The costs of sex in seaweeds

The brown seaweeds (Fucales) include dioecious and hermaphrodite species and genera with one, two, tour or eight eggs per oogonium. The costs of gamete production, measured as biomass, are very small. Eggs represent only 0.1–0.4% of body weight. Females of dioecious species do not produce more eggs per gramme of tissue than hermaphrodites. Hermaphrodites occupy upper shore zones and dioecious species the biotically richer submerged zones. Neither egg size nor number correlate with habitat or sexuality. Some of these observations are hard to reconcile with theoretical concepts of the costs of sex.