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Exposed to the low temperatures of high latitudes Thorson’s rule suggests a reduced speed of development in marine invertebrates. This raises the question how the development and succession of assemblages of respective species in the arctic is affected. The duration and chronology of succession, as well as the influence of environmental impacts on arctic benthic assemblages, is not fully understood, especially concerning long-term studies. By analysing species abundances and substrate coverage over an exposure time of one decade the following hypotheses are tested: (i) Exposition time significantly modifies the structure of arctic benthic hard-bottom assemblages, (ii) the macroscopic structure of the substrate surface has a significant influence on the structure of benthic hard-bottom assemblages, and (iii) the succession of benthic hard-bottom assemblages in the Arctic is in general slower compared to the benthic succession in all non-polar climatic zones. In 2002 forty Polyethylene growth panels were installed in about 20 m water depth on an underwater cliff in Kongsfjorden (Svalbard, Norway). Six of these were grooved to create structural diversity on the panel surface. Once a year the ripening epibenthic assemblages were photographed by scientific divers. Until 2007 about eight panels were sampled and replaced annually, thus creating starting points for succession in different years. Additionally a ground truthing was carried out for reference. The findings of this study show a resilience time exceeding a decade. Further the sampling year, age group and exposition time have a notable influence on the different successional stages. The structural diversity of the substrate in contrast showed no significant influence. Lastly the results are discussed in comparison with results of related studies from this and other regions to demonstrate the comparable slow succession.

Das Ziel der operativen Frakturbehandlung ist die Fixierung der korrekt reponierten Fragmente. Dafür stehen die Platte, der Fixateur externe und die intramedullären Kraftträger zur Verfügung. Im Rahmen der „biologischen Osteosynthese“ sind außer der Stabilisierung der Bruchfragmente auch die natürlichen Gesetzmäßigkeiten der Knochenheilung zu berücksichtigen. Dazu müssen die Durchblutung der Fragmente in ihrem ursprünglichen Zustand erhalten und die Gefäße des intramedullären Raums weitgehend geschont werden. Diese Bedingungen wurden bisher weder durch den Verriegelungsnagel mit ausgedehnter Freilegung der Bruchstelle noch durch den Rundnagel mit Verklemmung im Markraum optimal erfüllt. Der zweite wichtige Aspekt der Osteosynthese ist die Garantie der Rotationsstabilität. Sie wird bisher am besten durch den Verriegelungsnagel erreicht, bleibt aber bei den Rundnägeln problematisch. Der Trilam-Nagel hat eine runde Grundform und drei in Längsrichtung verlaufende Lamellen, die sich beim Einschlagen in die Innenkortikalis des frakturierten Knochens einkerben. Um Rotationsstabilität zu erreichen, ist damit ein viel geringerer Druck auf die innere Kortikalis erforderlich als beim Rundnagel. Das wirkt sich hinsichtlich der Erhaltung einer optimalen Durchblutung der Kompakta vom Endost her günstig aus. Im Frakturbereich gewährleistet der Trilam-Nagel bei der Reposition und Stabilisierung der Fraktur den Erhalt des geschlossenen Weichteilmantels. Damit werden zusätzliche, operativ bedingte Gefäßverletzungen des Weichteilmantels um die Bruchstelle vermieden. Das Ziel dieser Arbeit bestand in der Überprüfung der biomechanischen Eigenschaften des Trilam-Nagels bezüglich seiner Rotationsstabilität. Die Messungen wurden an separierten Leichenknochen von Hund und Katze vorgenommen. Humerus, Femur und Tibia jeweils der linken Körperhälfte wurden durchsägt, genagelt und dann den Rotationskräften einer speziellen Rotationsmaschine ausgesetzt, bis es zum Zusammenbruch der Osteosynthese kam. Die Messergebnisse ließen sich mittels der Gerätschaften der Firma Hauser aus Remscheid in der Maßeinheit Nm dokumentieren. Die entsprechenden kontralateralen intakten Röhrenknochen des selben Tieres dienten zum Vergleich. Insgesamt wurden 47 Hunde und 33 Katzen untersucht. The aim of fracture treatment is the fixation of the correctly placed fragments. Therefore the plate, fixateur externe and intramedullary pins can be used. Within the scope of “biological osteosynthesis” and in addition to the stability of the fragments, the physiological components of fracture healing have to be kept in mind. The blood supply of the fragments has to be left in its physiological condition and the intramedullary blood vessels have to be treated with care. So far these conditions have not been reached neither by the interlocking nail with its traumatic approach to the fracture site nor by intramedullary nails with round diameter. An other important aspect of osteosynthesis is to obtain rotational stability. Up to now this is best achieved by using interlocking nails, but is still problematic by using nails with round diameter. The Trilam-nail has a round diameter and three in longitudinal direction placed lamellae, which notch into the inner cortex of the fractured bone. To achieve rotational stability, the Trilam-nail puts less pressure to the inner cortex than nails with round diameter. In the fractured area the Trilam-nail ensures the preservation of the soft tissue surrounding the bone. Thus, additional injuries, caused by the surgeon, can be avoided. The aim of this study was to test the biomechanical characteristics of the Trilam-nail referring to its rotational stability. The measurements took place on separated bones of corpses of dogs and cats. Humerus, femur and tibia of the left body site were sawed and the a Trilam-nail was placed inside. A machine, simulating rotational forces, was fixed on the bones. Forces were brought to the bone until it fractured. The results were seen on a display of the machines built by Hauser Company from Remscheid. The forces were measured in Nm. The intact bones from the other body site were needed for comparison to the fractures bones of the left site. In total 47 dogs and 33 cats were examined. From taking the bone samples until the beginning of the tests an average time of 4 weeks was needed. The storage of the samples was performed like recommended in literature by –25°C.

For marine invertebrates living at low temperatures of high latitudes Thorson’s rule suggests a comparatively reduced speed of development. Several studies conducted in different climatic zones have revealed the processes involved in the maturation of benthic assemblages. However, the duration and chronology of succession, as well as the influence of environmental impacts on arctic benthic assemblages is only scarcely analysed. Long-term studies are still rare. By analysing species abundances and substrate coverage over an exposure time of one decade the following hypotheses are tested: (i) Exposition time significantly modifies the structure of arctic benthic hard-bottom assemblages, (ii) the macroscopic structure of the substrate surface has a significant influence on the structure of benthic hard-bottom assemblages, and (iii) the succession of benthic hard-bottom assemblages in the Arctic is in general slower compared to the benthic succession in all non-polar climatic zones. In 2002 forty Polyethylene growth panels were installed on an underwater cliff in Kongsfjorden (Svalbard, Norway) in about 20 m water depth. Six of these were grooved to create structural diversity on the panel surface. Once a year the ripening epibenthic assemblages were photographed by scientific divers. Until 2007 annually about eight panels were sampled and replaced, thus creating starting points for succession in different years. Additionally a ground truthing was carried out for reference. The findings of this study indicate a resilience time exceeding a decade. A strong heterogeneity can be observed between the assemblages on different panels, signifying an influence of different starting points. The results are discussed in comparison with results of related studies from this and other cold-water regions.