Larval fish assemblages from channels and fjords of south Pacific Patagonia: effects of environmental conditions

Abstract

Resumen.-Los fiordos de la Patagonia chilena, se caracterizan por fuertes gradientes físico-químicos horizontales y verticales que ejercen consecuencias en la distribución y abundancia del ictioplancton. Se recolectaron muestras de plancton mediante arrastre oblicuo con una red bongo en 40 estaciones, a bordo de un crucero bio-oceanográfico en fiordos interiores de la XI región sur de Chile (47° a 51°S). Los datos ambientales de la columna de agua fueron obtenidos mediante un perfilador de conductividad-temperatura-profundidad (CTD), y la turbidez fue medida con un turbidímetro portátil entre 0 y 100 m de profundidad. Las estaciones se distribuyeron por zona oceánica, canales y área de influencia de agua dulce. Se recolectó un total de 1424 larvas, representando 21 familias y 41 taxa. Los taxa dominantes fueron Maurolicus parvipinnis (31%), Sebastes oculatus (12%), Merluccius australis (11%), Lampanyctodes hectoris (10%) y Bathylagichthys parini (8%). La mayor variabilidad ambiental fue dada por la salinidad, principalmente en la zona con descarga de agua dulce. La zona oceánica presento una columna de agua mezclada con la mayor presencia de mictófidos como L. hectoris y peces hacha M. parvipinnis. No hubo un efecto significativo de los gradientes de turbidez sobre los ensambles de larvas de peces durante primavera. La zona de los canales se aprecia una mayor estratificación de la salinidad, densidad y una disminución de la turbidez, donde se distribuyeron en general las especies con menores abundancias. Por lo tanto, es posible definir dos ensambles ictioplanctónicos, uno con influencia oceánica y el otro de canales y zonas interiores.Abstract.-Chilean Patagonian fjords are characterized by strong stratification and chemical gradients which influence the ichthyoplankton distribution and abundance. Plankton samples were collected through bongo net oblique tows in 40 stations from onboard a bio-oceanographic cruise took place in inner fjords of southern Chile (47° to 51°S). Water column physical data were obtained with a conductivity-temperature-depth profiler (CTD) and turbidity was measured with a portable turbidimeter from 0 to 100 m depth. Stations were distributed by three zones: oceanic, channels and continental waters. A total of 1424 larvae were collected, representing 21 families. Dominant taxa were Maurolicus parvipinnis (31%), Sebastes oculatus (12%), Merluccius australis (11%), Lampanyctodes hectoris (10%), and Bathylagichthys parini (8%). Most of the environmental variability was determined by salinity, mainly in the area where continental waters are discharged. The water column in the oceanic zone presented mixed waters dominated by the myctophid L. hectoris and the sternoptychid M. parvipinnis. No significant effect of turbidity gradients on larval fish assemblages was evident during spring. The channel zone was both more saline, and density stratified with less turbidity, and lower abundance of species. Two ichthyoplanktonic assemblages were evident, one living in oceanic waters, and the other from...

High-concentration sediment plumes, Horseshoe Island, western Antarctic Peninsula

“…In general, average turbidity values were higher than those found on the Danco Coast in the Antarctic Peninsula (~10 vs ~3.0 mg l -1 ) (Rodrigo et al 2016, unpublished data 2021) and higher than those of King George Island (~5.1 mg l -1 ) (Yoo et al 2015). However, for the stations closer to the glacier, the values were considerably higher compared to those of the Chilean Patagonian fjords, for example (maximum value < 5 NTU or 22 mg l -1 ) (Castilla-Hidalgo et al 2018). The maximum reported data are graphed as a function of latitude (Fig.…”

Unraveling the morphological patterns of a subantarctic eelpout: a geometric morphometric approach

“…2), a functional hypothesis (H1) and a structural hypothesis (H2). H1 assumes that the sensory canals and the anterior morphology (neurocranium, oral jaw apparatus) have different, but complementary functions (i.e., prey detection and capture, respectively), especially under low-light conditions (Mogdens 2019), such as the turbid, coastal waters of west Patagonia (>4 NTU, Castillo-Hidalgo et al 2018). By contrast, H2 is a hypothesis of developmental modularity derived from the observation that zoarcid have different rates of ossification during larval development (Voskoboinikova & Laius 2003), and the opercular region (where the preoperculo-mandibular canal is located) increases its relative size during early development (Marcinkevicius & Gosztonyi 2013).…”

“…Also, 2 large temperate icefields, the Northern Patagonian icefield, and Southern Patagonian icefield, located between 47°and 50°S, represent 83% of the total ice loss in the southern Andes, and are responsible for a total of 3.3 mm of sea-level rise between 1961 and 2006 (Bravo et al 2021). Both ice melting and river discharge affect visibility of marine organisms through an increase of turbidity (Castillo-Hidalgo et al 2018). Additionally, and because of the latitudinal extension of Patagonia, important sea surface temperature gradients also occur, varying from 4°C to 18°C (Bruno et al 2018;Molina-Valdivia et al 2021).…”

Reproductive biology and population structure of white warehou Seriolella caerulea and silver warehou Seriolella punctata in the austral zone off Chile

“…australis ), M. novaezelandiae and pink cusk‐eel G. blacodes (Aguayo et al ., , Balbontin & Bernal, , Córdova et al, , Lillo et al, , Rubilar et al ., ). In addition, given the presence of egg and larvae of both species in the fjords south of 47° S (Bustos et al ., ; Castillo‐Hidalgo et al ., ), the mature females ( I GS > 3) observed offshore between 47° and 50° S could indicate another spawning area.…”