Marine organisms represent an enormous resource of natural products. In particular, marine algae are one of the most important producers of biomass in the marine environment. They include a wide variety of plants that range from diatoms, which are microscopic, unicellular organisms, to seaweeds extending over 30 m. Therefore, two major types of algae can be identied: macroalgae (seaweeds) and microalgae. Microalgae are found in both benthic and littoral habitats and also throughout the ocean waters as phytoplankton (Garson 1989). Phytoplankton comprises organisms such as diatoms (Bacillariophyta), dinoagellates (Dinophyta), green and yellow-brown agellates (Chlorophyta, Prasinophyta, Prymnesiophyta, Cryptophyta, Chrysophyta, and Rhaphidiophyta), and blue-green algae (Cyanophyta). As photosynthetic organisms, this group plays a key role in the productivity of oceans and constitutes the basis of the marine food chain (Bold and Wynne 1985). Meanwhile, the macroalgae (seaweeds) are classied as green algae (division Chlorophyta), red algae (division Rhodophyta), and brown algae (division Phaeophyta). Seaweeds are widely distributed in the ocean, occurring from the tide level to considerable depths, free-oating or anchored, and include kelp, dulse, rockweed, and sea lettuce. Many are of economic importance as food, fertilizer, agar, potash, or a source of iodine (Schaeffer and Krylov 2000). Interestingly, marine algae are considered a source of bioactive compounds as they are able to produce a great variety of secondary metabolites characterized by a broad spectrum of biological activities.