Coastal bivalve parasitism and its response to anthropogenic influences : a geohistorical approach

Abstract

[EMBARGOED UNTIL 05/01/2025] Parasites are common and essential parts of healthy ecosystems that influence biodiversity and trophic structure. Understanding how parasite-host dynamics have changed over time proves difficult due to the lack of body fossil record for these organisms. This thesis uses parasite-induced malformations, specifically trematode-induced pits and spionid polychaete mudblisters, to track parasitic prevalence and parasite-host dynamics over time periods often beyond traditional ecological monitoring. In the northern Adriatic Sea, we examine trematode-induced pit prevalence, aggregation, and size across two distinct time bins over the last [approx] 2ky years. Over this period prevalence decreased by an order of magnitude along with decreases in number of pits per host and pit aggregation, signaling a breakdown of this parasite-host interaction at this locality. At San Juan Island, WA we use parasitic malformations in live collected bivalves to examine parasite-host dynamics over nearly two decades. Through replicating a previous study using samples collected in 2004 we observe changes in trematode-induced pitting and mudblister prevalence over these two decades. Additionally, we see decreased parasitic prevalence among an introduced species collected in 2023 when compared to a confamilial native species indicating host selectivity among parasites in the region.Includes bibliographical references