The USGS Comprehensive Sturgeon Research Project is a multi-year, interdisciplinary research study to determine factors leading to spawning and survival of the endangered pallid sturgeon and the closely related shovelnose sturgeon.
Sediment Burial Reduces Sturgeon Embryo Survival and Hatch
January 15, 2023
Researchers from the U.S. Geological Survey, Columbia Environmental Research Center (CERC) recently published the scientific article, “Effects of Substrate and Sediment Burial on Survival of Developing Pallid Sturgeon (Scaphirhynchus albus) and Shovelnose Sturgeon (S. platorynchus) Embryos” in the journal, Environmental Biology of Fishes. The endangered pallid sturgeon and common shovelnose sturgeon both spawn in flowing water, depositing their adhesive eggs on the river bottom, near or over coarse substrate (typically gravel and cobbles). Surveys have shown that the habitats where sturgeon spawn in the Missouri and Yellowstone Rivers are dynamic and that coarse substrates in these areas may be episodically buried by finer, mobile sediments, such as sand and silt (see previous blog, USGS Scientists Assess Pallid Sturgeon Spawning Habitat). Fine sediment can dislodge adhesive eggs of riverine species or bury them and deprive them of oxygen during incubation.
In this controlled laboratory study, researchers evaluated the survival of both pallid sturgeon and shovelnose sturgeon embryos (fertilized eggs) in various substrate conditions designed to simulate possible fates in a sand-bedded river. Newly fertilized embryos were allowed to develop on substrates of clean glass (control), gravel, medium-coarse sand, or fine sand-silt in aquaria for 10 days (5 days beyond expected onset of hatching). Embryos in aquaria with medium-coarse sand and fine sand-silt were tested with three different burial scenarios; unburied, partially buried, and fully buried. Embryos in partial burial treatments were uniformly covered by sediment without being fully buried. Embryos in the full burial treatments were completely covered to a depth of approximately 1–2 mm. For both species, hatch of normally developed free embryos was significantly reduced by burial in fine sediments. Results from this study indicate that these sturgeon species are intolerant of burial by even small amounts of mobile, fine sediment. Suitability of spawning and incubation habitats for endangered pallid sturgeon and shovelnose sturgeon may be dependent on river conditions that result in persistent patches of clean, coarse substrate.