Examinando por Autor "Guerrero, Alicia"

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  • Miniatura
    Ítem
    Long-term monitoring for conservation: closing the distribution gap of Arctocephalus australis in central Chile
    (Bmc, 2021) Cárcamo, Daniel; Pizarro, Marlene; Orellana, Muriel; Canto, Anahi; Herrera, Pablo; Muñoz, Lily; Vásquez-Calderón, Piera; Guerrero, Alicia; Sepúlveda, Maritza; René Durán, L.; Oliva, Doris
    Objectives. Here, we present the first record of stable colonies of the South American fur seal (Arctocephalus australis), in an area where their presence has never been documented (hereafter distribution gap), as well as an update of the current distribution range of the species in central Chile. Results. A national synoptic aerial census of pinnipeds was performed during the austral summer of 2019 on the Chilean coast. An additional aerial census was conducted in the same area during the austral spring of 2019 as well as a maritime census during the austral summer of 2020. The data showed the presence of South American fur seals in central Chile within their well-known distribution gap. The total abundance was registered in three colonies where fur seals were sighted: one non-breeding colony, Punta Topocalma (summer 2019: mean = 46 ± 3; spring 2019: mean = 9 ± 1); and two breeding colonies, Punta Curaumilla (summer 2019: mean = 595 ± 7; spring 2019: mean = 45 ± 4; summer 2020: mean = 744 ± 5) and Isla Santa María (summer 2019: mean = 246 ± 6). Specifically, we suggest that it is crucial to elucidate the origin of the described settled colonies, and to determine whether there has been an augment in the distribution range from either the northern population, the southern population, or both simultaneously.
  • Ítem
    Turbulent Mixing in Patagonian Fjords and Channels
    (EGUsphere. Preprint repository, 2025) Rojas Celis, Marcela; Castillo Silva, Manuel; Pérez Santos, Iván; Barrios Guzmán, Carmen; Garcés Vergara, José; Guerrero, Alicia; Landaeta Díaz, Mauricio; Piñones, Andrea; Sepúlveda, Maritza
    The fjords and channels of Chilean Patagonia form a complex estuarine system where freshwater input, tidal currents, and stratification interact to modulate vertical mixing. We combined velocity microstructure profiles (VMP-250) and CTD-SRDL observations collected between 2023 and 2025 to quantify turbulent kinetic energy dissipation (ε) and vertical diffusivity (Kshear) across northern (42–46°S) and southern (52–55°S) Chilean Patagonia. Dissipation rates spanned 10⁻⁹–10⁻⁵ W kg-2 with maxima near sills and narrow passages such as Paso Desertores, where semidiurnal tides dominate energy input. Northern Patagonia exhibited seasonal stratification driven by freshwater inputs, while southern Patagonia remained weakly stratified and vertically well mixed throughout the year, aided by strong tidal currents and westerly winds. The tidal mixing parameter h/U³ indicated that semidiurnal tides account for ~97% of energy dissipation in the north and ~77% in the south. These findings highlight the strong spatial heterogeneity of turbulent mixing in Patagonian fjords and the key role of the interaction between tidal forcing and stratification in controlling vertical exchange. The results provide a framework for understanding how fjord systems may respond to changing freshwater inputs and atmospheric forcing under a warming climate.