Exploring the Variety of Parasites and Genes in Big-Scale Sand Smelt Fish

Jenn Hoskins
7th March, 2024

Exploring the Variety of Parasites and Genes in Big-Scale Sand Smelt Fish

Image Source: Natural Science News, 2024

Key Findings

  • In Ukraine, sand smelt fish have fewer parasites in new river habitats than in their native Black Sea
  • The fish's parasite types are influenced by environmental factors like water type and prey
  • Genetic tests show the fish maintain connections between sea and river populations
The National Academy of Science of Ukraine has conducted a study[1] on the big-scale sand smelt, an amphidromous fish that migrates between the sea and freshwater to complete its lifecycle. This study aimed to understand how the expansion of this fish species into new areas affects its relationship with parasites, which can be crucial for the health of fish populations and ecosystems. The big-scale sand smelt is native to the Black Sea but has expanded into the Lower and Middle River Dnipro. The researchers compared the parasite fauna of the fish in its natural habitat in the northwestern Black Sea with those in the expansion range within the river. They discovered that the fish in their original habitat had a more diverse array of parasites than those in the newly colonized river environment. This finding suggests that the fish's expansion into new territories has impacted its parasite community. To explore this phenomenon further, the team used microsatellite analysis, a genetic fingerprinting technique, to compare the genetic makeup of the fish populations from different locations. Interestingly, while the parasite communities varied, only the fish from the Danube Delta showed significant genetic differences from other populations. One of the key findings was that environmental factors like habitat type, water salinity, and prey composition seem to be the primary influences on the parasite community composition in the big-scale sand smelt. For instance, the Gulf of Odesa had a unique parasite community, and the Dnipro Reservoir had no parasites at all, indicating that the newest and most distant expansion locality might be less suitable for the parasites known to infect this fish species. The study also found evidence of connectivity between populations in the River Dnipro reservoirs and native marine populations. This was shown by the presence of marine parasites, such as Telosentis exiguus, in freshwater reservoirs and freshwater parasites in marine habitats. This finding supports the amphidromous nature of the big-scale sand smelt, as it indicates that these fish can move and adapt to different environments while maintaining some level of genetic connectivity. The research builds upon earlier studies that have identified and characterized parasites in related fish species and environments. For example, a new parasite species, Gyrodactylus ginestrae, was recently discovered in the big-scale sand smelt from the Black Sea[2]. This discovery expanded our knowledge of the parasites that can affect this fish host and provided molecular data that can be used for further comparative studies. Additionally, the study of Timoniella spp. flukes in the Black and Baltic seas[3] helped clarify the taxonomy of these parasites and suggested historical connections between different sea populations. This background is invaluable for understanding how parasite communities might shift as their hosts expand into new areas. The insights from this study have implications for the field of invasion genetics, which investigates the genetic changes in species that colonize new areas[4]. Understanding how genetic variation and environmental factors influence the success of invasive species can inform conservation strategies and predict how species might respond to changing environments. In conclusion, the National Academy of Science of Ukraine's research sheds light on the complex interplay between genetics, environment, and parasite communities in the big-scale sand smelt. It underscores the importance of considering multiple factors when studying the ecological impacts of species expansion and provides a foundation for future research on the evolutionary dynamics of host-parasite relationships in changing habitats.

GeneticsEcologyMarine Biology


Main Study

1) Parasite and genetic diversity of big-scale sand smelt (Atherina boyeri Risso, 1810) populations in their natural and expansion ranges in Ukraine.

Published 6th March, 2024


Related Studies

2) Gyrodactylus ginestrae n. sp. (Monogenea: Gyrodactylidae), a parasite of the big-scale sand smelt, Atherina boyeri Risso, 1810 (Actinopterygii: Atherinidae) from the Black Sea.


3) The taxonomic and phylogenetic status of digeneans from the genus Timoniella (Digenea: Cryptogonimidae) in the Black and Baltic seas.


4) What we still don't know about invasion genetics.


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