Intersexuality in benthic harpacticoid copepods in the Firth of Forth, Scotland

Abstract

Following the discovery of a high frequency of intersexuality in Paramphiascella hyperborea in the vicinity of Edinburgh's long-sea sewage outfall, the seabed off the Edinburgh coast was surveyed in spring and autumn to examine the distribution of intersexuality in relation to the sewage outfall. From these and previously collected samples it was found that intersexuality was common in both P. hyperborea and Stenhelia gibba and also present in two species of Halectinosoma. Intersexuality was widespread along the Edinburgh coastline, being recorded up to 10 km from the discharge but there was no evidence for a correlation between intersex frequency and proximity to the discharge. Possible reasons for the high level on intersexuality in the Firth of Forth are discussed. Most intersexes displayed similar secondary sexual characters, with the sexually dimorphic prosome appendages taking the female form, the 5th leg intermediate between male and female and the 6th leg and urosome segmentation male in character.