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Temporal variability of enterococci and associated sources at three subtropical recreational beaches

León-López C. E., Arreola-Lizárraga J. A., Padilla-Arredondo G., Chávez-Villalba J. E., Mendoza-Salgado R. A., Méndez-Rodríguez L. C., García-Hernández J.

Oceanological and Hydrobiological Studies

2018

Vol. 47, No. 4

327--336

We have examined enterococci concentrations in water and sand (dry and wet) at three semi-arid subtropical recreational beaches to assess public health risks. To determine the concentration of enterococci, water and sand samples were collected before, during and after the Easter Week (when the largest influx of users occurs), and in the wintertime. The lowest concentrations (< 100 MPN 100 ml-1) were recorded before the Easter Week, the highest concentrations (> 1500 MPN 100 ml-1) during and after the Easter Week, and concentrations < 500 MPN 100 ml-1 in the wintertime. Enterococci concentrations in sand were generally < 200 MPN 100 ml-1. Variability in enterococci concentrations can be explained by the influx of users during the Easter Week, rainfall runoff and the increase in water temperature after the Easter Week, as well as by winds and the presence of dogs and birds in the wintertime. The highest health risks occur during and after the Easter Week.

Analysis of hydrobiological responses to anthropogenic and natural influences in a lagoon system in the Gulf of California

Arreola-Lizárraga J. A., Padilla-Arredondo G., Medina-Galván J., Méndez-Rodríguez L., Mendoza-Salgado R., Cordoba-Matson M. V.

Oceanological and Hydrobiological Studies

2016

Vol. 45, No. 1

112--120

The hydrological characteristics and the rate of organic matter supply from coastal lagoons help to understand their responses to nutrient input by anthropogenic and natural sources. The aim of this study was to determine the hydrologic and trophic status of the El Rancho-Empalme lagoon system in a semiarid region in the Gulf of California, Mexico. This lagoon system consists of two geomorphological subsystems which are affected by nutrient inputs from shrimp farm effluents and coastal upwelling. Sampling was conducted over the course of one year and included measurements of temperature, salinity, and dissolved oxygen, surface water grab samples to analyze nitrite, nitrate, ammonia, orthophosphate, and chlorophyll a. The trophic status was assessed using the TRophic IndeX (TRIX). The subsystems El Rancho and Empalme had a similar hydrological behavior throughout the year, reflecting a good exchange of water, materials and energy. The TRIX index showed oligotrophic state during spring, summer and autumn, and a mesotrophic state in winter. Nutrient inputs from shrimp farm effluents were not responsible for trophic status increases, however, coastal upwelling in the region plays an important role in the growing rate of seasonal supply of organic matter to these coastal lagoons.