The Macapule Lagoon (25º 21' and 25º 24' N; 108º 30' and 108º 45' W) is part of the San Ignacio-Navachiste-Macapule lagoon system, located in the southern region of the Gulf of California (Fig. 1). In 2000, it has been declared an "Area of Reserve and Refuge for Migratory Birds and Wildlife – Gulf of California Islands". This lagoon is very productive due to its location in the Gulf of California (Lluch-Cota et al. 2007). Water temperature, dissolved oxygen, pH, and salinity were measured in situ with an YSI (55-12FT) probe and a portable refractometer (RHS-10ATC). Nutrient (nitrate, ammonium, and phosphate) concentrations were determined in the laboratory during each sampling month using a photometer (YSI, 9500).