46 research outputs found
Introdução de peixes em ecossistemas continentais brasileiros: revisĂŁo, comentários e sugestões de ações contra o inimigo quase invisĂvel
The introduction of species is a major threat to the conservation of biodiversity, being the main precursor of a prominent global biotic homogenization. In the case of perception, control or eradication, aquatic species are among the most problematic. In this sense, fish introductions become serious threats because these organisms are very widespread, mobile and of difficult perception and/or detection by the society. In the early stages of introduction, they may be considered “invisible” (e.g. less exposed than the majority of the introduced organisms, especially terrestrial organisms). Thus, it is common fact that introductions of this group of organisms are perceived only when they are already in advanced stages of the invasion process and the damage is irreversible. A species of fish can be considered non-native, even at the level of basins or sub-basins. This makes the perception or detection of introduced fish even more complex in Brazil, due to its continental dimensions and rich continental aquatic environments. Often, the cultural aspects and time of release contribute to the “invisibility” of the problem. Even fish coming from other continents, such as carp, tilapia and trout are incorporated in the country for so long that they are considered “native”. Even in the scientific field the theme is under-explored in Brazil, but information about problems that may arise from biological invasions is building up. Indeed, not all introductions have catastrophic consequences, but many do. However, we can understand older impacts and detect new ones in the near future if we want to do so. In view of the exposed, and given the magnitude of the problem, and disproportion in the search for answers and impacts, a review of the theme with suggestions for actions is presented. Key words: introduction of species, threats, non-native species, biological invasions, biodiversity, aquatic ecosystems.A introdução de espĂ©cies Ă© uma grande ameaça para a conservação da diversidade biolĂłgica, e a principal precursora da homogeneização global. Em se tratando de percepção, controle ou erradicação, espĂ©cies aquáticas encontram-se entre as mais problemáticas. Neste sentido, os peixes tornam-se graves ameaças, pois sĂŁo organismos muito disseminados, mĂłveis e de difĂcil percepção por parte da sociedade. Nas fases iniciais da introdução, peixes nĂŁo-nativos podem ser considerados ameaças “invisĂveis”, pois sĂŁo menos expostos que a maioria dos organismos introduzidos, principalmente os terrestres. Assim, se torna comum que introduções deste grupo sejam percebidas apenas quando já se encontram em estágios avançados e os danos sĂŁo irreversĂveis. TambĂ©m Ă© imprescindĂvel se compreender que uma espĂ©cie de peixe pode ser considerada nĂŁo-nativa, numa mesma bacia ou sub-bacia hidrográfica. Isto torna a percepção ou detecção de peixes introduzidos ainda mais complexa no Brasil, devido a suas dimensões continentais e riqueza de ambientes. Aspectos culturais e tempo de introdução contribuem para a “invisibilidade” do problema. Mesmo peixes advindos de outros continentes, como as carpas e tilápias, já se encontram incorporados há tanto tempo no paĂs, que sĂŁo considerados “nativos” por algumas comunidades ribeirinhas e/ou ignorados pela população. No campo cientĂfico o tema das introduções ainda Ă© sub-explorado no Brasil, mas as informações sobre problemas estĂŁo crescendo. Nem todas as introduções causam problemas, mas muitas causam. AlĂ©m dos problemas ecolĂłgicos de curto prazo, introduções podem estar causando mudanças que sĂł serĂŁo percebidas em longo prazo. Em vista da magnitude do problema e da discrepância entre o nĂşmero de introduções e a busca por suas consequĂŞncias ou impactos Ă© feita uma revisĂŁo sobre o tema com comentários e sugestões de ações prioritárias e urgentes. Palavras-chave: introdução de espĂ©cies, ameaças, espĂ©cies nĂŁo nativas, invasões biolĂłgicas, biodiversidade, ecossistemas aquáticos
Ecologia alimentar do lambari, Deuterodon langei Travassos, 1957 (Characidae, Tetragonopterinae), de diferentes tamanhos em um riacho da Floresta Atlântica, Paraná (Brasil)
Estudos sobre a alimentação de uma determinada espécie geralmente
resultam em uma contribuição para o conhecimento da mesma
e sĂŁo fundamentais para a compreensĂŁo do funcionamento do
ecossistema do qual esta faz parte. O presente trabalho buscou
ampliar o conhecimento sobre a ecologia alimentar de Deuterodon
langei Travassos, 1957, por meio de análises sobre a composição
da dieta, partilha de recursos, estratégia alimentar e o papel dos
componentes intra- e inter-individuais na amplitude do nicho alimentar
da espécie, enfocando variações entre diferentes classes de
comprimento num mesmo intervalo temporal e espacial. A dieta de
D. langei foi considerada de um modo geral como onĂvora, apesar
da notável diminuição dos itens animais e concomitante aumento da importância de itens de origem vegetal durante o processo
ontogenético. Foi constatada a existência de diferentes estratégias
alimentares e de uma certa partilha de recursos entre as diferentes classes
de comprimento.
ABSTRACT
Studies on feeding behaviour in general contribute significantly for
the knowledge about the biology of the species, and are crucial for the
understanding functional relations within the ecosystem in which the
species is inserted. The present study aimed the knowledge about the
feeding ecology of Deuterodon langei Travassos, 1957, through
analyses of diet composition, resource partitioning, feeding strategies,
and the role of intra- and inter-individual components on the determination
of the amplitude of the species´ feeding niche. The study was conducted
focusing on variations between different size classes within a
same time and space interval. The diet of D. langei was in general
considered omnivorous despite the remarkable reduction in animal items
and concomitant increase in vegetal items during ontogenesis. Different
feeding strategies and a certain degree of resource partitioning between
different size classes of this species was thus detected.
RESUMÉ
Des récherches sur la nourriture concourent pour la
connaissance des espèces et sont rélevants pour la compréhension
du fonctionnement de lécosystème. On a déterminé dans ce travail
la composition du régime de nourriture de Deuterodon langei
Travassos, 1957, la partage de ressources, la stratégie de la nourriture
et le rĂ´le des composantes intra et interindividuales dans lamplitude
du créneau alimentaire de lespèce, en focalisant variations entre
des classes différentes de longueur dans un même intervalle temporal
et spatial. Le régime de D. langei est omnivore, malgré la
remarquable réduction des itens animaux et augmentation de la rôle de itens végétales pendant son développement ontogénétique. On a été
constatée lexistence de différentes stratégies de nourriture et de partage
de ressources entre les différentes classes de longueur
Structuring evidence for invasional meltdown: broad support but with biases and gaps
Negative interactions have been suggested as a major barrier for species arriving in a new habitat. More recently, positive interactions drew attention from community assembly theory and invasion science. The invasional meltdown hypothesis (IMH) introduced the idea that positive interactions among non-native species could facilitate one another’s invasion, even increasing their impact upon the native community. Many studies have addressed IMH, but with contrasting results, reflecting various types of evidence on a multitude of scales. Here we use the hierarchy-of-hypotheses (HoH) approach to differentiate key aspects of IMH, organizing and linking empirical studies to sub-hypotheses of IMH. We also assess the level of empirical support for each sub-hypothesis based on the evidence reported in the studies. We identified 150 studies addressing IMH. The majority of studies support IMH, but the evidence comes from studies with different aims and questions. Supporting studies at the community or ecosystem level are currently rare. Evidence is scarce for marine habitats and vertebrates. Few sub-hypotheses are questioned by more than 50% of the evaluated studies, indicating that non-native species do not affect each other’s survival, growth, reproduction, abundance, density or biomass in reciprocal A ↔ B interactions. With the HoH for IMH presented here, we can monitor progress in empirical tests and evidences of IMH. For instance, more tests at the community and ecosystem level are needed, as these are necessary to address the core of this hypothesis
Invasive aquatic pets: failed policies increase risks of harmful invasions
Businesses in the pet trade collect and transport many aquatic species around the globe, and some of these individuals are released into new habitats. Some jurisdictions have introduced laws intended to regulate this trade, but these regulations have rarely had the desired effects. Laws regarding pets and the pet trade are often poorly communicated, poorly enforced, and not aligned with hobbyists’ beliefs. Consequently, some laws may increase the number of unwanted introductions instead of decreasing them. A significant change in approach is needed, involving far greater communication with scientists, administrations, politicians, the pet industry, and pet owners, promoting euthanasia of unwanted pets rather than release, and the creation and promotion “white lists” of low risk species that can be sold in the pet trade
AusĂŞncia do mexilhĂŁo dourado invasor em um reservatĂłrio perto de Curitiba, Brasil: um possĂvel caso de invasĂŁo malsucedida
Although most cases of non-native species introductions do not result in the final phases of the invasion process or in negative impacts, there are few reports of failure through their different stages, especially for unintentional introductions. However, unsuccessful invasion cases may help understand which factors are predominant during the invasion process. The golden mussel, Limnoperna fortunei, is an invasive species in South America. Since its first record in RĂo de la Plata watershed, it has spread and caused several ecological and economic impacts in different hydrographic basins. Based on larval sampling through conventional and molecular techniques and visual census by scuba diving, we report the absence of this invasive species after its occurrence recorded in 2003, at the Piraquara I reservoir, Upper Iguaçu River basin, Brazil. It is the only potential record of juvenile individuals of this species in a reservoir environment without their population establishment and spreading. Understanding the causes of failures in the invasion process may be crucial to avoid their negative impacts. In this context, the accuracy of non-native species records in new environments is fundamental; recording invasion failure of non-native species may be as important as reporting new occurrences.Keywords: Bivalvia, alien species, ecosystem engineers, invasiveness, naturalization, propagule pressure.Embora a maioria dos casos de introdução de espĂ©cies nĂŁo-nativas nĂŁo resulte nas fases finais do processo de invasĂŁo ou em impactos negativos, há poucos relatos de insucesso em suas diferentes etapas, especialmente para introduções nĂŁo intencionais. No entanto, casos de invasĂŁo sem sucesso podem ajudar a entender quais fatores sĂŁo predominantes durante o processo de invasĂŁo. O mexilhĂŁo dourado, Limnoperna fortunei, Ă© uma espĂ©cie invasora na AmĂ©rica do Sul e, desde seu primeiro registro na bacia do Prata, tem se espalhado e causado impactos ecolĂłgicos e econĂ´micos em diferentes bacias hidrográficas. Com base em amostragens de larvas por meio de tĂ©cnicas convencionais e moleculares e censo visual por mergulho autĂ´nomo, relatamos a ausĂŞncia dessa espĂ©cie invasora apĂłs seu registro em 2003, no reservatĂłrio de Piraquara I, Bacia do Alto Rio Iguaçu, Brasil. Esse Ă© o Ăşnico potencial registro de indivĂduos juvenis dessa espĂ©cie em ambiente de reservatĂłrio sem seu estabelecimento e propagação. A compreensĂŁo das causas de invasões malsucedidas pode ser crucial para prevenir seus impactos negativos. Assim, a precisĂŁo dos registros de espĂ©cies nĂŁo nativas em novos ambientes Ă© fundamental, e relatos de invasões malsucedidas de espĂ©cies nĂŁo nativas podem ser tĂŁo importantes quanto o informe de novas ocorrĂŞncias.Palavras-chave: Bivalvia, espĂ©cies exĂłticas, engenheiro ecossistĂŞmico, invasĂŁo, naturalização, pressĂŁo de propágulos
Protected areas: A focus on Brazilian freshwater biodiversity
Brazil has a variety of aquatic ecosystems and rich freshwater biodiversity, but these components have been constantly damaged by the expansion of unsustainable activities. An array of different conservation strategies is needed, especially the creation of protected areas (PAs, hereafter). However, Brazil's PAs are biased towards terrestrial ecosystems and we argue that current PAs have limited efficacy in the protection of freshwater biodiversity. New PAs should better consider aquatic environments, covering entire basins, rivers and other freshwater habitats. We recommend ways to implement these PAs and provide guidance to avoid social impacts. Freshwater systems in Brazil provide essential goods and services but these ecosystems are being rapidly degraded and will be lost if not adequately protected. © 2018 The Authors. Diversity and Distributions Published by John Wiley & Sons Lt
Distribuiçao, abundância e estrutura populacional de peixes introduzidos no rio Guaraguaçu, Paranaguá, Paraná, Brasil
Orientador: JosĂ© Marcelo Rocha AranhaTese (doutorado) - Universidade Federal do Paraná, Setor de Ciencias BiolĂłgicas, Programa de PĂłs-Graduaçao em Zoologia. Defesa: Curitiba, 2008Inclui bibliografia e anexosArea de concentraçao: ZoologiaResumo: Introduções de espĂ©cies podem causar vários danos ao ambiente. A introdução de peixes de água doce em nosso paĂs Ă© um fato paradoxal, uma vez que o Brasil Ă© uma das regiões mais ricas e diversas do planeta em relação ao grupo. Neste trabalho foram registradas as espĂ©cies de peixes introduzidas no rio Guaraguaçu, o maior rio do litoral paranaense e principal tributário da baia de Paranaguá, suas constâncias, distribuição, focos de contaminação, verificadas a eficiĂŞncia de diferentes aparelhos de pesca, sua estrutura populacional e variações espaço/temporais. Para as coletas, a bacia hidrográfica foi dividida em oito trechos amostrais, onde foram armadas as baterias de petrechos e verificadas, caracterĂsticas fĂsicas e parâmetros abiĂłticos. O esforço de pesca foi de 24 h de pesca em cada trecho, com despescas diurnas e noturnas. Foram realizadas 24 fases de campo e capturados 12.342 indivĂduos com biomassa de 351.774 g pertencentes a 50 espĂ©cies de peixes (44 nativas e 6 introduzidas: Astyanax altiparanae, Clarias gariepinus, Ictalurus punctatus, Oreochromis niloticus, Piaractus mesopotamicus, Salminus brasiliensis) distribuĂdas em 26 famĂlias e 8 ordens. Nos meses de primavera e verĂŁo, foi capturado proporcionalmente o maior nĂşmero de espĂ©cies introduzidas. As redes de malhas maiores, os espinhĂ©is e as varas de mĂŁo, foram os petrechos mais eficientes na captura das espĂ©cies introduzidas, capturando uma menor proporção de espĂ©cies nativas. A quantidade de gramĂneas invasoras e qualidade ambiental do trecho foram fatores que influenciaram nas capturas das espĂ©cies introduzidas. As espĂ©cies introduzidas tiveram maior representatividade nos trechos mĂ©dios, mais lĂŞnticos e menos preservados da bacia hidrográfica. O bagre-africano C. gariepinus foi mais freqĂĽente e constante que muitas espĂ©cies nativas devido a sua rusticidade, maior porte e/ou maior tempo de introdução. A participação desta espĂ©cie foi notĂłria, principalmente em relação Ă biomassa.Abstract: The introduction of alien species can cause severe environmental disturbance. The introduction of freshwater fishes in Brazil is entirely out of sense, given that the country harbors a very rich continental piscine fauna. In this study, the introduced fishes had been surveyed, into Guaraguaçu river, the largest coastal river of the State of Paraná, and the main tributary of Paranaguá Bay, as well as their constancy, distribution, contamination foci, efficiency of several fishing devices, their population structure, and time/space fluctuations. The studied basin had been divided into 8 sampling sections, where the fishing gears had been set. Abiotic parameters had also been surveyed. The fishing effort was standardized in 24 h of fishing for every river section, performed both during daytime and nighttime. Twenty-four field samples had been conducted, and 50 fish species had been caught, 44 of which were native species; the remaining 6 were alien species: Astyanax altiparanae, Clarias gariepinus, Ictalurus punctatus, Oreochromis niloticus, Piaractus mesopotamicus, and Salminus brasiliensis. As a whole, the species caught belonged to 26 families and 8 orders, in a total of 12,342 individuals, and a total biomass of 351,774 g. Proportionally, most alien species were caught in spring and summer. The larger mesh gill nets, long-lines and rods and hook were the most efficient gears in the capture of alien fish. The coverage by alien grass, and the environmental quality of the section had great influence on the capture of alien species. Alien species were more abundant in the middle section of the river, in lentic and less preserved areas. The African catfish C. gariepinus was more frequent and constant than many native species, as it is very though, attains a larger size, and had already a long time of introduction into this habitat. This species had a very relevant participation in the samples, especially with respect to biomass