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71.
Mark C. Hove Bernard E. Sietman Matthew S. Berg Erika C. Frost Kiru Wolf Tony R. Brady 《Journal of Natural History》2016,50(9-10):523-542
Managing a rare species can be improved with knowledge of its natural history. The sheepnose (Plethobasus cyphyus) is a freshwater mussel recently listed by the US as federally endangered. We used standard methods to study P. cyphyus brooding behaviour, host fishes in the laboratory and under natural conditions, and glochidial morphology. We monitored a population of P. cyphyus in the Chippewa River, WI during spring and summer 2007–2009 and 2011 and found brooding animals between mid-May and early August. Gravid individuals ranged between 5 and 27 yr (mean age ± 1 s.d. = 13 ± 4 yr). Plethobasus cyphyus brooded glochidia in outer gills, which varied in colour from red, orange, pink, cream, or white. We observed mature glochidia more commonly in individuals with cream or white gills and these glochidia were released in a clear, adhesive, mucus matrix. In laboratory trials we found several minnow and topminnow species (29 spp.) served as productive suitable native hosts. The mean number of juvenile mussels released per cyprinid per day was significantly higher for trials conducted at 22–25°C compared with those at 18–20°C, and 83% of trials conducted at 18–20°C using suitable host species produced no juveniles. Glochidia had a unique outline and shell morphometrics that distinguished P. cyphyus from seven other Chippewa River mussel species that produce similar sized glochidia. Using morphometrics we determined that mimic shiners (Notropis volucellus) were natural hosts for P. cyphyus, round pigtoe (Pleurobema sintoxia), and Wabash pigtoe (Fusconaia flava). Releasing mucus-bound glochidia has evolved in a variety of mussel species and may be more common than is currently realized. Our data show that P. cyphyus is a cyprinid host specialist, and propagation efforts for this species can be strengthened through improved access to mature glochidia by using females with cream-coloured gills and increased juvenile production through warmer fish holding temperatures. 相似文献
72.
分析工业现场LED数据显示屏主要是将各种类型传感器采集的数据,提出利用数据采集转换芯片,或者利用接口传送到LED显示屏上,进行数据的实时显示方案。 相似文献
73.
为研究模拟再现虚拟物体的几何形状、材质以及粗糙度等属性信息,提出基于单喷嘴喷气再现点触觉的方法,并建立手指皮肤和喷嘴的流固耦合有限元模型.将触摸小球时采用有限元模型的计算结果作为标准来分析气动喷嘴再现点触觉.提出有效触感宽度的概念,结合应变能密度及SS率等表征触觉的物理量分析了喷嘴直径、接触高度和入口压力对点触觉的影响.实验表明,分析结论与实验结果相符,为气动喷嘴设计提供了很好的参考依据. 相似文献
74.
网络教学,即通过网络或借助于物理媒体和网络应用软件相结合的一种教学活动模式,本文提出一种基于虚拟显卡的屏幕信息抓取技术的思想,并给出网络教学系统的解决方案。 相似文献
75.
76.
包俊东 《内蒙古师范大学学报(自然科学版)》2001,30(2):95-98
研究了一类带有强迫项的具有连续型滞量的非线性微分方程组解的渐近性,进一步推广了文[6]中的主要结果,得到了系统的解趋于零的充分条件。 相似文献
77.
《Journal of Natural History》2012,46(4):767-776
The puparia of two species of Mepachymerus and three species of Steleocerellus (Diptera: Chloropidae, Chloropinae), reared from wild grasses in West Africa, are described. 相似文献
78.
《Journal of Natural History》2012,46(19-20):1195-1206
Limnomedusa is a monotypic genus that occurs in association with rocky outcrops and stream beds. Based on observational and mark–recapture fieldwork from 2005 to 2008, we report the breeding biology of Limnomedusa macroglossa in southern Brazil. The reproductive season lasted from late August to early February. Tadpoles were recorded from early September to late February. A clear pattern of emergence/recruitment was observed in juveniles. The occurrence of reproductive activities was clearly related to the longest photoperiods, when the highest temperatures occur. Males called from rocky or concrete substrates, mostly under rocks. Amplexus was axillary and the operational sex ratio was nearly even. Spawn occurred in lentic water bodies but tadpoles also completed their development in slow‐flowing water. Although using similar habitats for reproduction, L. macroglossa reached lower levels of specialization toward terrestriality than did the cycloramphids Cycloramphus and Thoropa. We classify L. macroglossa as a breeding habitat specialist that would be threatened by river damming. 相似文献
79.
80.
谢达 《科技情报开发与经济》2011,21(18):50-51
介绍了LED全彩显示屏在图书馆服务中的重要作用,总结了全彩显示屏的功能特点和制作经验,并归纳出一些设计要点。 相似文献