Zooplankton dynamics in a lowland river along temporal and spatial gradients

Studies on zooplankton ecology have traditionally dealt with lentic systems, while research on lotic assemblages has lagged far behind. It is especially in the last decades that riverine zooplankton has become the focus of an increasing number of investigations, showing that large lowland rivers often host extremely rich and abundant plankton communities. Surveys conducted in rivers all over the world highlighted the major role played by abiotic constraints in shaping the development of riverine zooplankton, while much fewer studies have dealt with biotic factors, which are generally thought to play a minor role in the main current of rivers. Despite this growing amount of research, questions still remain to be answered regarding the origin of river plankton, how these communities are able to persist in the current and the major mechanisms involved in regulating their spatio-temporal dynamics. The present work deals with different aspects of the ecology of zooplankton in a large lowland river (Po River, Northern Italy). A multi-level approach was adopted, combining different surveys carried out at distinct spatial and temporal resolutions, based on the following main research questions: 1. What are the main abiotic and biotic factors controlling the spatio-temporal dynamics of zooplankton abundance and composition in the potamal reach of a lowland river? What is the effect of disturbance events like floods on community structure? Is the community able to exhibit regular successional patterns? These research topics have been addressed by means of a two-year sampling campaign carried out in the potamal reach of the Po River. Results confirmed the role of abiotic constraints related to seasonality and hydrology, together with that of trophic conditions, as the major drivers of zooplankton dynamics. The comparison of two hydrologically different years suggested that the uncoupling between seasonality and hydrology can significantly influence community density and diversity temporal patterns. The relationship between discharge and zooplankton abundance is not univocally negative, as increases in river flow may at times bring about a net increment of the assemblage, when resuspension of organisms from the river bottom and/or littoral zones prevails over advective losses. Discharge fluctuations strongly affect zooplankton diversity too, both taxonomical and functional, with higher diversity associated with increases in river flow, up to a threshold over which destructive effects dominate. However, the impact of hydrodynamic forcings in shaping lotic zooplankton appears to lose importance in favour of that of seasonality and trophic state when moving down the longitudinal dimension of the river system, and a clear downstream shift towards a truly planktonic community occurs, especially during summer low-flow conditions. 2. Can biotic interactions (predation/competition) within the zooplankton become crucial drivers of community structure under advective conditions? A short-term, high-frequency sampling campaign was carried out in summer 2005 in the potamal stretch of the Po River. To test for the presence of association patterns among zooplankters, which might be suggestive of potential trophic interactions (predation/competition), taxa were aggregated into functional groups according to their feeding ecology, and time series of their abundances were analysed by means of a variance ratio test and multivariate autoregressive models, which revealed the occurrence of compensatory dynamics among functional groups under low and stable, although truly advective, discharge conditions. Evidence on the importance of predator-prey interactions and intra-population regulation mechanisms also came from further analyses on the dominant predator's gut contents and on its main prey's population dynamics. Results showed that, under certain conditions, zooplankton is able to exhibit internal, self-regulatory mechanisms also in the main current of a large river and the view of riverine zooplankton as a mere assemblage of taxa exclusively abiotically controlled is therefore oversimplified. 3. What are the main changes within the plankton community during its downstream transport and how can the observed longitudinal dynamics be explained? What is the contribution of the major tributaries to the main channel zooplankton assemblage? These questions have been addressed by means of a Lagrangian sampling experiment carried out in May 2010 on a 330-km river stretch. Results highlighted how water residence time under spring conditions is too short to allow longitudinal development of zooplankton, which is merely transported downstream without significant changes in abundance and composition. One of the tributaries, the Mincio River, hosted an exceptionally abundant zooplankton community, which resulted in a significant increase in total zooplankton densities in the Po River downstream of its inflow. The Mincio lower course is highly regulated and artificially modified. The result is a system where current is extremely impaired and slowed down, creating favourable conditions for phyto- and zooplankton massive development. As a consequence, the influence of this tributary on the Po River zooplankton during the survey was still detectable as far as 100 km downstream of its mouth and the community composition recorded downstream of the Mincio inflow was more similar to the assemblage found in the tributary than to that found at the upstream stations of the Po River itself. 4. Does the presence of an hydrological discontinuity along the river course, such as a man-made reservoir, induce relevant changes in zooplankton composition and abundance? Are there significant differences in community structure along cross-channel transects (middle channel versus river banks) or is the river a completely well-mixed environment with homogeneously distributed plankton assemblages? A sampling campaign was carried out in summer 2009 at four stations respectively upstream, inside (mid-channel vs. shore) and downstream of the artificial impoundment of Isola Serafini, located in the middle reach of the Po River. The study revealed that longitudinal and lateral hydrogeomorphic heterogeneity may affect community abundance and diversity, so that the assemblage found at one site along the river may also be related to local hydroecological features and not only to processes taking place further upstream. However, in a rectified and channelized river like the Po, this appears to be the case only at extremely low discharge rates and high water residence time. Results of the surveys carried out along extremely artificialized traits of both the Po River (Isola Serafini dam) and its tributaries (lower section of the Mincio River) showed how anthropogenic modifications of the river's natural hydrogeomorphic features may have strong impacts also on biotic components that are usually overlooked by standard monitoring programs, even though their role in the functioning of lotic systems is still not completely understood

Advancing estuarine ecological forecasts: seasonal hypoxia in Chesapeake Bay

Ecological forecasts are quantitative tools that can guide ecosystem management. The coemergence of extensive environmental monitoring and quantitative frameworks allows for widespread development and continued improvement of ecological forecasting systems. We use a relatively simple estuarine hypoxia model to demonstrate advances in addressing some of the most critical challenges and opportunities of contemporary ecological forecasting, including predictive accuracy, uncertainty characterization, and management relevance. We explore the impacts of different combinations of forecast metrics, drivers, and driver time windows on predictive performance. We also incorporate multiple sets of state-variable observations from different sources and separately quantify model prediction error and measurement uncertainty through a flexible Bayesian hierarchical framework. Results illustrate the benefits of (1) adopting forecast metrics and drivers that strike an optimal balance between predictability and relevance to management, (2) incorporating multiple data sources in the calibration data set to separate and propagate different sources of uncertainty, and (3) using the model in scenario mode to probabilistically evaluate the effects of alternative management decisions on future ecosystem state. In the Chesapeake Bay, the subject of this case study, we find that average summer or total annual hypoxia metrics are more predictable than monthly metrics and that measurement error represents an important source of uncertainty. Application of the model in scenario mode suggests that absent watershed management actions over the past decades, long-term average hypoxia would have increased by 7% compared to 1985. Conversely, the model projects that if management goals currently in place to restore the Bay are met, long-term average hypoxia would eventually decrease by 32% with respect to the mid- 1980

The new checklist of the Italian Fauna: Rotifera

5openInternationalInternational coauthor/editorWe present a data set reporting the checklist of the species of the phylum Rotifera for Italy, updating the one previously published in the series ‘Checklist delle Specie della Fauna d'Italia’ in 1995. The records of the updated checklist refer to the 483 taxa at the species and subspecies level currently known from national Italian territories (119 Bdelloidea, 362 Monogononta, 2 Seisonacea) at the regional level (22 terrestrial and nine marine geographical units). The records refer to various freshwater, limno-terrestrial, and marine coastal habitats. The previous checklist reported 245 taxa (54 Bdelloidea, 189 Monogononta, 2 Seisonacea): three taxa were removed because currently considered not valid and 241 were added,scanning 21 papers we found that were published between 1993 and 2020, expanding the regional records and including four papers older than 1993 with overlooked records in the previous checklist. The Rotifera data are part of the updated Checklist of the Italian Fauna, which is viewable on the LifeWatch Italy platform at https://www.lifewatchitaly.eu/en/initiatives/checklist-fauna-italia-en/checklist and is freely available on the LifeWatch Italy Data Portal (https://dataportal.lifewatchitaly.eu/data). The checklist will be dynamically updated with new records; this paper describes the state of the art of the data set regarding Rotifera on May 2021.openFontaneto, D.; Bertani, I.; Cancellario, T.; Rossetti, G.; Obertegger, U.Fontaneto, D.; Bertani, I.; Cancellario, T.; Rossetti, G.; Obertegger, U

Multiple models guide strategies for agricultural nutrient reductions

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136504/1/fee1472_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136504/2/fee1472-sup-0008-WebTable7.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136504/3/fee1472-sup-0004-WebTable3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136504/4/fee1472.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136504/5/fee1472-sup-0006-WebTable5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136504/6/fee1472-sup-0002-WebTable1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136504/7/fee1472-sup-0005-WebTable4.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136504/8/fee1472-sup-0007-WebTable6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136504/9/fee1472-sup-0003-WebTable2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136504/10/fee1472-sup-0001-WebFig1.pd

Measurement of the proton form factor by studying e+e−→ppˉe^{+} e^{-}\rightarrow p\bar{p}

Using data samples collected with the BESIII detector at the BEPCII collider, we measure the Born cross section of $e^{+}e^{-}\rightarrow p\bar{p}$ at 12 center-of-mass energies from 2232.4 to 3671.0 MeV. The corresponding effective electromagnetic form factor of the proton is deduced under the assumption that the electric and magnetic form factors are equal $(|G_{E}|= |G_{M}|)$. In addition, the ratio of electric to magnetic form factors, $|G_{E}/G_{M}|$, and $|G_{M}|$ are extracted by fitting the polar angle distribution of the proton for the data samples with larger statistics, namely at $\sqrt{s}=$ 2232.4 and 2400.0 MeV and a combined sample at $\sqrt{s}$ = 3050.0, 3060.0 and 3080.0 MeV, respectively. The measured cross sections are in agreement with recent results from BaBar, improving the overall uncertainty by about 30\%. The $|G_{E}/G_{M}|$ ratios are close to unity and consistent with BaBar results in the same $q^{2}$ region, which indicates the data are consistent with the assumption that $|G_{E}|=|G_{M}|$ within uncertainties.Comment: 13 pages, 24 figure

Confirmation of a charged charmoniumlike state Zc(3885)∓Z_c(3885)^{\mp} in e+e−→π±(DDˉ∗)∓e^+e^-\to\pi^{\pm}(D\bar{D}^*)^\mp with double DD tag

We present a study of the process $e^+e^-\to\pi^{\pm}(D\bar{D}^*)^{\mp}$ using data samples of 1092~pb$^{-1}$ at $\sqrt{s}=4.23$~GeV and 826~pb$^{-1}$ at $\sqrt{s}=4.26$~GeV collected with the BESIII detector at the BEPCII storage ring. With full reconstruction of the $D$ meson pair and the bachelor $\pi^{\pm}$ in the final state, we confirm the existence of the charged structure $Z_c(3885)^{\mp}$ in the $(D\bar{D}^*)^{\mp}$ system in the two isospin processes $e^+e^-\to\pi^+D^0D^{*-}$ and $e^+e^-\to\pi^+D^-D^{*0}$. By performing a simultaneous fit, the statistical significance of $Zc(3885)^{\mp}$ signal is determined to be greater than 10$\sigma$, and its pole mass and width are measured to be $M_{\rm{pole}}$=(3881.7$\pm$1.6(stat.)$\pm$1.6(syst.))~MeV/$c^2$ and $\Gamma_{\rm{pole}}$=(26.6$\pm$2.0(stat.)$\pm$2.1(syst.))~MeV, respectively. The Born cross section times the $(D\bar{D}^*)^{\mp}$ branching fraction ($\sigma(e^+e^-\to\pi^{\pm}Z_{c}(3885)^{\mp}) \times Br(Z_{c}(3885)^{\mp}\to(D\bar{D}^*)^{\mp})$) is measured to be $(141.6\pm7.9(\text{stat.})\pm12.3(\text{syst.}))~\text{pb}$ at $\sqrt{s}=4.23$~GeV and $(108.4\pm6.9(\text{stat.})\pm8.8(\text{syst.}))~\text{pb}$ at $\sqrt{s}=4.26$~GeV. The polar angular distribution of the $\pi^{\pm}$-$Z_c(3885)^{\mp}$ system is consistent with the expectation of a quantum number assignment of $J^P=1^+$ for $Z_c(3885)^{\mp}$

Observation of the isospin-violating decay J/ψ→ϕπ0f0(980)J/\psi \to \phi\pi^{0}f_{0}(980)

Using a sample of 1.31 billion $J/\psi$ events collected with the BESIII detector at the BEPCII collider, the decays $J/\psi \to \phi \pi^{+}\pi^{-}\pi^{0}$ and $J/\psi \to \phi \pi^{0}\pi^{0}\pi^{0}$ are investigated. The isospin violating decay $J/\psi \to \phi \pi^{0} f_{0}(980)$ with $f_{0}(980) \to \pi\pi$, is observed for the first time. The width of the $f_{0}(980)$ obtained from the dipion mass spectrum is found to be much smaller than the world average value. In the $\pi^{0} f_{0}(980)$ mass spectrum, there is evidence of $f_1(1285)$ production. By studying the decay $J/\psi \to \phi\eta'$, the branching fractions of $\eta' \to \pi^{+}\pi^{-}\pi^{0}$ and $\eta' \to \pi^{0}\pi^{0}\pi^{0}$, as well as their ratio, are also measured.Comment: 10 pages, 10 figures, published in Phys. Rev.

An amplitude analysis of the π0π0\pi^{0}\pi^{0} system produced in radiative J/ψJ/\psi decays

An amplitude analysis of the $\pi^{0}\pi^{0}$ system produced in radiative $J/\psi$ decays is presented. In particular, a piecewise function that describes the dynamics of the $\pi^{0}\pi^{0}$ system is determined as a function of $M_{\pi^{0}\pi^{0}}$ from an analysis of the $(1.311\pm0.011)\times10^{9}$ $J/\psi$ decays collected by the BESIII detector. The goal of this analysis is to provide a description of the scalar and tensor components of the $\pi^0\pi^0$ system while making minimal assumptions about the properties or number of poles in the amplitude. Such a model-independent description allows one to integrate these results with other related results from complementary reactions in the development of phenomenological models, which can then be used to directly fit experimental data to obtain parameters of interest. The branching fraction of $J/\psi \to \gamma \pi^{0}\pi^{0}$ is determined to be $(1.15\pm0.05)\times10^{-3}$, where the uncertainty is systematic only and the statistical uncertainty is negligible.Comment: Submitted to Phys. Rev. D 19 pages, 4 figure

Measurement of the e+e−→ηJ/ψe^{+}e^{-} \to \eta J/\psi cross section and search for e+e−→π0J/ψe^{+}e^{-} \to \pi^{0} J/\psi at center-of-mass energies between 3.810 and 4.600~GeV

Using data samples collected with the BESIII detector operating at the BEPCII collider at center-of-mass energies from 3.810 to 4.600 GeV, we perform a study of $e^{+}e^{-} \to \eta J/\psi$ and $\pi^0 J/\psi$. Statistically significant signals of $e^{+}e^{-} \to \eta J/\psi$ are observed at $\sqrt{s}$ = 4.190, 4.210, 4.220, 4.230, 4.245, 4.260, 4.360 and 4.420 GeV, while no signals of $e^{+}e^{-} \to \pi^{0} J/\psi$ are observed. The measured energy-dependent Born cross section for $e^{+}e^{-} \to \eta J/\psi$ shows an enhancement around 4.2~GeV. The measurement is compatible with an earlier measurement by Belle, but with a significantly improved precision