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https://repositoriobibliotecas.uv.cl/handle/uvscl/16619

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Benthic food distribution as a predictor of the spatial distribution for shorebirds in a wetland of central Chile
(Revista de Biología Marina y Oceanografía, 2016) Pérez Vargas, Alfredo; Bernal, Mariano; Delgadillo Recabarren, Camila; González Navarro, Eduardo; Landaeta Díaz, Mauricio
Coastal landscapes of central Chile are important places for species of resident and migratory shorebirds. Estuarine environments are critical habitats that provide resting places and food resources for large concentrations of shorebirds to replenish their energy during their migration. We hypothesized that shorebirds choose particular habitats based on food availability in a tidal wetland of Aconcagua River, central Chile. We evaluated composition and abundance of benthic ensemble in foraging areas, and its local spatial distributions in these foraging areas. The main prediction was that selected trophic items may reflect the main distribution of shorebirds. The total benthic invertebrates registered were 11,514 individuals, corresponding to 25 taxa, being crustaceans, polychaetes, oligochaetes, and insects the major taxonomic groups. The total and foraging shorebirds registered were 2,105 and 1,136 individuals, respectively; corresponding to 18 species belonged to 4 Families: Charadriidae, Haematopodidae, Recurvirostridae and Scolopacidae. Tidal flats around the study site exhibit non random spatial distributions of feeding shorebirds, responding to food availability within the Aconcagua river wetland. Our integrated analysis showed significant differences between tidal flat areas based on abundance and composition of benthic trophic items (mediated by sediment characteristics), and some relationships between foraging shorebirds and trophic items in particular tidal flat areas. These results have implications for shorebird conservation and future wetland management, mainly in relation to environmental changes and other causes of habitat loss and destruction linked with worldwide decline in many shorebird populations.
Effect of ENSO on the distribution and concentration of catches and reproductive activity of anchovy Engraulis ringens in northern Chile
(Universidad de Valparaíso, 2017) Hernández Santoro, Carola; Landaeta Díaz, Mauricio
Anchovy makes up 90% of pelagic fishery catches in northern Chile. For the present work, anchovy (Engraulis ringens, Jenyns 1842) catches between 1997 and 2016 were analyzed to determine changes in distribution, concentration, and reproductive behavior before, during, and after ENSO events, using spatial indexes: gravity center (GC), inertia, coverage (CI), Gini index, and gonadosomatic index (GI). At the start of ENSO, anchovy catches increased and concentrated along the coast (rising Gini index), while CI decreased. During ENSO, Gini decreased, registering a southward displacement of the GC and smaller catches. In the long run, anchovy occupied les ser area (
Environmental determinants in morphospace and diet of the larval blenny Calliclinus geniguttatus from an upwelling ecosystem.
(Universidad de Valparaíso, 2020) Galeano Chavarría, Ana María; Landaeta Díaz, Mauricio
The effects of two contrasting environmental conditions in nearshore waters off cen tral Chile on the diet and morphospace of two cohorts of larval labrisomid blenny Cal liclinus geniguttatus were studied using geometric morphometrics and gut content analysis. The two environmental conditions corresponded to (a) a cold period with upwelling-favourable southwesterly winds and a mixed water column of cooler water and (b) a warm period with calm winds and stratified warmer water. During the cold period, fish larvae had a more hydrodynamic head shape, longer jaws and a higher feeding incidence, suggesting a greater food supply due to upwelling events and a possible increase in encounter rates in the turbulent environment. In contrast, the lar vae from the warm period had a more robust head shape with smaller jaws and a lower feeding incidence, which was related to higher water temperatures and lower wind intensities. The present study suggests that larvae have a rapid response to environmental changes on a short time scale (i.e., from weeks to months), showing a link between environmental conditions and changes in the phenotypic traits and diet of the larval stages of this cryptobenthic species
Growth and mortality of larval anchoveta Engraulis ringens, in northern Chile during winter and their relationship with coastal hydrographic conditions
(Fisheries Oceanography, 2017) Conteras Herrera, Jorge; Rodriguez Valentino, Camilo; Landaeta Díaz, Mauricio; Plaza, Guido; Castillo Silva, Manuel; Alvarado Niño, Mónica
Larval growth, age, growth effect and instantaneous mortality were estimated in anchoveta, Engraulis ringens, collected biweekly during the austral winter of 2014 in nearshore waters off Bay of Antofagasta (23°41′W–70°30′S), northern Chile. Through measuring standard length (SL) and sagitta microstructure analysis, it was estimated that the growth rate of E. ringens larvae decreased from June (0.85 mm day−1) to August (0.50 mm day−1). However, the water temperature was homogeneous during the sampling dates (14.6, 15.2, 14.4, and 14.6°C), suggesting that the decelerating larval growth was not linked to changes in sea temperature. Additionally, larvae with slow growth have larger otoliths compared with conspecifics with fast growth (growth effect). Larval mortality rates tended to decrease until the middle of July (0.18 per day) but increased to 0.25 per day in early August, which coincided with lower food availability (i.e., chlorophyll-a, 2.7–5.6 mg m−3) and a high occurrence of smaller larvae (1.58–11.5 mm). Partial least squares analysis indicates low covariance between the biological and oceanographic variables (PLS: 11.71%), suggesting that other factors, such as parental effects, may explain the abrupt decrease in the larval growth rates.
Influence of coastal oceanography on early life history traits of larval Patagonian sprat, Sprattus fuegensis along southeastern Pacific Ocean
(Fisheries Oceanography, 2024) López Soto, Erika; Ord, Gillian K.; Castillo Silva, Manuel; Plaza, Guido; Cáceres Muñoz, Mario; González, María Teresa; Sepúlveda, Maritza; Guerrero, Alicia; Piñones, Andrea; Landaeta Díaz, Mauricio
Early life history traits of small pelagic fish are usually affected by environmental conditions. Patagonian sprat, Sprattus fuegensis, is a small pelagic fish that inhabits the continental shelf, fjords and channels of Patagonia. Their larvae are usually exposed to large variations in physical and biological conditions. We evaluated the effects of environmental conditions on early life history traits of this key species encompassing over 20 years of information. The characterization of oceanographic features, larval abundance and distribution was carried out in western Patagonia between 1996 and 2019, while the growth and mortality rates were estimated for the austral spring 2019 between 49°54′S and 53°55′S. Larval abundance decreased three to ten times from 1996 to 1997 to the rest of the study period (2008–2010 and 2014–2019), with larger abundances being found over the shelf. In spring 2019, the growth rate was 0.20 ± 0.05 mm d−1 for larvae between 9 and 19 days after hatching. The growth rate was similar in partially stratified (7–50 J m−3) and stratified waters (50–100 J m−3), but slower in mixed waters (< 7 J m−3). GAM modelling showed that the faster larval growth occurred in partially stratified waters with temperatures above 7.5°C. Natural mortality rates were higher in partially stratified waters (24% of daily loss), lower in stratified areas (14%) and the lowest in the mixed water column (12%). Accordingly, larvae living in channels had faster growth rates but higher daily mortality, while those that hatched or were advected to water parcels on the continental shelf had slower growth but lower daily mortality. Finally, these latter traits may be an example of an inverse growth-selective survival strategy.
Significado paleoambiental y paleoecológico de la fauna marina del plioceno de la Formación Horcón, Región de Valparaíso, Chile central
(Universidad de Valparaíso, 2011) Carrillo Briceño, Jorge Domingo; Landaeta Díaz, Mauricio
La Formación Horcón corresponde a una unidad geológica, caracterizada principalmente por una litología compuesta de areniscas poco consolidadas, las cuales fueron depositadas en un ambiente completamente marino durante el Plioceno superior. Esta Formación aflora en superficie, en forma de estratos subhorizontales, en los acantilados costeros que se encuentran entre la caleta Horcón y Maitencillo, en la Comuna de Puchuncaví. En el siguiente trabajo, se realiza un análisis del registro paleontológico de la fauna marina recolectada para la Formación Horcón, discutiéndose la importancia que los mismos representan como indicadores bioestratigráficos y paleoambientales. El material fósil fue recolectado en prospecciones superficiales, y preparado bajo técnicas paleontológicas que permitieron su identificación taxonómica, la cual se basó, en la comparación con ejemplares actuales y fósiles depositados en colecciones nacionales y extranjeras. El ensamble faunístico registrado está caracterizado por un total de 60 taxa de invertebrados y vertebrados, correspondientes a 6 phyla, 12 clases, 32 órdenes, 48 familias y 46 géneros. El análisis de las características sedimentarias, condiciones tafonómicas e inferencias paleoecológicas de los taxa fósiles reconocidos, en especial aquellos asociados al medio bentónico demersal, permitieron ratificar un ambiente de depositación sobre una zona nerítica de aguas someras. El patrón de distribución biogeográfica de los actuales taxa, utilizados como referencia comparativa con sus congéneres fósiles reconocidos para la Formación Horcón, demuestran que las mismas están asociadas a condiciones más parecidas a las actuales en el Pacífico suroriental, relacionadas con las condiciones imperante actualmente en la Provincia Perú-Chile. Sin embargo, la mayor parte de los condrictios fósiles reconocidos, permiten inferir que las condiciones climáticas frente a la costa de Chile central durante el Plioceno superior, deberían haber estado caracterizadas por la presencia de aguas más cálidas que las que se encuentran actualmente frente a la zona. Toda esta información incrementa y actualiza el registro fósil conocido hasta el momento para la Formación Horcón, ampliándose el conocimiento sobre la diversidad y paleobiogeografía de las biotas marinas del Neógeno superior de Chile y de la costa Pacífica de América del Sur.
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.

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Examinando Tesis Postgrado por Autor "Landaeta Díaz, Mauricio"

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