Mauricio F. Landaeta

Spawning and early nursery areas of anchoveta Engraulis ringens Jenyns, 1842 in fjords of southern Chile

espanolLa anchoveta, Engraulis ringens, ha mostrado fluctuaciones en su abundancia y distribucion a escala interdecadal a lo largo del Pacifico Sur. Sin embargo, la variabilidad espacial y temporal reciente de los eventos reproductivos es desconocida en su distribucion geografica mas austral. Por ello, se analizo la variabilidad espacial y temporal del desove de E. ringens en la region de los fiordos del sur de Chile, entre 1995 y 2005. El ictioplancton recolectado con redes Bongo en el mar interior de Chile austral entre 42oS y 47oS mostro un incremento en la abundancia promedio de huevos desde 38 huevos por 10 m2 durante octubre de 1995 hasta >14.000 huevos por 10 m2 durante noviembre de 2005. Ademas, al comparar nuestros resultados con informacion previamente publicada de tamano de huevos de anchoveta a lo largo de la costa chilena (Llanos-Rivera & Castro 2004), los huevos recolectados durante noviembre de 2005 fueron mas largos, anchos y con mayor volumen que los huevos de anchoveta recolectados frente al norte y centro de Chile. Durante noviembre de 2005, el desove de la anchoveta se localizo principalmente dentro de fiordos (estuario Reloncavi y fiordo Comau); la abundancia de huevos y larvas en preflexion notocordal (i.e., 5.000 huevos por 10 m2; hasta 2.178 larvas por 10 m2, respectivamente) comparado con las aguas someras frente a la isla de Chiloe (9 mm) exclusivamente dentro de fiordos (10�505 larvas por 10 m2). La frecuencia de Brunt-Vaisala (N2) se correlaciono positivamente en forma significativa con la abundancia de huevos y larvas de anchoveta; esto significa que las mayores abundancias de huevos y larvas fueron obtenidas en areas con columnas de agua mas estables. La estabilidad de la columna de agua podria estar relacionada con una mayor tasa de supervivencia de los estados tempranos de anchoveta y podria estar relacionada con el reciente incremento en el desembarco de otros peces pelagicos pequenos como la sardina fueguina (Sprattus fuegensis). EnglishThe anchoveta, Engraulis ringens, has shown fluctuations of their abundance and distribution at interdecadal scale along the South Pacific. However, the recent spatial and temporal variability of the reproductive events are unknown in their southernmost geographic distribution. Therefore, the spatial and temporal variability in the spawning of E. ringens in the fjord region of southern Chile between 1995 and 2005 was analysed. The ichthyoplankton samples collected in the inland sea of southern Chile between 42oS and 47oS during 1995-2005 with Bongo nets showed an increase in the mean abundance of anchoveta eggs, varying from mean values of 38 eggs per 10 m2 during October 1995 to >14,000 eggs per 10 m2 during November 2005. Moreover, comparing our data with previously published information on anchoveta egg size along Chile (Llanos-Rivera & Castro 2004), the eggs collected during November 2005 in the inland sea were larger, wider and with higher volume than eggs collected from northern and central Chile. In the inland sea during November 2005, the anchoveta spawning was located mainly inside deep fjords (Comau and Reloncavi fjords); in such deep fjords abundance of both, eggs and preflexion larvae (i.e., 5,000 eggs per 10 m2; up to 2,178 larvae per 10 m2, respectively) than at shallow waters of Chiloe Island (9 mm larval length) were collected exclusively in the fjord region (10�505 larvae per 10 m2). The Brunt-Vaisala frequency (N2) showed positively significant correlations with anchoveta eggs and larvae abundance, meaning that higher abundance of both eggs and larvae were collected in areas with more stable water columns. This stability may induce higher survival rates of early life stages of anchoveta and may be related with the recent increasing in the landings of other small pelagic fishes such as the Falkland sprat (Sprattus fuegensis).

Larval fish assemblages off central Chile upwelling ecosystem

Se detectaron diferencias espaciales (a escala vertical y horizontal) y estacionales en las asociaciones de larvas de peces recolectadas en estaciones fijas sobre el talud y plataforma continental frente a Chile central muestreadas por 24 h durante octubre de 1998 y julio de 1999. Durante octubre, la columna de agua en las estaciones de la plataforma y talud estuvo caracterizada por aguas frias y salinas, indicativa de un reciente evento de surgencia; durante este periodo las asociaciones de larvas de peces estuvieron estructuradas por la hora del dia en la estacion de la plataforma. Esta asociacion larval estuvo dominada por el pez mesopelagico Maurolicus parvipinnis y anchoveta Engraulis ringens. Por otra parte, sobre el talud continental, el ictioplancton estuvo estructurado verticalmente, con diferentes asociaciones en funcion de la profundidad. La asociacion estuvo dominada por M. parvipinnis y el mictofido Hygophum bruuni. Durante julio de 1999, las condiciones oceanograficas se caracterizaron por una mayor temperatura superficial, inversion termica y una capa superficial de baja salinidad (33,6-33,8). Las asociaciones ictioplanctonicas de la plataforma y el talud estuvieron estratificadas verticalmente, y se agregaron bajo la haloclina. Las larvas de E. ringens y H. bruuni fueron altamente abundantes en ambas estaciones, y varias especies de habitat submareal/intermareal (Hypsoblennius sordidus, Sebastes capensis) fueron recolectadas sobre la plataforma. La importancia de las caracteristicas oceanograficas en la estructura de las asociaciones de larvas de peces frente a Chile central cambio entre ambos periodos de muestreo, siendo mas notable durante julio (efectos de la capa de baja salinidad) que en octubre (presencia de aguas de surgencia)

Efectos ambientales sobre la variabilidad espacial del ictioplancton de Chile austral durante noviembre de 2005

Se analiza la distribucion y abundancia del ictioplancton de Chile austral (41-45° S) durante noviembre de 2005 en relacion a las caracteristicas oceanograficas de la columna de agua (temperatura, salinidad y estratificacion). Durante el periodo de estudio, se recolecto un total de 44.606 huevos de peces y 2.016 larvas correspondientes a 28 taxa. Los estados tempranos de peces pelagicos pequenos dominaron en las muestras, con densidades de ~ 14.000 huevos 10 m-2 de anchoveta (Engraulis ringens) y > 100 larvas 10 m-2 de clupeidos. Analisis multivariados indicaron la formacion de dos grupos de estaciones, uno asociado a la zona de fiordos, de mayor profundidad, con fuertes gradientes verticales de temperatura y salinidad y mayor estratificacion, y otro grupo asociado al borde oriental de la isla Chiloe, de menor profundidad y mayor mezcla en la columna de agua. En las zonas de mayor estratificacion (Le., mayor frecuencia de Brunt-Vaisala, N-2), se encontraron mayores densidades de huevos y larvas de peces pelagicos y mesopelagicos (Strangomera bentincki y Maurolicus parvipinnis). Al comparar esta informacion con un crucero oceanografico llevado a cabo 10 anos antes en la misma zona (octubre de 1995), se detectaron cambios en la composicion especifica de ictioplancton, lo que puede indicar diferencias en las especies de peces marinos que utilizan la zona de fiordos y canales como area de desove y crianza larval.

The contrasting hatching patterns and larval growth of two sympatric clingfishes inferred by otolith microstructure analysis

Larval abundance, age, growth and hatching patterns of two sympatric clingfishes, Gobiesox marmoratus and Sicyases sanguineus (Pisces, Gobiesocidae), were estimated by using otolith microstructure analysis and compared on the basis of collections performed during the austral spring in 2010 off the coast of central Chile. G. marmoratus larvae were more abundant than S. sanguineus larvae during the study period. For both species, the sagittae deposited micro-increments during embryonic development (before hatching) and a hatch mark was observable in all examined otoliths. The sagittae otoliths of G. marmoratus grew in radius, perimeter and area faster than did the otoliths of S. sanguineus. Both species showed significant (P  3 mm) during the first-quarter and full moons and grew at slower rates (0.14 ± 0.01 mm day–1) during the initial 25 days. The high abundance of larval clingfish in near-shore waters, temporal decoupling among the hatching events, and the different growth rates may be tactics to increase self-recruitment in coastal waters.

Distribución del ictioplancton en la Patagonia austral de Chile: potenciales efectos del deshielo de Campos de Hielo Sur

In October-November 2009, an oceanographic survey was carried out between 50 and 53°S off southern Chile, near the Southern Ice Field. The stations near the glacier showed low temperatures (1-3oC) and salinity ( 0.1 cycles s -1 ). Main ichthyoplankton taxa were eggs and larvae of southern sprat Sprattus fuegensis, lightfish Maurolicus parvipinnis, Macrouridae, and southern hake Merluccius australis. The main spawning area of S. fuegensis (~8000 eggs 10 m -2 ) occurred in mixed zones of the adjacent continental shelf, whereas the spawning of M. parvipinnis occurred in intermediate channels associated with medium stability values (N~0.06 cycles s -1 ). Fish egg and larval abundances were null or scarce near the glacier, and the abundance of M. parvipinnis eggs was positively related to the temperature and salinity of the water column, and negatively related to water column stability. Moreover, a negative relationship was observed between seawater density and the diameter of S. fuegensis eggs. The relation between ice melting and ichthyoplankton may have consequences for advective transport and mass mortality of fish eggs and larvae, as well as pelagic-benthic coupling in the Chilean South Patagonia. Global climate change has increased glacier ice melting at high latitudes, and the increased entry of colder, less saline waters in coastal areas may have consequences for the ichthyoplankton in the Chilean Patagonia.

Condrictios fósiles del Plioceno Superior de la Formación Horcón,Región de Valparaíso, Chile central

Se describen doce taxa de condrictios fosiles provenientes de rocas asignadas al Plioceno Superior de la Formacion Horcon, region de Valparaiso, Chile central; se discuten sus registros previos, implicancias paleobiogeografi cas y paleoambientales. La fauna comprende Callorhinchus sp., Heterodontus sp., Carcharodon carcharias, Isurus oxyrinchus, Galeorhinus galeus, Carcharhinus brachyurus, Hexanchus griseus, Squatina sp., Pristiophorus sp., Rajidae, Dasyatidae y Myliobatidae. Esta es una de las asociaciones de condrictios mas diversas del Neogeno Tardio de Chile y del resto de America del Sur.

Larval growth, condition and fluctuating asymmetry in the otoliths of a mesopelagic fish in an area influenced by a large Patagonian glacier

Abstract The interaction of melting glaciers and oceanic stormy weather produce a large variability in the water column structure of the coastal sea from the south Pacific coast of Patagonia. This area is largely utilized as spawning and nursery ground for the mesopelagic fish Maurolicus parvipinnis (Sternoptichyidae) during the austral spring. Using microstructure analysis of sagittal otoliths and fluctuating asymmetry of M. parvipinnis larvae from 4.0 to 11.4 mm standard length (SL), we studied the spatial distribution, the variation of larval condition and recent growth during October–November 2009 between 50°06′ and 52°45′S. Hydrographic conditions varied between 1.4 and 9.5°C, 14.6–33.5 units of salinity, 11.5–26.5 units of sigma-t and the stability ranged from 3.6 to 594 cycles h−1. Larval abundance ranged between 3.1 and 293.7 ind. 10 m−2, with the highest abundance associated with channels connecting fjords and the adjacent ocean. Larvae grew at a rate of 0.174 mm day−1, and those individuals collected in areas with intermediate water column stability (216–270 cycles h−1) showed greater body condition, measured as recent otolith growth index (ROGI). However, these larvae had a similar departure from ideal symmetry (FA1 residual model) as larvae collected in more stratified or well-mixed areas. Overall, larvae showed size-dependent asymmetry, sagittal otoliths of smaller larvae (< 7 mm SL) being more asymmetrical than those of large larvae (P < 0.05). This suggests that M. parvipinnis larvae may be experiencing the impacts of water column variability differently, as well as other ecological interactions at different larval stages. Thus, water column structure at hatching would be important for the survival of this fish inhabiting the Patagonian fjords of southern Chile.

Distribution of microplankton and fish larvae related to sharp clines in a Patagonian fjord

Vertical distribution of microzooplankton and fish larvae was studied in a Patagonian fjord from Chile. Zooplankton collection, including larvae of the sprat...

Feeding of a larval clinid fish in a microtidal estuary from southern Chile

Es ampliamente reconocida la utilizacion de estuarios como zonas de crianza para peces e invertebrados, pero el exito en la explotacion de los recursos variara entre las especies residentes del estuario y las oportunistas. Se estudio la distribucion y dieta de larvas de Myxodes viridis (Pisces, Clinidae) en 2 localidades del estuario de Bahia Corral (estuario-arriba y estuario-abajo), uno de los estuarios mas grandes del sur de Chile, durante la primavera austral de 2009 a 3 profundidades (superficie, picnoclina, profundo) durante la fase llenante y vaciante de 4 ciclos mareales. Las larvas fueron recolectadas principalmente en la estacion estuario-abajo durante fase vaciante. La incidencia alimentaria tambien fue mayor en la fase vaciante; las larvas cambiaron de omnivoria a carnivoria a medida que se desarrollaban, depredando principalmente sobre nauplii y copepoditos calanoideos. Aunque el exito alimentario fue similar para cada estado de desarrollo en la columna de agua, la dieta de larvas en preflexion y flexion estuvo basada en diferentes items presa dentro de los primeros 3-4 m de la columna de agua (superficie y picnoclina) con respecto de aguas mas profundas (7-10 m, cerca del fondo). Esto sugiere que la picnoclina pudiera afectar la composicion de la dieta de larvas pequenas de M. viridis, pero no el tamano, numero o volumen de presas ingeridas. Ademas, ya que el forrajeo esta basado predominantemente en diferentes estados de desarrollo de copepodos, las larvas que emergen durante vaciante pueden incrementar la adveccion fuera del estuario hacia zonas costeras cercanas, indicando que esta especie no es un usuario frecuente del estuario durante su desarrollo larval.

Planktonic duration in fourteen species of intertidal rocky fishes from the south-eastern Pacific Ocean

The planktonic duration (PD) was determined in fourteen intertidal rocky fishes from the south-eastern Pacific Ocean by counting the otolith micro-increments from hatch check to a transition mark (TM). TMs were validated by comparing the PDs estimated from post-settlers with the total increment counts from otoliths of more recent (new) settlers. In 11 species (79%), the most common TM corresponded to a notable decrease in increment width after settlement. The PDs ranged from 45 days in the kyphosid Girella laevifrons to 135 days in the labrisomid Auchenionchus variolosus, and eight species (57%) had mean PDs of longer than three months. The mean observed size-at-settlement (SASM) values ranged from 17.5 ± 7.2 mm TL in Gobiesox marmoratus (Gobiesocidae) to 40 ± 5.5 mm TL in Calliclinus geniguttatus (Labrisomidae) and showed low variability within species of the same family. PDs were markedly longer in intertidal rocky fishes than in other littoral and reef fishes in tropical and temperate waters. A lengthy and variable duration of the pre-settlement phase, along with a relatively consistent size-at-competence within closely related species, are suggested as mechanisms through which these fishes may increase their probability to settle in the spatially restricted habitat of exposed rocky pools.