temperature (Tc) during dormancy = 12.4 +/−1.0°C; Majority of dormancy period at < 20°C |
| Gender | Male/Female | Male/Female | Male/Female | Female |
| Location of Brumating Terrapins | Beyond the edges of sloped embankments; underwater burial on cove’s bay floor | Underwater burial on bottom of bay floor; atop creek banks and undercuts | Shallow intertidal mud | Burial in mud of intertidal zone |