Sign In or Create an Account. Sign In. Advanced Search. Article Navigation. Close mobile search navigation Article Navigation.
Table 1 from A Simple Adjustment for Bandwidth Snooping - Semantic Scholar
Volume Oxford Academic. Google Scholar. Cite Citation. Permissions Icon Permissions.
Abstract Kernel-based estimators such as local polynomial estimators in regression discontinuity designs are often evaluated at multiple bandwidths as a form of sensitivity analysis. Issue Section:. You do not currently have access to this article.
Download all figures. Sign in. You could not be signed in.
Sign In Forgot password? Don't have an account? Sign in via your Institution Sign in. Purchase Subscription prices and ordering Short-term Access To purchase short term access, please sign in to your Oxford Academic account above. This article is also available for rental through DeepDyve. View Metrics. Another issue is that leucine might act as fertilizer for bacterial growth, as it is labile and especially in oligotrophic conditions stimulating growth.
Moreover, enrichment bioassays performed with water from both stations Fig.
How the differences in specific growth rates in OF affect the net growth rates of bacteria we can only speculate at this stage. Interestingly, flow cytometer plots indicated a shift in bacterial community or activity. Scatter plots of samples from WSW at the start of the dilution experiments showed two distinct populations of bacteria Fig.
For bacteria from IF Fig. In OF Fig. Gasol et al. They suggested that HNA bacteria are large and active cells preferable grazed on and as a consequence of reduced grazing pressure HNA bacteria increased.
- Justin Weaver and The Star Maker?
- Magnetophotonics: From Theory to Applications (Springer Series in Materials Science)?
- The Spellsong War: The Second Book of the Spellsong Cycle.
- Jesus calling: Christian Personal Development;
We find one case where HNA and LNA developed similar in the dilution experiment IF and one case where they showed opposite net growth along a gradient of dilutions with filtered seawater OF. Filtered seawater is not only predator free but also contains a different level of metabolites released from phytoplankton cells during filtration or reduced during filtration compared with unfiltered seawater. Therefore, we cannot determine whether HNA bacteria in dilutions of OF grow better due to decreased grazing or due to change in concentrations of metabolites. However, the increase of specific growth rate in OF corresponds well with the increase of HNA bacteria numbers in OF and most importantly constitutes a violation of one of the basic assumptions of the dilution method Landry and Hassett Pasulka and colleagues were not aiming for retrieving rates for bacterivory from their experiments but suggest that altered growth of bacteria in dilutions have an impact on the other communities like picophytoplankton and consequently the grazing rates.
Findings of Pasulka et al. Dynamics within grazer community during incubation are important to consider during dilution experiments because, e.
By subtraction of chromatographic profiles of control samples it was made sure that only metabolites in the seawater and no contaminations contributed to this difference. This result is in line with the other parameters previously used to indicate different bloom status despite similar Chl a concentrations at the two stations Table 2. For dilution experiments at both sampling sites significant differences in the metabolic profile of the seawater were observed when comparing FSW and WSW Fig.
Thus, filtration has a clear impact on the metabolic composition of seawater masking the initial differences of metabolic profiles of seawater of IF and OF Fig. Score plot of a canonical analysis of principal coordinates CAP showing a clear separation of WSW samples circles compared with 0. The 0. This can be due to an adsorption effect on the filter or depletion due to a lack of stability of metabolites during filtration. Further, we also detected several metabolites that were more abundant after filtration Table 4 b , possibly released due to stress and disruption of cells during filtration.
Unfortunately most metabolites remain unknown, however, some fatty acids and dodecanol could be tentatively assigned by spectral library search. The main objective of this study was to provide a relatively simple adjustment of the dilution method to test the first basic assumption of Landry and Hassett by measuring bacterial production additional to abundance.
We provide results of two dilution experiments used to derive bacterivory rates where in one case IF specific growth rates were not affected by dilution and another case OF where these were significantly affected. Chemical analysis revealed differences in metabolic profiles of metabolites in seawater from the two stations as well as a change in metabolic profiles caused by the filtration.
- Small Steps, Big Impact! Part II.
- Navigation menu;
- 77 Shadow Street.
- Miniature Schnauzer: A Comprehensive Guide to Owning and Caring for Your Dog (Comprehensive Owners Guide);
- Priest in the Pyrenees!
- Breaking into the REO Business: How I Went from Bankruptcy to $7.2 Million in 7 Years While Making Friends;
Bacteria growth might be affected by release of allelochemicals but also by the adsorption of metabolites, such as saccharides due to filtration. Obviously, our study is limited to dilution experiments during a P. Nevertheless, Phaeocystis sp. Moreover, change of metabolic profiles when filtering seawater for dilution experiments is not only an issue during blooms of Phaeocystis but has also been shown during other phytoplankton blooms such as Skeletonema marinoi Stoecker et al.
However, the suggested modification of including BP measurements as a proxy of specific growth when using dilution method for bacterivory helps to unravel uncertainties coming along with the method and to understand whether derived bacterivory rates are reliable or not. For previous studies of bacterivory using dilution method based on flow cytometric analysis, one could reanalyze the scatter plots and check whether two different populations HNA, LNA are distinguishable.
Further, if they developed differently during incubation in dilutions and WSW the assumption can be drawn that either bacterial community or bacteria specific growth was affected by filtration and bacterivory rates are biased. We recommend including measurements of BP to the protocol of the dilution method for bacterial grazing to test and validate the effect of dilution with 0. By that, one can identify the circumstances under which the dilution technique provides reliable estimates for bacterivory and minimize the uncertainty the impact filtration might have on bacterial growth.
In case of different specific growth rates in dilutions and WSW the derived grazing rates are inaccurate. If future studies show that in the majority of dilution experiments specific growth rates differ between WSW and dilutions, alternative methods not using a filtration step should be preferred. At the same time, improvement of the filtration protocol, by combining biological and chemical measurements, is a necessity for further developing the dilution method toward more accurate estimates of bacterivory rates.
A Simple Adjustment
Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries other than missing content should be directed to the corresponding author for the article. Julia Althammer is acknowledged for her help during sampling and extraction on board and for fruitful discussion.
Thanks to T. Frede Thingstad and Jessica L. Ray for helpful discussions. Volume 14 , Issue 2. If you do not receive an email within 10 minutes, your email address may not be registered, and you may need to create a new Wiley Online Library account. If the address matches an existing account you will receive an email with instructions to retrieve your username. Limnology and Oceanography: Methods Volume 14, Issue 2. Evaluations of Existing Methods Open Access. Andrey F. Sazhin Laboratory of Plankton Ecology, P.