Effects of Short-Duration and Diel-Cycling Hypoxia on Predation of Mussels and Oysters in Two Tributaries of the Chesapeake Bay

Abstract

Although the effects of persistent hypoxia have been well established, few studies have explored the community-level effects of short-duration and diel-cycling hypoxia, for example on predator−prey interactions. Consumer stress models predict that mobile predators will flee hypoxia, while prey stress models predict that sessile species, unable to avoid hypoxic water, will be more susceptible to predation. To test these hypotheses, we studied the effects of diel-cycling hypoxia on predation of the hooked mussel, Ischadium recurvum, and eastern oyster, Crassostrea virginica, in field experiments in two Chesapeake Bay, USA tributaries. We conducted a complementary laboratory experiment that tested the impact of short-duration hypoxia on predation of the two bivalve species by the ecologically and commercially important blue crab, Callinectes sapidus. Although we did not observe a significant effect of diel-cycling hypoxia on predation in the field, we did observe an effect of short-duration hypoxia in the laboratory. Callinectes sapidus exhibited depressed feeding rates and reduced preference for I. recurvum in hypoxic conditions. In both field and lab results, we observed a strong preference of predators for I. recurvum over C. virginica, indicating that the relatively understudied mussel I. recurvum merits greater consideration as a part of estuarine food webs.

Keywords

• water quality
• food web
• prey preference
• crassostrea virginica
• ischadium recurvum
• callinectes sapidus