Distribution and nutrient limitation of surfgrass, Phyllospadix scouleri and Phyllospadix torreyi, along the Pacific coast of Baja California (México)

Three field surveys and an extensive review of surfgrass (Phyllospadix) specimens from herbarium collections in USA and Mexico were performed to delimit the geographical distribution of Phyllospadix scouleri and Phyllospadix torreyi along the coasts of Baja California (Mexico) which showed that both species had the same distribution in the peninsula with a southern limit at 24°31′ N. Cover estimates along three to eight transects laid in the lower intertidal and upper subtidal of three locations in Baja California indicated that P. scouleri occurs shallower than P. torreyi when coexisting. A preliminary, short-term experimental increase of nutrient availability in the water column at one of the study sites suggested that the biomass and growth rates of P. torreyi were more limited by the availability of nutrients than those of P. scouleri.