Losing threatened freshwater fishes could remove unusual ecological traits
A peer-reviewed analysis links human uses of freshwater fishes to distinctive combinations of body traits. Researchers compared thousands of species and simulated the disappearance of used species already facing conservation risks. Those losses removed more morphological diversity than random losses, highlighting how counting species alone can miss the loss of unusual feeding and movement strategies.
Science··Evening
Body traits reveal different uses
A peer-reviewed global analysis examined human uses alongside body measurements across 8,970 freshwater fish species, using 11 traits. FishMORPH, a database of fish body measurements, supplied traits such as size, eye position, mouth shape and fins; FishBase supplied use categories. The 2,334 used species represented 26 per cent of the sample and occupied 45.2 per cent of its morphological space. However, a random selection could occupy a statistically comparable total volume.[1]
Fishing and aquariums select different shapes
Different uses nevertheless selected different combinations of traits. Large fish featured disproportionately in both commercial harvests and recreational angling. Aquarium-trade species clustered around particular combinations, while aquaculture covered a wider range. Species could appear in several use categories. The measurements represent feeding and movement strategies through body form; ecological functions were not directly measured in the field.[1]
Simulated losses remove unusual combinations
Researchers simulated losses among used species facing conservation risks. They removed 396 species in the threatened and near-threatened categories. The remaining trait space contracted more than after random losses, especially when large predators and bottom-feeding sturgeons disappeared. These are simulated extinctions, without a timetable for actual losses. The global analysis can miss species distinctive within individual river basins and does not separately quantify dams, pollution or invasive species.[1]
