Sobre a invasão de parasitas de peixes em ambientes de água doce: desenovelando eventos de spillback e spillover.

Abstract

Free-living invasive species are frequently considered in ecological studies, while parasitic invaders are neglected. Given the current concerns regarding emerging diseases, parasites circulating in wildlife communities have demonstrated their significant impact on the environment and public health. In this context, this study aims to conduct a systematic review in order to identify the focal areas of parasite invasions in freshwater fish worldwide and the characteristics of hosts and parasites associated with these invasion events. Searches were conducted in Web of Science and Scopus, yielding 16,121 studies, of which 233 published between 1974 and 2021 were eligible according to pre-established criteria, with 834 invasion records. There was no trend regarding increase or decrease in studies on this subject when controlled for academic production growth. The main groups of recorded parasites were Platyhelminthes, Nematoda, and Arthropoda, mostly endoparasites, generalists, and with heteroxenous life cycles. Spillover events were found to be more prevalent compared to spillback across all continents. The North American and European regions exhibited greater abundance of invasion records, which can be attributed to higher sampling efforts in these areas. Regarding the introduction routes of parasites in the analyzed studies, pisciculture, followed by aquarism and ballast water, were identified as the main pathways. However, a considerable number of studies did not report the invasion route or lacked knowledge regarding it. The processes related to spillover and spillback are complex, and the higher frequency of spillover events seems to be due to the perception that invasive parasites infecting native species are more severe than native parasites infecting invasive species. Most of spillover events are associated to parasites indigenous to Asia, where is the global focus of fishing trade. These findings highlight the importance of considering parasitic invaders in ecological studies, and the potential association of commercial routes to the invasion events registered herein.