Data from: Geographic variation of parasitic and predatory traces on mollusks in the northern Adriatic Sea, Italy: implications for the stratigraphic paleobiology of biotic interactions

Parasitic trematode worms leave characteristic pits in their bivalve
mollusk hosts and represent an ideal system for analyzing parasite-host
interactions through space and time with statistically meaningful sample
sizes. Previous work in Late Pleistocene–Holocene sequences from the Po
plain revealed significant long-term fluctuations in trematode prevalence
values: higher prevalence in retrogradational environments (TST) and
negligible prevalence in progradational environments (HST). Here we expand
upon this work by investigating traces of parasitism, kleptoparasitism,
and predation on mollusk death assemblages from two domains along the
northern Adriatic coastline. The domain north of the Po delta (TST-like)
and the southern domain (including the Po delta; HST-like) comprise
environments comparable to those recovered in late Holocene (<6
Kyr) subsurface progradational deposits. We collected 17,299 specimens
representing 111 species from 11 locations on the northern Adriatic coast
of Italy. Our results reveal high predation pressure, a high diversity of
host taxa, and widespread presence of trematode infestation in starved,
oligotrophic, environmentally more stable (i.e., TST-like) settings north
of the Po delta. Immediately south of the Po delta, in settings with
strong and variable sedimentary input, almost no infestation is recorded.
The reappearance of infestation is evident in the southern portion of the
study area (i.e., Cattolica-Montemarciano), relatively far from the highly
stressed environments south of the Po River. There is no significant
difference in trematode prevalence values between fossil and modern
samples. The distribution of spionid traces (an indicator of stressed
environments) was nearly the opposite of that displayed by trematodes.
Drilling frequency is highest in TST-like environments and is not
correlated with diversity indices. These results suggest that temporal
trends of trematode prevalence (and possibly also other biotic
interactions) in sedimentary successions are controlled by environmental
changes driven by glacio-eustatic dynamics, and reaffirm the importance of
interpreting temporal trends in the context of spatial variation.