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1.
  1. Although the frequency of occurrence of plastic ingestion in the large-sized dolphinfish and tunas taken by the Hawai'i longline fishery is very low (frequency of occurrence < 5% of sampled individuals), the ingestion of plastic in smaller-sized specimens caught with pole-and-line gear by commercial and recreational fishers has not been investigated.
  2. This study examined ingestion of >0.25 mm marine plastic debris (MPD) by four predatory fish species caught by commercial fishers around the Main Hawaiian Islands, and documented ingestion in three species: 85.7% of albacore tuna (n = 7), 40.0% of skipjack tuna (n = 10) and 12.5% of dolphinfish (n = 8).
  3. Yellowfin tuna (n = 10) did not contain any MPD, probably owing to the high proportion of empty stomachs (60%).
  4. For skipjack tuna, the frequency of occurrence of MPD ingestion was significantly higher for the smaller-sized specimens caught with pole-and-line (40%), compared with the larger-sized specimens caught with longlines (0%).
  5. For dolphinfish, the frequency of occurrence of MPD ingestion was similar for the similar-sized specimens caught with pole-and-line and with longlines.
  6. The ingested MPD items were micro–meso plastics, between 1 and 25 mm. While most ingested items were fragments, albacore also ingested line and skipjack also ingested sheets.
  7. The predatory fishes ingested light MPD items that float in sea water, but there were species-specific differences in their polymer composition: albacore contained more polypropylene and polyethylene, and skipjack contained more elastomers, characterized by a high percentage of ester plasticizers.
  8. Altogether, these results suggest that albacore and skipjack tunas ingest plastic of different types and polymers. Yet more research is needed to understand how differences in vertical distribution, foraging ecology and diet influence the MPD sampled by these predatory fish species.
  相似文献   
2.
  1. Freshwater communities are threatened by the conversion of natural landscapes for urban and agricultural purposes. Changes to land use may disrupt stream nutrient and geomorphological processes and reduce water quality, increase sedimentation, and decrease habitat heterogeneity eventually leading to species loss and decreases in ecosystem productivity. Endemic species are frequently at greater risk of habitat-mediated fragmentation and extirpation due to their constrained distributions.
  2. The Kanawha darter (Etheostoma kanawhae) is an understudied fish endemic to the New River Drainage in North Carolina and Virginia, USA. To investigate the potential effect(s) of land-use change on Kanawha darters, naïve occupancy was modelled using instream habitat characteristics and upstream forest cover.
  3. Generalized linear models revealed that instream habitat and forest cover are reliable predictors of Kanawha darter site occupancy. Specifically, models demonstrated that occupancy increased in reaches with reduced stream width, velocity, and bedrock substrate but higher concentrations of coarse woody material. Kanawha darter occupancy was also positively associated with the extent of forest cover in upstream catchments.
  4. Although Kanawha darters are not currently considered imperilled, most populations occurred in isolated reaches separated by large sections of unoccupied habitat. Continuing ex-urban development in riparian zones is likely to be the primary threat to Kanawha darters and other endemic species in this catchment. Resource managers and stakeholders should preserve forest cover in headwaters and occupied tributaries and protect or restore riparian zones along the main-stem South and North Forks of the New River to preserve high-quality habitat and enhance connectivity among isolated Kanawha darter populations.
  5. As human populations in montane regions continue to grow, there is a need to understand how land-use change affects endemic freshwater species. This study further supports the importance of retaining forest cover as an effective strategy for protecting and restoring populations of endemic fishes in high-gradient streams.
  相似文献   
3.
In the present study, the location, histology and number of corpuscles of Stannius (Sc), which are endocrine glands associated with the kidneys of teleost fish, were investigated for the first time in Lake Van fish (Alburnus tarichi), an anadromous and endemic inhabiting Turkey's Lake Van Basin. The Sc, which were ovoid or spheroid and white or cream in colour, were found to vary in number between three and five among the examined fish. The glands were located in the caudal part of the kidney, and either partially or completely embedded, and found to be present on both the ventral and dorsal surface of either side of the caudal part of the kidney. The Sc were surrounded by a connective tissue capsule that penetrated and divided the gland into incomplete lobules. Two types of cells were determined in the parenchyma of the gland. Type-I cells were predominant throughout the parenchyma and larger than the second (type-II). In the type-I cells, the cytoplasm was observed as weakly or moderately eosinophilic with haematoxylin and eosin staining and weakly or moderately acidophilic with Mallory's triple staining. In the type-I cells, the cytoplasm exhibited weak to moderate periodic acid-Schiff staining and slight or uniform staining with aldehyde fuchsin. The type-II cells were round, had a darkly stained spherical nucleus and were dispersed among the type-I cells. They displayed no cytoplasmic staining with the abovementioned stains.  相似文献   
4.
  1. The amplitude, duration, frequency, and predictability of runoff and inundation of aquatic habitats are key hydrological characteristics linked to aquatic ecosystem functioning and biodiversity, but they are seldom integrated into analyses of Amazon floodplain ecology. Remote sensing approaches, measurements and modelling of floodplain hydrology provide a basis for this integration.
  2. Effective legislation to protect floodplains and other wetlands depends on operational definitions that require application of hydrological data.
  3. Extent and changes of flooded areas are linked to fish diversity and to presence and growth of flooded forests and floating plants.
  4. Dam construction reduces river system connectivity and modifies the flood pulse, with major negative implications for floodplain ecosystems adapted to and dependent on a natural flood regime.
  5. Trends and variability in climate plus deforestation are altering the Amazon's hydrological cycle, causing changes in discharge and flooded area with concomitant ecological impacts.
  相似文献   
5.
自2006年以来,长江豚类极度濒危的生存状况得到广泛关注,在其自然保护区实施一系列生态修复工程,为镇江长江豚类省级自然保护区内的江豚提供良好的生存环境。于2015—2018年在和畅洲水域建设生态浮岛、人工鱼巢和放流底栖动物进行水域生态修复,对生态修复工程进行跟踪监测和效果评价。结果表明:生态浮岛的建设可提高区域内浮游植物和浮游动物的生物多样性和群落结构复杂程度;人工鱼巢对产黏性卵鱼类具有一定增殖效果,增殖种类主要为鲤、鲫、䱗和黄尾鲴;生态浮岛和人工鱼巢的建设对鱼类均有较好的聚集效果;底栖动物增殖放流显著增加了放流物种的丰度、生物量及保护区底栖动物群落生物量,增殖放流效果评价为中等。该自然保护区水域生态修复效果明显,为工程施工影响下水生生物保护区生态修复提供科学依据。  相似文献   
6.
随着转基因技术发展和应用,转基因外源基因表达蛋白在环境中富集和降解情况成为公众关注的问题, 外源蛋白在环境中的检测和监测成为转基因研究和监管的一个方向。本研究利用模拟自然降解和蛋白酶K两种 方式,处理转基因大豆种子(5% GTS 40-3-2),采用Western blot、双抗夹心快速检测试纸条和酶联免疫吸附测定 (ELISA)等手段检测CP4-EPSPS蛋白降解情况,结果发现在模拟自然降解条件下,CP4-EPSPS蛋白呈现逐渐被降 解的趋势,且在17周被彻底降解;蛋白酶K处理大豆匀浆情况下,9小时CP4-EPSPS蛋白被快速降解。该研究探索 了CP4-EPSPS蛋白在自然环境下的降解规律,为今后寻求一种快速、安全、有效降解转基因CP4-EPSPS蛋白研究提 供一些启示。  相似文献   
7.
The channel catfish (Ictalurus punctatus, Rafinesque) ovary (CCO) cell line is the standard cell line used for channel catfish diagnostics. Next‐gen sequencing studies of a virus cultured in the CCO cells revealed mitochondrial sequences matching those of brown bullhead (Ameiurus nebulosus, Lesueur). Therefore, we systematically performed partial cytochrome oxidase 1 gene sequencing of several sources of the CCO cell line and all matched the brown bullhead and not the channel catfish.  相似文献   
8.
【目的】拟轮枝镰孢(Fusarium verticillioide)是一种主要的病原真菌,侵染玉米可以导致穗粒腐病、茎腐病、苗期根腐病及引起种子腐烂。由拟轮枝镰孢引起的病害不仅影响玉米的产量和品质,而且其病原菌代谢过程中产生的伏马菌素等多种真菌毒素严重威胁了人畜安全。通过宿主诱导的基因沉默(host-induced gene silencing,HIGS)技术创制抗拟轮枝镰孢的玉米种质,为玉米抗病育种提供新的优异抗源。【方法】通过同源克隆方法克隆可能与拟轮枝镰孢生长发育相关的关键基因,并通过体外转录获得相应的dsRNA片段;将不同基因的dsRNA与拟轮枝镰孢的分生孢子悬浮液预混后,用于后续的体外RNA沉默试验;对感病玉米自交系西502的种子进行消毒与接种,在培养皿中28℃避光培养48 h,调查种子的发病程度;在混有dsRNA的孢子悬浮液中加入葡萄糖,25℃培养24 h后,在显微镜下观察孢子萌发与菌丝生长情况;将三叶期的西502幼苗转移至预混dsRNA的孢子悬浮液中进行培养,7 d后观察苗期根腐病发病状况;通过种子鉴定与苗期鉴定体系,逐步筛选具有显著抑制效果的沉默靶标基因;合成筛选出的重点靶标基因片段,构建沉默载体并转化感病玉米自交系西502;对转基因株系的种子接种鉴定,验证转化玉米株系的抗性;提取接种后转基因种子的总RNA,对拟轮枝镰孢的靶标基因进行荧光定量分析,确定HIGS株系的沉默效果。【结果】从拟轮枝镰孢中克隆出18个与其生长发育相关的候选基因;通过种子接种鉴定,发现11个候选基因被沉默后,种子的发病等级极显著降低;进一步筛选出6个沉默后影响拟轮枝镰孢的孢子萌发和菌丝生长的候选靶标基因deoRas2DpdcHsp90Frp1Atg15;通过苗期接种鉴定,最后筛选出3个在体外具有显著抑制效果的沉默靶标基因deoAtg15Frp1;进而将3个靶标基因的特异区段人工融合成一段序列并构建沉默载体,获得转基因植株;鉴定发现转基因植株的T2代种子对拟轮枝镰孢的抗性显著增强,且3个靶标基因的表达量均显著下降。【结论】拟轮枝镰孢基因deoAtg15Frp1与其生长发育密切相关,且沉默后能够显著提升玉米对拟轮枝镰孢的抗性。  相似文献   
9.
本研究旨在探讨鱼油对高脂日粮饲喂小鼠发情周期和机体代谢产热的影响。试验选用36只4周龄C57BL/6 J雌性小鼠,随机分成3组(n=12):对照组、高脂组和高脂+鱼油组。对照组饲喂标准啮齿动物饲料(AIN-93G),高脂组和高脂+鱼油组分别饲喂高脂日粮(脂肪提供60%能量)和添加5%鱼油(等能替代猪油)的高脂日粮。试验期间,对小鼠体组成(12周龄)、整体代谢(16周龄)、褐色脂肪温度(18周龄)、体核温度(直肠温度,18周龄)和发情周期(20周龄)等进行检测。试验结束后,眼球采血分离血清,检测促卵泡激素(follicle-stimulating hormone,FSH)和雌二醇(estradiol,E2)的水平。此外,采集皮下脂肪、腹部脂肪和肩胛间褐色脂肪,称重并使用Western blot检测脂肪组织中产热相关基因的蛋白表达(UCP1、Cyto C),使用实时荧光定量PCR检测褐色脂肪组织中产热基因的mRNA表达(UCP1, PRDM16,PGC1α,CideaElovl3)。结果显示,与对照组相比,高脂日粮显著增加了小鼠的体脂含量(12周龄)及皮下和腹部脂肪的沉积量(21周龄)(P<0.05),而添加鱼油显著降低了高脂饮食引起的体脂含量增加(P<0.05)。另外,高脂日粮导致小鼠的发情周期紊乱,伴随着周期延长、发情期缩短,以及血清中FSH和E2的水平降低(P<0.05),而添加鱼油可缓解高脂日粮导致的小鼠发情周期紊乱,提高血清中FSH和E2的水平(P<0.05)。同时,添加鱼油可增加高脂饲喂小鼠肩胛间褐色脂肪(interscapular brown adipose tissue,iBAT)和腹股沟白色脂肪(inguinal white adipose tissue,iWAT)中产热相关基因的表达(P<0.05),进而促进iBAT激活/产热和iWAT褐色化。结果提示,日粮鱼油可缓解高脂日粮导致的发情周期紊乱,可能与BAT激活和WAT褐色化造成的机体代谢产热增强有关。  相似文献   
10.
2017-2019年,对大渡河上游鱼类种类组成、优势种和多样性指数等进行了调查。结果显示:大渡河上游采集到鱼类2目6科24种,其中包括了四川省级保护鱼类2种、长江上游特有鱼类8种以及外来物种3种。大渡河上游现有分布鱼类以齐口裂腹鱼(Schizothorax prenanti)和重口裂腹鱼(S.davidi)等为优势种群,生态类群以杂食性、底层、冷水性为主;鱼类种类数、Shannon-Weiner多样性指数、Margalef物种丰富度指数和Pielou均匀度指数均表现为泸定电站库区最高。结果表明大渡河上游鱼类区系组成简单,属典型的青藏高原类群,但受梯级电站的开发、肆意地人工放生活动等影响,鱼类资源呈现衰退趋势,外来鱼类入侵现象严重。  相似文献   
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