Marine Parasites and Disease in the Era of Global Climate Change

Abstract

Climate change affects ecological processes and interactions, including parasitism. Because parasites are natural components of ecological systems, as well as agents of outbreak and disease-induced mortality, it is important to summarize current knowledge of the sensitivity of parasites to climate and identify how to better predict their responses to it. This need is particularly great in marine systems, where the responses of parasites to climate variables are less well studied than those in other biomes. As examples of climate's influence on parasitism increase, they enable generalizations of expected responses as well as insight into useful study approaches, such as thermal performance curves that compare the vital rates of hosts and parasites when exposed to several temperatures across a gradient. For parasites not killed by rising temperatures, some simple physiological rules, including the tendency of temperature to increase the metabolism of ectotherms and increase oxygen stress on hosts, suggest that parasites’ intensity and pathologies might increase. In addition to temperature, climate-induced changes in dissolved oxygen, ocean acidity, salinity, and host and parasite distributions also affect parasitism and disease, but these factors are much less studied. Finally, because parasites are constituents of ecological communities, we must consider indirect and secondary effects stemming from climate-induced changes in host–parasite interactions, which may not be evident if these interactions are studied in isolation. Expected final online publication date for the Annual Review of Marine Science, Volume 13 is January 3, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Tilapia Farming in Bangladesh: Adaptation to Climate Change

“…Climate change may affect water quality and disrupt host-pathogen interactions [144], sometimes creating beneficial conditions for pathogen amplification and spread [144][145][146], or for microbial and ecological dysbiosis [147]. Water quality disruptions stemming from climate change that may have consequences for the outbreak of marine parasites and diseases include changes in temperature, hypoxia, CO 2 accumulation (reduced pH), precipitation (leading to increased or decreased salinity), and cyclone frequencies and intensities [144,148]. Changes in water quality may result in immediate impacts on host-pathogen equilibriums or long-term impacts such as the expansion of hosts (primary and secondary) and pathogens into new regions [149].…”

Mediterranean Aquaculture in a Changing Climate: Temperature Effects on Pathogens and Diseases of Three Farmed Fish Species

“…Ecological models that predict climate change effects on parasitic interactions must consider the influence of temperature on multiple variables. The overlapping of parasite and host thermal preference curves (TPCs), the prevalence, intensity and mode of transmission, and the availability, abundance and distribution of the hosts are all factors that can be positively or negatively affected by temperature [ 315 , 320 ]. Even though each case should be examined independently, it seems that whenever the increase of temperature does not exceed the tolerance limit of the parasite or of the host, the intensity of parasitism and its transmission are commonly favoured ( Table 4 ).…”

The Importance of Marine Bivalves in Invasive Host–Parasite Introductions

“…For example, the protistan oyster pathogen Perkinsus marinus first expanded northwards in the United States in the early 1990s and was well established in the new range by 1996-97, suggesting that range expansion had not limited its prevalence, infection capacity or proliferation (Ford and Smolowitz, 2001). Although rising temperatures are posited to be favourable to parasites, it is important to note that parasites with complex life-cycles may be adversely affected, as if secondary or definitive hosts breach their environmental thresholds for survival and undergo mortality events this will in turn negatively affect parasite abundance (Byers, 2020).…”