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为了研究大型海洋掠食性鱼类胃含物中角质颚的分类效果,于2017年10月,2018年3、5和11月,收集了南大西洋、中东太平洋和西印度洋海域的大型海洋掠食性鱼类的36个胃并分析其残留角质颚的形态。对采集的角质颚形态侧视图和顶视图进行种类鉴定,建立检索表,提取椭圆傅里叶描述子(EFDs)系数进行聚类分析。结果显示,通过对胃含物角质颚形态进行种类鉴定,共发现头足类2目10科17种。根据角质颚形态分类检索分析,17种头足类角质颚形态种间差异明显。枪形目(Teuthoidea)的13种头足类角质颚喙部形态分别为三角形和等腰三角形,侧壁为近似菱形,翼部发达;八腕目(Octopoda)的4种头足类角质颚有喙部发育,侧壁近似长四边形,有翼部发育。角质颚形态信息聚类分析在目级别区分效果显著。通过对胃含物角质颚形态进行分类研究,不仅可佐证胃含物头足类的识别,而且丰富了胃含物头足类的鉴定内容,也为大型海洋掠食性鱼类胃含物头足类分类鉴定体系奠定基础。 相似文献
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I. Growns P. C. Gehrke K. L. Astles & D. A. Pollard 《Fisheries Management and Ecology》2003,10(4):209-220
Fish assemblages in six reaches of the Hawkesbury–Nepean River were studied to identify the effects of two types of riparian vegetation; well‐vegetated banks supporting complex flora dominated by trees and shrubs, and grassed banks, that have been colonised only by grasses after historical deforestation. The fish assemblages showed both spatial and temporal differences and habitats adjacent to grassed banks supported more individuals and more fish species than well‐vegetated banks. Three small species of fish, firetail gudgeon, Hypseleotris galii (Ogilby), flathead gudgeon, Philypnodon grandiceps (Krefft), and empire gudgeon, Hypseleotris compressa (Krefft), occurred in greater abundances adjacent to grassed banks, but freshwater mullet, Myxus petardi (Castelnau), were less abundant near grassed banks than beside well‐vegetated banks. Differences were also shown in the size frequencies of the four larger fish species between riparian vegetation types. The observed differences in the distributions of fish species appeared to be related to the greater abundance aquatic macrophytes near grassed banks, probably an effect of shading of macrophytes near well‐vegetated banks. 相似文献
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[目的]研究天津市3座水库大型底栖动物群落结构及其与环境因子的关系。[方法]2011年5月、7月、9月分别对天津市于桥水库、北大港水库、尔王庄水库的14个采样点的大型底栖动物进行调查,分析各水库大型底栖动物物种多样性状况,并评价各水库的水质情况。[结果]所有采样点共采集到大型底栖动物22种,其中水生昆虫6种,软体动物7种,甲壳类2种,寡毛类7种。于桥水库5月、7月、9月大型底栖动物的种类分别为11种、8种、10种,大型底栖动物的平均密度和平均生物量分别为132.43 ind./m2、50.09 g/m2;采用Margalef物种丰富度指数d值、Shannon多样性指数(H)和Pielou均匀度指数综合评价,于桥水库为轻-中度污染。北大港水库5月、7月、9月种类分别为5种、5种、5种。大型底栖动物的平均密度和平均生物量分别为218ind./m2、2.70 g/m2;采用物种丰富度指数d值、Shannon多样性指数H值和均匀度指数综合评价,北大港水库为重度污染。尔王庄水库5月、7月、9月大型底栖动物的种类分别为3种、5种、5种。大型底栖动物的平均密度和平均生物量分别为104 ind./m2、0.20 g/m2;采用物种丰富度指数d值、Shannon多样性指数H值和均匀度指数综合评价,结果表明尔王庄水库为中度污染。[结论]三座水库均受到了富营养化污染,污染程度为:北大港水库尔王庄水库于桥水库。 相似文献
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K. David Hyrenbach Zora McGinnis Kathleen Page Dan Rapp F. David Horgen Jennifer M. Lynch 《水产资源保护:海洋与淡水生态系统》2021,31(2):408-419
- 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.
- 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).
- Yellowfin tuna (n = 10) did not contain any MPD, probably owing to the high proportion of empty stomachs (60%).
- 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%).
- For dolphinfish, the frequency of occurrence of MPD ingestion was similar for the similar-sized specimens caught with pole-and-line and with longlines.
- 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.
- 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.
- 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.
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European Bison (Bison bonasus) barely escaped extinction in the early 20th century and now only occur in small isolated herds scattered across Central and Eastern Europe. The species’ survival in the wild depends on identifying suitable habitat for establishing bison metapopulations via reintroductions of new herds. We assessed European Bison habitat across the Carpathian Mountains, a stronghold of European Bison and one of the only places where a viable bison metapopulation may be possible. We used maximum entropy models to analyze herd range maps and habitat use data from radio-collared bison to identify key habitat variables and map European Bison habitat across the entire Carpathian ecoregion (210,000 km2). Forest cover (primarily core and perforated forests) and variables linked to human disturbance best predict bison habitat suitability. Bison show no clear preference for particular forest types but prefer managed grasslands over fallow and abandoned fields. Several large, suitable, but currently unoccupied habitat patches exist, particularly in the eastern Carpathians. This available suitable habitat suggests that European Bison have an opportunity to establish a viable Carpathian metapopulation, especially if recent trends of declining human pressure and reforestation of abandoned farmland continue. Our results also confirm the suitability of a proposed Romanian reintroduction site. Establishing the first European Bison metapopulation would be a milestone in efforts to conserve this species in the wild and demonstrate a significant and hopeful step towards conserving large grazers and their ecological roles in human-dominated landscapes across the globe. 相似文献
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为有效利用紫花苜蓿Medicago sativa深加工工业所得的浆汁和草渣,对紫花苜蓿浆汁和草渣的发酵进行了初步研究。研究发现苜蓿浆汁发酵较草渣发酵更容易。适当添加葡萄糖和发酵汁可以促进发酵,但添加葡萄糖质量分数超过2%后,促进作用并不明显,添加浆汁和草渣发酵的葡萄糖的最适宜质量分数分别为1%和2%。适当提高发酵温度可以加速发酵,过高和过低的温度均不利于发酵的顺利进行,研究中最适宜的发酵温度为35℃。在试验所选取的3个不同发育时期(分枝期、开花期和结荚期)的发酵原料中,结荚期苜蓿的发酵效果最好。 相似文献
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