Mechanisms by Which Marine Algae Respond to Environmental Variables Affecting Reproductive Success

Many marine species reproduce by external fertilization. This mode of reproduction might be expected to result in low levels of fertilization and recruitment because of the dilution of eggs and sperm by the turbulent sea. Recent work, however, demonstrates that fucoid algae (i.e., brown seaweed\u27s that are important components of rocky, intertidal zones and estuaries) sense water motion and release eggs and sperm only when the sea is calm. Nearly 100% of their eggs are fertilized. The proposed experiments will determine how these algae sense water motion and whether similar responses are found in several other species that are harvested commercially or are important nuisance species. Studies of the reproductive tissues with electron microscopic and physiological techniques will establish the basis of the mechanical forces that expel eggs and sperm from adults and how these are blocked by high water motion. Field studies of natural communities in New England estuaries will complement the laboratory work. These studies will advance understanding of the mechanisms by which marine algae respond to environmental variables that affect reproductive success. This information should be useful to basic scientists, marine engineers, coastal zone managers, and mariculturists