Parasitism in ecosystem engineer species: A key factor controlling marine ecosystem functioning.

Area of Science:

• Marine Ecology
• Parasitology
• Ecosystem Functioning

Background:

• Parasites are abundant in marine ecosystems, yet their impact on ecosystem processes via host behavior modification is poorly understood.
• Thalassinid crustaceans, like mud shrimp (Upogebia pusilla), are key ecosystem engineers in intertidal zones.

Purpose of the Study:

• To investigate the effects of the ectoparasite Gyge branchialis on the behavior of Upogebia pusilla.
• To assess the cascading impacts of altered host behavior on ecosystem processes such as bioturbation and nutrient regeneration.

Main Methods:

• Laboratory experiments were conducted to quantify the activity levels of parasitized and non-parasitized mud shrimp.
• Measurements included time allocated to burrowing and ventilation activities.
• Bioturbation rates and biogeochemical fluxes at the sediment-water interface were analyzed.

Main Results:

• Parasitized mud shrimp exhibited a 3.3-fold reduction in overall activity.
• Burrowing and ventilation activities decreased by 1.9- and 2.9-fold, respectively, in infected individuals.
• Reduced shrimp activity led to significant decreases in bioturbation rates and nutrient fluxes.

Conclusions:

• Parasite-induced behavioral changes in mud shrimp substantially alter key ecosystem processes.
• Host-parasite interactions, including trait-mediated indirect effects, are critical for understanding species' contributions to ecosystem properties and services.
• The findings emphasize the need to incorporate parasite impacts into ecological assessments of marine coastal systems.