2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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6/08/2017  |   10:15 AM - 10:30 AM   |  THE DILUTION EFFECT IN A MUTUALISM: EFFECTS OF HOST DENSITY AND HOST DIVERSITY ON ECTOSYMBIONT ABUNDANCE   |  305A

THE DILUTION EFFECT IN A MUTUALISM: EFFECTS OF HOST DENSITY AND HOST DIVERSITY ON ECTOSYMBIONT ABUNDANCE

The dilution effect describes the effect of host diversity on parasite proliferation—with greater host diversity, parasite prevalence per host is lower due to a higher probability of parasites encountering unsuitable hosts. No previous research has examined whether host dilution affects mutualistic symbionts. Using the crayfish-branchiobdellidan worm mutualism, we performed an experiment investigating the effect of host density (1 vs 2 Cambarus chasmodactylus per aquarium) and host diversity (1 C. chasmodactylus paired with 1 Orconectes cristavarius) on branchiobdellidan (Cambarincola ingens) abundance. Worm numbers decreased over time on C. chasmodactylus alone and in the treatment in which it was paired with O. cristavarius, the latter being a poor host for C. ingens. Worm numbers declined the least in the 2 C. chasmodactylus treatment. While increased host diversity may reduce levels of parasitism (a positive effect of increased biodiversity) it could have negative effects on the abundance of mutualistic symbionts depending on the quality of alternative hosts.

• C11 Community Ecology
• C18 Biodiversity
• S12 Challenges, insights, and opportunities in crayfish conservation and ecology