Weed seed availability,carabid intraspecific interference and their interaction drive weed seed consumption by carabid beetles

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Spatial and temporal variation in artisanal catches of dolphinfish Coryphaena hippurus off north‐eastern Brazil

The sampling of fish from the artisanal fleet operating with surface lines off north‐eastern Brazil was carried out between 1998 and 2000. Generalized linear models (GLMs) were used to standardize mean abundance indices using catch and fishing effort data on dolphinfish Coryphaena hippurus and to identify abundance trends in time and space, using 1215 surface line deployments. A standard relative abundance index (catch per unit effort, CPUE) was estimated for the most frequent vessels used in the sets, employing factors and coefficients generated in the GLMs. According to the models, C. hippurus catches are affected by the operating characteristics and power of different fishing vessels. These differences highlight the need for standardization of catch and effort data for artisanal fisheries. The highest mean abundance values for C. hippurus were off the state of Rio Grande do Norte, with an increasing tendency in areas with greater depths and more distant from the coast, reaching maximal values in areas whose depths range from 200 to 500 m. The highest mean abundance values occurred between April and June. The higher estimated abundance of C. hippurus in this period off the state of Rio Grande do Norte and within the 200–500 m depth range may be related to a migration pattern of food sources, as its main prey, the flying fish Hirundichthys affinis, uses floating algae as refuge and to deposit its pelagic eggs.     

A mechanistic model for understanding invasions: using the environment as a predictor of population success

Aim We set out to develop a temperature‐ and salinity‐dependent mechanistic population model for copepods that can be used to understand the role of environmental parameters in population growth or decline. Models are an important tool for understanding the dynamics of invasive species; our model can be used to determine an organism’s niche and explore the potential for invasion of a new habitat. Location Strait of Georgia, British Columbia, Canada. Methods We developed a birth rate model to determine the environmental niche for an estuarine copepod. We conducted laboratory experiments to estimate demographic parameters over a range of temperatures and salinities for Eurytemora affinis collected from the Nanaimo Estuary, British Columbia (BC). The parameterized model was then used to explore what environmental conditions resulted in population growth vs. decline. We then re‐parameterized our model using previously published data for E. affinis collected in the Seine Estuary, France (SE), and compared the dynamics of the two populations. Results We established regions in temperature–salinity space where E. affinis populations from BC would likely grow vs. decline. In general, the population from BC exhibited positive and higher intrinsic growth rates at higher temperatures and salinities. The population from SE exhibited positive and higher growth rates with increasing temperature and decreasing salinity. These different relationships with environmental parameters resulted in predictions of complex interactions among temperature, salinity and growth rates if the two subspecies inhabited the same estuary. Main conclusions We developed a new mechanistic model that describes population dynamics in terms of temperature and salinity. This model may prove especially useful in predicting the potential for invasion by copepods transported to Pacific north‐west estuaries via ballast water, or in any system where an ecosystem is subject to invasion by a species that shares demographic characteristics with an established (sub)species.     

Nasal Discs and the Vital Rates of Lesser Scaup

Nasal discs have been used to identify ducks in studies of survival and reproduction. To date, there has not been a comprehensive assessment of nasal-disc effects on the vital rates of wild ducks. We applied nasal discs to 603 juvenile and 784 adult lesser scaup (Aythya affinis) females from a population breeding in southwest Montana, USA, and released 1,399 juvenile and 71 adult females wearing only metal leg bands between June 2005 and September 2016. Using resighting, recapture, and hunter-recovery data collected from those individuals, we estimated survival and recovery probability with multistate capture-recapture models in Program MARK. We also assessed if recovery distance from our study site and pre-breeding and brood-rearing body condition were diminished for females wearing nasal discs. Model-averaged survival probabilities were 0.231 ± 0.035 (SE) for juveniles and 0.482 ± 0.019 for adults released with nasal discs. Survival was 1.8–3.4 times higher for females released with metal leg bands when compared to those released with nasal discs; survival of these juveniles was 0.433 ± 0.049 and 0.693 ± 0.039 for adults. We did not find evidence for recovery probability or recovery distance varying between females that wore nasal discs and those that did not. During the pre-breeding and brood-rearing seasons, we did not find females wearing nasal discs to be in lower body condition when compared to unmarked females. Our comprehensive assessment of nasal discs on wild lesser scaup suggests that survival probabilities estimated from nasal-marked study populations should be cautiously interpreted as minimum estimates. © 2021 The Wildlife Society.     

河南省二种菊头蝠的核型研究

取骨髓细胞采用空气干燥法对河南省二种菊头蝠的核型进行研究。结果：1．中菊头蝠染色体数为2n=62,N,F=60,属于Harada等划分的菊头蝠属的第1类群,即最原始的类群;2．马铁菊头蝠染色体数为2n=58．N．F=60,属于Harada等划分的菊头蝠属的第2类群;3．马铁菊头蝠的核型为国内首次报道。     

四川2种丛生竹木质素和纤维含量的研究

以四川4个地区2种丛生竹(慈竹和硬头黄)为研究对象,对其木质素和综纤维含量进行研究.结果表明,不同地区竹种间综纤维素含量差异显著;除青神地区外,其它几个地区木质素含量差异不大.纬度对木质素积累的作用因竹种而异,对慈竹木质素含量的作用呈极明显的正效应,对硬头黄的作用则呈不明显的正效应,对综纤维含量的影响不大.竹龄影响木质素和综纤维素含量的积累,对慈竹木质素和综纤维的积累呈显著的正效应,但对硬头黄的作用却不明显.研究认为,青神、长宁和绵阳地区的硬头黄以及长宁地区的慈竹是造纸的较好原料.     

A new photobioreactor for continuous microalgal production in hatcheries based on external-loop airlift and swirling flow

This study deals with the scale of a new photobioreactor for continuous microalgal production in hatcheries. The combination of the state-of-art with the constraints inherent to hatcheries has turned the design into a closed, artificially illuminated and external-loop airlift configuration based on a succession of elementary modules, each one being composed of two transparent vertical interconnected columns. The liquid circulation is ensured pneumatically (air injections) with respect to a swirling motion (tangential inlets). A single module of the whole photobioreactor was built-up to scale its geometry (diameter and length) and to optimize its design (air sparger, tangential inlets). The volumetric productivities were predicted by modeling radiative transfer and growth of Isochrysis affinis galbana (clone Tahiti). The hydrodynamics of the liquid phase was modeled in terms of global flow behavior (circulation and mixing times, Péclet number) and of swirling motion decay along the column (Particle Image Velocimetry). The aeration performances were determined by overall volumetric mass transfer measurements. Continuous cultures of Isochrysis affinis galbana (clone Tahiti) were run in two geometrical configurations, generating either an axial or a swirling flow. Lastly, the definitive options of design are presented as well as a 120-L prototype, currently implemented in a French mollusk hatchery and commercialized.     

Spatial and temporal patterns in the occurrence of peritrich ciliates as epibionts on calanoid copepods in the Chesapeake Bay, USA

We investigated temporal and spatial patterns of distribution in two peritrich ciliates (i.e. Zoothamnium intermedium and Epistylis sp.) living as epibionts on calanoid copepods (i.e. Acartia tonsa and Eurytemora affinis) in Chesapeake Bay. Net tow samples collected along the main axis of the Bay were analyzed to estimate the occurrence of epibionts on copepods and to explore relationships among infestation prevalence, host abundance, and environmental variables. Zoothamnium intermedium and Epistylis sp. colonized populations of A. tonsa during spring and summer months, while only Z. intermedium colonized E. affinis during spring. Occurrence of epibionts on copepods showed high interannual variation, marked seasonality, and geographic heterogeneity. Extensive statistical analyses rejected simple scenarios of interactions between epibiosis, environmental variables, and host density, suggesting a more complex dynamics for the system. Analyses of epibiont colonies and zooids per host area (i.e. the sum of width and length of the body including antennae and swimming legs calculated assuming a cylindrical shape) were also performed. Overall, epibiont infestation prevalence (i.e. colonies/host area) and load (i.e. zooids/host area) were higher on copepodites than on adults for both host species, suggesting a preferential attachment to juveniles, or a higher predation pressure on adult stages. Infestation density and loads of both epibiont species were higher on the cephalothorax and abdomen of A. tonsa and E. affinis in comparison to the antennae and swimming legs, suggesting that ciliates can more easily colonize less active parts of the host.     

近亲幽灵蛛的核型分析（蜘蛛目：幽灵蛛科）

报告近亲幽灵蛛的核型分析,包括:染色体数目、形态结构和性染色体组成。实验材料采自石家庄郊区的校园中,细胞学数据主要来自对肝胎细胞有丝分裂中期的观察。实验结果表明:近亲幽灵蛛的染色体数目是:雄体细胞为25条,雌体细胞为26条。性别决定机制属XO系统,X染色体是核型中最长的1条(对),也是唯一1条(对)典型的业中部着丝粒染色体,这在我们过去的实验中尚属第一次发现。对近亲幽灵蛛的C-带标本分析表明:所有染色体都有明显的着丝粒带,只是X染色体及1~＃常染色体的着丝粒带为淡染带。4~＃常染色体长臂中部有一宽染深带。极具识别特点。5~＃常染色体中的1条具一般着丝粒带,另1条全部深染,表明它富含结构异染色质。此外,其常染色体1~＃、3~＃、4~＃、8~＃、11~＃、12~＃和X染色体上,除有着丝粒带外,在长臂末端均出现端粒带(T带),其产生机制有待进一步研究。在染色体G-显带标本中,获得了较清晰的带纹。