Parasitism and host behavior in the context of a changing environment: The Holocene record of the commercially important bivalve Chamelea gallina, northern Italy

Abstract

Rapid warming and sea-level rise are predicted to be major driving forces in shaping coastal ecosystems and their services in the next century. Though forecasts of the multiple and complex effects of temperature and sea-level rise on ecological interactions suggest negative impacts on parasite diversity, the effect of long term climate change on parasite dynamics is complex and unresolved. Digenean trematodes are complex life cycle parasites that can induce characteristic traces on their bivalve hosts and hold potential to infer parasite host-dynamics through time and space. Previous work has demonstrated a consistent association between sea level rise and increasing prevalence of trematode traces, but a number of fundamental questions remain unanswered about this paleoecological proxy. Here we examine the relationships of host size, shape, and functional morphology with parasite prevalence and abundance, how parasites are distributed across hosts, and how all of these relationships vary through time, using the bivalve Chamelea gallina from a Holocene shallow marine succession in the Po coastal plain. Trematode prevalence increased and decreased in association with the transition from a wave-influenced estuarine system to a wave-dominated deltaic setting. Prevalence and abundance of trematode pits are associated with large host body size, reflecting ontogenetic accumulation of parasites, but temporal trends in median host size do not explain prevalence trends. Ongoing work will test the roles of temperature, salinity, and nutrient availability on trematode parasitism. Parasitized bivalves in one sample were shallower burrowers than their non-parasitized counterparts, suggesting that hosts of trematodes can be more susceptible to their predators, though the effect is ephemeral. Like in living parasite-host systems, trematode-induced malformations are strongly aggregated among hosts, wherein most host individuals harbor very few parasites while a few hosts have many. We interpret trace aggregation to support the assumption that traces are a reliable proxy for trematode parasitism in the fossil record.

Chamelea gallina reproductive biology and Minimum Conservation Reference Size: implications for fishery management in the Adriatic Sea

“…Considering that the physical and chemical parameters of the seas are changing due to water acidification, global warming, sea level rise and decreased nutrient availability [79][80][81], the environmental perturbations are likely to frequently raise increasing the pressure on the species. For example, Huntley & Scarponi [82] found an association between sea level rise and increasing prevalence of digenean trematodes in C. gallina fossil records from a Holocene shallow marine succession in the Po coastal plain. Moreover, Delgado & Silva [83] noted that, where levels of prevalence of diagenetic-trematode-like parasite were higher they induced castration in the wedge clam (Donax trunculus) specimens.…”

Taxonomy, taphonomy, and ecology of Silurian (late Telychian) conulariids from the Waukesha Lagerstatte, Wisconsin

“…3.3) tend to possess more epibionts. This suggests that larger and presumably older specimens have more holdfasts, which would be consistent with the accumulation of parasites or epibionts throughout ontogeny (Huntley & Scarponi, 2021). Frequency distributions corroborate this finding.…”

Food Contents Analysis of Waterfowl Passing Through Indus the River at Taunsa, South Punjab, Pakistan

“…Dietary studies of waterfowl are an essential to comprehend their environmental adaptations. Also, it includes details on the nutritional makeup of food and species overlaps for ducks (Huntley and Scarponi 2021). Depending on the goals of each study, different techniques must be utilized to collect data from diet studies.…”