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  • 1
    Keywords: Hochschulschrift
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (75 Seiten = 6 MB) , Illustrationen, Graphen
    Edition: 2021
    Language: German
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  • 2
    Keywords: Hochschulschrift
    Type of Medium: Online Resource
    Pages: Online-Ressource
    Series Statement: Berichte zur Polar- und Meeresforschung 622
    DDC: 570
    Language: English
    Note: Zugl.: Bremen, Univ., Diss., 2010
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  • 3
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    PANGAEA
    In:  Supplement to: Riascos, José M; Carstensen, Daniel; Laudien, Jürgen; Arntz, Wolf E; Oliva, Marcelo; Güntner, Andreas; Heilmayer, Olaf (2009): Thriving and declining: climate variability shaping life-history and population persistence of Mesodesma donacium in the Humboldt Upwelling System. Marine Ecology Progress Series, 385, 151-163, https://doi.org/10.3354/meps08042
    Publication Date: 2023-05-12
    Description: Large-scale environmental patterns in the Humboldt Current System (HCS) show major changes during strong El Niño episodes, leading to the mass mortality of dominant species in coastal ecosystems. Here we explore how these changes affect the life-history traits of the surf clam Mesodesma donacium. Growth and mortality rates under normal temperature and salinity were compared to those under anomalous (El Niño) higher temperature and reduced salinity. Moreover, the reproductive spatial-temporal patterns along the distribution range were studied, and their relationship to large-scale environmental variability was assessed. M. donacium is highly sensitive to temperature changes, supporting the hypothesis of temperature as the key factor leading to mass mortality events of this clam in northern populations. In contrast, this species, particularly juveniles, was remarkably tolerant to low salinity, which may be related to submarine groundwater discharge in Hornitos, northern Chile. The enhanced osmotic tolerance by juveniles may represent an adaptation of early life stages allowing settlement in vacant areas at outlets of estuarine areas. The strong seasonality in freshwater input and in upwelling strength seems to be linked to the spatial and temporal patterns in the reproductive cycle. Owing to its origin and thermal sensitivity, the expansion and dominance of M. donacium from the Pliocene/Pleistocene transition until the present seem closely linked to the establishment and development of the cold HCS. Therefore, the recurrence of warming events (particularly El Niño since at least the Holocene) has submitted this cold-water species to a continuous local extinction-recolonization process.
    Keywords: CENSOR; Climate variability and El Niño Southern Oscillation
    Type: Dataset
    Format: application/zip, 7 datasets
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  • 4
    Publication Date: 2023-05-12
    Keywords: CENSOR; Chipana; Chipana, Chile; Climate variability and El Niño Southern Oscillation; Counting, visual; Date/Time of event; DEPTH, sediment/rock; DIVER; Elevation of event; Event label; Frond, width; Holdfast, diameter; Latitude of event; Length; Longitude of event; Research station; Ruler tape; Sampling by diver; Sori number; Sporophylls number; Stipes number; T_2005-07-07_1,1; T_2005-07-07_1,2; T_2005-07-07_1,3; T_2005-07-07_2,1; T_2005-07-07_2,2; T_2005-07-07_2,3; T_2005-07-07_3,1; T_2005-07-07_3,2; T_2005-07-07_3,3
    Type: Dataset
    Format: text/tab-separated-values, 54 data points
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  • 5
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    Kohlhammer
    In:  Natur und Landschaft, 86 (9/10). pp. 442-446.
    Publication Date: 2017-02-27
    Description: Die Fauna-Flora-Habitat- und Vogelschutzrichtlinie (FFH-RL und VRL) bilden die Basis zur Schaffung eines zusammenhängenden Netzwerks von marinen Natura-2000-Gebieten in Europa. Die deutschen Meeresgebiete von Nord- und Ostsee unterliegen einem starken Fischereidruck. So zählt die Nordsee zu den weltweit am intensivsten befischten Gewässern. Die Konsequenzen sind neben der Überfischung zahlreicher kommerziell genutzter Fischbestände erhebliche negative Auswirkungen auf die Lebensraumtypen und Arten, die gemäß der FFH-RL und VRL einen besonderen Schutz genießen. Im Rahmen des BfN/ICES-Projekts (Environmentally sound fisheries management in Marine Protected Areas - EMPAS) wurde auf der Basis von Fischereiaktivitäten und Schutzzielen eine Konfliktanalyse durchgeführt. Basierend auf dieser Analyse hat ICES räumlich und zeitlich differenzierte Beschränkungen der Fischerei in den Natura-2000-Gebieten der deutschen Ausschließlichen Wirtschaftszone vorgeschlagen. Die Umsetzung von Maßnahmen in den Natura-2000-Gebieten soll zukünftig einen besseren Schutz der Lebensraumtypen und seiner Arten gewährleisten. Darüber hinaus ist es im Rahmen der Reform der europäischen Gemeinsamen Fischereipolitik von höchster Relevanz, neue rechtliche Grundlagen wie die Meeresstrategie-Rahmenrichtlinie zu nutzen, um langfristig eine nachhaltigere Zukunft für Natur und Fischerei zu sichern.
    Type: Article , NonPeerReviewed
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  • 6
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    Bundesamt für Naturschutz
    In:  Bundesamt für Naturschutz, Putbus, Rügen, Germany, 33 pp.
    Publication Date: 2014-12-15
    Type: Report , NonPeerReviewed
    Format: text
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  • 7
    Publication Date: 2019-08-08
    Description: El Niño-Southern Oscillation (ENSO) is a global climate variablility, which fundamentally influences environmental patterns of the Humboldt Current System (HCS) off Chile and Peru. The surf clams Donax obesulus and Mesodesma donacium are dominant and highly productive bivalves of exposed sandy beaches of the HCS. Existing knowledge indicates that El Niño (EN, warm phase of ENSO) and La Niña (LN, cold phase of ENSO) affect populations of both species in a different way, although understanding of the mechanisms underlying these effects is still lacking. The aim of this study was to test hypotheses attempting to explain field observations on the effect of strong EN or LN events by using controlled experimental conditions. Growth and mortality rates of both species were registered during a four-week experiment under EN temperature conditions, normal temperature conditions and LN temperature conditions. While D. obesulus exhibited reduced growth and higher mortality under LN conditions, M. donacium showed reduced growth and higher mortality under EN conditions. The results clearly indicate different temperature tolerance windows for each species, possibly reflecting the evolutionary origins of the Donacidae and Mesodesmatidae in regions with contrasting temperature regimes. These results provide experimental support for previous hypotheses suggesting that thermal tolerance is the driving factor behind observed changes in the species distributions of D. obesulus and M. donacium during the extreme phases of ENSO. 2010 Elsevier Ltd. All rights reserved.
    Type: Article , PeerReviewed
    Format: text
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  • 8
    Publication Date: 2019-08-08
    Description: The taxonomy of two sympatric surf clams Donax marincovichi Coan, 1983 and Donax obesulus Reeve, 1854, inhabiting the coastal Humboldt Current Upwelling System is revisited. Because both species are exploited by artisanal fisheries, it is essential to verify that they are indeed distinct species that have to be managed separately. In this study, both taxa were sampled across their shared distributional area and specimens were indentified according to their respective morphological characteristics. Although width/height and height/length ratios revealed significant differences within sampling areas, the two morphotypes were frequently incongruent for taxonomically important morphometric parameters. In addition, they showed no significant mitochondrial genetic differentiation within or among populations and exhibited indistinguishable sperm ultrastructure. We conclude that the two morphotypes do not represent distinct species and should be included together under D. obesulus.
    Type: Article , PeerReviewed
    Format: text
    Format: other
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  • 9
    Publication Date: 2019-08-08
    Description: Large-scale environmental patterns in the Humboldt Current System (HCS) show major changes during strong El Niño episodes, leading to the mass mortality of dominant species in coastal ecosystems. Here we explore how these changes affect the life-history traits of the surf clam Mesodesma donacium. Growth and mortality rates under normal temperature and salinity were compared to those under anomalous (El Niño) higher temperature and reduced salinity. Moreover, the reproductive spatial–temporal patterns along the distribution range were studied, and their relationship to large-scale environmental variability was assessed. M. donacium is highly sensitive to temperature changes, supporting the hypothesis of temperature as the key factor leading to mass mortality events of this clam in northern populations. In contrast, this species, particularly juveniles, was remarkably tolerant to low salinity, which may be related to submarine groundwater discharge in Hornitos, northern Chile. The enhanced osmotic tolerance by juveniles may represent an adaptation of early life stages allowing settlement in vacant areas at outlets of estuarine areas. The strong seasonality in freshwater input and in upwelling strength seems to be linked to the spatial and temporal patterns in the reproductive cycle. Owing to its origin and thermal sensitivity, the expansion and dominance of M. donacium from the Pliocene/Pleistocene transition until the present seem closely linked to the establishment and development of the cold HCS. Therefore, the recurrence of warming events (particularly El Niño since at least the Holocene) has submitted this cold-water species to a continuous local extinction–recolonization process.
    Type: Article , PeerReviewed
    Format: text
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  • 10
    Publication Date: 2020-07-20
    Description: Donax hanleyanus Philippi, 1847 (Bivalvia: Donacidae) dominates fine to coarse sandy beach communities of the northern Argentinean Atlantic coast. The population biology of this intertidal wedge clam was studied by determining population structure, growth and production at the three locations Santa Teresita, Mar de las Pampas (both from December 2005 to December 2006) and Faro Querandí (from March 2005 to December 2006). Von Bertalanffy growth functions were established from length-frequency distributions using an asymptotic length (L∞) of 44 mm and the growth constants (K) of 0.46 and 0.47 y-1 respectively of Mar de las Pampas and Faro querandí. Compared with growth studies four decades ago, D. hanleyanus today is growing more slowly, but is reaching a higher maximum length. Longevity is estimated to be approximately five years. The present study confirms that the overall growth performance index is habitat-specific, grouping Donacidae into tropical/subtropical, temperate and upwelling species. The intertidal biomass of D. hanleyanus ranged between 0.04 and 1.32 g ash-free dry mass (AFDM) m-2yr-1. Individual production revealed the highest value at 30 mm length (0.16 g AFDM m-2yr-1) and annual production ranged between 0.08 and 0.99 g AFDM m-2yr-1, resulting in renewal rate values (P/) between 0.82 and 2.16. The P/ ratios of D. hanleyanus populations increased with decreasing latitude from temperate to tropical regions. Only at Santa Teresita D. hanleyanus was found living with the sympatric yellow clam Mesodesma mactroides. A significant negative correlation between abundances of both surf clams suggests that abundance peaks of D. hanleyanus are related with population crashes of M. mactroides. Spatial differences in abundance are significantly related to sand texture as confirmed by nonmetrical multidimensional scaling, but not to sea surface temperature. However, the decrease of D. hanleyanus seems to be principally related to human activities.
    Type: Article , PeerReviewed
    Format: text
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