Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Tyler L. Mosley; Wendell R. Haag; James A. Stoeckel
    Date: 2014
    Source: Freshwater Biology 59(10) 2137-2149
    Publication Series: Scientific Journal (JRNL)
    Station: Southern Research Station
    PDF: Download Publication  (404.25 KB)


    1. Small or sparse populations can experience Allee effects if egg fertilisation is reduced because of a shortage of sperm.
    2. Freshwater mussels are spermcasters that often occur as sparse, patchy populations. Previous studies suggested that sperm shortage limits these populations unless facultative hermaphroditism and selffertilisation occur at low density. We conducted experiments in ponds to examine fertilisation in the mussel, Lampsilis straminea, in response to flow, presence of and distance from males, male density, and the presence of upstream females that could compete for sperm with downstream females.
    3. Self-fertilisation in the absence of males did not occur in either experiment. Female fertilisation success was uniformly high in most treatments and was not related to flow or distance from males (1–25 m). Fertilisation success was significantly lower at low male density (0.02 m-2, compared with 0.16 m-2) but remained relatively high even in most low male density treatments. The proportion of females that became gravid was higher in the presence of upstream females, but fecundity was significantly lower when upstream females were present; these conflicting results made it difficult to assess the role of competition among females for sperm.
    4. Overall, high fertilisation success occurred at densities three orders of magnitude lower than previously proposed thresholds for mussels. Sperm dispersal and acquisition and egg fertilisation appear to be complex processes associated with adaptations for spermcasting. These adaptations are likely to facilitate persistence at low population density and buffer mussels from reproductive Allee effects

    Publication Notes

    • You may send email to to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Mosley, Tyler L.; Haag, Wendell R.; Stoeckel, James A. 2014. Egg fertilisation in a freshwater mussel: effects of distance, flow and male density. Freshwater Biology. 59(10): 2137-2149. 13 p. 10.1111/fwb.12417


    Google Scholar


    Allee effects, fertilisation, population density, spermcasting, unionid

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page