Hatchling
and Juvenile Diamondback Terrapin (Malaclemys
terrapin) Prey Availability in Two Marshes in the Barnegat Bay Ecosystem
The diamondback terrapin (Malaclemys terrapin) is endemic to estuarine environments in North America. Hatchling and juvenile terrapins typically utilize the high salt marsh for cover and foraging. We conducted a prey availability study at Sedge Island and High Bar Harbor (HBH) to compare differences in physiognomy and food resources between the two salt marsh locations. We used a 0.25 m2 quadrat to sample 30 sites at each salt marsh where we recorded the time, date, location (GPS coordinates), marsh type (low/mixed/high), edaphic conditions (flooded/saturated/moist), and tidal cycle. Within each quadrat, we identified plant species, estimated vegetation cover, inventoried invertebrates, and noted the presence or absence of crab burrows. As Melampus bidentatus is a primary food source for young terrapins, we measured the length and width (mm) of all M. bidentatus found in each quadrat and calculated density. We collected 10 adult M. bidentatus from the high and low marsh at each location and measured their mass (g). There was a positive relationship between M. bidentatus length/mass and marsh type for both locations (Sedge, r2 = 0.92; HBH, r2 = 0.88) with a higher density of smaller-sized snails occurring in the high marsh. The mean length of snails was 9.61 mm (± 1.21) for the low marsh and 7.73 mm (± 0.99) for the high marsh. These data suggest that the foraging pressure of young terrapins may influence the distribution of M. bidentatus in the marsh. However, more research is needed to determine how differences in marsh type influence juvenile terrapin foraging behavior.
The diamondback terrapin (Malaclemys terrapin) is endemic to estuarine environments in North America. Hatchling and juvenile terrapins typically utilize the high salt marsh for cover and foraging. We conducted a prey availability study at Sedge Island and High Bar Harbor (HBH) to compare differences in physiognomy and food resources between the two salt marsh locations. We used a 0.25 m2 quadrat to sample 30 sites at each salt marsh where we recorded the time, date, location (GPS coordinates), marsh type (low/mixed/high), edaphic conditions (flooded/saturated/moist), and tidal cycle. Within each quadrat, we identified plant species, estimated vegetation cover, inventoried invertebrates, and noted the presence or absence of crab burrows. As Melampus bidentatus is a primary food source for young terrapins, we measured the length and width (mm) of all M. bidentatus found in each quadrat and calculated density. We collected 10 adult M. bidentatus from the high and low marsh at each location and measured their mass (g). There was a positive relationship between M. bidentatus length/mass and marsh type for both locations (Sedge, r2 = 0.92; HBH, r2 = 0.88) with a higher density of smaller-sized snails occurring in the high marsh. The mean length of snails was 9.61 mm (± 1.21) for the low marsh and 7.73 mm (± 0.99) for the high marsh. These data suggest that the foraging pressure of young terrapins may influence the distribution of M. bidentatus in the marsh. However, more research is needed to determine how differences in marsh type influence juvenile terrapin foraging behavior.