Primary producers as indicators of anthropogenic intervention in the Colombian Pacific

The coastal ecosystems, including estuaries and mangroves, are highly vulnerable to anthropogenic intervention, particularly due to activities such as urbanization, wastewater discharge, and industrial development, which can alter their ecosystem services and affect habitat quality. In order to evaluate the impact of these interventions through the carbon and nitrogen isotopic composition of two macroalgae Boodleopsis verticillata and Bostrychia spp in four coastal ecosystems of the Colombian Pacific (Valencia - VAL, San Pedro - SPE, Chucheros – CHU with low intervention, and Piangüita - PIA with high intervention) were used to understand the sources of these elements. δ¹⁵N values is a commonly used to providing information about nitrogen sources in primary producers. δ¹³C values is used to investigate carbon sources i.e. terrestrial or marine. Samples were collected during 2014, 2015, and 2016, and analyzed by isotope ratio mass spectrometer. The results show that the δ¹³C values ranged from -33.97 to -31.93 ‰ in VAL, -33.78 to -30.09 ‰ in SPE, -31.12 to -28.45 ‰ in CHU, and -33.32 to -21.71 ‰ in PIA. δ¹⁵N values ranged from 0.32 to 3.18 ‰ in VAL, 0.57 to 5.47 ‰ in SPE, 1.82 to 3.39 ‰ in CHU, and 2.32 to 10.16 ‰ in PIA. Significant differences were found among the four areas with mean δ¹³C values by locality (VAL -30.21 ‰, SPE -31.71 ‰, CHU -30.09 ‰, and PIA -30.52 ‰) and δ¹⁵N values (VAL 1.74 ‰, SPE 2.30 ‰, CHU 2.40 ‰, and PIA 4.47 ‰) reflecting the impacts of human activities on the coastal ecosystems. This work contributes to understanding the effects of anthropogenic intervention on pollution and wastewater discharge in coastal ecosystems, providing key tools for the development of environmental management policies that support conservation in the Colombian Pacific.