1,721,501 research outputs found
Bioenergetics of early life-history stages of the brachyuran crab Cancer setosus in response to changes in temperature
Full text linkIn many marine invertebrates, a latitudinal cline in egg size is considered an adaptive response to a decrease in temperature, and enhances the energetic fitness of their larvae at hatching. However, the amount of energy carried over from the egg to the larval stage depends on the metabolic efficiency of egg development. In the present study, eggs of the brachyuran crab Cancer setosus were sampled for their dry mass (DM), carbon (C), nitrogen (N), and fatty acid (FA) content throughout development from blastula stage until hatching of zoea 1-larvae at Antofagasta (23°S) and Puerto Montt 41°S (Chile) under different temperature treatments (12, 16 and 19 °C). Hatching zoea 1 larvae contained 60 ± 3% of the initial blastula egg C content, regardless of site or temperature. However, the ontogenetic decrease in egg C content was to a significantly higher extend based on the utilization of energy-rich FA at 12 °C (? 1.16 µg/egg) compared to the 19 °C treatments in Antofagasta and Puerto Montt (? 0.63 to ? 0.73 µg FA per egg). At 19 °C egg-metabolism was based to a substantial extend on protein, which allowed for the saving of energy-richer lipids. We conclude that the production of larger eggs with high FA content appears to be adaptive not only to fuel the larval development, but is also a response to the prolonged egg developmental times at lower temperatures.<br/
Triterpenols in mangrove sediments as a proxy for organic matter derived from the red mangrove (Rhizophora mangle)
Full text linkMangroves are the dominant type of vegetation along many tropical coasts. Organic matter (OM) derived from mangrove leaf litter and root material is stored in sediments and is a major contributor to the amount and chemical composition of sedimentary OM. A set of organic biomarkers in sediments was applied as a palaeo-indicator for the Holocene dynamics of a mangrove Estuary (Rio Caeté, Pará, Brazil). Six sediment cores were collected perpendicular to the present coast line and analysed for triterpenols and sitosterol. The influence of microbial biomarker degradation was implemented from a previous study. Biomarker profiles were validated with pollen data and multivariate statistics to test whether these compounds were suitable indicators for the palaeo-vegetation. Sediments deposited up to 2 Ma BP showed biomarker assemblages similar to those of recent surface sediment. In two cores, the biomarker composition revealed a transition from marsh to mangrove vegetation. Taraxerol, germanicol and b-amyrin provided the most significant chemotaxonomical information and, especially in combination, served as reliable proxies for OM from Rhizophora mangle in northern Brazil. The maximum age of the mangrove system ranged between 1000 and 5100 yr depending on the topographic elevation of the drilling location.Fil: Koch, Boris Peter. Alfred Wegener Institute for Polar and Marine Research; Alemania. University of Applied Sciences; AlemaniaFil: Souza Filho, Pedro. Federal University of Pará; BrasilFil: Behling, Hermann. University of Göttingen; AlemaniaFil: Cohen, Marcelo C. L.. University of Pará; BrasilFil: Kattner, Gerhard. Alfred Wegener Institute for Polar and Marine Research; AlemaniaFil: Rullkötter, Jürgen. Carl von Ossietzky University of Oldenburg; AlemaniaFil: Scholz Böttcher, Barbara. Carl von Ossietzky University of Oldenburg; AlemaniaFil: Lara, Ruben Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Center for Tropical Marine Ecology; Alemani
Inorganic nutrients measured on water bottle samples during POLARSTERN cruise ARK-XXIII/2
No full text
9th International Estuarine Biogeochemistry Symposium Estuaries and Enclosed Seas under Changing Environmental Conditions
No full text(Table 1) Temperature, salinity and dissolved organic carbon during POLARSTERN cruise ARK-XIII/3
No full text(Table 1) Temperature, salinity and dissolved organic carbon during POLARSTERN cruise ARK-XIII/
(Table 2) Composition and concentration of total hydrolyzable neutral sugars in samples taken during POLARSTERN cruise ARK-XIII/3
No full text(Table 2) Composition and concentration of total hydrolyzable neutral sugars in samples taken during POLARSTERN cruise ARK-XIII/
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
