Aplicação da cromatografia de partição gás-líquido no estudo da ecologia trófica da fase adulta de lampreia-marinha (Petromyzon marinus L.)

Apesar da relevância biológica e do impacto económico associado à sua exploração comercial, a informação existente acerca dos hábitos alimentares na fase marinha parasitária da lampreia-marinha é muito limitada e poucos estudos têm examinado a organização metabólica desta espécie. A inactividade alimentar associada à migração reprodutora confere algumas garantias de que a composição em ácidos gordos dos lípidos totais e/ou dos triacilgliceróis do músculo reflecte, até certo ponto, a dieta destes animais na fase marinha e, consequentemente, o grupo de hospedeiros preferenciais. O presente estudo foi conduzido com o intuito de caracterizar qualitativamente os ácidos gordos dos lípidos totais do músculo de 45 animais capturados durante a migração reprodutora nas bacias hidrográficas do Minho, Tejo e Guadiana e de avaliar se a existência de eventuais diferenças na composição em ácidos gordos poderiam indiciar dietas distintas, porventura características das zonas geográficas onde os animais foram capturados. Os lípidos totais do músculo foram extraídos pelo método de Folch et al. (1957). Os ésteres metílicos dos ácidos gordos dos lípidos totais foram preparados pelo método de Morrison & Smith (1964). De seguida, os ésteres metílicos dos ácidos gordos foram analisados num cromatógrafo Hewlett Packard HP 6890 Series GC System, com software HPChem (2002), equipado com injector split-splitless e detector de ionização por chama (FID). Foi utilizada uma coluna capilar Omegawax 320 (30 m de comprimento x 0.32 mm de diâmetro interno, 0.25 m de espessura de filme, da Supelco). A fase móvel foi hélio com um fluxo de 1,2 ml/min. A temperatura do injector e do detector foi de 250C e a temperatura do forno foi mantida a 200C. A razão de split foi de 100:1 A corrida foi feita a 200C sem rampa de temperatura durante 55 minutos. Os ésteres metílicos dos ácidos gordos foram identificados recorrendo à comparação dos tempos de retenção obtidos com os tempos de retenção dos ésteres metílicos dos ácidos gordos de uma mistura padrão de referência (Supelco). Cada éster metílico foi expresso em percentagem do total de ésteres metílicos identificados. Foi utilizada uma análise discriminante múltipla para avaliar o nível de segregação das amostras pertencentes às três bacias, tendo por base a composição em ácidos gordos dos lípidos totais do músculo. Verificou-se que os ácidos gordos mais abundantes no músculo das lampreias estudadas foram os ácidos gordos monoinsaturados, seguidos dos ácidos gordos saturados e por último dos ácidos gordos poliinsaturados. Constatou-se a existência de segregação das populações a nível geográfico, com uma separação mais evidente para a bacia hidrográfica do Tejo, sendo que os ácidos gordos que contribuíram para este resultado foram o ácido merístico (C14:0), o ácido eicosenóico (C20:1ω9), o ácido erúcico (C22:1ω9) e o ácido nervónico (C24:1ω9), estes três últimos pertencentes à família ω9. Verificando-se a hipótese destes ácidos gordos serem originários dos hospedeiros seleccionados pelas lampreias, então poder-se-á concluir que a sua proveniência geográfica promove diferenças na ecologia trófica desta espécie durante a fase marinha parasitária

Passage and freshwater habitat requirements of anadromous lampreys: Considerations for conservation and control

Understanding the relationship between a species and its habitats is important for both conservation of imperiled species and control of invasive species. For migratory species, we hypothesize that maintaining connectivity between segregated habitats is more important than improving the quality of each habitat. In the case of anadromous lampreys of conservation concern, we posit that restoring passage routes between spawning, rearing and feeding habitats will result in higher larval abundance upstream from barriers than efforts to improve quality of these freshwater habitats. To explore this hypothesis, we reviewed conservation actions for native anadromous lampreys in freshwater and found that: i) improving passage between habitats results in immediate and quantifiable increases in larval abundance, ii) anadromous lampreys are capable of existing in suboptimal habitats, and iii) small reservoirs of production drive rapid expansion when anadromous lampreys are released from passage constraints. Hence, maintaining habitat connectivity is clearly crucial for conservation of anadromous lampreys. There are fewer examples of improvements to freshwater habitat that increased larval lamprey abundance, perhaps because lampreys are rarely the focus of these efforts. However, habitat limitations such as stream de-watering, chemical pollution, and scour occur and will likely be exacerbated by climate change. Documenting habitat actions that reverse these problems may provide evidence for the merits of lamprey-specific habitat improvement. Our observations are relevant to sea lamprey control in the Great Lakes because barriers and chemical treatment are key instruments of population regulation, and can be strategically deployed to limit production

European lampreys: new insights on postglacial colonization, gene flow and speciation.

Ice ages are known to be the most dominant palaeoclimatic feature occurring on Earth, producing severe climatic oscillations and consequently shaping the distribution and the population structure of several species. Lampreys constitute excellent models to study the colonization of freshwater systems, as they commonly appear in pairs of closely related species of anadromous versus freshwater resident adults, thus having the ability to colonize new habitats, through the anadromous species, and establish freshwater resident derivates. We used 10 microsatellite loci to investigate the spatial structure, patterns of gene flow and migration routes of Lampetra populations in Europe. We sampled 11 populations including the migratory L. fluviatilis and four resident species, L. planeri, L. alavariensis, L. auremensis and L. lusitanica, the last three endemic to the Iberian Peninsula. In this southern glacial refugium almost all sampled populations represent a distinct genetic cluster, showing high levels of allopatric differentiation, reflecting long periods of isolation. As result of their more recent common ancestor, populations from northern Europe are less divergent among them, they are represented by fewer genetic clusters, and there is evidence of strong recent gene flow among populations. These previously glaciated areas from northern Europe may have been colonized from lampreys expanding out of the Iberian refugia. The pair L. fluviatilis/L. planeri is apparently at different stages of speciation in different locations, showing evidences of high reproductive isolation in the southern refugium, and low differentiation in the north

Can a restocking event with European (glass) eels cause early changes in local biological communities and its ecological status?

In an attempt to assist the recovery of the panmictic population of the European eel, declining since the late 1980s, the restocking of areas with low or no natural recruitment has been one of the measures adopted to reverse this trend. However, the main focus in several monitoring programmes for these actions, has been in the best interest of its viability and cost/benefit relationships and, for that, the condition of the released stocks has been the main concern. Yet, so far, no studies have assessed the potential ecological impacts that restocking might have on other biological communities. This pioneer pilot study aimed to evaluate the early ecological impact of a restocking event on other biological communities, considering inter-specific competition (other fish species) and feeding impact (macroinvertebrates).The reference condition of the biological communities of an inland tributary of the Mondego river, the River Ceira, was determined in three sites inaccessible to the natural recruitment of eels, followed by a post-stocking assessment. The results showed no significant changes in the fish assemblages in restocked areas, contrary to the macroinvertebrate community. However, the ecological status for the macroinvertebrate community showed no deleterious effects, with the results suggesting exactly the opposite. This may be related to the low density of the restocked eels and factors influencing the local trophic web. This study confirms the suitability of the habitat for restocking with glass eels, during its early stages, without disrupting the local ecological status, using densities close to those of natural recruitment

Can heart tissue fatty acid profile be used as a tool to discriminate sea lamprey (Petromyzon marinus, L.) populations in several Portuguese river basins?

This study proposes to evaluate the use of heart tissue fatty acid signature and multivariate analysis of fatty acid profile as a possible discriminating tool for sea lamprey P. marinus populations sampled in Portuguese river basins. Local fisherman collected adult sea lampreys in eight Portuguese river basins (Minho, Lima, Cávado, Douro, Vouga, Mondego, Tagus and Guadiana) at the beginning of their spawning migration. Heart total lipid extraction was obtained by accelerated solvent extraction (ASE) and FAMEs were prepared by transesterification with methanol-boron trifluoride and analysed by GC. FAMEs were identified by comparison of their retention times with known standards chromatographed in identical gas chromatography conditions. The fatty acid profile of the heart tissue varied among the individuals of the different river basins. In order to identify which fatty acid contributed most to the differences between river basins heart tissue, MDA was employed. The MDA proved to be statistically significant and the overall corrected classification rate estimated from cross-validation procedure was 86.2%. Although in the case of the individuals of Tagus and Guadiana 100% and 94.7 % of subjects were correctly classified, respectively, there are always a few individuals of the other 5 watersheds that have characteristics identical to those observed in these two river basins.The results are discussed in terms of fatty acid origin and hypothesis concerning the migratory behavior that could lead to these results. The fatty acid profile of heart is considered more stable than other organs, but it still exhibits some variability. This study seems to point out the potential for fatty acid compositions to discriminate sea lampreys from Portuguese river basins, which are probably related with environmental variables that they may have been exposed during early stages of their life cycle

Managing native and non-native sea lamprey (Petromyzon marinus) through anthropogenic change: A prospective assessment of key threats and uncertainties.

Sea lamprey (Petromyzon marinus) is a species of conservation concern in their native range of the Atlantic coasts of Europe (Near Threatened to Critically Endangered) and North America (Secure to Critically Imperiled), and an invasive species of great economic and ecological concern in the Laurentian Great Lakes. Despite differences in life history strategy (anadromous natives vs adfluvial non-natives), the biology of sea lamprey is sufficiently similar to expect comparable responses to large-scale environmental change. We take a prospective look at the future (50 to 100 years) of sea lamprey management in an era of considerable environmental disturbance, and consider biological responses, management actions, and the future status of populations across the native and non-native ranges. Based on facilitated discussion by a diverse group of international experts, two major but poorly characterized classes of threats to sea lamprey were identified: climate change and socio-political issues. We discuss how climate induced changes affect growth, bioenergetics, and phenology of sea lamprey, and associated effects on control tactics (pesticides and barriers) and conservation. We consider tensions surrounding improving connectivity in the Great Lakes while controlling invasive sea lamprey, and discuss supplements and alternatives to pesticides and their wider effect, as well as the effects of new invasive species. To prevent the extirpation of native sea lamprey populations, or the re-expansion of non-native populations, we conclude with a call for new and ongoing dialogue and collaboration among all sea lamprey biologists and managers across the native and non-native range

Quinze anos de monitorização das comunidades biológicas do estuário do Tejo no âmbito da construção e funcionamento das ETARs do Portinho da Costa e da Mutela (Concelho de Almada): Experiência adquirida e ensinamentos para futuros casos semelhantes.

Desde 2001 que a Câmara Municipal de Almada tem vindo a promover, em colaboração com o MARE, a monitorização ambiental das regiões estuarinas sob influência das ETARs do Portinho da Costa e da Mutela, que vieram substituir efluentes não tratados emitidos sensivelmente nas mesmas regiões. O objetivo deste programa de monitorização consiste em avaliar as principais alterações ocorridas (na maioria dos casos positivas) nos ecossistemas estuarinos dos vários locais, após a entrada em funcionamento de ambas as infraestruturas. Estes 15 anos de estudos das comunidades bentónicas e de peixes locais têm permitido identificar variações nos padrões espácio-temporais destes compartimentos biológicos e identificar quais dessas evoluções podem ser presumivelmente relacionáveis com o funcionamento das infraestruturas e quais derivam provavelmente de flutuações naturais. Nesta comunicação são enunciados os pressupostos do estudo, descritos os delineamentos experimentais e metodologias de tratamento dos dados adotados, apresentados os principais resultados obtidos e discutidas as grandes dificuldades sentidas para cumprir os objetivos estabelecidos. Este conjunto de elementos será analisado numa perspetiva de como a experiência adquirida pode ser útil, no futuro, para casos semelhantes, sobretudo numa ótica da correta identificação dos verdadeiros efeitos infraestruturais e de despiste da influência de outros fatores concorrentes

Widespread hybridization between Invasive bleak (Alburnus alburnus) and Iberian chub (Squalius spp.): A neglected conservation threat

Hybridization between native and nonnative fish species is a major conservation issue, especially in ecosystems with high levels of endemism, such as Iberian streams. To date, hybridization with the invasive bleak Alburnus alburnus has been reported for the Iberian chub Squalius alburnoides and S. pyrenaicus and in scattered locations only. However, the bleak is spreading in the region, potentially increasing the risks of hybridization with other Squalius species. To gather a more comprehensive picture on the current geography of hybridization, we compiled records on hybrids between bleak and chub in Portugal and conducted genetical assessments of hybrids between bleak and S. carolitertii. We found that hybridization with bleak is widespread throughout Portuguese river basins and involves at least S. alburnoides, S. pyrenaicus and S. carolitertii. Hybridization with bleak may not only cause waste of reproductive effort and damage the genetic integrity of these endemic species but also promote shifts in the reproductive dynamics of the S. alburnoides hybrid complex, which includes individuals with various ploidy levels and combinations of parental genomes, reproducing sexually and asexually. We recommend that future studies characterize the fitness of bleak hybrids and their ecological and genetic interactions with native fish, in order to design effective conservation measures

Peixes

Os peixes sao organismos aquaticos que associamosde imediato aos rios, mas sobre os quais existe aindamuito desconhecimento. Neste capitulo damos a conhecer asespecies que existem em Portugal, como estao distribuidasno nosso territorio, que fatores ambientais determinam a suaocorrencia, que comportamentos exibem, que ameacas pairamsobre as suas populacoes, ou como podem ser utilizadoscomo sentinelas para monitorizar o estado ecologico dos rios.Sao ainda descritas as principais caracteristicas dos habitatsdulciaquicolas portugueses e das associacoes piscicolas que neles ocorrem, e discutidos quais os principais fatores ambientaisque terao contribuido para a distribuicao das especiesno nosso territorio. Face as pressoes de natureza antropica aque estao sujeitos, e dado destaque aos principais fatores deameaca a conservacao dos peixes dulciaquicolas e migradores,e as medidas de mitigacao mais adequadas a sua proteção