Evaluation of beach quality as perceived by users

Recreational beaches are strategic ecosystems for tourism and should be used in a sustainable manner. We studied three beaches in the municipality of Guaymas (NW Mexico), in order to assess their beach quality and identify key management issues. The evaluation was based on the perceptions of users concerning: (1) the user profile; (2) the recreational habits of users; and (3) the biophysical characteristics, infrastructure, services, and cleanliness of each beach. The results showed that the beaches were of different quality. The key management issues identified were the need to design and apply specific management programs for each beach, specifically in regards to improving infrastructure and services, and obtaining certification as a sustainable beach. The evaluation of the beaches as perceived by users suggests that it would be useful to assess beach quality in order to support management goals and be applicable to other beaches, both nationally and internationally.     

Persistent organic pollutants (POPs) in populations of the clam Chione californiensis in coastal lagoons of the Gulf of California

This study examines the potential public health risk due to the massive use of organochlorine pesticides (OCs) in agriculture in the Gulf of California. Specimens of the clam Chione californiensis were collected from three coastal lagoons (Yavaros, Altata and Reforma). Sites were classified as polluted/nonpolluted based on the presence/absence of OCs as an indicator of the persistence of these pollutants; in polluted sites, the time elapsed since pesticide application (past or recent) was estimated. Screening values (SV) for protecting human health as per the U.S. Environmental Protection Agency (EPA) were used for risk assessment. OCs detected were ranked according to frequency of occurrence as follows: γ-chlordane (75%) > endrin (54%) > aldrin (48%) > heptachlor, and dichlorodiphenyl-trichloroethane (DDE) (37%) > β-heptachlor epoxide (30%) > lindane (α-BHC, δ-BHC) and endosulphan I (≤ 6%). Specifically, OCs detected at the highest concentration were heptachlor in Yavaros (0.0168 µgg^?1) and Altata (0.0046 µgg^?1), and aldrin in Reforma (0.0019 µgg^?1). β-Heptachlor epoxide in Altata and Reforma was the only OC with a concentration exceeding the EPA Screening Value. From our results and based on the monthly consumption limit set forth by EPA, the maximum safe consumption of clams to avoid a carcinogenic risk derived from β-heptachlor epoxide in the fishing villages of Yavaros and Altata is 4 servings per month (1 serving = 0.227 kg) by a 70-kg person. These findings suggest that concentrations of OCs and their isomers in C. californiensis populations reflect environmental persistence as well as recent inputs of OCs into coastal lagoons in the Gulf of California.     

Identifying rainfall effects in an arid Gulf of California coastal lagoon

At Ensenada de La Paz, a coastal lagoon on the western side of the Gulf of California, nutrient and salinity data before and after rain events were evaluated using a mass balance model to estimate the exchange of conservative and non-conservative variables with the adjacent sea. Surface salinity, nitrogen (N-NO3, N-NO2), and phosphorus (PO4) were used in the model to obtain the hydraulic balance, water residence time, and nitrogen and phosphorus fluxes. Results showed that residual volume was mainly influenced by evaporation. Rainfall and runoff increased the mixed volume and reduced water residence time. Pre-rainfall hydraulic balance conditions were reestablished about 10 days after a rain storm. Rainwater inputs also modified the quality of the coastal lagoon: the pre-rainfall scenario showed that more nitrogen is consumed than produced, and there is a phosphorus sufficiency. A rain disturbance induces a nitrogen and phosphorus increase. Eleven days after a rain storm, nitrogen and phosphorus levels did not return to the pre-rainfall scenario. Rain disturbances in arid zone coastal lagoons modify their water quality and exchange with the adjacent ocean; some management strategies are suggested.