Marine zooplankton volumes and ichthyoplankton distribution during summer 2006 in the Peruvian littoral

Los volúmenes de zooplancton variaron de 0,3 a 150 mL/m2, en dos núcleos: a) entre Caleta La Cruz y Chimbote y b) al sur de San Juan. Se determinaron 53 familias de ictioplancton, las más frecuentes fueron Engraulidae (31%), Myctophidae (18%) y Photichthyidae (16%). Huevos y larvas de anchoveta se distribuyeron desde caleta La Cruz hasta Matarani. Huevos en concentraciones importantes frente a bahía de Sechura, Salaverry y Supe y larvas frente a Chicama y Supe. La abundancia fluctuó de 3 a 26.385 huevos/m2 (47,7% de frecuencia), y de 3 a 6.210 larvas/m2 (66,4% de frecuencia). Tamaño de larvas varió de 1,5 a 20 mm (recién nacidas a 37 días de vida). La mayor frecuencia de tallas estuvo entre 2 y 4 mm en las áreas B y D, el área C presentó mayor rango de tallas. Huevos y larvas de Vinciguerria lucetia cercanos a la costa de Caleta La Cruz-Paita, (ingreso de Aguas Subtropicales Superficiales) y al sur del Callao. Especies con baja abundancia: merluza, sardina, perico; caballa y jurel, registradas en el norte y centro a excepción de la sardina que se presentó frente a San Juan

ABUNDANCIA, FRECUENCIA Y DISTRIBUCIÓN DE EUFAUSIDOS FRENTE A LA COSTA NORTE DEL

Se analizó la distribución, abundancia y frecuencia de eufáusidos de la costa norte del mar del Perú, desde Punta Sal (4°S) hastaHuarmey (10°S) durante el verano 2011-12 a bordo del RV Kaiyo Maru. Las muestras se colectaron mediante una Red Bongo operada en arrastres oblicuos desde 30m de profundidad hacia la superficie con barco en movimiento, provista con mallas de 350 micras de abertura. Se determinaron 5 especies y 3 hasta nivel de género, siendo la más abundante Euphausia mucronata con una abundancia relativa del 45,29%, seguida de E. eximia con 17,64% y Euphausia sp. con el 15,95%. A diferencia de la abundancia, la especie más frecuente fue E. eximia presente en el 16,98%, seguida por E. mucronata y Nematoscelis sp., ambas con una frecuencia del 11,32%. Se observó que E. mucronata estuvo distribuida en casi toda el área explorada, asociada principalmente a Aguas Costeras Frías, (ACF) en tanto que otras como E. eximia mostraron una relación con Aguas Subtropicales Superficiales (ASS). Por otro lado E. tenera y Nematoscelis sp no se definieron por ninguna de estas dos masas de agua en particular, presentando una mayor afinidad en las zonas de mezcla entre ella

Variabilidad espacial y temporal de larvas de jurel Trachurus murphyien el Perú entre 1966 –2010

Constant presence of Jack mackerel Trachurus murphyilarvae in the Peruvian sea between 1966 and 2010 was confirmed by an analysis of their spatial and temporal variability. In general, there is a slight positive trend in abundance of Jack mackerelT. murphyilarvae, with noticeable changes in their spatial distribution and high interannual variability. High abundance of larvae is observed in some years, which are usually followed by a longer sequence of poor abundance years. Yearly averages varied between 3 and 79 larvae/m 2 . The spatial distribution of average larvae density showed three notorious periods along time: the first between 1970 and 1979 with higher larvae densities south of 14°S; the second between 1980 and 1999 with the higher densities to the north of 14°S; and the third between 2000 and 2010 with higher densities south of 18°S. The displacement of the centers of gravity of the spatial distribution marked three noticeable periods: between 1966 and 1978 were more coastal, south of 14°S; between 1979 and 1994 more oceanic and north of 14°S; and between 1995 and 2010 which were at an intermediate position. The relationship of larvae density with oceanographic variables as well as with the distribution of adult and juvenile Jack mackerel T. murphyiare discussed, stressing the observation that there is a main center of permanent spawning activity of this species in Peruvian watersEl análisis espacial y temporal de larvas de jurel Trachurus murphyien el mar peruano entre los años 1966 y 2010 confirma su presencia constante durante todo el periodo estudiado. En general, en este periodo la abundancia de larvas de jurel T. murphyimuestra una tendencia ligeramente ascendente destacándose cambios en la distribución espacial y una alta variabilidad interanual, con cortos periodos de alta abundancia promedio, intercalados con periodos más prolongados y de baja abundancia. El promedio anual estimado varió entre 3 y 79 larvas/ m2 . La distribución espacial presentó tres periodos importantes: uno con mayores densidades de larvas al sur de los 14°S, entre 1970 y 1979; cambió hacia el norte de esta latitud, entre 1980 y 1999; y otro de mayor densidad al sur de los 18°S, en el último periodo 2000 – 2010. Los centros de gravedad de la distribución de larvas presentaron tres periodos muy notorios: fueron más costeros hacia el sur de los 14°S, entre 1966 y1978; más oceánicos y al norte de los 14°S, entre 1979 y 1994; y con una posición intermedia entre 1995 – 2010. Se discute la relación entre la distribución de las larvas con las variables oceanográficas y la distribución de T. murphyiadultos y juveniles, además se destaca que el mar del Perú es un centro principal y permanente de actividad reproductiva de esta especie

Spatial patterns of Anchoveta (Engraulis ringens) eggs and larvae in relation to p CO 2 in the Peruvian upwelling system

Large and productive fisheries occur in regions experiencing or projected to experience ocean acidification. Anchoveta (Engraulis ringens) constitute the world's largest single-species fishery and live in one of the ocean's highest pCO2 regions. We investigated the relationship of the distribution and abundance of Anchoveta eggs and larvae to natural gradients in pCO2 in the Peruvian upwelling system. Eggs and larvae, zooplankton, and data on temperature, salinity, chlorophyll a and pCO2 were collected during a cruise off Peru in 2013. pCO2 ranged from 167-1392 µatm and explained variability in egg presence, an index of spawning habitat. Zooplankton abundance explained variability in the abundance of small larvae. Within the main spawning and larva habitats (6-10°S), eggs were found in cool, low-salinity, and both extremely low (less than 200 µatm) and high (more than 900 µatm) pCO2 waters, and larvae were collected in warmer, higher salinity, and moderate (400-600 µatm) pCO2 waters. Our data support the hypothesis that Anchoveta preferentially spawned at high pCO2 and these eggs had lower survival. Enhanced understanding of the influence of pCO2 on Anchoveta spawning and larva mortality, together with pCO2 measurements, may enable predictions of ocean acidification effects on Anchoveta and inform adaptive fisheries management

The anchovy spawning biomass in the north central zone of peruvian sea (4o36,5’ – 14o40’s) at the late austral winter 2005

5 p.La biomasa desovante entre Punta Infiernillos (14O40’S) y Paita (4°36,5S) fue estimada en 6,1 millones de toneladas (límites de confianza del 95% de 42,29%), y un coeficiente de variación de 21,15%. El peso promedio de las hembras (W) fue 16,27 g, la fecundidad parcial (E), 11.386 ovocitos/hembra, con una proporción sexual (R) de 0,51 y una frecuencia de desove de 0,0984.IMARP

Descripción morfológica y organoléptica de frutos de mango (Mangifera indica L.) cultivados en el cantón Jipijapa en Ecuador

In the year 2016, seventeen cultivars of mango (Mangifera indica L.) were collected in local markets and farmers'field of Jipijapa Canton, Ecuador, with the aim of describing and analyzing mango fruits due to their morphologicalcharacteristics of sugars (°Brix) and total solids. Collections were carried out by students and teachers of the ResearchMethodologies course of the Agricultural Engineering Career, of the Southern State University of Manabí(UNESUM). The fruits were characterized by using 16 qualitative and quantitative variables for fruit and seed recommended by UPOV and IPGRI. The percentage of total solids and Brix grades of each harvested crop were alsoanalyzed in the UNESUM bromatology laboratory. Results showed that in the Jipijapa Canton, Ecuador, there is agreat biodiversity of native mangoes, which were not characterized. Fruit shapes, pulp color and variable fiber contents were observed. The length of fruit was 6.33 to 12.50 cm, and the width was 5.27 to 8.50 cm, with a length/widthratio between 0.77 and 1.83 cm. The fruit weight was 63.3 to 500 g. No significant differences were observed in thesugars content (°Brix). Finally, it was observed that the range of consumable pulp was 63 to 94% in native cultivarsand 86% to 97% in the improved ones.(UNESUM), km 11/2 vía Noboa s/nCampus los Ángeles, Jipijapa, Ecuador. 2Facultad de Ciencias Naturales y de laAgricultura, Universidad Estatal del Surde Manabí (UNESUM), km 11/2 víaNoboa s/n Campus los Ángeles, Jipijapa, Ecuador. 3Laboratorio de Bromatología de la Universidad Estatal del Sur de Manabí (UNESUM), km 11/2 vía Noboa s/n Campus los Ángeles, Jipijapa, Ecuador. *Dirección de contacto: 1Facultad de Ciencias Naturales y de laAgricultura, Universidad Estatal del Surde Manabí (UNESUM), km 11/2 víaNoboa s/n Campus los Ángeles, Jipijapa, Ecuador. Telf. 05-2600229. Julio Gabriel Ortega E-mail address : [email protected], Julio.gabriel@[email protected] el año 2016, fueron colectados 17 cultivares de mango (Mangifera indica L.) en mercados locales y fincas deagricultores del Cantón Jipijapa, Ecuador, con el objetivo de describir morfológicamente y organolépticamente losfrutos de mango de cultivares colectados. Las colectas fueron realizadas por estudiantes y docentes de la asignatura demetodologías de la investigación de la Carrera de Ingeniería Agropecuaria, de la Universidad Estatal del Sur deManabí (UNESUM). Los frutos fueron caracterizados utilizando 16 variables cualitativas y cuantitativas para fruto ysemilla recomendados por la UPOV y el IPGRI. También se analizó en el laboratorio de bromatología de laUNESUM el porcentaje de sólidos totales y el contenido de azúcares (°Brix) de cada cultivar recolectado. Los resultados mostraron que en el Cantón Jipijapa, Ecuador, existe una gran biodiversidad de mangos nativos, que no fueroncaracterizados. Se observó formas de frutos, color de pulpa y contenidos en fibra variables. La longitud de fruto fue6.33 a 12.50 cm, y el ancho fue 5.27 a 8.50 cm, con una relación de longitud/ancho entre 0.77 a 1.83 cm. El peso defruto fue de 63.3 a 500 g. En el contenido de azúcares (°Brix) no se observó diferencias notables. Finalmente seobservó que el rango de pulpa consumible fue de 63 a 94% en los cultivares nativos y de 86 a 97% en los mejorados

Factors controlling plankton community production, export flux, and particulate matter stoichiometry in the coastal upwelling system off Peru

Eastern boundary upwelling systems (EBUS) are among the most productive marine ecosystems on Earth. The production of organic material is fueled by upwelling of nutrient-rich deep waters and high incident light at the sea surface. However, biotic and abiotic factors can modify surface production and related biogeochemical processes. Determining these factors is important because EBUS are considered hotspots of climate change, and reliable predictions of their future functioning requires understanding of the mechanisms driving the biogeochemical cycles therein. In this field experiment, we used in situ mesocosms as tools to improve our mechanistic understanding of processes controlling organic matter cycling in the coastal Peruvian upwelling system. Eight mesocosms, each with a volume of ∼55 m3, were deployed for 50 d ∼6 km off Callao (12∘ S) during austral summer 2017, coinciding with a coastal El Niño phase. After mesocosm deployment, we collected subsurface waters at two different locations in the regional oxygen minimum zone (OMZ) and injected these into four mesocosms (mixing ratio ≈1.5 : 1 mesocosm: OMZ water). The focus of this paper is on temporal developments of organic matter production, export, and stoichiometry in the individual mesocosms. The mesocosm phytoplankton communities were initially dominated by diatoms but shifted towards a pronounced dominance of the mixotrophic dinoflagellate (Akashiwo sanguinea) when inorganic nitrogen was exhausted in surface layers. The community shift coincided with a short-term increase in production during the A. sanguinea bloom, which left a pronounced imprint on organic matter C : N : P stoichiometry. However, C, N, and P export fluxes did not increase because A. sanguinea persisted in the water column and did not sink out during the experiment. Accordingly, export fluxes during the study were decoupled from surface production and sustained by the remaining plankton community. Overall, biogeochemical pools and fluxes were surprisingly constant for most of the experiment. We explain this constancy by light limitation through self-shading by phytoplankton and by inorganic nitrogen limitation which constrained phytoplankton growth. Thus, gain and loss processes remained balanced and there were few opportunities for blooms, which represents an event where the system becomes unbalanced. Overall, our mesocosm study revealed some key links between ecological and biogeochemical processes for one of the most economically important regions in the oceans

Life in the fast lane: Revisiting the fast growth—High survival paradigm during the early life stages of fishes

Early life survival is critical to successful replenishment of fish populations, and hypotheses developed under the Growth-Survival Paradigm (GSP) have guided investigations of controlling processes. The GSP postulates that recruitment depends on growth and mortality rates during early life stages, as well as their duration, after which the mortality declines substantially. The GSP predicts a shift in the frequency distribution of growth histories with age towards faster growth rates relative to the initial population because slow-growing individuals are subject to high mortality (via starvation and predation). However, mortality data compiled from 387 cases published in 153 studies (1971–2022) showed that the GSP was only supported in 56% of cases. Selection against slow growth occurred in two-thirds of field studies, leaving a non-negligible fraction of cases showing either an absence of or inverse growth-selective survival, suggesting the growth-survival relationship is more complex than currently considered within the GSP framework. Stochastic simulations allowed us to assess the influence of key intrinsic and extrinsic factors on the characteristics of surviving larvae and identify knowledge gaps on the drivers of variability in growth-selective survival. We suggest caution when interpreting patterns of growth selection because changes in variance and autocorrelation of individual growth rates among cohorts can invalidate fundamental GSP assumptions. We argue that breakthroughs in recruitment research require a comprehensive, population-specific characterization of the role of predation and intrinsic factors in driving variability in the distribution and autocorrelation of larval growth rates, and of the life stage corresponding to the endpoint of pre-recruited life. -- Keywords : critical period ; growth-mortality ; individual characteristics ; larval physiology ; predation ; recruitment endpoint

Zooplankton of the low-oxygen waters of Bahia Callao (Central Peru) - with special reference to the reproductive activity of the copepod Acartia tonsa

Zooplankton distribution in the Bahia Callao, a low oxygen bay in Central Peru, was studied during surveys in March (austral summer) and September (austral spring) 2006. In March temperature was higher, but oxygen concentrations were much lower, especially near the sea floor. Zooplankton abundance at 14 repeated stations (March/September = 457/2356 ind. m−3), taxa number (35/97), and community composition changed drastically, but Acartia tonsa was dominant during both surveys. In contrast, abundance of meroplanktonic larvae did not change. The reproductive activity of A. tonsa was studied bi-weekly from November 2005 to August 2007 at a fixed station close to shore (9 m water depth). Population egg production rate ranged from 0.9 to 12.6 eggs female−1d−1 and was significantly related to Chlorophyll a, temperature, and dissolved oxygen. Individual clutch size ranged from 1 to 43 eggs. Egg hatching rate varied from 3.4 to 100%; the lowest values were associated with very low concentrations of dissolved oxygen in the surface layer and red tides. In feeding experiments at saturated oxygen concentrations >30 eggs female−1d−1 were produced, indicating continuous inhibition of egg production in the field. Oceanographic data demonstrate that the bay, and probably also the adjacent shelves, are exposed to frequent environmental changes, which challenge the survival and production of zooplankton and fish. The relationship between seemingly adverse environmental conditions and high biological productivity still needs to be understood

Apropiación social de las bibliotecas por jóvenes de bachillerato de la Universidad de Guadalajara

En una pretendida sociedad de la información y el conocimiento, las bibliotecas pueden entenderse como espacios clave para que los alumnos y profesores accedan a amplios universos de información, de manera gratuita y en formatos diversos. En el caso de la Universidad de Guadalajara, los datos oficiales indican que pese al esfuerzo realizado por mejorar los servicios que ofrecen sus bibliotecas escolares -a partir de fuertes inversiones en equipamiento tecnológico y acervos tanto impresos como electrónicos-, éstos son poco utilizados por los estudiantes de nivel medio superior. En este contexto, nos preguntamos de qué manera se apropian de las bibliotecas los estudiantes de bachillerato de la Universidad de Guadalajara, así como qué tipo de prácticas académicas y cotidianas llevan a cabo en esos espacios y cómo contribuye lo anterior al desarrollo de hábitos informativos que propician cambios socioculturales