Influences of individual phenotypic traits on the habitat preferences of the sand fiddler crab, Uca pugilator

Recognizing which phenotypic traits are predictors for habitat choice can have important implications for understanding population dynamics. This study determined whether body size, sex, activity level, or origin habitat affected the preference of the fiddler crab,Uca pugilator, in selecting either a marsh or open mudflat, two habitats differing in risk level and food availability. Combining field and laboratory experiments, this study indicated a significant difference in body size and activity level of crabs between habitats. Further investigation of phenotypic dependency on habitat preference resulted in interactions between origin habitat and carapace width and activity level. When split by origin habitat, habitat preference for the open mudflat was predicted by body size for crabs originating from the open mudflat and by activity level for the crabs originating from theSpartinamarsh. These results suggest that, forU. pugilator, body size plays a large role in the preference for exposed habitat.

Infaunal Burrows Are Enrichment Zones for Vibrio parahaemolyticus

ABSTRACTVibrio parahaemolyticus, a species that includes strains known to be pathogenic in humans, and otherVibrionaceaeare common, naturally occurring bacteria in coastal environments. Understanding the ecology and transport of these organisms within estuarine systems is fundamental to predicting outbreaks of pathogenic strains. Infaunal burrows serve as conduits for increased transport of tidal waters andV. parahaemolyticuscells by providing large open channels from the sediment to salt marsh tidal creeks. An extensive seasonal study was conducted at the North Inlet Estuary in Georgetown, SC, to quantifyVibrionaceaeand specificallyV. parahaemolyticusbacteria in tidal water, fiddler crab (Uca pugilator,Uca pugnax) burrow water, and interstitial pore water. Numbers ofV. parahaemolyticusbacteria were significantly higher within burrow waters (4,875 CFU ml−1) than in creek water (193 CFU ml−1) and interstitial pore water (128 CFU ml−1), demonstrating that infaunal burrows are sites ofV. parahaemolyticusenrichment. A strong seasonal trend of increased abundances ofVibrionaceaeandV. parahaemolyticusorganisms during the warmer months of May through September was observed. Multilocus sequence typing (MLST) analysis of isolates presumed to beV. parahaemolyticusfrom creek water, pore water, and burrow water identified substantial strain-level genetic variability amongV. parahaemolyticusbacteria. Analysis of carbon substrate utilization capabilities of organisms presumed to beV. parahaemolyticusalso indicated physiological diversity within this clade, which helps to explain the broad distribution of these strains within the estuary. These burrows are “hot spots” ofVibrionaceaeandV. parahaemolyticuscell numbers and strain diversity and represent an important microhabitat.