Resource-use,body condition and parasite load metrics indicate contrasting health of stocked and native game fishes in Canadian prairie lakes

This study evaluated the status of native and stocked fish species in 13 prairie lakes in central Canada over eight years (2007–14) using three metrics: resource-use (benthic versus pelagic carbon via stable isotopes); body condition (relative weight index W_r); and parasite load (cestode gut enumerations). Analyses included game and non-game fishes, like naturally occurring northern pike, Esox lucius L., and yellow perch, Perca flavescens Mitchill, but focused on stocked walleye, Sander vitreus (Mitchill) because it supports a robust recreational fishery. Walleye and northern pike were significantly more reliant on benthic carbon than yellow perch or forage fishes (p < 0.05), but this reliance was not associated with any measured environmental variables for any species. In lakes with game fishes, forage fishes exhibited higher reliance on benthic energy, possibly due to predator avoidance strategy, particularly yellow perch. Walleye body condition index was consistently lower (<95–105) than values exhibited by the other two game fishes (81–139), and parasites were only common in walleye and associated with lake-water salinity (r² = 0.93, p < 0.05) and sex (p < 0.05). Based on the results, the most desirable game fish, walleye, appears less resilient to environmental variability than northern pike and yellow perch, making this species more susceptible to impacts of future climate change.     

Stable carbon isotopes of tree rings as a tool to pinpoint the geographic origin of timber

Illegal logging is a major cause of worldwide deforestation, and demands for scientific methods to identify the geographic origin of timber are increasing. “Dendroprovenancing” is one such method, in which the origin of unknown wood is estimated by calculating correlations of the ring-width series of the unknown wood with reference trees of known geographic origins. We applied the dendroprovenancing method to carbon isotope network data of pinyon pines (Pinus edulis and Pinus monophylla) from the southwestern United States to test the efficacy of using a carbon isotope time series for provenancing wood. First, we calculated correlations (t values) between test trees temporarily assumed to be of unknown origin and reference trees from 13 surrounding sites. Then, we plotted the t values on a map. When provenancing was successful, the tested trees showed the strongest correlation with reference trees from sites close to the actual origins of the test trees, and the correlations decreased with the distance between the original sites of test and reference trees. This conical distribution of t values enabled provenancing of wood with precision of 114–304 km. Although isotope measurement is more expensive and laborious than ring-width measurement, our tests of provenancing pinyon pines in the southwestern United States showed a higher success rate with carbon isotopes.     

A Backstage Look at Crop Protection and Environmental Quality

Abstract

A list of weeds and their maximum intensity of infestation observed in agricultural areas in the southwestern Arabian Peninsula is presented.     

南疆巴旦杏园朝鲜球坚蚧不同发育期的防治措施研究

为了探寻不同发育期朝鲜球坚蚧的有效防治新措施,根据朝鲜球坚蚧不同发育阶段的形态特征和生物学习性,对不同龄期的若虫采取刮皮涂干、树干注射和常规喷雾等措施进行防治.试验结果表明;在施药方法上,刮皮涂干和常规喷雾是最为适用的;在药效方面,在1龄若虫期喷雾施用的几种药剂中醋盐合剂对1龄若虫的喷洒防效达到了90%以上.通过施用脱叶剂处理叶片的方法来防治2龄若虫,试验所设3种浓度的脱叶剂均能间接起到防治作用,其效果均达到了95%以上.在3龄若虫期喷雾施用的几种药剂中95%酒精合剂的喷洒防效达到了90%以上.涂干防治3龄若虫期供试的几种药剂中,20%吡虫啉可溶性液剂1∶10的稀释液防效达到了90%以上.     

Pathological findings in the bulbourethral glands of bulls

The bulbourethral glands of 323 Bos indicus or B. indicus crossbred bulls more than 1 1/2 years old were examined in an abattoir study. Bulbourethral adenitis was diagnosed grossly and confirmed by histological examination in 4 (1.2%). Unilateral chronic interstitial inflammation was seen in 2 cases; one of these was associated with a degenerative-type seminal vesiculitis. In the others adenitis was bilateral; in one case it was associated with a concretion and foreign (plant) material in the principal duct of the left bulbourethral gland; in the other bilateral case, numerous calculi were present and microscopically, a chronic active and diffuse inflammation was observed. Chemical analysis of the calculi showed calcium oxalate and tricalcium phosphate to be the most important components. Corynebacterium spp was isolated from the lesion with multiple calculi but attempts to isolate Chlamydia spp, Mycoplasma spp and Brucella abortus from the 4 adenitis cases were unsuccessful. Congenital abnormalities such as glandular fusion (2.2%) or unilateral aplasia (0.6%) were also observed. Cysts were the most common finding (19.2%), and duct dilation was frequent (7.1%). The significance of these findings in relation to fertility is considered.     

Calves Born after Direct Transfer of Vitrified Bovine In Vitro-produced Blastocysts Derived from Vitrified Immature Oocytes

Vitrification has been the method of choice for the cryopreservation of bovine oocytes, as rapid cooling decreases chilling sensitivity. The aim of this study was to determine the in vitro and in vivo survival and the viability of immature oocytes vitrified using super‐cooled liquid nitrogen. Immature oocytes were randomly allocated to three groups: (i) non‐vitrified control group, (ii) vitrified in normal (?196°C) liquid nitrogen (LN₂) and (iii) vitrified in super‐cooled LN₂ (≤?200°C). Open‐pulled glass micropipettes were used as vitrification containers. Immature oocytes were in vitro‐matured, fertilized and cultured to the blastocyst stage. In vitro viability was assessed by cleavage and blastocyst rates on days 2 and 7 of culture respectively. Vitrified blastocysts derived from the immature vitrified oocytes were directly transferred to synchronous recipients. The in vitro embryo development of vitrified immature oocytes was not influenced by the LN₂ state. After direct transfer (one embryo per recipient) of 16 embryos obtained from immature vitrified oocytes (eight from each vitrified group), two healthy calves were born in each group. These results indicated that vitrification of immature bovine oocytes using glass micropipettes under normal or super‐cooled LN₂, resulted in viable blastocysts and live calves following in vitro embryo production.