The importance of habitat complexity, refuge, and prey availability on the attraction of grass shrimp, white perch, and striped bass to structure

We examined how differing levels of habitat complexity affect interactions among a prey species (grass shrimp), an intermediate predator (white perch), and a top predator (striped bass).  In laboratory mesocosms five predator–prey treatment combinations (shrimp only, white perch only, shrimp / white perch, shrimp / striped bass, and shrimp / white perch / striped bass) were paired with each of three habitat complexities (sand control, medium, and high) and replicated five times.  Grass shrimp were significantly attracted to the highest complexity habitat in the presence and absence of both fish predators.  White perch utilized the sand control least and the high complexity habitat most in the presence and absence of shrimp and striped bass.  White perch utilized the medium complexity habitat least when shrimp and striped bass were absent, but usage of this complexity was comparable to high complexity habitat when shrimp and/or striped bass were present.  Swimming and schooling activity of white perch decreased with an increase in habitat complexity.  Striped bass were most attracted to high complexity habitat and exhibited ambush behavior. We conclude that fish are attracted to structure for food resources, but predatory threat will extend the time that fish spend on structurally complex habitat.