Use of intertidal macroalgae as bioindicators of anthropogenic nutrient disturbance in the rocky coasts of the tropical central Mexican Pacific

Bahía de Zihuatanejo, Mexico, exhibits disturbances in its rocky shores due to large amounts of nutrients that enter the sea due to urbanization and mass tourism. These nutrients are traced in macroalgae using stable isotopes. The objective of this study was to use 4 species of macroalgae as bioindi...

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Autores principales: Vergara-Carranza, Careli, López, Norma, Piñón-Gimate, Alejandra
Formato: Online
Lenguaje:eng
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Publicado: Iniversidad Autónoma de Baja California 2024
Acceso en línea:https://www.cienciasmarinas.com.mx/index.php/cmarinas/article/view/3416
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Sumario:Bahía de Zihuatanejo, Mexico, exhibits disturbances in its rocky shores due to large amounts of nutrients that enter the sea due to urbanization and mass tourism. These nutrients are traced in macroalgae using stable isotopes. The objective of this study was to use 4 species of macroalgae as bioindicators to infer nutrient sources in the system through δ15N and the elemental nitrogen (N) content. Samples were collected in the rainy and dry seasons of 2021 at 3 sites in the Zihuatanejo region: La Madera, Las Salinas, and La Majahua. Water samples were taken at each site and season to determine nitrate (NO3) and phosphate (PO4) concentrations. Isotopic signals and N content were evaluated in Hypnea spinella, Padina gymnospora, Ulva intestinalis, and Ulva lactuca for each site and season. The concentrations of NO3 and PO4, which were highest at Las Salinas and showed no differences between La Madera and La Majahua, were similar to those previously reported for the region. The highest δ15N signals were found in U. intestinalis and H. spinella at Las Salinas (16.12‰ and 15.38‰, respectively) and La Madera (15.12‰ and 13.58‰, respectively) and were close to the isotopic wastewater signal. In La Majahua, low signals were obtained for H. spinella (13.54‰), P. gymnospora (9.24‰), and U. lactuca (8.24‰), with values that were close to the isotopic signal of nutrient-rich oceanic waters. The N content varied depending on the species and site, although it was generally higher at Las Salinas. The isotopic signals agreed with those reported for anthropogenic and natural nutrient-enriched coasts. The species U. intestinalis and H. spinella can be used as bioindicators of anthropogenic disturbance due to sewage discharge in the region.