SUMMARY: Hydromedusae collected in epipelagic waters of the channels in southern Chile, between the Corcovado Gulf and the Pulluche-Chacabuco channels, were analysed. A total of 23 species were identified and recorded for the first time in this region. The most abundant species were Hydractinia minuta (44.4%), Clytia spp. (21.0%), Solmundella bitentaculata (14.5%), and Amphogona apicata (9.8%). H. minuta was the only species whose maximum abundance occurred in interior, low temperature, low salinity waters. Most of the species identified in the southern channels are common inhabitants of the Humboldt Current System, although a rare species (Heterotiara minor) was recorded for the first time in Chilean waters. High-diversity values (> 2.5 bits) were recorded in the oceanic waters of the adjacent Pacific Ocean.
RESUMEN. Se analizó la abundancia estacional y distribución vertical del zooplancton gelatinoso colectado en cuatro cruceros efectuados frente a la bahía de Mejillones. En esta zona se identificaron 44 especies macroplanctónicas distribuidas en 23 de sifonóforos, 17 de hidromedusas, y 4 de ctenóforos, de las cuales 8 especies, Sphaeronectes irregularis, Rhizophysa eysenhardti, Amphogona apicata, Proboscidactyla stellata, Sarsia coccometra, Pleurobrachia bachei, Thalassocalyce inconstans y Velamen parallelum, se registran por primera vez para el Sistema de la Corriente de Humboldt. Se determinó un incremento de abundancia en primavera y verano, con densas agregaciones (> 2.600 ind•100 m-3) en octubre de Aglaura hemistoma, Solmundella bitentaculata, Muggiaea atlantica y Pleurobrachia bachei, y en febrero de Obelia spp. Las mayores densidades se determinaron en la estación más costera y en el frente oceánico, mientras que en la estación oceánica se registró una fuerte disminución de abundancia. La mayoría de las especies dominantes se encontraron en los primeros 100 m de la columna de agua, con una mayor concentración de ejemplares en los primeros 25 o 50 m de profundidad. Esta distribución vertical estaría limitada por la capa de mínimo oxígeno (< 1 ml•L-1) que se detectó en aguas muy someras (30-50 m) durante los eventos de surgencia.
We identified 36 species of cnidarians (27 hydromedusae, 9 siphonophores) collected from the Moraleda, King, Darwin, and Pulluche channels, located in southern Chile. The hydromedusae Gossea brachymera, Hybocodon unicus, and Sarsia coccometra, and the siphonophores Rosacea cymbiformis and R. plicata were recorded for the first time in the southern channels. Diversity values were higher for Hydromedusae (2.66 bits) than for Siphonophorae (1.15 bits). The largest aggregates were found in the Moraleda and Pulluche channels, with densities that exceeded 7,000 ind•1000 m-3. The vertical distribution of the dominant species showed Solmundella bitentaculata to be located near the surface (0-20 m), whereas Sphaeronectes gracilis, Muggiaea atlantica, Clytia simplex, and Proboscidactyla ornata were found in subsurface waters (20-50 m) and Amphogona apicata in deeper waters (50-100 m). According to the Pearson analysis, salinity correlated positively with S. gracilis and S. bitentaculata and negatively with P. ornata. C. simplex was indirectly associated with temperature and the dissolved oxygen concentration.
La península de Mejillones está inserta en el Sistema de la Corriente de Humboldt (SCH) y se caracteriza por frecuentes eventos de surgencia, donde afloran Aguas Ecuatoriales Subsuperficiales (AESS) asociadas a la corriente subsuperficial Perú-Chile, que generan la Zona de Mínimo Oxígeno (ZMO), con
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