Flatworm Predation on Juvenile Freshwater Mussels
type: CreativeWork
description: Free-living flatworms (Phylum Platyhelminthes, Class Turbellaria) are important predators on small aquatic invertebrates. Macrostomum tuba, a predominantly benthic species, feeds on juvenile freshwater mussels in fish hatcheries and mussel culture facilities. Laboratory experiments were performed to assess the predation rate of M. tuba on newly transformed juveniles of plain pocketbook mussel, Lampsilis cardium. Predation rate at 20°C in dishes without substrate was 0.26 mussels worm -¹·h-¹. Predation rate increased to 0.43 mussels worm -¹·h-¹ when a substrate, polyurethane foam, was present. Substrate may have altered behavior of the predator and brought the flatworms in contact with the mussels more often. An alternative prey, the cladoceran Ceriodaphnia reticulata, was eaten at a higher rate than mussels when only one prey type was present, but at a similar rate when both were present. Finally, the effect of flatworm size (0.7-2.2 mm long) on predation rate on mussels (0.2 mm) was tested. Predation rate increased with predator size. The slope of this relationship decreased with increasing predator size. Predation rate was near zero in 0.7 mm worms. Juvenile mussels grow rapidly and can escape flatworm predation by exceeding the size of these tiny predators. Captive culture for even a few weeks might improve the survival of propagated juveniles if flatworm predation also occurs in nature.
abstract: Free-living flatworms (Phylum Platyhelminthes, Class Turbellaria) are important predators on small aquatic invertebrates. Macrostomum tuba, a predominantly benthic species, feeds on juvenile freshwater mussels in fish hatcheries and mussel culture facilities. Laboratory experiments were performed to assess the predation rate of M. tuba on newly transformed juveniles of plain pocketbook mussel, Lampsilis cardium. Predation rate at 20°C in dishes without substrate was 0.26 mussels worm -¹·h-¹. Predation rate increased to 0.43 mussels worm -¹·h-¹ when a substrate, polyurethane foam, was present. Substrate may have altered behavior of the predator and brought the flatworms in contact with the mussels more often. An alternative prey, the cladoceran Ceriodaphnia reticulata, was eaten at a higher rate than mussels when only one prey type was present, but at a similar rate when both were present. Finally, the effect of flatworm size (0.7-2.2 mm long) on predation rate on mussels (0.2 mm) was tested. Predation rate increased with predator size. The slope of this relationship decreased with increasing predator size. Predation rate was near zero in 0.7 mm worms. Juvenile mussels grow rapidly and can escape flatworm predation by exceeding the size of these tiny predators. Captive culture for even a few weeks might improve the survival of propagated juveniles if flatworm predation also occurs in nature.
author: Delp, Angela
keywords: Biology
date published: 2002-01-01T08:00:00Z
date modified: 2026-07-24T03:15:42Z
provider: Missouri State University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Missouri State University