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  • 1
    Publication Date: 2021-05-19
    Description: Ichthyoplankton was sampled in 9 exploratory cruises in the sea off Buenos Aires province (Argentina), Uruguay and Brazil, during the spawning peak of the anchovy in spring-early summer and mid-autumn. The most abundant speices in the ichthyoplankton was Engraulis anchoita, representing 88. of the eggs and 76. of the larvae collected in all the cruises. These percentages vary boath regionally and seasonally; as regards eggs, the lowest percentage (10. ) was found in January. The distribution of anchovy eggs and larvae, covered almost entirely the surveyed area, with the exception of hte region influenced by the River Plate estuary. Minimum salinity tolerance for the species eggs was 23.5o/oo. The eastern limit of the distribution of anchovy eggs, extends in spring-early summer to the 200 m isobath in the northern part of the study area, whereas in the south rarely extends beyond the 50 m isobath. Anchovy larvae showed a wider distribution, penetrating in November and December in the brackish waters of the Samborombón bay, extending over more off-shore waters in January. As the spawning season progressed a southwards movement of intensive reproduction nuclei was observed. The average daily egg production during spring-early summer was estimated at 260 anchovy eggs/m2/day; in autumn, a ten-fold reduction of this production was observed. On the basis of the seasonal egg production for spring-early summer, calculated at 3.5238 E15 eggs and the larvae census carried out in mid-January a 98.2. mortality during the imbryonic and larval stages of the anchovy could be assumed. The spawning biomass of the anchovy during this period was calculated at 2,514,970 t. Preliminary results on the vertical distribution of anchovy eggs and larvae show that their distribution is generally restricted to the upper 50 m water layer, with higher concentrations at 10 to 25 m depths.
    Description: Publisher permission
    Description: Published
    Description: Clupeiformes, Engraulidae, evaluación de efectivos, huevos de peces, distribución vertical, poblaciones desovantes
    Keywords: Vertical distribution ; Fish eggs ; Spawning populations
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 2
    Publication Date: 2021-05-19
    Description: A bongo sampler fifted with nets of two different mesh sizes, 330 and 505 u. was used to collected 137 ichthyoplankton samples in the coastal areas off Buenos Aires Province in October, 1981. The efficiency of the two meshes for catching anchovy eggs and larvae and total ichthyoplankton was examined. The statistical analysis of the samples shows that there are no significant differences between the numbers of anchovy and total eggs collected by the different meshes. As regards anchovy and total larvae the finer mesh showed as significantly higher catching efficiency. The results of this partial estimate do not suggest that a major revision of the total assessment of the complete stock is necessary.
    Description: Publisher permission
    Description: Published
    Description: Clupeiformes, Engraulidae, Engraulis anchoita, evaluación de efectivos, huevos de peces
    Keywords: Stock assessment ; Stock assessment ; Fish eggs
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 3
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    Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP)
    Publication Date: 2021-05-19
    Description: Fecundity and spawning frequency were estimated in the northern(off Buenos Aires Province)and southern (patagonian)argentine anchovy Engraulis anchoita populations in 1993, during the peak of the spawning season. Relative fecundity, expressed as eggs per ovary-free weight was 574±21 (CI 95. ) and 605±49 (CI 95. ) in the northern and southern populations. The difference was not statistically significant between stocks (P0.13). Relative fecundity was higher in anchovies larger than 130 mm. The mean batch fecundity for the northern and southern populations was 13675±856 (CI 95. ) and21677±2.753 (CI 95. ) respectively. Batch fecundity (F)expressed as alinear function of ovary-free weight (W)was: F=-1310+649 * W(northern), F=-5935+786 * W (southern). The daily spawning incidence was estimated in 12,6. ±3.3 (CI 95. ) for the northern population and 15,5. ±8.5 (CI 95. ) for the southern. The females spawned about every 7.9 and 6.5 days respectively. A low incidence of alpha and bethastages atresia in ovaries was founded in both populations (less than 2. yolked oocytes affected). Relative egg production for anchovies ages 1-2 and ages 2-3 were estimated to contribute 74. and 64. to egg production in the northern and southern stocks during the peak of the spawning season. It was observed a direct relationship between collections with male-dominated schools and females with hidrated and recent post-ovulattory follicles.
    Description: Publisher permission
    Description: Published
    Description: Engraulidae, Engraulis anchoita, anchoíta, ovarios, fecundidad, estaciones de desove, huevos de peces, poblaciones desovantes
    Keywords: Ovaries ; Fecundity ; Ovaries ; Fecundity ; Spawning populations ; Fish eggs ; Spawning seasons
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 4
    Publication Date: 2021-05-19
    Description: Ichthyoplankton samples were collected during an exploratory cruise carried out by the RV Dr.Holmberg during the spring spawning peak of 1981 in the sea-shelf off Buenos Aires province (Argentina). The cruise was designed to carry out population studies in a restricted area of intense reproduction activity, in order to gather information on the time-space patterns of distribution of the eggs and larvae of the species.
    Description: Publisher permission
    Description: Published
    Description: Clupeiformes, Engraulidae, larvas de peces, huevos de peces, curvas de crecimiento, condiciones controladas, mortalidad
    Keywords: Fish larvae ; Mortality ; Fish larvae ; Mortality ; Growth curves ; Controlled conditions ; Fish eggs
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 5
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    Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP)
    Publication Date: 2021-05-19
    Description: Lagrangian changes in distribution and survival within an anchovy egg and larvae patch were studied by means of multiple opening/closing sampling following a free drifting buoy. The buoy was equipped with a radar reflector and flashing light, and it was connected to a current cross drogue floating at 15 m depth, which corresponded to the main egg and larvae concentration within the patch. The drifter was launched on the Buenos Aires continental shelf, off Necochea during the spring spawning peak of 1983. Three discrete depths (within, below and above the thermocline)were repeatedly sampled close to the drogue with a Motoda sampler. Egg and larval abundances in the vicinity of the drogue were monitored at 3/4 hour intervals for a period of three days. Each plankton station included a set of hydrographic and climatological data registered simultaneously. The efficiency of the drogue as a Lagrangian marker was examined by means of the application of multifactorial ANOVA to test the significance of variability between days, light regime, sampling depths, population structure and their interactions. Wind drag on the surface unit did not significantly affect the trajectory of the drogue. Patterns of embryonic and larval vertical distribution are discussed by means of the variations in the centre of mass, in the vertical dispersion and patchiness indexes for each developmental stage analyzed. There is evidence of diel vertical migration in larvae larger than 8 mm SL. Although the incidence of feeding based on observations of the presence of undigested food in the gut content of larvae was low, a daily feeding pattern over a 14-hour period starting after sunrise, was evident. Evening ascent of larger larvae was not related to feeding activity. A single equation two-stage model, assuming age dependent mortality in the embryonic and post-larval period is derived and compared to standard models based on constant exponential decay during each developmental phase.
    Description: Publisher permission
    Description: Published
    Description: Engraulidae, Engraulis anchoita, anchoíta, relevamientos ictioplanctónicos, relevamientos pesqueros, larvas de peces, huevos de peces, distribución vertical, abundancia, boyas a la deriva, efectos ambientales, alimentación, supervivencia, migraciones verticales
    Keywords: Feeding ; Fish larvae ; Survival ; Fish larvae ; Fish eggs ; Vertical migrations ; Feeding ; Environmental effects ; Ichthyoplankton surveys ; Vertical distribution ; Survival ; Abundance ; Drifting data buoys ; Fishery surveys
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 6
    Publication Date: 2021-05-19
    Description: This dissertation is focused on the study of implications of spatial patterns on survival of eggs and larvae and subsequent recruitment of the SW Atlantic anchovy, Engraulis anchoita. The study of distribution patterns is encompassed within the conceptual framework of the analysis of reproductive strategies of marine bony fish, as adaptations that enable them to cope with and actively exploit environmental variability, regulating their abundance and avoiding extinction. The SW Atlantic anchovy, is ideally suitable for studies on reproductive biology and recruitment on a comparative basis. Its spawning and nursery grounds are located in very diverse ecosystems. This variety refers to their physico-chemical properties, carrying capacity, the influence of several water masses, and the contribution of fresh water runoffs from different origins. Important physical features are seasonal thermocline formation, and the presence of transitional regions such as oceanic, shelf-break and tidal shelf fronts, and upwelling areas. The aim of this dissertation was to study the biological response to that environmental heterogeneity. The central issue of the discussion was the implication of that apparent lack of association between reproductive activity and environmental conditions, on the rates of growth and mortality during the early developmental stages, and subsequent recruitment. As a working hypothesis the existence of some degree of dependence between those population attributes and the evolution of the distributional patterns during the early ontogeny was postulated. To prove this assumption distributions were studied not only in their usual connotation (i.e. spatial arrangement, geographic location), but also in their ecological and statistical sense, in a variety of time-space scales, from the Eulerian and Lagrangian perspectives. The final outcome, based on the identification of factors influencing the survival of the early developmental stages of the species, was the derivation of models that could describe mechanisms of demographic regulation.
    Description: Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales.
    Description: Tesis (Doctorado). Copia en PDF: portada, índice, resumen, referencias bibliográficas.
    Description: Engraulis anchoita, Engraulidae, huevos, larvas de peces, ictioplancton, biomasa, reproducción, distribución, desarrollo de estadíos, desarrollo larval, desarrollo embrionario, mortalidad, evaluación de efectivos, condiciones ambientales
    Keywords: Biomass ; Developmental stages ; Stock assessment ; Fish larvae ; Reproduction ; Mortality ; Environmental conditions ; Fish eggs ; Fish larvae ; Recruitment ; Ichthyoplankton ; Biomass ; Reproduction ; Developmental stages ; Mortality ; Stock assessment ; Environmental conditions
    Repository Name: AquaDocs
    Type: Theses and Dissertations
    Format: 7135732 bytes
    Format: application/pdf
    Format: 630
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  • 7
    Publication Date: 2021-05-19
    Description: This paper reviews the information on pelagic and demersal fish eggs and larvae, describing the distribution and seasonality of different species and their arrangement in icthyoplankton assemblages in the Southern patagonian waters. It also reports on 11 surveys conducted by INIDEP during 1992-1995. A total of 488 ichthyoplankton samples were analyzed. Fish eggs have been recognized in 47. of all ichthyoplankton samples. They belong to three species: Coelorhynchus fasciatus, Macrourus whitsoni and Micromesistius australis. Fish larvae of 23 species and 17 families have been identified in 96. of all samples analyzed. Spawning of most species begins in autumn, and progresses through winter, when the southern blue whiting and grenadier fish contribute to more than half of all eggs present in our samples. Nototheniid and myctophiid larvae were caught during all year long. Four larval groups were detected using cluster analysis: the first group, formed exclusively by nototheniids, which occupied a vast area on the continental shelf between 100 and 200 m depth, the second formed by Agonopsis chiloensis, Eleginops maclovinus, Macruronus magellanicus and Sprattus fuegensis in coastal waters, the third formed by myctophiids, Gymnoscopelus spp. and Micromesistius australis, inhabit the outer continental shelf and slope, and the fourth included Protomyctophum spp., Krefftichthys anderssoni and Bathylagus antarcticus, species typically found in Subantarctic waters of the Malvinas Current. Comparing the distribution of eggs and larvae of blue whiting from collections obtained during the 70's and 80's, with those of recent surveys, it is evident, that a significant contraction of the spawning grounds of the species has take place, particularly to the west of the archipelago.
    Description: Sánchez, R.P.; ed. 1999. Reproductive habitat, biology and acoustic biomass estiomates of the southern blue whiting (Micromesistius australis) in the sea off southern patagonia. INIDEP Documento Científico, 5: 93 p.
    Description: Published
    Description: larvas de peces, huevos de peces, distribución estacional, abundancia de asociaciones, ictioplancton
    Keywords: Fish larvae ; Ichthyoplankton ; Fish larvae ; Fish eggs ; Seasonal distribution ; Abundance
    Repository Name: AquaDocs
    Type: Journal Contribution
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  • 8
    Publication Date: 2011-08-24
    Description: An improved model of Earth's gravitational field, Goddard Earth Model T-3 (GEM-T3), has been developed from a combination of satellite tracking, satellite altimeter, and surface gravimetric data. GEM-T3 provides a significant improvement in the modeling of the gravity field at half wavelengths of 400 km and longer. This model, complete to degree and order 50, yields more accurate satellite orbits and an improved geoid representation than previous Goddard Earth Models. GEM-T3 uses altimeter data from GEOS 3 (1975-1976), Seasat (1978) and Geosat (1986-1987). Tracking information used in the solution includes more than 1300 arcs of data encompassing 31 different satellites. The recovery of the long-wavelength components of the solution relies mostly on highly precise satellite laser ranging (SLR) data, but also includes Tracking Network (TRANET) Doppler, optical, and satellite-to-satellite tracking acquired between the ATS 6 and GEOS 3 satellites. The main advances over GEM-T2 (beyond the inclusion of altimeter and surface gravity information which is essential for the resolution of the shorter wavelength geoid) are some improved tracking data analysis approaches and additional SLR data. Although the use of altimeter data has greatly enhanced the modeling of the ocean geoid between 65 deg N and 60 deg S latitudes in GEM-T3, the lack of accurate detailed surface gravimetry leaves poor geoid resolution over many continental regions of great tectonic interest (e.g., Himalayas, Andes). Estimates of polar motion, tracking station coordinates, and long-wavelength ocean tidal terms were also made (accounting for 6330 parameters). GEM-T3 has undergone error calibration using a technique based on subset solutions to produce reliable error estimates. The calibration is based on the condition that the expected mean square deviation of a subset gravity solution from the full set values is predicted by the solutions' error covariances. Data weights are iteratively adjusted until this condition for the error calibration is satisfied. In addition, gravity field tests were performed on strong satellite data sets withheld from the solution (thereby ensuring their independence). In these tests, the performance of the subset models on the withheld observations is compared to error projections based on their calibrated error covariances. These results demonstrate that orbit accuracy projections are reliable for new satellites which were not included in GEM-T3.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B2; p. 2815-2839
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  • 9
    Publication Date: 2011-08-19
    Description: The GEM-T2 is the latest in a series of Goddard Earth Models of the terrestrial field. It was designed to bring modeling capabilities one step closer towards ultimately determining the TOPEX/Poseidon satellite's radial position to an accuracy of 10-cm RMS (root mean square). It also improves models of the long wavelength geoid to support many oceanographic and geophysical applications. The GEM-T2 extends the spherical harmonic field to include more than 600 coefficients above degree 36 (which was the limit for its predecessor, GEM-T1). Like GEM-T1, it was produced entirely from satellite tracking data, but it now uses nearly twice as many satellites (31 vs. 17), contains four times the number of observations (2.4 million), has twice the number of data arcs (1132), and utilizes precise laser tracking from 11 satellites. The estimation technique for the solution has been augmented to include an optimum data weighting procedure with automatic error calibration for the gravitational parameters. Results for the GEM-T2 error calibration indicate significant improvement over previous satellite-only models. The error of commission in determining the geoid has been reduced from 155 cm in GEM-T1 to 105 cm for GEM-T2 for the 36 x 36 portion of the field, and 141 cm for the entire model. The orbital accuracies achieved using GEM-T2 are likewise improved. Also, the projected radial error on the TOPEX satellite orbit indicates 9.4 cm RMS for GEM-T2, compared to 24.1 cm for GEM-T1.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 22043-22
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  • 10
    Publication Date: 2019-06-28
    Description: This report documents progress to date in an ongoing study to analyze and model emissions leaving a proposed High Speed Civil Transport (HSCT) from when the exhaust gases leave the engine until they are deposited at atmospheric scales in the stratosphere. Estimates are given for the emissions, summarizing relevant earlier work (CIAP) and reviewing current propulsion research efforts. The chemical evolution and the mixing and vortical motion of the exhaust are analyzed to track the exhaust and its speciation as the emissions are mixed to atmospheric scales. The species tracked include those that could be heterogeneously reactive on the surfaces of the condensed solid water (ice) particles and on exhaust soot particle surfaces. Dispersion and reaction of chemical constituents in the far wake are studied with a Lagrangian air parcel model, in conjunction with a radiation code to calculate the net heating/cooling. Laboratory measurements of heterogeneous chemistry of aqueous sulfuric acid and nitric acid hydrates are also described. Results include the solubility of HCl in sulfuric acid which is a key parameter for modeling stratospheric processing. We also report initial results for condensation of nitric acid trihydrate from gas phase H2O and HNO3.
    Keywords: GEOPHYSICS
    Type: NASA-CR-189688 , NAS 1.26:189688 , ARI-RR-902
    Format: application/pdf
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