The global drop in biodiversity is one symptom of our current environmental crisis and a driver of conservation efforts. However, what should our starting point for biodiversity be; against which we can measure the current loss? Fifty, 500, 5000 years ago? And what about new species? In the last year alone 18,000 new species have been described (some of them are fossils!). And what about under-explored realms, such as the deep-sea? Well new research published in Frontiers in Marine Science demonstrates that our current knowledge of deep-sea life is heavily biased. This biases the species-richness of the deep-sea towards wide-ranging species that were described earlier in the exploration of the ocean depths.
Calculating global estimates for total species richness is fraught by the uncertainty in estimating the number of species left to be discovered. The deep-sea is widely regarded as one of the largest sources of uncertainty in these calculations, since so much of this realm has not yet been explored. Most estimates of species left to be discovered are reliant on previous rates of species description, yet these rates are likely to be biased. One well-known bias from terrestrial studies is that wide-ranging species tend to be described earlier..... Results show a historical bias in species descriptions, with wide-ranging species over-represented in our current catalogs of deep-sea species richness. This suggests that current estimates of deep-sea species richness underestimate the true proportion of narrow-ranged species and hence total species in the deep oceans.