Dataset: Mud crab predation near blue crabs

Mud crab perceptive range trials were performed in enclosures (2.2 m by 0.75 m by 0.3 m) that contained an oyster reef as a refuge for mud crabs at one end. Oyster shells were glued together to create artificial oyster clusters that were used to manipulate the placement of oyster spat within the enclosure. Four oyster spat (10-16 mm) were epoxied to the artificial oyster clusters and 4 clusters were placed within the constructed oyster reef and 4 clusters outside the reef. Fifteen mud crabs (8 crabs 15-20 mm CW, 4 mud crabs 20-25 mm CW, and 3 mud crabs 25-30 mm CW) were added to the oyster reef in the enclosure. Caged blue crabs (12-16 cm CW) were placed either 0.25, 0.5, 1.0, 1.5, or 2.0 m away from the center of the oyster reef. A caged blue crab was placed on both sides of the oyster reef in the direction of tidal flow with one caged blue crab in the enclosure and the other outside the enclosure. Empty blue crab cages were used for the control treatment.

Enclosures were deployed on intertidal mudflats at either Priest Landing or Skidaway Narrows during either mean tide or spring tide. Flow parameters differed between sites and tidal types based on previous work (Wilson et al. 2013). The number of oyster spat eaten by mud crabs inside and outside the refuge was counted after 24 hours. See Pruett and Weissburg, 2018 for full methods. 

Data were statistically analyzed using R version 3.3.1.