Size bias in the documentation of marine biodiversity

Biodiversity is one of nature’s most precious elements but our exploration of this diversity is still far from complete. There is a huge gap between the known species and unknown species. Biases are occurring in these taxonomic descriptions, favouring the larger, more easily seen and common species, leading to a skewed representation of ecological diversity, especially in the marine ecosystem where the diversity of deep-sea organisms and small invertebrates remain underexplored. This not only affects our understanding of ecosystems, but also poses challenges for biodiversity conservation.

A recent study analysed data from more than 62,000 marine animals from nine phyla and revealed a striking phenomenon: there is a significant negative correlation between the size of a species and the time of its formal description. Specifically, smaller species tend to be described and classified later. This pattern is prevalent across different groups and habitats, and shows fluctuations in time, especially at key points in historical events and technological advances. The findings have important implications for ecological understanding and conservation efforts. First, it highlights the importance of completing an inventory of marine biodiversity, especially of species that are smaller and potentially threatened. Second, it reminds us that understudied species, especially small ones, should not be overlooked in biodiversity conservation efforts. By strengthening research on small species, we can more fully understand the complexity of marine ecosystems and provide a more scientific basis for biodiversity conservation.

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