El género Porphyra (Bangiaceae, Rhodophyta) en la costa Pacífico de México. III. Porphyra gardneri (G. M. Smith et Hollenberg) Hawkes

The occurrence and seasonality of Porphyra gardneri (G. M. Smith et Hollenberg) Hawkes (Bangiaceae,Rhodophyta) is recorded for the Pacific coast of México on the basis of field trips to the western coast of Baja California, conducted in 1992, 1995, 2001, 2002, 2003. Specimens previously deposited in various herbaria were also examined. Populations from Islas de Todos Santos, Caminitos and La Bufadora, are new records of P. gardneri from western Baja California and they represent the southern limit of this species along the Pacific coast of North America. The small size, low frequency and epiphytic character of P. gardneri could be the reasons for its poor presence in floristic studies previously done in Baja California. We describe in detail the vegetative and reproductive structures on the thallus as well as the habitat and geographic distribution of the species.Se registra la presencia y estacionalidad de Porphyra gardneri (G. M. Smith et Hollenberg) Hawkes(Bangiaceae, Rhodophyta) para la costa del Pacífico de México, con base en material recolectado en la costa occidental de Baja California, durante 1992, 1995, 2001, 2002 y 2003; además de ejemplares depositados en herbarios. Las poblaciones localizadas en las Islas de Todos Santos, Caminitos y La Bufadora, representan poblaciones nuevas de P. gardneri para la costa occidental de Baja California y además, definen el límite sur de ésta especie en el Pacífico de Norteamérica. La escasa presencia, tamaño y carácter epifítico de las plantas de P. gardneri, probablemente sean las causas del porque no se haya registrado con una mayor frecuencia, ya que la mayoría de los especímenes recolectados consisten de talos pequeños. Se describen en detalle los caracteres morfo-anatómicos y estructuras reproductoras de los talos; así como su hábitat y distribución geográfica de la especie

Growth, nutrient uptake and proximate composition of Rhodomonas sp. cultured using f/2 medium and agricultural fertilizers

We determined the growth, nutrient (PO43–, NO3–, NH4+) uptake and proximate composition of Rhodomonas sp. cultured during seven days in batch culture using f/2 medium and agricultural fertilizers. The growth rate was similar with both media (µ = 0.37 and 0.38 day–1). Protein content in Rhodomonas sp. cultured with f/2 medium was higher than with agricultural fertilizers (10.7 and 8.96 pg cell–1, respectively). Carbohydrate and lipid contents decreased during the exponential growth phase and there were no significant differences (P = 0.027 and 0.08, respectively) between both experiments. Carbohydrate content was higher during the slow growth phase in cultures using f/2 medium, whereas lipid content showed little variation during the slow growth phase, but was higher in cells cultured using agricultural fertilizers. During the first five days, total phosphate uptake by Rhodomonas sp. was 39.9 µM (94.3%) in the f/2 medium and 40 µM (99%) in the agricultural fertilizer medium. A total of 667.3 µM of nitrate (72.2%) was consumed during the first four days in the f/2 medium, whereas in the agricultural fertilizer medium formulated with ammonium nitrate, ammonium uptake (418.1 µM, 78.7%) in the first three days was higher than nitrate uptake (37.7 µM, 7.3%); however, when ammonium concentration decreased to 1.83 µM, the nitrate uptake increased. In conclusion, the cellular quantity and quality of Rhodomonas sp. was similar when both media were used and agricultural fertilizers can be used in marine aquaculture programs