Temporal changes in the biomass and distribution of Sargassum beds along the southeastern coast of the Baja California Peninsula

Abstract

Changes in the distribution, surface canopy, biomass, and standing crop of Sargassum beds (Phaeophyceae) along the southeastern coast of the Baja California Peninsula (Mexico) are described and compared with previous estimates. Also, Sargassum biomass was correlated with latitude. Species were identified and surface canopy, biomass, standing crop, and length structure were estimated for 72 Sargassum beds in 3 localities in 2006. The extent of each bed was determined using GPS. The perimeter of each bed was drawn and its canopy area was calculated. The average biomass was estimated, using quadrats that were randomly distributed over the beds. The highest average biomass was found at Mulegé, with significant differences in the other 2 study areas (Concepción and La Paz bays). The largest bed, surface canopy area, and standing crop were recorded in Concepción Bay. Coverage area, location, and seasonal changes in surface canopy, standing crop, and biomass of Sargassum beds along the southeastern coast of the Baja California Peninsula were compared with the different phenological stages of Sargassum thalli, variations in the available rocky sea floor, and oceanographic characteristics. These aspects must be considered to maintain sustainable exploitation of this potential resource.