Save it to cherish or leave it to perish

As the saying goes, “Save it to cherish or leave it to perish”

If each scientist could keep track of one species, we would need 81 thousand scientists just for molluscs alone (that is more than double the size of the population of Monaco). One way to study diversity and to validate specimens collected is via modern DNA analyses. Every organism that belongs to the same species shares a number of genetic traits in their DNA that are unique from all other species. By comparing the DNA of known representatives of a species we can determine the status of undefined specimens based on these similarities. This can help, especially when morphological or anatomical characters are less informative or confusing to the eye.

DNA extraction at Justus Liebig University, Giessen.

Today ecologists and conservationists are beginning to recognise the importance of this tool, most especially in invertebrates (those small little guys at the bottom of the food chain nobody really cares about), which have seen far less historical interest compared to large mammals or birds. However, invertebrates provide an immense array of ecological services; bees pollinate (a service predicted to be worth 153 billion Euros a year), woodlice help process decaying matter, earthworms aerate soil (increasing its fertility), and aquatic snails, like the genus Theodoxus, help control harmful algae and provide a useful food source for many fish species. And while we notice the decline of the sturgeon or the wild salmon, we often fail to think about what is happening to their food.

A Theodoxus sp. from the Balkans foraging on algae.                                                          

Theodoxus species are small aquatic snails, traditionally common in fresh and brackish water ecosystems from Western Europe to the Near East, where they provide a valuable contribution to ecosystems. However, scientific reports are becoming rifer, suggesting their absence in once abundant areas and even showing localised extinctions in some places. Importantly, if fish can’t eat or waters get overgrown with algae or plants, then the fish die, and who knows what that would mean for us as humans. Conservation in Europe and the Near East remains challenging, let alone for snails. Pressure for land resources, agriculture and housing mean conservation efforts in this part of the world need to have robust strategies and conserve the most diversity in the least amount of space.

Various shell patterns of different Theodoxus spp.

Probably the most striking feature of Theodoxus is their intriguing shell. The range in patterns, shapes and colours have lead naturalist, even as famous as Lamarck, to describe species of Theodoxus. Unfortunately recent studies suggest shell patterns may be poor characters for distinguishing Theodoxus species as, even within species, there is a lot of variation. Basing a conservation strategy or a management plan simply on morphology, without the aid of a genetic perspective, may thus be poor for conserving diversity of this primary, but very important, group. As part of the EU project PRIDE program (European Union Horizon 2020 Innovative Training Network), in the Institute for Animal Ecology and Systematics at Justus Liebig University, Giessen, Germany, the questions are being investigated. By undertaking a broad scale genetic study, the diversity we have left in the genus is being unearthed, areas where multiple species of Theodoxus may be present are being identified and regions where species may have retreated to in the past are being discovered.

Collecting Theodoxus for DNA analyses in the Limans of Ukraine

The question still remains though, “why care about conserving the diversity rather than conserving the areas where the highest biomass occurs?”. The answer is quite a simple one; different species or even different genetic lineages have different characteristics. For example, one species may be able to process higher amounts of harmful algae than others, while another species may be able to handle a greater range in water temperatures (allowing it to survive in harsher environments), a third may be able to reproduce faster and be a better food source for fish. Unfortunately at this stage we just not that sure what is what, and till we know the potentials of each species it is important we conserve as much diversity as possible.

Stephan Covey once said about human ethnicity, “Strength lies not in our similarities, but in our differences.” This is no truer for humans as it is for nature in general and Theodoxus in particular.        

  • By: Arthur Sands   
  • PRIDE early stage researcher at the Justus Liebig University, Germany
  • Office: +49 6419935721
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