Elsevier

Journal of Experimental Marine Biology and Ecology

Research Article

Predation by Callinectes sapidus (Rathbun) within Spartina alterniflora (Loisel) marshes☆

Abstract

This study examined predation by the blue crab, Callinectes sapidus Rathbun, within intertidal Spartina alterniflora (Loisel) marshes of Dauphin Island, Alabama. Species and size preferences displayed by the predator when foraging within the marsh were investigated using nektonic, epifaunal, and infaunal prey populations including Fundulus similis Baird and Girard, Littorina irrorata Say, and Geukensia demissa Dillwyn.

Short-term field experiments involving the use of predator inclusion cages, in which the relative abundances of all prey species and the density of macrophyte vegetation were manipulated, indicated that mean mortality differed significantly among species. Blue crabs exhibited a distinct species preference for Littorina, and to a lesser extent, for Fundulus. However, the predator rarely choses infaunal individuals. Within predator inclusion cages, size selection by the crabs among three size classes of each prey was evident for Littorina and Fundulus but not for Geukensia. Blue crabs tended to select intermediate-sized snails and large fish while not exhibiting a size preference for infaunal bivalves.

In the marsh, mean percentage of the Littorina population within the 14–18 mm size class exhibited an increased mortality as compared to two other size classes, which was negatively correlated with increasing tidal height. Such a relationship may have been due to a decreasing gradient of crab predation associated with increasing tidal height. Geukensia size class distributions showed little evidence of differences along the tidal height gradient. No data are available for Fundulus, a mobile species which would not experience such differential predation along a marsh gradient.

In comparing crab predation patterns among prey species, it is apparent that Callinectes utilizes prey species differentially. Such differential utilization may be based on optimization of energy yield and minimization of energy expenditure. Thus, the preference of blue crabs for nektonic and epifaunal prey is hypothesized to be the result of a smaller energy expediture as a result of the crab's visual evaluation of these prey. Infaunal prey species (e.g., Geukensia) require a greater energy investment because of the necessity of excavating the prey item. Such prey also allow little selection by size because of being cryptic.

Cited by (71)

  • Impacts of a large-bodied, apex predator (Alligator mississippiensis Daudin 1801) on salt marsh food webs

    2013, Journal of Experimental Marine Biology and Ecology

    Thus, blue crabs appeared to regulate their risk and seek prey with lower handling time in presence of alligators. Similarly, West and Williams (1986), found that blue crabs preferentially consumed snails opposed to mussels and attributed these differences to increased energy and time investment required to excavate and consume infaunal mussels opposed to epifaunal snails. In natural salt marsh creeks, where refuge habitats are plentiful (e.g., oyster reefs, deep holes) and Spartina canopies along banks are dense, we expect blue crabs would either retreat to deeper habitats to forage within oyster beds or flee to higher marsh elevations within Spartina canopies where vulnerability to alligator predation would be minimized.

  • Predator-induced defenses in a salt-marsh gastropod

    2012, Journal of Experimental Marine Biology and Ecology

    Taken together with our current study, the distribution of induced defenses in gastropods suggests that the phenomenon is widespread in environments where durophagy is sufficiently variable and the potential for genetic fixation is low. Spatial heterogeneity in predation is vital to the maintenance of diversity, function, and stability of prey populations in salt-marsh communities (Kneib, 1984; Minello and Zimmerman, 1983; West and Williams, 1986). The structural complexity provided by marsh macrophytes, and the interaction of that complexity with tidal dynamics and local topography, produce a gradient of predatory environments ranging from intense predation pressure in the low marsh to a near-release of risk in the high marsh.

  • Body temperature and desiccation constrain the activity of Littoraria irrorata within the Spartina alterniflora canopy

    2012, Journal of Thermal Biology

    Therefore, a more complete understanding of the constraints on L. irrorata's life history behaviors would need to incorporate biotic interactions. For instance, L. irrorata is known to migrate up stalks of S. alterniflora with tidal inundation to avoid crab predation (West and Williams, 1986; Vaughn and Fisher, 1992). Vertical migration would introduce the snails to a different microclimate and could lead to different energetic behaviors.

  • Experiencing the salt marsh environment through the foot of Littoraria irrorata: Behavioral responses to thermal and desiccation stresses

    2011, Journal of Experimental Marine Biology and Ecology

    Littoraria irrorata (Say) is a major herbivore in salt marshes and is typically found on stalks of the dominant habitat-forming plant S. alterniflora (Stiven and Hunter, 1976; Stiven and Kuenzler, 1979). The snails are known to migrate up the S. alterniflora stalks with tidal inundation to avoid predators such as blue crabs (Vaughn and Fisher, 1992; West and Williams, 1986), and have also been found to migrate vertically to avoid high sediment temperatures at low tide (McBride et al., 1989). Such movement, whether due to biotic or abiotic interactions, alters the snail's microclimatic conditions, as environmental parameters such as solar radiation, temperature, humidity, and wind velocity change with height from the ground.

View all citing articles on Scopus
View full text

Copyright © 1986 Published by Elsevier B.V.