Longitudinal Population-Level Shifts in Infectious Disease-Specific Health Literacy During and After the COVID-19 Pandemic in Zhejiang, China: Six-Round Cross-Sectional Study.

Threats to populations of bivalve molluscs (Mollusca, Bivalvia) have been observed worldwide for a long time. Molluscs account for 42% of species that have gone extinct since 1500, including 31 species of bivalves. As of 2015, 44% of freshwater bivalve species were classified as endangered or near-endangered [, ]. In Europe, three species of bivalves are critically endangered (CR: river pearl mussel and ), two species are endangered (EN: and ), and four species are vulnerable (VU: and ) (according to the IUCN Red List) []. is distributed across Europe and Western and Northern Asia and was a common inhabitant of rivers and streams until the end of the nineteenth century. In the second half of the twentieth century, however, its range in Central Europe contracted by about 50%. The main drivers of this decline were industrial development, river canalisation and increasing water pollution [, ], together with changes in the composition of the fish community that reduced the availability of the host fish on which the glochidial larvae depend for metamorphosis []. In addition, the introduction of muskrat () in Europe has had a negative impact on local populations of , as this rodent, despite its predominantly plant-based diet, actively consumes bivalves []. It is believed that viable populations have survived in Eastern European river systems. However, complete information is not yet available, as the species is not subject to regular monitoring observations here. Significant declines in thick-shelled river mussel () populations were observed in many European countries in the 1980s. In 2014, the species was included in the IUCN Red List as Endangered (EN) and the European Red List (Vulnerable), but the degree of its threat varies in different parts of Europe and depends on the country [, ]. The species is also included in Resolution 6 of the Bern Convention and the Red Data Book of Ukraine (2021 edition).