摘要：The imperiled pallid sturgeon (Scaphirhynchus albus) and closely
related, but more common, shovelnose sturgeon (S. platorynchus)
are believed to broadcast adhesive, demersal eggs in the current
and over coarse substrate in turbid rivers of the North American
midcontinent. It has been hypothesized that eggs settle immediately
following fertilization, but field conditions preclude direct
observation. We conducted laboratory studies to characterize the
diameter, shape, settling velocity, and specific gravity of pallid
sturgeon and shovelnose sturgeon eggs. Based on these laboratory
measurements, we then modeled the potential fate of pallid
sturgeon eggs by considering these physical properties in the
context of two field sites where spawning has occurred. Although
eggs of pallid sturgeon and shovelnose sturgeon were of a similar
size and shape, shovelnose sturgeon eggs had slightly higher specific
gravity and settling velocity. For representative hydraulic conditions
at documented spawning sites in the mainstem Missouri
and Lower Yellowstone Rivers, eggs of both species will likely be
concentrated near the bed although some eggs may be distributed
throughout the water column. Simulations of egg transport
indicate that eggs may be transported up to several hundred
meters downstream from spawning locations in the approximate
length of time required for eggs to become adhesive. Estimates
of egg transport presented here rely on simplifying assumptions
about river hydraulics and limited understanding of how eggs
interact with the complex substrates and flow near the bed;
results highlight the need for additional studies to evaluate the
fate of eggs and fertilized embryos of both species.
关键词：Sturgeon ; pallid sturgeon ; egg characteristics ; egg specific gravity ; egg transport ; egg dispersal ; spawning habitat
