Spelling suggestions: "subject:"larval development"" "subject:"narval development""
1 |
Endocrinology of photoperiodic diapause induction in two species of DipteraRichard, David Seward January 1987 (has links)
No description available.
|
2 |
Biology and systematics of some polydorid species (Polychaeta: Spionidae)Jassim, Mohammad Kadum January 1989 (has links)
No description available.
|
3 |
Aspects of priapulid developmentWennberg, Sofia A January 2008 (has links)
<p>The phylum Priapulida is a small group of marine worms that is allied with the nematodes, kinorhynchs, loriciferans and nematomorphs in a clade called the Cycloneuralia or Introverta. Together with the arthropods they are generally considered to comprise the Ecdysozoa, a clade of moulting animals. A number of recent priapulid species possess features that resemble the predicted Ecdysozoan ancestor. In addition, recent molecular studies have also shown that they are basal within the Ecdysozoa/Cycloneuralia (Garey 2001, Webster et al. 2006). Their putative basal position thus makes priapulids highly interesting research objects for understanding the evolution of Ecdysozoa. </p><p>Earlier investigations of the early embryology of the priapulid <i>Priapulus caudatus</i> are critically revised with the aid of modern techniques and equipment, confirming earlier studies that the early cleavages are highly symmetrical, total, subequal, radial and stereotypical. New results show that up to the sixth cleavage, the spindles are oriented along the animal/vegetal axis at both poles. This unique cleavage pattern has only limited similarities to other animals. During the sixth cleavage two cells move inwards and gastrulation commences. If the mesoderm is derived from both cells, its origin differs from that of many other protostomes.</p><p>Two previously undescribed larval stages of <i>P. caudatus</i>; the light bulb shaped hatchling and the first lorica larva are described. The second lorica larva superficially resembles the previously described type 2 lorica larva (Higgins et al 1993). Differences between the second lorica larva and the type 2 lorica larva, with respect to possible ecophenotypical variation and sub-specialization, are described. </p><p>Preliminary data are presented on musculature development of <i>P. caudatus</i>. Preliminary data have also been obtained on the early development of a second priapulid, <i>Halicryptus spinulosus</i>. Comparison of <i>Halicryptus</i> and <i>Priapulus</i> may help to resolve developmental ground pattern of the priapulids.</p>
|
4 |
Aspects of priapulid developmentWennberg, Sofia A January 2008 (has links)
The phylum Priapulida is a small group of marine worms that is allied with the nematodes, kinorhynchs, loriciferans and nematomorphs in a clade called the Cycloneuralia or Introverta. Together with the arthropods they are generally considered to comprise the Ecdysozoa, a clade of moulting animals. A number of recent priapulid species possess features that resemble the predicted Ecdysozoan ancestor. In addition, recent molecular studies have also shown that they are basal within the Ecdysozoa/Cycloneuralia (Garey 2001, Webster et al. 2006). Their putative basal position thus makes priapulids highly interesting research objects for understanding the evolution of Ecdysozoa. Earlier investigations of the early embryology of the priapulid Priapulus caudatus are critically revised with the aid of modern techniques and equipment, confirming earlier studies that the early cleavages are highly symmetrical, total, subequal, radial and stereotypical. New results show that up to the sixth cleavage, the spindles are oriented along the animal/vegetal axis at both poles. This unique cleavage pattern has only limited similarities to other animals. During the sixth cleavage two cells move inwards and gastrulation commences. If the mesoderm is derived from both cells, its origin differs from that of many other protostomes. Two previously undescribed larval stages of P. caudatus; the light bulb shaped hatchling and the first lorica larva are described. The second lorica larva superficially resembles the previously described type 2 lorica larva (Higgins et al 1993). Differences between the second lorica larva and the type 2 lorica larva, with respect to possible ecophenotypical variation and sub-specialization, are described. Preliminary data are presented on musculature development of P. caudatus. Preliminary data have also been obtained on the early development of a second priapulid, Halicryptus spinulosus. Comparison of Halicryptus and Priapulus may help to resolve developmental ground pattern of the priapulids.
|
5 |
Effects of ocean acidification combined with multiple stressors on early life stages of the pacific purple sea urchinStavroff, Leslie-Anne 07 May 2014 (has links)
Decreases in ocean pH through ocean acidification has shown to have direct negative impacts on the early life stages of the Pacific purple sea urchin, Strongylocentrotus purpuratus. Research has suggested that multiple stressors could exacerbate, cancel, or even alleviate the impacts of ocean acidification on echinoderms. This study assessed the combined effects of changes in pCO2 concentrations (390, 800, 1500 ppm), salinities (28, 31, 34 ppt) and temperatures (12, 15, 18°C) on fertilization and larval development in S. purpuratus. Increased pCO2 was the predominant stressor, with additive and antagonistic effects from temperature changes, and no effect from salinity changes. Stressor combinations significantly decreased the rate of normal larval development by 28 – 68%, whereas fertilization and larval survival were unaffected. The strong impact on normal larval development likely indicates that later development stages could be detrimentally affected and could influence the population dynamics of S. purpuratus.
|
6 |
Avaliação da toxicidade da água residuária da usina de beneficiamento da casca do coco verde em girinos de Leptodactylus vastus (Amphibia, anura, leptodactylidae) / Evaluation of the toxicity of the wastewater plant with the bark of the coconut in tadpoles of Leptodactylus vastus (Amphibia, Anura, Leptodactylidae)Viana, Sidarta Lopes January 2010 (has links)
VIANA, Sidarta Lopes. Avaliação da toxicidade da água residuária da usina de beneficiamento da casca do coco verde em girinos de Leptodactylus vastus (Amphibia, anura, leptodactylidae). 2010. 78 f. Dissertação (Mestrado em ecologia e recursos naturais)- Universidade Federal do Ceará, Fortaleza-CE, 2010. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-05-27T17:35:19Z
No. of bitstreams: 1
2010_dis_slviana.pdf: 817917 bytes, checksum: 92c46a8430dd24028846f5b3adfcdb6b (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-05-27T20:41:24Z (GMT) No. of bitstreams: 1
2010_dis_slviana.pdf: 817917 bytes, checksum: 92c46a8430dd24028846f5b3adfcdb6b (MD5) / Made available in DSpace on 2016-05-27T20:41:24Z (GMT). No. of bitstreams: 1
2010_dis_slviana.pdf: 817917 bytes, checksum: 92c46a8430dd24028846f5b3adfcdb6b (MD5)
Previous issue date: 2010 / Amphibians have several characteristics that make them particularly sensitive bioindicators for environmental quality. In this study, tadpoles of the anuran species Leptodactylus vastus A. Lutz, 1930 were used in bioassays to evaluate the toxicity of the liquid from the coconut shell (LCCV), a byproduct of the processing of the green coconut shell. It was analyzed acute effects as lethality and chronic effects as changes in the rate of metamorphosis, in the length of the larval period and in the mass of the tadpoles at metamorphosis. It was performed a total of six experiments, each lasting ninety days, using both LCCV extracted from fresh coconut shells still greenish and LCCV extracted from dry coconut shells that had already became yellowish. The first four experiments had seven treatments each, with concentrations of 0% (control), 0,1%, 0,2%, 0,3%, 0,4%, 0,5% and 0,6% of LCCV. The other two experiments had six treatments each, with concentrations of 0% (control); 0,3%; 0,6%; 0,9%; 1,2% and 1,5% of LCCV. Each treatment had three replicates with ten tadpoles each. The tadpoles were collected at Campus do Pici, Fortaleza, Ceará, in different places and days to avoid pseudo-replication in space and time. The LCCV had a toxic effect on the tadpoles of Leptodactylus vastus, causing an increase in mortality and a decrease in size at metamorphosis, in the highest concentrations tested. However, in some intermediate concentrations, the LCCV contributed to an increase in the mass of tadpoles during metamorphosis. Moreover, in the concentrations tested, the LCCV did not affect the ability of surviving tadpoles to complete metamorphosis or the length of the larval period. Tadpoles of L.vastus showed a positive correlation between mass at metamorphosis and length of the larval period, except in the highest concentrations tested. These results indicate that the LCCV can negatively affect the biota of aquatic environments, making necessary to determine safe parameters of its emission to the environment. The tadpoles of Leptodactylus vastus showed a good potential for use in ecotoxicological studies and as bioindicators of disturbance in aquatic environments, as L.vastus is a quite common species that it is not under threat or danger of extinction, and that produce conspicuous ovipositions with many eggs and larvae relatively large and easily manipulated as they do not require aeration or filtration of water or a special diet. / Os anfíbios apresentam algumas características que os tornam bioindicadores particularmente sensíveis da qualidade ambiental. No presente estudo, girinos da espécie de anuro Leptodactylus vastus A. Lutz, 1930 foram utilizados em bioensaios para avaliar a toxicidade do líquido da casca do coco verde (LCCV), subproduto do processo de beneficiamento da casca do coco verde. Foram analisados efeitos agudos como letalidade, e crônicos, como alterações na taxa de metamorfose, na duração da fase larval e na massa dos girinos por ocasião da metamorfose. Foi realizado um total de seis experimentos, cada um com duração de noventa dias, utilizando tanto LCCV extraído de cascas de coco mais frescas e que conservavam a coloração verde quanto LCCV extraído de cascas de coco mais secas cuja coloração tinha se tornado amarelada. Os quatro primeiros experimentos tiveram sete tratamentos cada, com concentrações de 0% (Controle); 0,1%; 0,2%; 0,3%; 0,4%; 0,5%; 0,6% de LCCV. Os outros dois experimentos tiveram seis tratamentos cada, com concentrações de 0% (Controle); 0,3%; 0,6%; 0,9%; 1,2%; 1,5% de LCCV. Cada tratamento teve três réplicas com dez girinos cada. Os girinos foram coletados no Campus do Pici, Fortaleza, Ceará, em locais e dias variados para evitar pseudo-replicação espacial e temporal. O LCCV apresentou um efeito tóxico sobre os girinos de Leptodactylus vastus, com aumento na letalidade e diminuição no tamanho na metamorfose, nas mais altas concentrações testadas. Entretanto, em algumas concentrações intermediárias, o LCCV contribuiu com um aumento na massa dos girinos por ocasião da metamorfose. Por outro lado, o LCCV nas concentrações testadas, não afetou a capacidade dos girinos sobreviventes de completar a metamorfose nem o tempo de duração da fase larval. Os girinos de L.vastus apresentaram uma correlação positiva entre massa por ocasião da metamorfose e duração do período larval, exceto nas mais altas concentrações de LCCV testadas. Os resultados indicam que o LCCV pode afetar negativamente as comunidades bióticas de ambientes aquáticos, se fazendo necessária a determinação de parâmetros seguros de sua emissão para o meio ambiente. Os girinos de Leptodactylus vastus mostraram um bom potencial de utilização em estudos ecotoxicológicos e como bioindicadores de perturbações em ambientes aquáticos, por sua espécie ser bastante comum e não se encontrar sob perigo ou ameaça de extinção, por suas fêmeas produzirem uma postura conspícua com grande número de ovos e larvas relativamente grandes e de fácil manipulação, e pelo fato destas larvas apresentarem fácil manejo em laboratório, não exigindo aeração ou filtração da água nem rações especiais.
|
7 |
Characterization of the larval habitat of Culicoides sonorensis (Diptera: Ceratopogonidae) with emphasis on the significance of animal manure and the associated bacterial communityErram, Dinesh January 1900 (has links)
Doctor of Philosophy / Department of Entomology / Ludek Zurek / The larval stages of Culicoides sonorensis Wirth and Jones, a confirmed vector of bluetongue and epizootic hemorrhagic disease viruses affecting ruminants in North America, have been observed to occur typically in animal waste enhanced muds. In this dissertation, I studied the larval development (first instar to adult stage) and oviposition (four-choice assays) of C. sonorensis on sterilized mud (autoclaved) enriched with manure of different farm animal species (dairy cattle, beef cattle, sheep, goats, pigs, horses, white-tailed deer, and chicken). In addition, to determine why only some manure-polluted sites are colonized by C. sonorensis even when they are in close proximity to each other, I examined the moisture levels and microbial concentrations (mud) and physicochemical characteristics (standing water) of a manure-overflow pond site producing C. sonorensis and compared them to nearby cattle stock pond site(s) that produced different Culicoides species. Finally, as the first step in examining the role of microbiome in various physiological functions of C. sonorensis and other suspected/potential vector Culicoides species, I assessed the bacterial communities in field-collected adult females of C. sonorensis, C. crepuscularis, C. haematopotus, and C. stellifer (Illumina sequencing of 16S rRNA gene).
In larval development experiments, the proportion of adults emerged and development time to adult stage varied with manure type and its concentration present in the substrate. Mud supplemented with chicken manure did not support C. sonorensis development, mud enriched with white-tailed deer manure poorly supported midge development, while C. sonorensis development in mud enhanced with manure of sheep, goats, beef cattle, dairy cattle, pigs, and horses varied. In oviposition experiments, colonized females preferred to deposit eggs on substrates without animal manure over substrates with animal manure. In subsequent studies, the manure-overflow pond site that produced mainly C. sonorensis contained significantly higher total aerobic culturable bacteria, pH, salinity, total dissolved solids, and conductivity levels than cattle stock pond sites that produced different Culicoides species. Finally, bacterial composition of field-collected C. sonorensis adult females comprised mainly of the phyla Proteobacteria and Firmicutes, while the majority of bacterial taxa identified from C. crepuscularis, C. haematopotus, and C. stellifer belonged to Proteobacteria. An unidentified bacterial genus (related to Tumebacillus), Propionibacterium, and Curvibacter were detected commonly across all four midge species.
These results suggest that manure of several farm animal species can contribute to C. sonorensis development in the field. However, oviposition preferences remain uncertain, as colonized females appeared to show aversion to animal manure, which is in contradiction to the typical presence of C. sonorensis larvae in animal waste enhanced muds. Nonetheless, variations in microbial and/or physicochemical conditions in the larval habitats likely play a role in the differential emergence of C. sonorensis from various manure-polluted sites. Moreover, some bacterial taxa are associated commonly with C. sonorensis and other suspected/potential vector Culicoides species. Future studies are needed to examine oviposition preferences of field-collected females, life history traits of adults emerging from various manure-enriched substrates, developmental requirements of larvae, and the role of microbiome in various physiological functions of the host including vector competence for orbiviruses.
|
8 |
Diversidade e história de vida dos camarões Alpheidae de regiões intermareais no limite sul do Estado de São Paulo, BrasilPescinelli, Régis Augusto. January 2019 (has links)
Orientador: Rogerio Caetano da Costa / Resumo: Estudos sobre a biodiversidade são fundamentais para o conhecimento biológico. Assim sendo, o presente estudo teve como objetivo conhecer a assembleia e a microdistribuição dos camarões Alpheidae presentes na região intermareal estuarina de Cananéia, São Paulo, Brasil. Além de caracterizar a história de vida de Alpheus brasileiro, espécie mais abundante nas áreas estudadas, a estrutura populacional, os parâmetros de crescimento, a longevidade e o desenvolvimento dos primeiros estágios larvais da espécie. As hipóteses de que as espécies apresentam microdistribuição diferenciada na região intermareal e de que a monogamia social influencia na estrutura populacional e nos parâmetros de crescimento de A. brasileiro foram testadas. A região estuarina de Cananéia é considerada uma das mais conservadas da costa brasileira, portanto, todo o conhecimento sobre esse importante ecossistema é fundamental, principalmente para comparações com áreas diferentes graus de conservação. A assembleia de Alpheidae se caracterizou por sete espécies: A. brasileiro, Alpheus buckupi, Alpheus carlae, Alpheus estuariensis, Alpheus petronioi, Athanas nitescens e Salmoneus carvachoi. A microdistribuição evidenciou a influência de A. brasileiro sobre as demais espécies, principalmente devido à maior abundância e constância que a espécie apresentou. Os resultados sobre a estrutura populacional da espécie estão diretamente relacionados ao seu comportamento monogâmico social, no qual se caracteriza pela formaç... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Studies about biodiversity are fundamental for biological knowledge. Therefore, the aim of the present study was to know the assemblage and the microdistribution of the Alpheidae shrimps present in the intertidal estuarine region of Cananéia, São Paulo State, Brazil. In addition to characterizing the life history of Alpheus brasileiro, the most abundant species in the studied areas. Population structure, growth parameters, longevity and development of the first larval stages of the species was also investigated. The hypotheses that the species show differentiated microdistribution in the intertidal region and that social monogamy influences the population structure and growth patterns of A. brasileiro were tested. The estuarine region of Cananéia is considered one of the most conserved of the Brazilian coast, therefore, all the knowledge about this important ecosystem is fundamental mainly for comparisons with areas in different degrees of conservation. The Alpheidae assemblage was characterized by seven species: A. brasileiro, Alpheus buckupi, Alpheus carlae, Alpheus estuariensis, Alpheus petronioi, Athanas nitescens e Salmoneus carvachoi. The microdistribution evidenced the influence of A. brasileiro on the other species, mainly due to the abundance and constancy that this species presented. The results on the population structure of the species are directly related to its monogamous social behavior, in which it is characterized by the formation of heterosexual pairs that s... (Complete abstract click electronic access below) / Doutor
|
9 |
Stratégies dévelopmentales chez les larves de Calliphoridae : entre régulation thermique et socialité / Developmental strategies of Calliphoridae larvae : between thermal regulation and socialityAubernon, Cindy 27 May 2019 (has links)
Les larves de Diptères nécrophages se développant sur un cadavre font face à de fortes pressions de sélection. Nous démontrons comment cet environnement extrême aurait favorisé l’apparition de stratégies comportementales efficaces et originales, basées sur des mécanismes comme la régulation thermique mais également la socialité.Ce travail pose en premier lieu les bases du comportement de régulation thermique des larves de Diptères Calliphoridae. En effet, celles-ci sont confrontées à un environnement thermique très hétérogène, dans lequel elles vont sélectionner la zone la plus appropriée à leur activité métabolique. Bien que différentes espèces exploitent la même ressource au même moment, nous avons observé que les larves de Lucilia sericata, Calliphora vomitoria et Calliphora vicina ont chacune une température préférentielle de développement. De plus, nous démontrons que ces larves sont en recherche constante de leur température préférentielle (thermorégulation), et qu’elles adaptent leur alimentation à la température du milieu. Ce premier volet d’expérimentations illustre ainsi le rôle prépondérant de la température dans le comportement des larves. En second lieu, ce travail s'intéresse à la dimension sociale des larves nécrophages, et plus particulièrement au comportement d'agrégation. Nous avons démontré chez Lucilia sericata un fort effet attractif et rétentif des congénères, rendant manifeste une prévalence de la socialité sur la régulation thermique. Les résultats sont cependant drastiquement différents dans des conditions hétérospécifiques, où la formation du groupe varie selon les températures préférentielles et les cinétiques d’agrégation de chaque espèce. Ainsi, la température sélectionnée par un groupe hétérospécifique émerge d'un compromis entre les comportements de thermorégulation et d'agrégation. Enfin, ce travail analyse l’effet de ces stratégies comportementales sur le développement des individus.Nous montrons que le comportement de thermorégulation et l’action des congénères affectent la température sélectionnée par les larves, et donc, leur développement. De tels résultats démontrent l’existence de véritables stratégies comportementales individuelles et collectives de développement, reposant sur l’optimisation de paramètres multiples permettant aux larves de se développer au mieux dans cet écosystème extrême qu’est le cadavre en décomposition. / On a cadaver, necrophagous dipteran larvae suffer from strong selection pressures during their development. The premise of this thesis is that such an extreme, competitive and constraining environment would have favored the emergence of efficient developmental strategies, based on mechanisms such as thermal regulation but also sociality. This PhD work is divided into three parts. The first part focuses on the thermal behavior of Calliphorids larvae, which are confronted with a heterogeneous thermic environment on the corps, in which they select the most appropriate area for their metabolic activity. Firstly, this part shows that larvae have a preferential developmental temperature, which is different according to the species (Lucilia sericata, Calliphora vomitoria and Calliphora vicina), although they exploit the same resource at the same time. Secondly, this part demonstrates that the larvae are always in search of this preferential temperature and thirdly, that they adapt both their displacement and their food intake according to the temperature of the nourishing substrate. This first part of experiments demonstrates that the temperature parameters have a strong effect on larval behavior. The second part of this work focuses on the social dimension of larval behavior by analyzing the influence of congeners, mainly through their active aggregation behavior. We show for Lucilia sericata a strong attractive and retentive effect of the group, making obvious that sociality prevails over thermal regulation. However, these results are radically different under heterospecific conditions where the group formation strongly depends on preferential temperatures as well as aggregation kinetics of each species. Finally, the third part of this work analyzes the effects of temperature and congeners on the development of individuals and shows that both the behavior of thermoregulation and the action of congeners impact the temperature selected by larvae, and therefore, their development. These results indicate the existence of individual and collective behavioral development strategies based on the optimization of multiple parameters that allow larvae to develop ideally in this extreme ecosystem of a decaying corpse.
|
10 |
AvaliaÃÃo da toxicidade da Ãgua residuÃria da usina de beneficiamento da casca do coco verde em girinos de Leptodactylus vastus (Amphibia, anura, leptodactylidae) / Evaluation of the toxicity of the wastewater plant with the bark of the coconut in tadpoles of Leptodactylus vastus (Amphibia, Anura, Leptodactylidae)Sidarta Lopes Viana 31 March 2010 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Os anfÃbios apresentam algumas caracterÃsticas que os tornam bioindicadores particularmente sensÃveis da qualidade ambiental. No presente estudo, girinos da espÃcie de anuro Leptodactylus vastus A. Lutz, 1930 foram utilizados em bioensaios para avaliar a toxicidade do lÃquido da casca do coco verde (LCCV), subproduto do processo de beneficiamento da casca do coco verde. Foram analisados efeitos agudos como letalidade, e crÃnicos, como alteraÃÃes na taxa de metamorfose, na duraÃÃo da fase larval e na massa dos girinos por ocasiÃo da metamorfose. Foi realizado um total de seis experimentos, cada um com duraÃÃo de noventa dias, utilizando tanto LCCV extraÃdo de cascas de coco mais frescas e que conservavam a coloraÃÃo verde quanto LCCV extraÃdo de cascas de coco mais secas cuja coloraÃÃo tinha se tornado amarelada. Os quatro primeiros experimentos tiveram sete tratamentos cada, com concentraÃÃes de 0% (Controle); 0,1%; 0,2%; 0,3%; 0,4%; 0,5%; 0,6% de LCCV. Os outros dois experimentos tiveram seis tratamentos cada, com concentraÃÃes de 0% (Controle); 0,3%; 0,6%; 0,9%; 1,2%; 1,5% de LCCV. Cada tratamento teve trÃs rÃplicas com dez girinos cada. Os girinos foram coletados no Campus do Pici, Fortaleza, CearÃ, em locais e dias variados para evitar pseudo-replicaÃÃo espacial e temporal. O LCCV apresentou um efeito tÃxico sobre os girinos de Leptodactylus vastus, com aumento na letalidade e diminuiÃÃo no tamanho na metamorfose, nas mais altas concentraÃÃes testadas. Entretanto, em algumas concentraÃÃes intermediÃrias, o LCCV contribuiu com um aumento na massa dos girinos por ocasiÃo da metamorfose. Por outro lado, o LCCV nas concentraÃÃes testadas, nÃo afetou a capacidade dos girinos sobreviventes de completar a metamorfose nem o tempo de duraÃÃo da fase larval. Os girinos de L.vastus apresentaram uma correlaÃÃo positiva entre massa por ocasiÃo da metamorfose e duraÃÃo do perÃodo larval, exceto nas mais altas concentraÃÃes de LCCV testadas. Os resultados indicam que o LCCV pode afetar negativamente as comunidades biÃticas de ambientes aquÃticos, se fazendo necessÃria a determinaÃÃo de parÃmetros seguros de sua emissÃo para o meio ambiente. Os girinos de Leptodactylus vastus mostraram um bom potencial de utilizaÃÃo em estudos ecotoxicolÃgicos e como bioindicadores de perturbaÃÃes em ambientes aquÃticos, por sua espÃcie ser bastante comum e nÃo se encontrar sob perigo ou ameaÃa de extinÃÃo, por suas fÃmeas produzirem uma postura conspÃcua com grande nÃmero de ovos e larvas relativamente grandes e de fÃcil manipulaÃÃo, e pelo fato destas larvas apresentarem fÃcil manejo em laboratÃrio, nÃo exigindo aeraÃÃo ou filtraÃÃo da Ãgua nem raÃÃes especiais / Amphibians have several characteristics that make them particularly sensitive bioindicators for environmental quality. In this study, tadpoles of the anuran species Leptodactylus vastus A. Lutz, 1930 were used in bioassays to evaluate the toxicity of the liquid from the coconut shell (LCCV), a byproduct of the processing of the green coconut shell. It was analyzed acute effects as lethality and chronic effects as changes in the rate of metamorphosis, in the length of the larval period and in the mass of the tadpoles at metamorphosis. It was performed a total of six experiments, each lasting ninety days, using both LCCV extracted from fresh coconut shells still greenish and LCCV extracted from dry coconut shells that had already became yellowish. The first four experiments had seven treatments each, with concentrations of 0% (control), 0,1%, 0,2%, 0,3%, 0,4%, 0,5% and 0,6% of LCCV. The other two experiments had six treatments each, with concentrations of 0% (control); 0,3%; 0,6%; 0,9%; 1,2% and 1,5% of LCCV. Each treatment had three replicates with ten tadpoles each. The tadpoles were collected at Campus do Pici, Fortaleza, CearÃ, in different places and days to avoid pseudo-replication in space and time. The LCCV had a toxic effect on the tadpoles of Leptodactylus vastus, causing an increase in mortality and a decrease in size at metamorphosis, in the highest concentrations tested. However, in some intermediate concentrations, the LCCV contributed to an increase in the mass of tadpoles during metamorphosis. Moreover, in the concentrations tested, the LCCV did not affect the ability of surviving tadpoles to complete metamorphosis or the length of the larval period. Tadpoles of L.vastus showed a positive correlation between mass at metamorphosis and length of the larval period, except in the highest concentrations tested. These results indicate that the LCCV can negatively affect the biota of aquatic environments, making necessary to determine safe parameters of its emission to the environment. The tadpoles of Leptodactylus vastus showed a good potential for use in ecotoxicological studies and as bioindicators of disturbance in aquatic environments, as L.vastus is a quite common species that it is not under threat or danger of extinction, and that produce conspicuous ovipositions with many eggs and larvae relatively large and easily manipulated as they do not require aeration or filtration of water or a special diet
|
Page generated in 0.076 seconds