What little we still know about our oceans! And this study seems to have focused primarily on small fish (what about bigger fish?).
This is one reason among others whey global warming/climate change is a hoax!
"... The problem with current mapping projects, which aim to chart where species live and the conditions they need to survive, is that they are based on limited information. Traditional methods such as nets and underwater cameras primarily target easy-to-reach areas and often miss small, elusive species. This means our picture of ocean biodiversity is far from complete. ...
To fill these knowledge gaps, research ... used a powerful technique called Environmental DNA (eDNA). This approach can detect multiple species and identify their ranges without capturing or photographing them.
The research team collected nearly 1,000 water samples from 542 locations worldwide, including polar regions and tropical islands. They then analyzed the fish DNA in those samples and compared it with occurrence databases, such as the Global Biodiversity Information Facility (GBIF).
These new eDNA surveys reveal just how incomplete our records are. According to results published by the team in PLOS Biology, 93% of geographic ranges were underestimated. This means species were living far outside the areas where they were historically mapped. For example, the crocodile icefish, which was previously known only to live in the freezing conditions of the Antarctic region, was detected in Patagonia (southern South America).
Additionally, 7% of species' ecological niches were also underestimated, meaning they were found to tolerate environmental conditions that were previously thought impossible for them to live. ...
The clear implication of these findings is that current mapping methods need to be updated, as they leave vast blind spots. ..."
From the abstract:
"Assessing species geographic distributions is critical to approximate their ecological niches, understand how global change may reshape their occurrence patterns, and predict their extinction risks. Yet, species records are over-aggregated across taxonomic, geographic, environmental, and anthropogenic dimensions.
The under-sampling of remote locations biases the quantification of species geographic distributions and ecological niche for most species.
Here, we used nearly one thousand environmental DNA (eDNA) samples across the world’s oceans, including polar regions and tropical remote islands, to determine the extent to which the geographic and ecological niche ranges of marine fishes are underestimated through the lens of global occurrence records based on conventional surveys.
Our eDNA surveys revealed that the known geographic ranges for 93% of species and the ecological niche ranges for 7% of species were underestimated, and contributed to filling them.
We show that the probability to detect a range filling for a given species is primarily shaped by the GBIF/OBIS sampling effort in a cell, but also by the number of occurrences available for the species. Most gap fillings were achieved by addressing a methodological sampling bias, notably when eDNA facilitated the detection of small fishes in previously sampled locations using conventional methods.
Using a machine learning model, we found that a local effort of 10 eDNA samples would detect 24 additional fish species on average and a maximum of 98 species in previously unsampled tropical areas. Yet, a null model revealed that only half of ecological niche range fillings would be due to eDNA surveys, beyond a random allocation of classical sampling effort. Altogether, our results suggest that sampling in remote areas and performing eDNA surveys in over-sampled areas may both increase fish ecological niche ranges toward unexpected values with consequences in biodiversity modeling, management, and conservation."
eDNA surveys substantially expand known geographic and ecological niche boundaries of marine fishes (open access)
Fig 1. Map of both GBIF/OBIS and eDNA surveys, and the distribution of their associated environmental and anthropogenic variables.
Fig 2. Map of the predicted number of fish species gained in a cell if 10 eDNA samples were added to GBIF/OBIS sampling records, if any.
