Food web persistence is enhanced by non-trophic interactions.

Area of Science:

• Ecology
• Food web dynamics
• Community ecology

Background:

• Food web stability is linked to interspecific interaction strength.
• Mechanisms influencing interaction strength and food web persistence require further investigation.

Purpose of the Study:

• Investigate how nonprey species affect predation risk and prey persistence.
• Determine if indirect interactions alter trophic interaction strengths and species persistence.

Main Methods:

• Assembled protist-prey and turbellarian predator interaction webs with varying nonprey species combinations.
• Monitored species abundances over 130 prey generations to assess persistence.

Main Results:

• Presence of nonprey species increased the persistence of predation-susceptible prey.
• Multiple nonprey species exhibited synergistic effects, enhancing prey persistence beyond predictions from simpler webs.
• Increased food web complexity appeared to weaken interspecific competition, benefiting poorer competitors.

Conclusions:

• Food web persistence in complex systems is not predictable from simplified models.
• Species not directly involved in consumptive interactions play crucial roles in maintaining ecosystem stability.
• Loss of biodiversity, including non-trophic species, may have unpredictable consequences for food web stability.