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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.
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   
7.
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   
8.
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   
9.
采用主成分分析法建立吸鱼泵的损伤综合评价方法,为吸鱼泵的研究与改进提供装备技术参数。使用真空吸鱼泵对鲫鱼进行吸捕试验,获取鱼体损伤数据。通过测定体表损伤面积比率、24 h存活率、红细胞数量、白细胞数量、超氧化物歧化酶(SOD)活力、谷丙转氨酶(ALT)活力、肌酐(Cr)含量等多个关键指标值,采用主成分分析法进行相关性分析,建立损伤综合评价模型。结果显示:采用主成分分析法提取出3个主成分的累积贡献率达到78.232%,可反映出鱼体损伤的大部分情况;损伤评价综合评价模型:F=0.285X1+0.111X2+0.316X3+0.366X4-0.118X5+0.234X6,真空吸鱼泵对鱼的体表和内脏无显著损伤情况,综合得分-0.102,与对照组接近,表明真空吸鱼泵对鱼的损伤影响很小。研究表明,SOD活力、白细胞数和体表损伤面积比率是对损伤评价影响较大的数据指标,采用主成分分析法建立的综合损伤评价模型可以作为评价鱼损伤情况的一种可行方法,为吸鱼泵的改进研究提供了有力参考。  相似文献   
10.
Non-edible parts of crustaceans could be a rich source of valuable bioactive compounds such as the carotenoid astaxanthin and peptides, which have well-recognized beneficial effects. These compounds are widely used in nutraceuticals and pharmaceuticals, and their market is rapidly growing, suggesting the need to find alternative sources. The aim of this work was to set up a pilot-scale protocol for the reutilization of by-products of processed shrimp, in order to address the utilization of this valuable biomass for nutraceutical and pharmaceuticals application, through the extraction of astaxanthin-enriched oil and antioxidant-rich protein hydrolysates. Astaxanthin (AST) was obtained using “green extraction methods,” such as using fish oil and different fatty acid ethyl esters as solvents and through supercritical fluid extraction (SFE), whereas bioactive peptides were obtained by protease hydrolysis. Both astaxanthin and bioactive peptides exhibited bioactive properties in vitro in cellular model systems, such as antioxidant and angiotensin I converting enzyme (ACE) inhibitory activities (IA). The results show higher astaxanthin yields in ethyl esters fatty acids (TFA) extraction and significant enrichment by short-path distillation (SPD) up to 114.80 ± 1.23 µg/mL. Peptide fractions of <3 kDa and 3–5 kDa exhibited greater antioxidant activity while the fraction 5–10 kDa exhibited a better ACE-IA. Lower-molecular-weight bioactive peptides and astaxanthin extracted using supercritical fluids showed protective effects against oxidative damage in 142BR and in 3T3 cell lines. These results suggest that “green” extraction methods allow us to obtain high-quality bioactive compounds from large volumes of shrimp waste for nutraceutical and pharmaceutical applications.  相似文献   
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