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Estudos sobre Variabilidade de Amostragem, Distribui-cao e Abundancia de Larvas de Peixes da Regiao Sudes-te do Brasil; Study on sampling variability, distribution and abundance of fish larvae off the Southeastern Coast of Brazil

Katsuragawa, Mario
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/04/1985 PT
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Utilizando-se materiais coletados durante qua-tro cruzeiros oceanográficos com o N/Oc ."Prof. W. Besnard", na região Sudeste do Brasil, compreendida entre Cabo Frio (RJ) e Florianópolis (SC), de janeiro de 1980 a março de 1982, foram realizados estudos quali quantitativos so-bre ocorrências de larvas de peixes, relacionando-as com fatores abióticos. Problemas concernentes aos processos de amostragem tambem foram verificadas. Realizaram-se dois tipos de arrastos: arrasto oblíquo com a rede Bongo usando-se malhagens de 0,333 mm (fina) e de 0,505 mm (regular), e arrasto horizontal de superfície com a rede de Neuston, de 0,333 mm de malhagem. Em cada estação oceanográfica, alem das amostras biologicas, efetuaram-se as medições de temperatura e coleta de água para determinação de salinidade. Um total de 35.090 larvas foram analisadas, incluíndo as coletas das redes fina e regular da Bongo e a rede de Neuston. Dentre estas, 61 grupos diferentes foram separados, chegando a níveis específicos em alguns casos.- Dois gêneros e quatro especies foram identificados pela primeira vez na região: Saurida spp, Hygophum spp, Trachinocephalus myops, Synodus foetens Bregmaceros can-tori e Maurolicus muelleri. As famílias predominantes foram Clupeidae...

Desenvolvimento de micropartículas contendo Lactobacillus acidophilus para alimentação de larvas de pacu (Piaractus mesopotamicus); Use of microparticles containing Lactobacillus acidophilus for feeding pacu larvae (Piaractus mesopotamicus)

Juliana Bürger Rodrigues
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 08/02/2012 PT
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Este estudo teve como objetivo produzir micropartículas por gelificação iônica associada à interação eletrostática, contendo constituintes nutricionalmente importantes para a alimentação de larvas de peixes. Na primeira parte deste estudo, foram desenvolvidas micropartículas por gelificação iônica, utilizando-se pectina e cloreto de cálcio para a formação das matrizes. O recheio das micropartículas era constituído de proteínas do soro de leite, na sua forma não-desnaturada ou desnaturada, e óleo de soja adicionado de oleoresina de páprica. Nas partículas em que o recheio era constituído somente de óleo, a proteína de soro de leite foi incluída por meio da interação eletrostática na superfície da micropartícula. Além disto, avaliou-se a influência do teor de cálcio e do grau de amidação da pectina na incorporação proteica, nos teores de umidade e na morfologia das micropartículas. As micropartículas produzidas por gelificação iônica, seguidas de recobrimento com proteínas do soro de leite (WPC) por interação eletrostática, foram as que apresentaram os melhores teores de umidade e proteína. Na segunda parte do estudo, partículas produzidas por gelificação iônica, utilizando pectina de baixo grau de esterificação amidada...

Flux of decapod larvae and juveniles at a station in the lower Canal de Mira (Ria de Aveiro, Portugal) during one lunar month

Pereira, F.; Pereira, R.; Queiroga, H.
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
ENG
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Emigration and immigration of decapod larvae from estuaries depend on timing of larvae occurrence in the water column relative to the tidal, tidal amplitude and day cycles. The phase relation of these natural cycles varies with tidal regime and geographically, resulting in different time-patterns of hatching of first stage larvae and of presence of late stage larvae in the water column. Vertical migration behaviour according to phase of tide also controls transport inside estuaries. These mechanisms were investigated in a field study conducted on the northwest coast of Portugal where neap ebb tides occur during the night around the quarters of the moon. Flux of decapod larvae through one sampling station was measured during one lunar month at the Canal de Mira (Ria de Aveiro) in the spring of 1990. The sampling programme was comprised of a set of 25-h fixed station studies, separated by 25-h intervals during which no sampling took place. Plankton samples were collected with a pump every hour at three depths. Current velocity and direction at the standard depths, as well as height of the water column, were also measured every hour. Hourly instantaneous flux of larvae through a 1-m-wide vertical section of the Canal de Mira was calculated for the most abundant forms. A total number of 13 combinations of species and larval stages were analyzed...

The unexpected occurrence of late Sardina pilchardus (Walbaum, 1792) (Osteichthyes: Clupeidae) larvae in a temperate estuary

Morais, P.; Faria, Ana Margarida da Silva; Chícharo, Alexandra; Chícharo, Luís
Fonte: Universidade do Algarve Publicador: Universidade do Algarve
Tipo: Artigo de Revista Científica
Publicado em //2009 ENG
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The presence of sardine larval stages inside estuaries has generally been regarded as accidental and restricted to the lower part of estuaries. Sampling done with a zooplankton net in the Guadiana estuary corroborated this hypothesis. Late sardine larvae (32.8 ± 2.0 mm) were, however, unexpectedly collected with an otter trawl, 14 km upstream from the mouth of the estuary. Thus, this work intends to: (1) discriminate and compare the abiotic characteristics of the sites where maximum abundance of sardine larval stages were registered, when captured with a zooplankton net, with the characteristics of the sites where late sardine larvae were collected with an otter trawl; (2) demonstrate that the presence of the late sardine larvae inside the Guadiana estuary was not accidental. The average salinity of the site were late larvae where collected was 4.2 ± 2.3, i.e. 87.3% lower than the average salinity where maximum abundance of early larvae was registered. We suggest that the presence of the late sardine larvae inside the Guadiana estuary was not accidental. In order to migrate to that location and remain in the estuary, counteracting river inflow, these late larvae must have employed active migration and retention strategies. New methodologies need to be implemented for routine sampling of all larval stages of sardine...

Estimation of starvation and diet variation of the RNA/DNA ratios in field-caught Sardina pilchardus larvae off the north of Spain

Chícharo, Alexandra; Chícharo, Luís; Valdes, L.; Lopez-Jamar, E.; Re, P.
Fonte: Universidade do Algarve Publicador: Universidade do Algarve
Tipo: Artigo de Revista Científica
Publicado em //1998 ENG
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The aim of this study was to analyse the general larval condition, to determine the lncidence of starvation and to investigate the effect of time of day on RNA/DNA ratios among field-caught Sardina pilchardus (L.) larvae. The larvae were collected during 4 research cruises off northern Spain, during March, April, May and June 1992. A highly sensitive fluorometric method for nucleic acid quantification was applied to larvae of S. pilchardus. The means of the RNA/DNA ratio were relat~vely high, so the larvae collected off northern Spain were generally in good condition. Low percentages of starving larvae (RNA/DNA ratio less than 1.3), ranging from 0 to 3.23%, were found over the 4 mo. The RNA/DNA ratios were significantly correlated with zooplankton biomass. Larvae collected at night revealed higher RNA/DNA ratios compared to larvae caught during the day. This seems to indicate that there is some endogenous rhythm in the production of RNA. It would then follow that, if there are die1 changes in RNA concentrations, average RNA Indices can be unrepresentative if there IS any day/night bias in sampling.

Starvation percentages in field caught Sardina pilchardus larvae off southern Portugal

Chícharo, Alexandra
Fonte: Universidade do Algarve Publicador: Universidade do Algarve
Tipo: Artigo de Revista Científica
Publicado em //1997 ENG
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Starvation has been proposed as a major event only in small larvae that are learning to feed on planktonic prey. However, there are few comparisons of percentages of starving larvae either among locations, times or phases of larval development. The percentage of starvation of Sardina pilchardus larvae of different lengths was analysed in four distinct areas off southern Portugal. A highly sensitive fluorometric method for RNA/DNA quantification was applied to field caught S. pilchardus larvae during April and May 1992. Using in situ determination of critical RNA/DNA ratio (1.3), we classified as starving only a small percentage (2.22%) of first-feeding (<8 mm) sardine larvae, but bigger larvae appeared to be more vulnerable to starvation. We concluded that sardine larvae analysed were generally in good condition (total percentage of starving larvae - 4.64%), but with some variation within each region.

Larvae and post-larvae of Penaeidae and Palaemonidae in coastal lagoons of the North of Rio de Janeiro (Macaé, RJ)

ALBERTONI,E. F.; PALMA-SILVA,C.; ESTEVES,F. A.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/1999 EN
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The northern part of the state of Rio de Janeiro shelters many coastal lagoons, located, mostly, in the "restinga" strip that stretches from the municipality of Macaé to the municipality of Quissamã. During 1995 and 1996 samplings were made aiming to verify the diversity and density of Natantia larvae in the Imboassica, Cabiúnas and Comprida lagoons. The monthly samples were taken with a 500 µ net, in horizontal drags from a boat. In Comprida lagoon no larvae of any family of these crustaceans were found. In Cabiúnas lagoon, the autumn was the season of the year with greatest relative abundance, the larvae belonging to only one genus: Macrobrachium. In Imboassica Lagoon samples were taken in two situations related to the variation of the water level and contact with sea water: horizontal boat dragging when the sandbar (the strip of sand that separates the lagoon from the sea) was closed, larvae of Macrobrachium sp. being found, and no seasonal variation being detected, and horizontal manual dragging with open and closed sandbar conditions, in a region close to the sandbar. With the sandbar open, larvae and post-larvae of Penaeus paulensis and P. brasiliensis were found, the greatest abundances being found in the months of April/96 and May/95.

Spatial and temporal distribution of anopheline larvae in two malarious areas in Sucre State, Venezuela

Berti,Jesus; Zimmerman,Robert; Amarista,Jesus
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/1993 EN
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The spatial and temporal distribution of anopheline larvae was studied in two coastal malarious areas of Sucre, State, Venezuela. Seven habitat types were sampled in the village of Guayana and eight species of Anopheles were collected. Anopheles aquasalis was the predominant species collected and was most abundant in the brackish marsh habitat (71 larvae per 100 samples). It was most abundant during the rainy season. At the second location, Santa F e, six habitat types were sampled and four anopheline species were collected. Habitats where An. aquasalis was most abundant were temporary freshwater ponds (34 larvae per 100 samples) and mangroves (10.5 larvae per 100 samples). At this location it was also most abundant in the rainy season. During the dry season it was collected in small numbers in river pools (1.3 larvae per 100 samples) along with large numbers of An. pseudopunctipennis (479 larvae per 100 samples). Larval control could be an important component of the malaria control program because major habitats could be defined and presence and abundance of larvae was limited to specific times of year.

The use of morphological and histological features as nutritional condition indices of Pagrus pagrus larvae

Diaz,Marina Vera; Arano,Maria Felisa; Pajaro,Marcelo; Aristizabal,Eddie Oscar; Macchi,Gustavo Javier
Fonte: Sociedade Brasileira de Ictiologia Publicador: Sociedade Brasileira de Ictiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2013 EN
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Morphometrical and histological techniques were employed to characterize Pagrus pagrus larvae nutritional condition. Larvae were reared in laboratory under controlled conditions with the main objective of testing whether these methodologies allowed finding differences between larvae from different feeding treatments. Once yolk was consumed (three days after hatching) larvae were assigned to a feeding treatment: starved during the whole experiment; delayed feeding, starved during three days; fed during the entire experiment. Algae (Nannochloropsis oculata) and rotifers (Brachionus plicatilis) were provided to larvae for feed treatments. Larvae were fixed daily; for morphometrical purposes in 5% formaldehyde solution, and in Bouin for histological sections. Results herein obtained showed that both methodologies are sensitive enough to distinguish larvae characterized by different nutritional condition states obtained from the feeding treatments. Consequently, these methodologies could be employed in wild red porgy larvae in order to asses their nutritional condition. These techniques could also be employed to check larval quality obtained with aquaculture purposes to estimate the effects of changes in rearing protocols or kind of food supply and thus...

Damage to Raisins, Almonds, and Walnuts by Irradiated Indianmeal Moth and Navel Orangeworm Larvae (Lepidoptera: Pyralidae)

Johnson, Judy A.; Vail, Patrick V.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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Damage to raisins, almonds, and walnuts due to feeding by irradiated larvae of the Indianmeal moth, Plodia interpunctella (Hübner), and the navel orangeworm, Amyelois transitella (Walker), was determined. Larvae of both species were reared on bran diet. Age of the larvae when irradiated was 8 d for Indianmeal moth and 13 d for navel orangeworm. Larvae were irradiated with doses ranging from 337 to 497 Gy (gray) before transfer to almonds, walnuts, and raisins. Adult emergence was prevented by all doses. In products containing irradiated larvae, damage was consistently reduced. The percentage of weight losses of almonds infested with untreated Indianmeal moth and navel orangeworm larvae and of walnuts infested with untreated navel orangeworm larvae was significantly higher than the percentage of weight loss of those infested with irradiated larvae. Radiation also improved the overall appearance of the product by reducing webbing and frass. These results indicate that although radiation-induced mortality may be delayed, damage to product quality due to infestation by larvae would be significantly reduced.

Larvae and post-larvae of Penaeidae and Palaemonidae in coastal lagoons of the north of Rio de Janeiro (Macaé, RJ)

Albertoni, Edélti Faria; Palma-Silva, Cleber; Esteves, Francisco de Assis
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
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The northern part of the state of Rio de Janeiro shelters many coastal lagoons, located, mostly, i the “restinga” strip that stretches from the municipality of Macaé to the municipality of Quissamã During 1995 and 1996 samplings were made aiming to verify the diversity and density of Natanti larvae in the Imboassica, Cabiúnas and Comprida lagoons. The monthly samples were taken with 500 µ net, in horizontal drags from a boat. In Comprida lagoon no larvae of any family of these crus taceans were found. In Cabiúnas lagoon, the autumn was the season of the year with greatest rela tive abundance, the larvae belonging to only one genus: Macrobrachium. In Imboassica Lagoon sample were taken in two situations related to the variation of the water level and contact with sea water horizontal boat dragging when the sandbar (the strip of sand that separates the lagoon from the sea was closed, larvae of Macrobrachium sp. being found, and no seasonal variation being detected, an horizontal manual dragging with open and closed sandbar conditions, in a region close to the sandba With the sandbar open, larvae and post-larvae of Penaeus paulensis and P. brasiliensis were found the greatest abundances being found in the months of April/96 and May/95.

Experimental infections, using a fluorescent marker, of two elasmobranch species by unciliated larvae of Branchotenthes octohamatus (Monogenea: Hexabothriidae): invasion route, host specificity and post-larval development

Glennon, V.; Chisholm, L.; Whittington, I.
Fonte: Cambridge Univ Press Publicador: Cambridge Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
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The infection biology of Branchotenthes octohamatus (Monogenea: Hexabothriidae) from the gills of the southern fiddler ray, Trygonorrhina fasciata (Rhinobatidae), was studied using the fluorescent dye, 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE). This is the first use of this technique on a monogenean species with unciliated larvae and the first for any monogenean larva infecting an elasmobranch host. CFSE-labelled post-larvae were recovered from gills of T. fasciata within 30 min of exposure to the host, providing strong evidence that larvae invade host gills directly and do not migrate after initial attachment elsewhere. The rapidity with which larvae settled suggests that the mode of infection may deliver larvae directly to the gills via the host's inhalant respiratory current. The specificity of B. octohamatus was investigated by exposing a sympatric rhinobatid host species, the western shovelnose ray, Aptychotrema vincentiana, to B. octohamatus larvae newly emerged from eggs laid by adult parasites from gills of T. fasciata. Experimental exposure of A. vincentiana to freshly hatched B. octohamatus larvae resulted in a persistent infection, indicating that B. octohamatus may not be strictly host specific. Post-larval development charted on these experimentally infected A. vincentiana specimens was slow. Parasites appeared to be sexually mature at 91 days at 21–25°C. Branchotenthes octohamatus larvae bear only 4 pairs of hooklets on the haptor whereas all other hexabothriid larvae described so far have 5 hooklet pairs. Ontogenetic changes to the haptor revealed that it is probably hooklet pair III that is lost from B. octohamatus prior to larval development.; V. Glennon...

Performance of Anastrepha obliqua (Diptera, Tephritidae) larvae fed on artificial diets; Desempenho das larvas de Anastrepha obliqua (Diptera, Tephritidae) alimentadas com dietas artificiais

FONTELLAS-BRANDALHA, Tânia M. L.; CRESONI-PEREIRA, Carla; LEAL, Thamara A. B. S.; MEDEIROS, Luanda; ZUCOLOTO, Fernando S.
Fonte: Fundação Zoobotânica do Rio Grande do Sul Publicador: Fundação Zoobotânica do Rio Grande do Sul
Tipo: Artigo de Revista Científica
ENG
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Fruit flies of the genus Anastrepha Schiner, 1868 are well-known for having economical importance since they damage commercially cultivated fruits. Nutritional demands during the immature and adult stages are different, so the larvae do not develop well using the same diet as the adults. Although the insect basic nutritional needs are well-known, there is also the challenge to elaborate rearing diets adequate to species with specific needs. The aim of this study was to determine the effect on the Anastrepha obliqua (Macquart, 1835) larvae performance of different kinds and amounts of carbohydrates in the diet. Larvae were individually reared until pupation in test tubes containing one of the artificial diets to be tested. The basic composition of the diets to be tested included 2.5 g agar, 3.25 g brewer's yeast and several different amounts of flour and sucrose. The suitability of the artificial diet for A. obliqua was tested evaluating the larvae and pupae survival (%) and the larvae, pupae and larvae-adults periods of development. The diet containing flour (2 g) and sucrose (2 g) and the diet containing only sucrose (5.5 g) have shown the best results regarding larval performance. All tested diets presented similar or superior results as compared to diets used in other studies. The importance of flour and its nutritional value for the larvae was discussed.; Moscas das frutas do gênero Anastrepha Schiner...

The use of morphological and histological features as nutritional condition indices o Pagrus pagrus larvae

Diaz, Marina Vera; Arano, María Felis; Pajaro, Marcelo; Aristizabal Abud, Eddie Oscar; Macchi, Gustavo Javier
Fonte: Soc Brasileira Ictiologia Publicador: Soc Brasileira Ictiologia
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
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Con el objeto de determinar si las técnicas morfométricas e histológicas permiten diferenciar larvas en estado de inanición de las sometidas a tratamientos de alimentación, ejemplares de Pagrus pagrus fueron criados en laboratorio bajo condicion escontroladas. Una vez que el vitelo fue consumido (tres días luego de la eclosión) las larvas fueron sometidas a diferentes tratamientos de alimentación: completamente privadas de alimento, privadas de alimento durante tres días y luego alimentadas, y alimentadas durante todo el experimento. Algas (Nannochloropsis oculata) y rotíferos (Brachionus plicatilis) fueron proporcionados a las larvas de los tratamientos de alimentación. Diariamente se fijaron ejemplares de los tres tratamientos en formol 5% para estudios morfométricos y en Bouin para estudios histológicos. Los resultados obtenidos dan evidencias de que las metodologías presentadas son suficientemente sensibles para determinar diferencias en la condición de larvas sometidas a los tratamientos de alimentación. Por lo tanto, podrían ser empleadas para determinar la condición nutricional de las larvas de besugo recolectadas en el mar. Por otra parte, éstas metodologías podrían ser empleadas para determinar la calidad de larvas producidas en acuicultura y evaluar los efectos de modificaciones introducidas en los protocolos de crianza o en el tipo de alimento suministrado con el objeto de mejorar la supervivencia de los estadios tempranos de desarrollo.; Morphometrical and histological techniques were employed to characterize Pagrus pagrus larvae nutritional condition. Larvae were reared in laboratory under controlled conditions with the main objective of testing whether these methodologies allowed finding differences between larvae from different feeding treatments. Once yolk was consumed (three days after hatching) larvae were assigned to a feeding treatment: starved during the whole experiment; delayed feeding...

Otolith growth of European sea bass (Dicentrarchus labrax L.) larvae fed with constant or varying food levels; Crecimiento del otolito en larvas de lubina europea (Dicentrarchus Labrax, L.) bajo régimen de alimentación constante o variable

Aguilera, Belén; Catalán, Ignacio Alberto; Palomera, Isabel; Olivar, M. Pilar
Fonte: CSIC - Instituto de Ciencias del Mar (ICM) Publicador: CSIC - Instituto de Ciencias del Mar (ICM)
Tipo: Artículo Formato: 465840 bytes; application/pdf
ENG
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10 pages, 6 figures, 2 tables.; [EN] Otolith growth and the value and properties of the Recent Otolith Growth Index (ROGI) were studied in sea bass (Dicentrarchus labrax L.) larvae that were reared for the first month of life with four different feeding regimes: fed, non-fed, late-feeding and late two-day fast. A marking experiment using alizarin complexone was previously carried out to validate increment deposition. Daily increment deposition was observed to take place from day two after hatching (DAH). The different feeding regimes did not significantly affect the periodicity of otolith increment deposition but did affect increment width. The ROGI was used as a tool for assessing feeding-induced differences in condition. Non-fed larvae had significantly smaller otoliths than fed larvae at the same age. In the late-feeding larvae (food available from 13 DAH), increment width increased progressively once food was supplied, and reached values similar to those for fed larvae after one week of feeding. Deprivation of food for two days in post-flexion larvae (in the fourth week of larval development) was reflected in the formation of progressively narrower increments which had still not returned to normal width two days after feeding was resumed. Our results show that the width of the outermost otolith increments reflect the past feeding history and that the ROGI can be used to distinguish well fed from suboptimally nourished larvae.; [ES] Se estudió el crecimiento del otolito y las propiedades del índice de crecimiento reciente de los anillos (ROGI) en otolitos de larvas de lubina (Dicentrarchus Labrax...

Depth regulation in parenchymella larvae of a demosponge: relative roles of skeletogenesis, biochemical changes and behavior; Depth regulation in demosponge parenchymella larvae

Maldonado, Manuel; George, Sophie B.; Young, Craig M.; Vaquerizo, Isabel
Fonte: Inter Research Publicador: Inter Research
Tipo: Artículo Formato: 922110 bytes; application/pdf
ENG
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To assess factors that influence depth regulation of sponge larvae, we documented ontogenetic changes In larval size and shape, lipid and protein content, skeletal development, and photoresponse in Sigmadocia caerulea, a shallow-water demosponge in the order Haplosclerida. We also measured size and biochemical differences among larvae from different parents to determine how depth regulation might vary across the population. Larvae were photonegative during the entire freeswimming period. Younger larvae swam faster than older larvae, but older larvae swam away from light for greater time and distances. Sinking rates of anesthetized larvae increased as a function of age, not because of lipid depletion or shape changes, but because addition of spicules Increased density. Neither lipid nor protein changed significantly during larval life, but protein content increased abruptly just after settlement. Minor differences In length and protein content among offspring from different parents had no apparent effect on depth regulation Both active movement and passive sinking play roles in moving late-stage larvae towards the sea floor, but increase in larval spicular mass appears to be the most important factor; This study was supported by a Fulbright Fellowship awarded to M.M. (FU93-0227057). This is contribution number 1149 of Harbor Branch Oceanographic Institution; Peer reviewed

Advection of continental water as an export mechanism for anchovy, Engraulis encrasicolus, larvae

Salat, Jordi; Olivar, M. Pilar; Sabatés, Ana
Fonte: CSIC - Instituto de Ciencias del Mar (ICM) Publicador: CSIC - Instituto de Ciencias del Mar (ICM)
Tipo: Artículo Formato: 1017841 bytes; application/pdf
ENG
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Publicación online disponible en: http://www.icm.csic.es/scimar/index.php; The presence of a surface layer of a less saline water of continental influence (CIW) along the continental slope off the Catalan coast (NW Mediterranean) was observed in June 1995. This CIW was formed in the Gulf of Lions from Rhône runoff and carried by the current associated with the shelf-slope front. This study analyses the spatio-temporal behaviour of that water of continental influence in relation to the shelf-slope front, and its effect on the distribution of fish larvae, in particular the larvae of the anchovy, Engraulis encrasicolus. Displacements of the front are observed to follow an oscillation with a period of eight days and an amplitude of 10 km. Anchovy larvae were associated with the presence of CIW, whereas the oceanic species Hygophum benoiti appeared in the region of the slope when the front, and the associated CIW layer, moved close inshore during its oscillation. The size frequency distribution for the anchovy larvae trapped within the CIW suggests that the larvae had been spawned further north, near the Gulf of Lions. It is concluded not only that larvae were transported by the current but also that their development had taken place entirely inside the CIW. The possible benefit to the survival of anchovy larvae of being kept inside that water...

Trophic ecology of bullet tuna Auxis rochei larvae and ontogeny of feeding-related organs

Morote, Elvira; Olivar, M. Pilar; Pankhurst, Patricia M.; Villate, Fernando; Uriarte, Ibon
Fonte: Inter Research Publicador: Inter Research
Tipo: Artículo Formato: 3016421 bytes; application/pdf
ENG
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12 pages, 12 figures, 2 tables.; The bullet tuna Auxis rochei, Risso 1810, is a small tuna widely distributed in tropical and temperate Seas. The present study reports on the first attempt to jointly monitor diet and food selection in larvae of this species and to assess the influence of the ontogenetic development of feeding-related organs on the diet. A. rochei larvae from 2 to 7 mm long are diurnal feeders and highly active predators, with high values of feeding incidence, gut fullness and number of ingested prey items. The rate of change in prey item size in relation to larval size was higher than in other species. Only small, non-motile prey items are eaten at the onset of feeding. Rapid mouth development and the early appearance of teeth allow larvae from 3 to 5 mm long to ingest a wide range of prey. However, niche breadth decreases at 5 mm, when larvae avoid small prey items in favour of larger ones with a higher carbon content. Chesson’s selectivity index indicated that small larvae (from 2 to 3 mm long) selected a variety of small prey items, mainly copepod nauplii. Larvae measuring 3 to 5 mm selectively ate cladocerans and appendicularians, and larvae with lengths ≥5 mm preferred appendicularians and fish larvae. Precocious body development (mouth...

Horizontal distribution of invertebrate larvae around the oceanic island of Gran Canaria: the effect of mesoscale variability; Distribución horizontal de las larvas de invertebrados alrededor de la isla oceánica de Gran Canaria: Efecto de la variabilidad de mesoescala

Landeira, José María; Lozano-Soldevilla, Fernando; Hernández León, Santiago; Barton, Eric D.
Fonte: Consejo Superior de Investigaciones Científicas (España) Publicador: Consejo Superior de Investigaciones Científicas (España)
Tipo: Artículo Formato: 259768 bytes; application/pdf
ENG
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11 pages, 7 figures, 1 table.-- Published online 21 April 2009.; [EN] In October 1991, the horizontal distribution of invertebrate larvae was studied in the waters surrounding the island of Gran Canaria (Canary Islands). The cruise was typified by the presence of three recurrent mesoscale hydrographic structures: a cyclonic eddy southwest of the island, a warm lee region downstream of the island and the offshore boundary of an upwelling filament from the African coast reaching the southeast of the island. Decapod larvae were the most abundant group. In general, a rather high spatial variability was found. The horizontal distribution of the invertebrate larvae groups showed that the highest values of abundance occurred in an elongated zone around the island oriented in the overall direction of flow, leeward and windward of the island, while the lowest values occurred off the eastern and western flanks of the islands. On the other hand, Stomatopoda and Mollusca larvae showed a distribution associated with the boundary of the upwelling filament and decapod larvae of pelagic species were distributed around the eddy structure. Our results suggest specific retention mechanisms for the larvae of neritic invertebrate populations that are related to the particular physical oceanography around Gran Canaria.; [ES] Se estudió la distribución horizontal de las larvas de invertebrados alrededor de la isla de Gran Canaria (Islas Canarias) en octubre de 1991. La campaña se caracterizó por la presencia de tres fenómenos oceanográficos de mesoescala recurrentes: un remolino ciclónico al suroeste de la isla...

Temporal and Spatial Distribution Patterns of Echinoderm Larvae in La Parguera, Puerto Rico

Williams,Stacey M; García-Sais,Jorge
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2010 EN
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This study describes temporal and spatial abundance patterns of echinoderm larvae in La Parguera, Puerto Rico. For the temporal study, larvae were sampled by a series of monthly tows taken with a 64μm mesh net between the new and full moon from April 2005 to July 2006, September 2006 and August 2007. In order to measure spatial variation of echinoderm larval bundances, oblique tows were taken with 64 and 202μm mesh nets at seven different sites within the shelf, at the shelf-edge, and at a nearby oceanic stations during August 2007. Overall, Echinoidea (sea urchin) exhibited the highest abundance with a total of 11 921 larvae, representing 52.5% of the total collection. Ophiuroidea (brittle star) ranked second in abundance with 45.6% of the total larvae. Holothuroidea (sea cucumber) and Asteroidea larvae (sea star) accounted for less than 2% of the total echinoderm larval collection. Early larval stages (2-8 day old) of Diadema antillarum represented 20% of the total Echinoidea larvae. There was no marked seasonal trend of echinoderm larval abundance; Echinoidea and Ophiuroidea larvae were present in all monthly samples indicating that reproduction occurs year-round. Peak abundances of later-stage Echinoidea larvae were observed during January...