Symbiotic interactions challenged by environmental stress in aquatic transitional habitats

Abstract

Estuaries present transitional habitats between freshwater and marine ecosystems. They are known for their changing abiotic conditions, influenced by daily and seasonal changes in sea levels, changes in temperature, and river influx. Estuaries are also significantly impacted by climate change, which affects them through changes of sea levels, water temperature, salinity and acidity. These changes will increase the environmental stress experienced by aquatic organisms and their symbiotic communities, which include bacteria and metazoan parasites, and influence their symbiotic relationships. The impact of climate change and environmental stress on aquatic estuarine organisms is underexplored on the level of symbiotic communities. This project is focused on understanding the effects of global climate change on these communities. We will research the diversity present in fish-parasite-microbiome communities on the east coast of the United States of America using the Atlantic mummichog (Fundulus heteroclitus) as a fish host model species; identify mechanisms of stress response to salinity change in fish ectoparasites; describe the genomic landscape of salinity tolerance in a symbiont community; and model the possible direction of change in a symbiont community under the influence of climate change. The project started with the research of ectoparasites of estuarine fishes from South Carolina. Species of Anchoa, Fundulus, Gambusia, Gobiosoma, Menidia and Mugil (n=11) were screened for the presence of ectoparasites. In total, 15 species belonging to different lineages of monopisthocotylan flatworms (Gyrodactylus, Ligophorus, Salsuginus), polyopisthocotylan flatworms (Metamicrocotyla) and copepods (Bomolochus, Caligus, Ergasilus, Naobranchia). From all screened hosts species Ligophorus have the highest mean intensity and prevalence. Furthermore, M. cephalus harbors the highest parasite species richness (seven). Some of the parasites identified present new records for the study area. These parasites show strong patterns of host-specificity and can be found in different habitats within the estuary, such as creeks, small lakes and water reservoirs.