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Settlement behavior of American lobster (Homarus americanus): effect of female origin and developmental temperature 下载免费PDF全文
The benthic settlement success of American lobster (Homarus americanus) postlarvae is a key factor in population dynamics, with the temperature being a key factor. Given the spatial distribution of the species, its pelagic larvae probably encounter various thermal zones during development. Little information is available on the ability of lobster larvae to acclimate to temperature or if this ability varies among geographic areas. The main objectives of this study were to characterize (i) the settlement behavior of the postlarvae in relation to (a) temperature during larval development and (b) the geographic origin of the maternal parent and (ii) the behavioral response of postlarvae with different thermal histories in the presence/absence of a thermocline. Results did not support the hypothesis of thermal adaptation among local populations, as settlement behavior of postlarvae did not differ among females from different geographic regions. In contrast, larval survival and settlement behavior and postlarval energetic conditions varied with development temperature. Behavioral plasticity in the benthic settlement was observed in relation to temperature structure of the experimental water column. This study suggests that there may be links between development temperature and the natural variability in survival and settlement of American lobsters. Findings emphasize the need for an integrated approach in lobster recruitment studies with the inclusion of behavior in dispersion models. 相似文献
54.
Garel Makouanzi Gilles Chaix Sophie Nourissier Philippe Vigneron 《Southern Forests》2018,80(2):151-158
Thirty-four Eucalyptus urophylla × Eucalyptus grandis hybrids were evaluated with a view to selecting for improved growth and wood-quality traits for plantations in the Congo. Height, circumference at breast height and volume were measured at 12, 27, 37, 49 and 60 months. Lignin content, the syringyl/guaiacyl ratio and total extractives content were predicted by near-infrared spectroscopy using wood powder samples collected from trees at breast height. While wood chemical properties were stable and under strong genetic control, growth traits were not. The genetic correlation between lignin content and growth was weak and negative, whereas the environmental correlation was also weak but positive. The genetic improvement of E. urophylla × E. grandis clones, based on growth features, leads to a limited decrease in lignin content and syringyl content and to a limited increase in extractives content. 相似文献
55.
Johan Gardères Gilles Bedoux Vasiliki Koutsouveli Sterenn Crequer Florie Desriac Ga?l Le Pennec 《Marine drugs》2015,13(8):4985-5006
Marine sponges harbor a rich bacterioflora with which they maintain close relationships. However, the way these animals make the distinction between bacteria which are consumed to meet their metabolic needs and opportunistic and commensal bacteria which are hosted is not elucidated. Among the elements participating in this discrimination, bacterial cell wall components such as lipopolysaccharides (LPS) could play a role. In the present study, we investigated the LPS chemical structure of two bacteria associated with the sponge Suberites domuncula: a commensal Endozoicomonas sp. and an opportunistic Pseudoalteromonas sp. Electrophoretic patterns indicated different LPS structures for these bacteria. The immunomodulatory lipid A was isolated after mild acetic acid hydrolysis. The electrospray ionization ion-trap mass spectra revealed monophosphorylated molecules corresponding to tetra- and pentaacylated structures with common structural features between the two strains. Despite peculiar structural characteristics, none of these two LPS influenced the expression of the macrophage-expressed gene S. domuncula unlike the Escherichia coli ones. Further research will have to include a larger number of genes to understand how this animal can distinguish between LPS with resembling structures and discriminate between bacteria associated with it. 相似文献
56.
Holocene floodplain sedimentation in the Rhine catchment is controlled by human and climate impacts. Intricate river behaviour modifies the fluvial response to the external impacts making cause–effect analysis difficult, especially on large spatial scales. To better understand the relative importance and interdependencies of external and internal controls, temporally resolved floodplain sedimentation rates are established using three different methods: i) floodplain storage studies on the trunk stream, ii) depth/age-analysis of overbank deposits from different parts of the catchment and iii) cumulative frequency distributions of 14C-ages from floodplain deposits from various parts of the catchment. The applied methodology strongly differs with the available temporal resolution and the size of the corresponding catchment. All three methods show a strong increase in sedimentation rate for more recent periods that can be linked to increasing human impact. Evidences for climate impacts and intricate river behaviour are less clear and hindered by insufficient temporal resolution of the currently available data. 相似文献
57.
Production of sheep (nursing ewes) grazing alternately with cattle (growing weaned heifers) was compared to the production
of sheep or cattle grazing alone (controls). Pasture production and sheep parasitism were also monitored. The herbage allowance
was higher for the control heifers than for the alternate heifers, but the leaf to green material ratio (LGMR) was lower,
and no difference on heifer growth was revealed (443 vs. 431g.d-1, P = 0.54). The LGMR was higher for the alternate sheep (+3 points) than for the control sheep, except during the dry season,
when the herbage density was lower. The effects of parasitism on the packed cell volume of alternate ewes and lambs were lower
than those of control ewes and lambs. However, the infection of sheep by Cooperia sp. (better adapted to cattle) was significantly higher for the alternate sheep than for the controls, and some indication
of cattle infection by Haemonchus contortus was suggested. The 70-day lamb weight was higher in the alternate grazing system than in the control (+0.76,+1.11 and+0.61kg
for the dry, intermediate and rainy seasons, respectively), and the average 70-day lamb production per ewe exposed was 21.42kg
in the alternate grazing system vs. 18.59kg in the control (P = 0.003). 相似文献
58.
The well-known fatty acids with a Δ5,9 unsaturation system were designated for a long period as demospongic acids, taking into account that they originally occurred in marine Demospongia sponges. However, such acids have also been observed in various marine sources with a large range of chain-lengths (C(16)-C(32)) and from some terrestrial plants with short acyl chains (C(18)-C(19)). Finally, the Δ5,9 fatty acids appear to be a particular type of non-methylene-interrupted fatty acids (NMA FAs). This article reviews the occurrence of these particular fatty acids in marine and terrestrial organisms and shows the biosynthetic connections between Δ5,9 fatty acids and other NMI FAs. 相似文献
59.
Nadine Brisson Philippe Gate David Gouache Gilles Charmet François-Xavier Oury Frédéric Huard 《Field Crops Research》2010
The last two decades are witnessing a decline in the growth trend of cereal yields in many European countries. The present study analyses yield trends in France using various sources of data: national and regional statistics, scattered trials, results of agroclimatic models using climatic data. Effects in genetic changes through breeding, agronomy and climate are investigated as possible causes. Our results show that genetic progress has not declined but it was partly counteracted, from 1990 on, by climate change which in general is unfavorable to cereal yields in temperate climates because of heat stress during grain filling and drought during stem elongation. We cannot however, from the decade beginning in 2000, rule out agronomic causes, related to policy and economy, in particular the decline of legumes in the cereal rotations, replaced by oilseed rape and to a lesser extent the decrease in nitrogen fertilization. 相似文献
60.
Christoforos Karanikas Vincent Walker Apostolos Scaltsoyiannes Gilles Comte Cédric Bertrand 《Annals of Forest Science》2010,67(4):412-412