In following years, she received support from the National Science Foundation for field studies and laboratory experiments to find out how Fucus adapted to such different chemical conditions. Her primary concern was the mechanism which allowed Fucus to avoid polyspermy, a lethal condition in which an egg is fertilized by more than one sperm. Seaweeds normally depend on high concentrations of sodium to prevent polyspermy, but the Baltic Sea populations didn't have much sodium to work with.

Brawley worked closely on this question with researchers at the University of Stockholm and University of Ume in Sweden. During her work, she also noticed that Fucus vesiculosis didn't release its gametes until slack high tide. She suspected that the plants were responding to water motion and, perhaps, to accompanying changes in salinity.

Back at the University of Maine in Orono, Brawley worked with Gareth Pearson, a post-doctoral researcher, and Esther Serrao, a graduate student, to study this possibility in earnest. They used Baltic specimens Brawley had brought from Scandinavia, and they collected plants from tide pools along the Maine coast. They also received plants from researchers in California.

"We were able to simulate in the laboratory that high salinity is one of the cues for the release of gametes, and all of that was done under calm conditions," says Brawley. "In the back of my mind, I kept thinking about the affect of water motion. Nearly every introductory biology book you read will have some statement that organisms that use external fertilization have to release lots and lots of gametes because fertilization success is low.

"Now with five different fucoid algae in California, the Baltic and here
'"/>

Contact: Nick Houtman
nick.houtman@umaine.edu
207-581-3777
University of Maine
17-Feb-1998