Effects of Sewage Discharge on Trophic State and Water Quality in a Coastal Ecosystem of the Gulf of California

This paper provides evidence of the effects of urban wastewater discharges on the trophic state and environmental quality of a coastal water body in a semiarid subtropical region in the Gulf of California. The concentrations of dissolved inorganic nutrients and organic matter from urban wastewater primary treatment were estimated. La Salada Cove was the receiving water body and parameters measured during an annual cycle were temperature, salinity, dissolved oxygen, nitrite, nitrate, ammonia, orthophosphate, and chlorophyll a. The effects of sewage inputs were determined by using Trophic State Index (TRIX) and the Arid Zone Coastal Water Quality Index (AZCI). It was observed that urban wastewater of the city of Guaymas provided 1,237 ton N yr−1 and 811 ton P yr−1 and TRIX indicated that the receiving water body showed symptoms of eutrophication from an oligotrophic state to a mesotrophic state; AZCI also indicated that the environmental quality of the water body was poor. The effects of urban wastewater supply with insufficient treatment resulted in symptoms of eutrophication and loss of ecological functions and services of the coastal ecosystem in La Salada Cove

Evaluation of growth, cell size and biomass of Isochrysis aff. galbana (T-ISO) with two LED regimes

In contrast to crops, there are fewer studies using LED-based light with green microalgae and none cultivating the microalga Isochrysis aff. galbana (T-ISO) even though of its importance in marine aquaculture.  The objective was to evaluate of white and red LEDs as an alternative source of light to cultivate I. aff. galbana (T-ISO). In order to carry this out white and red LEDs were used with a laboratory built Erlenmeyer-type photobioreactor to determine productivity, cell number and size and biomass composition. Results were compared with standard fluorescent lights of the same light intensity.  The culture system consisted of 3 flasks for applying red LEDs and three for white LEDs and 3 control group flasks illuminated with the normal fluorescent lighting at the similar light intensity of ~60 mM m–2 s–1. It was found that the population cell density did not significantly increase with either red LEDs or white LEDs (p > 0.05), if at all. Standard fluorescent lighting (control group) showed significant increases in population cell number (p < 0.05). Through microscopic observation cell size was found to be smaller for white LEDS and even smaller for red LEDs compared to fluorescent lighting. Biochemical composition of proteins, carbohydrates and lipids was similar for all light regimes. The authors suggest that the unexpected non-growth I. aff. galbana (T-ISO), a haptophyte microalga, with white and red LEDs is possibly due to fact that to initiate cell growth this microalgae requires other wavelengths (possibly green) besides red and blue, to allow other pigments, probably fucoxanthin, to capture light

Evaluation of growth, cell size and biomass of Isochrysis aff. galbana (T-ISO) with two LED regimes

In contrast to crops, there are fewer studies using LED-based light with green microalgae and none cultivating the microalga Isochrysis aff. galbana (T-ISO) even though of its importance in marine aquaculture. The objective was to evaluate of white and red LEDs as an alternative source of light to cultivate I. aff. galbana (T-ISO). In order to carry this out white and red LEDs were used with a laboratory built Erlenmeyer-type photobioreactor to determine productivity, cell number and size and biomass composition. Results were compared with standard fluorescent lights of the same light intensity. The culture system consisted of 3 flasks for applying red LEDs and three for white LEDs and 3 control group flasks illuminated with the normal fluorescent lighting at the similar light intensity of ~60 mM m–2 s–1. It was found that the population cell density did not significantly increase with either red LEDs or white LEDs (p > 0.05), if at all. Standard fluorescent lighting (control group) showed significant increases in population cell number (p < 0.05). Through microscopic observation cell size was found to be smaller for white LEDS and even smaller for red LEDs compared to fluorescent lighting. Biochemical composition of proteins, carbohydrates and lipids was similar for all light regimes. The authors suggest that the unexpected non-growth I. aff. galbana (T-ISO), a haptophyte microalga, with white and red LEDs is possibly due to fact that to initiate cell growth this microalgae requires other wavelengths (possibly green) besides red and blue, to allow other pigments, probably fucoxanthin, to capture ligh

Goat milk fatty acid composition in the Peninsula of Baja California, Mexico

Objective. The objective of the study was to determine the composition of fatty acids in milk of Creole goats in an extensive production system in an arid region of the peninsula of Baja California and compare it to two seasons of the year (rainy and dry). Materials and methods. Sampling was conducted during the dry season (June) and after the rainy season (December) in the municipality of Comondú in Baja California Sur. The extensive production system used involved releasing goats to roam freely in the rangeland to graze for food, and no additional food or supplements were provided. Results. The most abundant fatty acids were saturated fatty acids (66.3 and 70.9% in the rainy and dry reasons, respectively). The most abundant of these were palmitic, myristic, and stearic acid in both seasons. Monounsaturated fatty acids (15-20%) were the most numerous in terms of isomers, but mostly in low concentrations. The largest average constituent of polyunsaturated fatty acids (5-6%) was linoleic acid (3%) and alpha-linolenic acid (1.2%) in both seasons. Branched, fatty acid concentrations were highly variable; the only stable constituents were C15:0 iso (1.5%) and C16:0 anti-iso, with 0.7% of total fatty acids. Conclusions. The seasons in this extensive production system significantly effected the composition of most monounsaturated and branched fatty acids in goat milk; however, saturated and polyunsaturated showed only a few compositional changes in abundance of fatty acids. Moreover, season effects were not significant on the total fatty acid content, except for branched fatty acids and omega-3

Survival and growth of Jacaratia mexicana seedlings inoculated with arbuscular mycorrhizal fungi in a tropical dry forest

Jacaratia mexicana is not only an endemic and typical tropical dry forest tree of México, it is considered as a direct ancestor of the papayo (Carica papaya). Locally it is mainly used in traditional medicine, for human food or for feeding backyard animals (forage plant), but its use value is very restricted or even unknown. Nevertheless, various abiotic and anthropogenic pressures in its Mexican habitat are causing populations of this tree to decline alarmingly. Arbuscular mycorrhizal fungi (AMF) are microorganisms that have an important role for the regeneration of tree species by increasing their ability to absorb water and nutrients. The aim of this study was to determine the effect of AMF on growth and survival of seedlings of J. mexicana transplanted within a fragmented area of the remaining dry forest located in the central portion of the state of Veracruz. We measured height, stem diameter, number of leaves, percent seedling survival and mycorrhizal colonization. Results showed increases in all growth-related variables when seedlings were inoculated with AMF. The results suggest that micosymbionts can play a critical role for the regeneration of J. mexicana and possibly other species of tree within the dry forest, especially helping this endemic species that is currently surviving in a fragmented environment under unfavorable conditions of low availability of water and nutrients.Jacaratia mexicana no es solo un árbol endémico y típico de los bosques tropicales secos de México, sino que se le considera como ancestro evolutivo del papayo (Carica papaya). Se le aprecia en la medicina tradicional, para alimentación del ser humano o cría de animales de traspatio (planta forrajera), pero su valor de uso es muy restringido o incluso desconocido. Sin embargo, presiones abióticas y antropogénicas de su hábitat natural están causando una alarmante reducción de las poblaciones naturales de esta Caricaceae. Los hongos micorrízicos arbusculares (HMA) son microorganismos que juegan un papel importante en la regeneración de especies debido al aumento de su capacidad para absorber agua y nutrientes. El objetivo de este estudio fue determinar el efecto de los HMA sobre el crecimiento y supervivencia de plántulas de J. mexicana trasplantadas dentro de un área fragmentada del bosque tropical seco ubicado en la parte central del estado de Veracruz. Se determinó en este estudio la altura, diámetro, número de hojas, porcentaje de supervivencia y colonización micorrízica. Los resultados muestran incrementos en todas las variables relacionadas con el crecimiento cuando las plántulas fueron inoculadas con HMA. Los resultados sugieren que estos micosimbiontes pueden desempeñar un papel fundamental para el establecimiento de árboles como J. mexicana y posiblemente de otros componentes dentro del bosque tropical seco, los cuales actualmente sobreviven en un entorno fragmentado y bajo condiciones desfavorables de baja disponibilidad de agua y nutrientes

Recovery of Vegetation Cover and Soil after the Removal of Sheep in Socorro Island, Mexico

For over 140 years, the habitat of Socorro Island in the Mexican Pacific has been altered by the presence of exotic sheep. Overgrazing, jointly with tropical storms, has caused soil erosion, and more than 2000 hectares of native vegetation have been lost. Sheep eradication was conducted from 2009 to 2012. Since then, the vegetation has begun to recover passively, modifying soil properties. The objective of our study was to verify that this island was resilient enough to be recovered and in a relatively short time scale. To confirm our hypothesis, we analyzed changes in the physical-chemical properties of the soil and vegetation cover, the last one in different times and habitats after sheep eradication. The change in vegetation cover was estimated by comparing the normalized difference vegetation index (NDVI) between 2008 and 2013. In sites altered by feral sheep, soil compaction was assessed, and soil samples were taken, analyzing pH, electrical conductivity, organic carbon, total nitrogen, phosphorus, calcium, and magnesium. After a year of total sheep eradication, clear indications in the recovery of vegetation cover and improvement of soil quality parameters were observed and confirmed, specifically compaction and nitrogen, organic carbon, phosphorus, and calcium. The results seem to support our hypothesis