Nuevos registros de Acetabularia schenckii y Acetabularia farlowii (Chlorophyta) para la costa del Pacífico de México

The occurrence of Acetabularia schenckii Möbius (Polyphysaceae, Chlorophyta) is reported for the first time in the Mexican Pacific coast, out of its common distribution range along the Atlantic coast (Caribbean and Gulf of Mexico). Likewise, new distribution localities are reported for Acetabularia farlowii Solms-Laubach in the Mexican Pacific coast. Specimens were sampled from the intertidal zone to the 2 m depth in coastal lagoons from Sinaloa State, Mexico, during 2004 and 2005. A revision of specimens deposited in herbaria was carried out to determinate the geographic distribution of both species in the Mexican Pacific coast. The scarce records of Acetabularia could be related with inaccurate identifications, the small sizes of these species and to the lack of floristic studies in the study area.Se reporta la presencia de Acetabularia schenckii Möbius (Polyphysaceae, Chlorophyta) para la costa Pacífico de México, siendo éste es el primer registro fuera de su área de distribución en la costa del Atlántico (Caribe y Golfo de México). Así mismo, se reportan nuevas localidades de distribución para Acetabularia farlowii Solms-Laubach en la costa Pacífico de México. Los ejemplares fueron recolectados desde la zona intermareal hasta los 2 m de profundidad en las Lagunas costeras de Sinaloa, México, durante 2004 y 2005. Se realizó una revisión de ejemplares depositados en herbarios para obtener la distribución geográfica de ambas especies en la costa Pacífico de México. Los escasos registros de Acetabularia, puede ser debido a las identificaciones inadecuadas, a las tallas pequeñas de éstas especies y a la escasez de estudios florísticos en el área de estudio

Species composition and seasonal changes in macroalgal blooms in lagoons along the southeastern Gulf of California

Abstract Species composition and seasonal changes in macroalgal blooms in six coastal lagoons highly impacted by human activities were tracked for the three seasons between May 2004 and April 2005. Though temperatures were lower during the cold season than during the dry and rainy seasons and some locations showed variations in salinity during the rainy season, nutrient concentrations showed no defined pattern and varied according to season and location. A total of 10 seaweed species and the cyanobacterium Microcoleus lyngbyaceus had biomasses )1 g m -2 dry weight, but only four species represented )1% of the annual biomass. During the dry season, Spyridia filamentosa had the highest biomass (57.5 g m ). Abundances of these species were higher than previously reported for this region. Correlation analyses showed a positive correlation between total phosphorus and the biomass of G. vermiculophylla, suggesting that this nutrient might be limiting its growth. C. sertularioides abundance had a positive correlation with N:P ratios, suggesting that high concentrations of nitrogen relative to low phosphorus levels favor its growth. These analyses revealed that nutrient concentrations are most likely to affect macroalgal growth, but temperature and salinity also play a role. This information may be useful for monitoring future blooms and determining changes over time

Evaluation of nitrogen sources in the Urias lagoon system, Gulf of California, based on stable isotopes in macroalgae

The concentrations of chemical forms of nitrogen (N) and their isotopic composition in the water column and the δ15N signals in 738 samples of macroalgae collected during one year across the Urías lagoon system (Mazatlán, Sinaloa, Mexico) were analyzed in order to study the N sources. The δ15N-macroalgae premise is that they register and integrate the variability of N and may provide time-integrated information about N pollution. To validate this premise, we applied two models to predict the isotopic variability of N available in the water column (δ15N-DIN): one is based on a physical mixing balance of N sources (simple model), and the second includes the effects of the biogeochemical processes on the signals (coupled model, CM). Both models showed significant R2, but CM better explained the δ15N-DIN variability. The relation between δ15N-DINCM and δ15N-macroalgae also showed a good fit, although lower than expected and with higher dispersion. The multiple N sources and co-occurring biogeochemical reactions, which produce a mixture of chemical species of N and of their isotopic compositions, as well as the high diversity of species (45) explained the elevated variability and lack of fit. Even so, δ15N in macroalgae is the most useful available tool to quantify the relative contributions of N to ecosystems from different sources. Based on Bayesian isotopic mixing models, the main anthropogenic sources of N to the Urías lagoonal system were domestic effluents (50%), atmospheric deposition (24%), and seafood processing plant effluents (21%), and to a lesser extent, aquaculture effluents (3%), agriculture runoff (1%), and oceanic N (1%).

Beneficios de los florecimientos macroalgales para la producción de biofertilizantes

In the present essay, an alternative for the production ofbiofertilizers is proposed based on the use of macroalgal blooms that are occurring in the coastal lagoons of Sinaloa. Coastal communities can obtain an economic benefit by properly harvesting part of the biomass resulting from such blooms. The extracted macroalgal biomass could be used to producebiofertilizers, with the following benefits: a)mitigate the ecological damage caused by macroalgal blooms to eutrophicized coastal ecosystems; b) the use of organic fertilizers in agricultural fields allows N and P to be recycled, thus avoiding the application of more synthetic fertilizers, which are primarily responsible for macroalgal blooms; c)in addition to containing biofertilizers based on macroalgae, N and P contain a set of micronutrients and substances with the potential to benefit crops and improve soils; d)it contributes to carbon sequestration and the reduction of greenhouse gases in the atmosphere; and e)economic benefits in the use ofa raw material, nowadays, of low value or without commercial value. Such biofertilizers would be used to produce fruits and vegetables of the so-called organic, which have a high surplus value and their demand is increasing in Mexico and in the world. This is an alternative focused on the production of biofertilizers for use in organic agriculture and production of fruits of high economic value, which can be accredited as organic and at the same time, contribute to the improvement of soils and the state ofhealth of coastal ecosystemsEn el presente ensayo se proponeuna alternativa para la producción de biofertilizantes a partir del aprovechamiento de los florecimientos macroalgales que se están suscitando en las lagunascosterasde Sinaloa. Las comunidades aledañas a las costas pueden obtener un beneficio económico al cosechar adecuadamente parte de la biomasa resultante de dichosflorecimientos. La biomasa macroalgal extraída podría ser usadapara la produccióndebiofertilizantes, conlos siguientesbeneficios: a)mitigar el daño ecológico provocado por los florecimientosmacroalgalesa los ecosistemascosteros eutrofizados;b)el uso de fertilizantes orgánicos en campos agrícolas permite reciclar N y P, evitando así, la aplicación de mas fertilizantes sintéticos, los cuales son los principales responsables de los florecimientosmacroalgales;c)los biofertilizantes a base de macroalgas además de contener, N y P, contienen un conjunto de micronutrientes y sustancias con el potencial de beneficiar a los cultivos y mejorar los suelos;d)se contribuye al secuestro de carbono y a la reducción de gases de efecto invernadero enla atmósfera; ye)beneficios económicos en el aprovechamiento de una materia prima, hoy en día, de bajo valor o sin valorcomercial.Tales biofertilizantes se utilizarían para producir frutos y vegetales de los denominados orgánicos, los cuales tienen una alta plusvalía y su demanda va en aumentoen México y en el mundo. Esta es una alternativa enfocada en la producción debiofertilizantesparasuutilizaciónen la agricultura orgánica yproducción defrutos de alto valor económico, los cualespueden ser acreditados como orgánicosy al mismo tiempo,contribuir al mejoramiento delos suelos y del estado de salud de los ecosistemas costeros