Suchergebnisse

Many of the processes influencing recruitment to an adult fish population or entry into a fishery occur very early in life. The variations in life histories and behaviours of young fish and the selective processes operating on this variation ultimately determine the identities and abundance of survivors. This important volume brings together contributions from many of the world's leading researchers from the field of fish ecology. The book focuses on three major themes of pressing importance in the analysis of the role that the early life history of fishes plays in the number and quality of recruits: the selective processes at play in their early life history; the contributions of early life history to the understanding of recruitment

Dekapode Krebse, die erfolgreich Lebensräume mit hypo-osmotischen Bedingungen besiedeln, weisen generell stark ausgeprägte hyper-osmoregulatorische Fähigkeiten auf, außerdem ein stabiles Wachstum auch bei niedrigen Salinitäten, differenzierte Ionen-Transport-gewebe, eine hohe Na+-K+-ATPase-Aktivität sowie eine erhöhte Expression der die Na+-K+-ATPase- -Untereinheit codierenden mRNA. Ontogenische Änderungen in der Fähigkeit zur Osmoregulation unter konstanten Laborbedingungen spiegeln charakteristische Änderungen in den Umweltbedingungen wider, denen die aufeinander folgenden Entwicklungsstadien in der Natur ausgesetzt sind.

Dr. Hoyt granted the American Fisheries Society Early Life History Section permission to prepare, update, and distribute his 13,717-record bibliography (comprehensive for literature through 1987, but out-of-print) as a personal computer file or searchable resource on the Internet so long as the file is made available to all interested parties and neither it nor printed versions of it are sold for profit. Because of computer search capabilities, it was deemed unnecessary to provide a computer text version of Dr. Hoyt's subject, scientific name, common name, family name, and location indices (Volume II). The file has now been further edited for duplicate records and errors. The update incorporates a file of records through 1997 provided by George W. Boehlert, references gleaned from over 25 academic and governmental web sites, and Current Contents software for published literature from 1999 to 5 August 2002. The bibliography now includes 15,596 records from 1842 through July 2002. Many references are yet to be identified and added to the bibliography for the period of 1988 through 1997 and especially the year 1998. Bibliographic format generally follows American Fisheries Society guidelines except that standard journal abbreviations are acceptable.

10 Páginas ; 3 Figuras ; 5 Tablas ; Studies examining the eVects of invasive species have focussed traditionally on the direct/lethal eVects of the invasive on the native community but there is a growing recognition that invasive species may also have non-lethal eVects. In terrestrial systems, non-lethal eVects of invasive species can disrupt early life-history phases (such as fertilisation, dispersal and subsequent establishment) of native species, but in the marine environment most studies focus on adult rather than early life-history stages. Here, we examine the potential for an introduced sessile marine invertebrate (Styela plicata) to exert both lethal and non-lethal eVects on a native species (Microcosmus squamiger) across multiple early life-history stages. We determined whether sperm from the invasive species interfered with the fertilisation of eggs from the native species and found no eVect. However, we did Wnd strong eVects of the invasive species on the post-fertilisation performance of the native species. The invasive species inhibited the settlement of native larvae and, in the Weld, the presence of the invasive species was associated with a tenfold increase in the post-settlement mortality of the native species, as well as an initial reduction of growth in the native. Our results suggest that larvae of the native species avoid settling near the invasive species due to reduced postsettlement survival in its presence. Overall, we found that invasive species can have complex and pervasive eVects (both lethal and non-lethal) across the early life-history stages of the native species, which are likely to result in its displacement and to facilitate further invasion. ; This project was funded by projects DPO666147 of the Australian Research Council, and CTM2007- 66635 and PIE 200730I026 of the Spanish Government ; Peer reviewed

11 páginas, 4 tablas, 4 figuras. ; All ontogenetic stages of a life cycle are exposed to environmental conditions so that population persistence depends on the performance of both adults and offspring. Most studies analysing the influence of abiotic conditions on species performance have focussed on adults, while studies covering early life-history stages remain rare. We investigated the responses of early stages of two widely introduced ascidians, Styela plicata and Microcosmus squamiger, to different abiotic conditions. Stressors mimicked conditions in the habitats where both species can be found in their distributional ranges and responses were related to the selection potential of their populations by analysing their genetic diversity. Four developmental stages (egg fertilisation, larval development, settlement, metamorphosis) were studied after exposure to high temperature (30uC), low salinities (26 and 22%) and high copper concentrations (25, 50 and 100 mg/L). Although most stressors effectively led to failure of complete development (fertilisation through metamorphosis), fertilisation and larval development were the most sensitive stages. All the studied stressors affected the development of both species, though responses differed with stage and stressor. S. plicata was overall more resistant to copper, and some stages of M. squamiger to low salinities. No relationship was found between parental genetic composition and responses to stressors. We conclude that successful development can be prevented at several life-history stages, and therefore, it is essential to consider multiple stages when assessing species' abilities to tolerate stress. Moreover, we found that early development of these species cannot be completed under conditions prevailing where adults live. These populations must therefore recruit from elsewhere or reproduce during temporal windows of more benign conditions. Alternatively, novel strategies or behaviours that increase overall reproductive success might be responsible for ensuring population survival. ; The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007–2013), through the Marie Curie International Reintegration Grant (EU-FP7-PEOPLE-2010-RG 277038) to S.L.-L. and a Marie Curie International Outgoing fellowship (EU-FP7-PEOPLE- 2009-IOF-254634) to M.R. Funding was also provided by the Spanish Government projects CTM2010- 22218 and CTM2010-17755, and by the South African Research Chairs Initiative of the Department of Science and Technology and the National Research Foundation. MCP was awarded with an APIF fellowship from the University of Barcelona travel to South Africa ; Peer reviewed

The widespread decline of anadromous Atlantic salmon (Salmo salar L.) populations makes it imperative to research the underlying cause and to develop mitigation measures. One of the most vulnerable phases in the life-cycle of salmon is the fry stage in early spring. Survival rates of juveniles emerging from the gravel of riverbeds are related to the three-dimensional complexity of bottom morphology and hence the variety of microhabitats within the nursery area. However, anthropogenically increased sediment supply due to changes in agricultural land-use reduces complexity, especially the roughness of the streambed. This study used a series of controlled manipulative field experiments conducted in a purpose built raceway system, to provide quantitative data on the impact of sediment pollution on salmon production in freshwaters. The comparison of in-stream habitat with an increased sediment load and control (i.e. simulated natural) situations revealed that increased sedimentation drastically reduced the salmon fry carrying capacity of a stream. A modest increase in sand bed load (15%) in semi-natural streams reduced the fry density by 50% ten days after stocking with unfed fry. Emigration patterns of fry from sedimented habitat and control habitat were significantly different. Fry from both habitat types showed unusual active upstream migration which compensated for densities exceeding the carrying capacity. Riverine habitat was optimised on a reach scale to complement the raceway results and to provide a temporary mitigation measure. The in-stream habitat of a mill leat was manipulated to build the first Eco-Hatchery for salmon in the UK based, on results from the raceway and on an extensive literature review. The hatchery achieved high survival rates of salmon juveniles throughout their freshwater life stages. Furthermore, in-stream sediment traps were developed to offer effective protection for key fry nursery habitat from excess sand bed load. The data provided by the raceway system and the Eco-Hatchery inform riparian management plans. However, addressing sedimentation related issues in salmon rivers is a politically sensitive issue and will take time. Stocking with unfed fry is being used in the interim to temporarily enhance or restore populations. But stocking programmes based on conventional hatchery methodology as a response to declining stocks have frequently failed in both respects. A semi-natural incubator for salmon eggs, the Bamberger-box, was developed to address extremely low survival of newly stocked fry from conventional hatcheries. The new incubator mimics a natural salmon redd and aims in essence to produce wild fish in a hatchery environment. The results of five years field experiments using genetically different broodstock were encouraging. There was a significant increase in the average length and body mass of fry emerging from Bamberger-boxes and the mean eyed-egg-to-fry survival was 93% - greatly exceeding published data for egg-to-fry survival in the wild. Fry from Bamberger-boxes showed a significantly different and more natural rheotactic behaviour, and fewer fry had deformities when compared with fry incubated in conventional hatchery troughs. Seasonal and diurnal emergence patterns from Bamberger-boxes correlated with natural emergence patterns. A potentially crucial advantage of this new semi-natural incubation system was to ensure larvae survival during environmental extremes when all juveniles incubated in conventional hatchery troughs did not survive. Large-scale commercial incubators based on the same principles as the Bamberger-Box were developed and proved equally effective in producing ecologically viable fry. Low costs of production and operation render the new incubators an economically viable alternative to traditional incubation systems. Exploratory research on the influence of hyporheic invertebrates abundance on fry size at emergence was carried out as a next step in continuously improving semi-natural incubation technology.

Carcinus maenas, Klimaänderung, Larvalentwicklung

In this abundantly illustrated volume, Bernard Herman provides a history of urban dwellings and the people who built and lived in them in early America. In the eighteenth century, cities were constant objects of idealization, often viewed as the outward manifestations of an organized, civil society. As the physical objects that composed the largest portion of urban settings, town houses contained and signified different aspects of city life, argues Herman. Taking a material culture approach, Herman examines urban domestic buildings from Charleston, South Carolina, to Portsmouth, New Hampshire, as well as those in English cities and towns, to better understand why people built the houses they did and how their homes informed everyday city life. Working with buildings and documentary sources as diverse as court cases and recipes, Herman interprets town houses as lived experience. Chapters consider an array of domestic spaces, including the merchant family's house, the servant's quarter, and the widow's dower. Herman demonstrates that city houses served as sites of power as well as complex and often conflicted artifacts mapping the everyday negotiations of social identity and the display of sociability