Even though up to 40% of species are parasitic, we know much less about the diversity of parasites than we do about their free-living counterparts. Most studies describe and monitor parasite diversity through surveys: hosts are collected and sampled for their parasites. However, surveys represent snapshots in time and cannot provide information on past communities. To gain insight on long-term diversity patterns, we can turn to fluid-preserved host specimens, which preserve parasite tissues alongside host tissues. We described temporal patterns of alpha and beta diversity of the parasite communities from fluid-preserved English sole (Parophrys vetulus) from Puget Sound (Washington, USA). As this area has experienced several anthropogenic pressures (e.g., pollution and fishing) over the past century, these temporal trends can reveal much about community level responses to stressors. We were thus able to answer three key questions: 1) What parasite species are present in English sole in this ecosystem? 2) Has parasite diversity in this host changed over the past nine decades? 3) How have community composition and community heterogeneity varied over time?
Results/Conclusions
We found that while parasite species richness remained consistent over time, community composition did not. Species composition varied across time, with both balanced variation (the substitution of individuals of one species with individuals of another species between sites) and unidirectional gradients (when individuals are lost between sites without replacement) contributing to the observed change. This knowledge can serve as a baseline for future comparisons as environmental change continues. Our research highlights the importance of using multiple measures of diversity to monitor and describe changes in communities over time, as species richness alone did not capture the community changes. To better understand the mechanisms that are driving changes in species richness and composition, our next line of inquiry will examine how diversity changed with host fish abundance and in response to environmental factors.