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Seawater Mg:Ca and Sr:Ca ratios are biogeochemical parameters reflecting the Earth–ocean–atmosphere dynamic exchange of elements. The ratios’ dependence on the environment and organisms' biology facilitates their application in marine sciences. Here, we present a measured single-laboratory dataset, combined with previous data, to test the assumption of limited seawater Mg:Ca and Sr:Ca variability across marine environments globally. High variability was found in open-ocean upwelling and polar regions, shelves/neritic and river-influenced areas, where seawater Mg:Ca and Sr:Ca ratios range from ∼4.40 to 6.40 mmol:mol and ∼6.95 to 9.80 mmol:mol, respectively. Open-ocean seawater Mg:Ca is semiconservative (∼4.90 to 5.30 mol:mol), while Sr:Ca is more variable and nonconservative (∼7.70 to 8.80 mmol:mol); both ratios are nonconservative in coastal seas. Further, the Ca, Mg, and Sr elemental fluxes are connected to large total alkalinity deviations from International Association for the Physical Sciences of the Oceans (IAPSO) standard values. Because there is significant modern seawater Mg:Ca and Sr:Ca ratios variability across marine environments we cannot absolutely assume that fossil archives using taxa-specific proxies reflect true global seawater chemistry but rather taxa- and process-specific ecosystem variations, reflecting regional conditions. This variability could reconcile secular seawater Mg:Ca and Sr:Ca ratio reconstructions using different taxa and techniques by assuming an error of 1 to 1.50 mol:mol, and 1 to 1.90 mmol:mol, respectively. The modern ratios’ variability is similar to the reconstructed rise over 20 Ma (Neogene Period), nurturing the question of seminonconservative behavior of Ca, Mg, and Sr over modern Earth geological history with an overlooked environmental effect.

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The swimming behavior of males and females of the seldom studied sub-tropical copepod Oncaea venusta was studied using scale-dependent (swimming speed and net-to-gross displacement ratio) and scale-independent (fractal dimension) metrics. The scale-dependent metrics were characterized by: (1) a considerable intra-and inter-individual variability that prevented the identification of any specific behavior and (2) a strong dependence on the number of data points available in each individual path. Conversely, the scale-independent metric (fractal dimensional) resolved reduced intra-and inter-individual variability and independence from the length of the swimming paths, leading to the identification of 4 groups of distinct swimming patterns. While additional behavioral experiments are needed to ensure the relevance and the generality of the present results, behavioral fractal analysis nevertheless demonstrates a promising ability to elucidate the complexity of zooplankton behavior.KEY WORDS: Zooplankton · Swimming · Behavior · Scale-dependence · Scale-independence · Fractal · ScalingResale or republication not permitted without written consent of the publisher

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The East China Sea is characterized by a complex hydrographic regime and high biological productivity and diversity. This environmental setting in particular challenged a case study on the use of mesozooplankton community parameters as indicators of water masses. In order to reveal spatial patterns of zooplankton communities during summer, a large scale oceanic transect study was conducted. Two transects were taken in the southwest East China Sea region, covering for the Wrst time the China shelf, slope, and the estuaries of the Yangtze river and of the Minjiang river, the northern Taiwan Strait, and the Kuroshio Current region. A total of 77 copepod species were quantiWed. Copepod abundance was signiWcantly higher in the estuary of the Yangtze River runoV mixture waters and lowest at the Kuroshio Current Region. The calanoid Parvocalanus crassirostris was the most frequently occurring and abundant species retrieved from 27 samples of a total of 39 samples. The use of multivariate cluster analysis separated the Mainland China Shelf from the northern Taiwan Strait and the Kuroshio Current Region at the Wrst hierarchical level. The use of an indicator value method (IndVal) associated with each cluster of stations revealed characteristic species assemblages. Two hierarchical levels deWned 4 assemblages within geographical sectors representing copepod assemblages of the Kuroshio Current Region, of the northern Taiwan Strait and the southern China Shelf near the estuary of the Minjiang River and northern stations near the estuary of the Yangtze River. Overall, there was a strong correspondence between the distribution of certain copepod species and water masses. DiVerences between the Mainland China shelf, the northern Taiwan Strait and the Kuroshio Current Region were characterized by diVerences in species composition and abundance. Water mass boundaries in the study area were exclusively indicated by distinct diVerences in species composition, emphasizing a correlation between copepod communities and water masses of the southwest East China Sea in summer.

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Predator-induced control of pests depends on the predator's preference for the target pest over naturally co-occurring prey species. We compared the larvivorous efficiency of three common freshwater predators: mosquitofish (Gambusia affinis; Baird and Girard, 1854), dragonfly naiads (Zyxomma petiolatum; Rambur, 1842) and copepods (Mesocyclops aspericornis; Daday, 1906) on different instars and the relative abundances of the mosquito Anopheles stephensi (Liston, 1901) in the presence of alternative cladoceran prey, either Moina macrocopa (Straus, 1820) or Daphnia similoides (Hudec, 1991). Larval removal rate decreased with increasing larval size and instar stage. The maximum consumption rate was by mosquitofish, followed by dragonfly naiads and copepods. The presence of either of the alternative prey significantly reduced larval consumption by all three predators, except in the D. similoides-mosquito larvae combination for naiads. Mosquitofish and copepods preferred early instars of the mosquito. Prey selectivity indices for early mosquito instars against D. similoides did not differ between mosquitofish and copepods, whereas naiads had significantly lower index values than the other two predators. Considering the negative impacts of mosquitofish on native assemblages, that is, its invasiveness and its lower selectivity for mosquito larvae, our results suggest that the feasibility of using copepods in large-scale control programs needs to be evaluated.