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Wadden Sea (wadden + sea)

Distribution by Scientific Domains
Life Sciences72%

Kinds of Wadden Sea

  • dutch wadden sea
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    Selected Abstracts

    Influence of water flow velocity, water depth and colony distance on distribution and foraging patterns of terns in the Wadden Sea

    FISHERIES OCEANOGRAPHY, Issue 3 2009
    PHILIPP SCHWEMMER
    Abstract Surface-feeding seabirds, such as Common (Sterna hirundo) and Arctic Terns (Sterna paradisaea) in the German Wadden Sea, are dependent on biological and physical processes that affect prey availability close to the water surface. We proposed the following four hypotheses: (i) relationships should exist between high water flow velocity and foraging activity of terns, as turbulence should enhance prey availability at the surface; (ii) the areas of highest foraging success should be located within areas of low water depth, due to enhanced biological productivity; (iii) as terns are known to have small foraging radii, the location of their breeding grounds should be related to the location of their foraging grounds; (iv) terns should forage intensely in river estuaries, as these should hold ample food supplies. The time between terns leaving the colony and their first foraging attempt differed significantly among different tidal stages: the time was shortest during flood and ebb tides (i.e., highest water flow velocities). Modelling of a long-term data set revealed the highest probability of foraging activity in conditions of high water currents, in both shallow areas and in areas of around 15,20 m depth. Foraging activity was negatively correlated with distance from colony. The distance to the closest estuary had no significant effect on foraging behaviour. Our findings emphasize the physical,biological coupling in the Wadden Sea and highlight the overall importance of small-scale physical processes in directly influencing prey availability for surface-feeding seabirds. [source]

    Rethinking the interface between ecology and society.

    JOURNAL OF APPLIED ECOLOGY, Issue 1 2008
    The case of the cockle controversy in the Dutch Wadden Sea
    Summary 1Applied ecology, like conservation research, may deal with societal issues if its scientifically based interventions have societal consequences. Human utilization plays a significant role in many ecosystems, so conservation ecologists often have to act on the interface between science and society, where controversies may arise. 2Using insights from science and technology studies, we have analysed the 15-year controversy on the ecological effects of cockle fishing in the Dutch Wadden Sea, which began around 1990 and involved nature protection and shellfish organizations, as well as several leading Dutch ecologists, in a heated debate. 3During this controversy, evaluative research on the ecological effects of cockle fishing was undertaken by a consortium of institutes in order to contribute to the process of political decision-making by the Dutch government on cockle fishery in this area. In addition to conservational and commercial interests, ecological research itself became part of the controversy. 4The research projects on the effects of cockle fishing during this controversy are examples of societally contextualized science, implying that interests and societal disputes are intertwined with scientific arguments. We have applied a dynamic model of contextualization in which societal stakes and scientific uncertainty are considered as the main factors determining the different contexts in which conservation research functions. 5Synthesis and applications. Conservation research, whether it is fundamental or managerially orientated, is related to greater societal aims and interests and might easily face more or less complex societally contextualized situations. Such situations imply extended responsibilities for scientists. Not only is there a need for sound science, but also for a sound way of interacting and communicating with the societal environment. Some elements of such a notion of extended accountability are presented. [source]

    Spatially structured genetic variation in a broadcast spawning bivalve: quantitative vs. molecular traits

    JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2003
    P. C. Luttikhuizen
    Abstract Understanding the origin, maintenance and significance of phenotypic variation is one of the central issues in evolutionary biology. An ongoing discussion focuses on the relative roles of isolation and selection as being at the heart of genetically based spatial variation. We address this issue in a representative of a taxon group in which isolation is unlikely: a marine broadcast spawning invertebrate. During the free-swimming larval phase, dispersal is potentially very large. For such taxa, small-scale population genetic structuring in neutral molecular markers tends to be limited, conform expectations. Small-scale differentiation of selective traits is expected to be hindered by the putatively high gene flow. We determined the geographical distribution of molecular markers and of variation in a shell shape measure, globosity, for the bivalve Macoma balthica (L.) in the western Dutch Wadden Sea and adjacent North Sea in three subsequent years, and found that shells of this clam are more globose in the Wadden Sea. By rearing clams in a common garden in the laboratory starting from the gamete phase, we show that the ecotypes are genetically different; heritability is estimated at 23%. The proportion of total genetic variation that is between sites is much larger for the morphological additive genetic variation (QST = 0.416) than for allozyme (FST = 0.000,0.022) and mitochondrial DNA cytochrome- c -oxidase-1 sequence variation (,ST = 0.017). Divergent selection must be involved and intraspecific spatial genetic differentiation in marine broadcast spawners is apparently not constrained by low levels of isolation. [source]

    Habitat differentiation vs. isolation-by-distance: the genetic population structure of Elymus athericus in European salt marshes

    MOLECULAR ECOLOGY, Issue 2 2003
    A.-C. Bockelmann
    Abstract We investigated genetic differentiation among populations of the clonal grass Elymus athericus, a common salt-marsh species occurring along the Wadden Sea coast of Europe. While E. athericus traditionally occurs in the high salt marsh, it recently also invaded lower parts of the marsh. In one of the first analyses of the genetic population structure in salt-marsh species, we were interested in population differentiation through isolation-by-distance, and among strongly divergent habitats (low and high marsh) in this wind- and water-dispersed species. High and low marsh habitats were sampled at six sites throughout the Wadden Sea. Based on reciprocal transplantation experiments conducted earlier revealing lower survival of foreign genotypes we predicted reduced gene flow among habitats. Accordingly, an analysis with polymorphic cross-species microsatellite primers revealed significant genetic differentiation between high and low marsh habitats already on a very small scale (< 100 m), while isolation-by-distance was present only on larger scales (60,443 km). In an analysis of molecular variance we found that 14% of the genetic variance could be explained by the differentiation between habitats, as compared to only 8.9% to geographical (isolation-by-distance) effects among six sites 2.5,443 km distant from each other. This suggests that markedly different selection regimes between these habitats, in particular intraspecific competition and herbivory, result in habitat adaptation and restricted gene flow over distances as small as 80 m. Hence, the genetic population structure of plant species can only be understood when considering geographical and selection-mediated restrictions to gene flow simultaneously. [source]

    Protoperidinium tricingulatum sp. nov. (Dinophyceae), a new motile form of a round, brown, and spiny dinoflagellate cyst

    PHYCOLOGICAL RESEARCH, Issue 4 2009
    Hisae Kawami
    SUMMARY A small, broadly ovoidal and heterotrophic dinoflagellate containing round, brownish, and spiny cyst was found in the water column of Huibertsplaat in the Wadden Sea off the coast of the Netherlands. This dinoflagellate had these conspicuous morphological characters: a five-sided first apical plate (1,), only three cingular plates, and an extremely small first antapical plate. Based on these morphological features, Protoperidinium tricingulatum Kawami, vanWezel, Koeman et Matsuoka is described as a new species. The flagellar pore of P. tricingulatum is covered with a small fin, which rises from the left side of the right sulcal plate to the large V-shaped posterior sulcal plate. This feature suggests that P. tricingulatum is assigned to the Abé's Monovela Group. The cyst stage of P. tricingulatum was positively linked to the vegetative stage by comparison of the ribosomal 5.8S rDNA, internal transcribed spacers (ITS1 and ITS2). Living cysts of P. tricingulatum are round, brownish, and covered with many slender spines bearing capitate or cauliforate distal ends. The cyst also possesses a theropylic archeopyle formed by a slit corresponding to parasutures between three apical and two apical intercaraly plates. These morphological characters indicate that this species is morphologically related to two dinoflagellate cyst-genera Islandinium and Echinidinium. [source]

    Visions of Nature and Environmental Sustainability: Shellfish Harvesting in the Dutch Wadden Sea

    RESTORATION ECOLOGY, Issue 1 2005
    J. A. A Swart
    Abstract The concept of sustainability has several, sometimes contrasting, meanings that may generate confusion, misunderstanding, and conflict concerning conservation and restoration practices. It is therefore desirable to clarify the concept of sustainability, thereby potentially contributing to mutual understanding, especially when social conflicts arise. This article discusses a recently published typology of three conceptions of sustainability that range from economic to ecocentric valuations of nature. We argue that the typology is incomplete because it does not include the arcadian approaches. For this reason, we introduce a "tripolar model" for conceptions of sustainability, applying it to the debate on shellfish harvesting in the Dutch Wadden Sea. We conclude that the particular visions or conceptions of sustainability held by relevant actors may have an impact on strategies for conservation. [source]

    Neues Leben im Weltnaturerbe Wattenmeer.

    BIOLOGIE IN UNSERER ZEIT (BIUZ), Issue 3 2010
    Globalisierung unter Wasser
    Abstract Neue Untersuchungen im Wattenmeer decken eine Überflutung durch eingeschleppte Arten auf, die sich in den vergangenen Jahren vor allem im Flachwasserbereich direkt unterhalb der Gezeitenzone ausbreiten konnten. Hier sind sie Nutznießer der durch den globalen Klimawandel verursachten ansteigenden Wassertemperaturen. Entstanden ist eine diverse Lebensgemeinschaft von Algen und Wirbellosen, die sich fortlaufend weiter verändert. Neben der strukturellen Komplexität der biogenen Habitate hat besonders die funktionelle Gruppe der filtrierenden Organismen zugenommen. Insgesamt ist das gesamte Ökosystem in einen Umbruch geraten, der nicht mehr umkehrbar ist. Globalization under water: Alien species in the Wadden Sea World Heritage Recent investigations reveal an increasing number of non-native species in the Wadden Sea which profit from warmer water temperatures caused by global change. These exotic species achieve highest occurrence and densities in shallow waters near the low tide water level. In this tidal zone, a highly diverse species community of algae and invertebrates became established and will continue to alter in composition. This leads to enhanced complexity of biogenic habitats and to a prevalence of filter feeding organisms. Thus, we observe a fundamental change of the whole Wadden Sea ecosystem which is without return. [source]