Copper reduces fertilisation success and exacerbates Allee effects in the field

Hollows, Cam F., Johnston, Emma L. and Marshall, Dustin J. (2007) Copper reduces fertilisation success and exacerbates Allee effects in the field. Marine ecology. Progress series., 333 51-60. doi:10.3354/meps333051

Author Hollows, Cam F.
Johnston, Emma L.
Marshall, Dustin J.
Title Copper reduces fertilisation success and exacerbates Allee effects in the field
Journal name Marine ecology. Progress series.   Check publisher's open access policy
ISSN 0171-8630
Publication date 2007
Sub-type Article (original research)
DOI 10.3354/meps333051
Open Access Status DOI
Volume 333
Start page 51
End page 60
Total pages 10
Editor Kinne, O.
Place of publication Oldendorf, Germany
Publisher Inter-Research
Collection year 2008
Language eng
Abstract The reproductive success of marine broadcast spawners depends on the concentration of sperm that surrounds eggs. Because sperm quickly dilute in the ocean, spawners must be sufficiently close to one another to ensure high rates of fertilisation. Thus, broadcast spawners can experience Allee effects-decreasing density can result in lower reproductive success because the costs of low fertilisation outweight any benefits of reduced intraspecific competition. Recently, there has been a dramatic increase in the number of studies examining the effects of toxicants on fertilisation success. These studies suggest that fertilisation is a highly sensitive stage and exposure to pollutants could severely reduce reproductive success in the field. However, we remain limited in our ability to predict the effects of toxicants under field conditions because most ecotoxicological studies utilise only a single sperm concentration. Moreover, all ecotoxicological studies of fertilisation to date have been limited to laboratory investigations, and it remains unclear whether the effects of a toxicant are overwhelmed in the dynamic and turbulent environment of the real world. We examined the effects of a common pollutant, copper, on the fertilisation success of the intertidal polychaete Galeolaria caespitosa in the laboratory and the field. In the laboratory, we examined the effects of copper over a range of sperm concentrations and in the field, we developed a new apparatus for examining fertilisation success in intertidal organisms. In the laboratory, copper had much stronger effects on fertilisation at low sperm concentrations than at high concentrations. We suggest that the use of single sperm concentrations in ecotoxicological. assays of fertilisation is inappropriate because the magnitude of the effect of the toxicant can be estimated incorrectly. Copper also reduced fertilisation success in the field, with eggs having to be much closer to a sperm source in order to achieve any fertilisation success in the presence of copper. For populations of marine invertebrates in which reproduction is limited by sperm availability, the presence of a toxicant has the potential to dramatically reduce fertilisation success and greatly exacerbate Allee effects.
Keyword Ecology
Marine & Freshwater Biology
fertilisation kinetics
Spawning Marine-invertebrates
Urchin Strongylocentrotus-franciscanus
Ascidian Phallusia-mammillata
Sperm Limitation
Comparative Sensitivity
External Fertilization
Sexual Conflict
Gamete Traits
Q-Index Code C1
Q-Index Status Confirmed Code

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Created: Mon, 18 Feb 2008, 16:49:25 EST