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排序方式: 共有777条查询结果,搜索用时 265 毫秒
1.
PAOLO GUIDETTI SIMONETTA FRASCHETTI ANTONIO TERLIZZI FERDINANDO BOERO 《Conservation biology》2004,18(5):1417-1423
Abstract: We surveyed shallow, rocky reefs in southwestern Apulia (Mediterranean Sea) to assess the effects on coastal fish assemblages of the date mussel ( Lithophaga lithophaga ) fishery, an illegal practice that strips the rocky reef bare. We visually sampled fish four times over 15 months at three locations, one affected by date-mussel fishery and two controls. The fish assemblage at the affected location differed significantly from those at the control locations over all sampling times. Herbivorous fishes, sparids, and labrids (genus Symphodus ) contributed most to the differences between the affected location and controls. Lower densities of Symphodus spp. were observed at the affected location, whereas detritivorous fishes were recorded exclusively at control sites. Small serranids and sparids showed temporal trends that differed between the affected location and the control locations. Our results suggest that the date-mussel fishery affects fish assemblages chiefly through reduction of arborescent macroalgae (contributing to habitat complexity and primary production) and emphasize the need for more effective policing against this destructive practice. 相似文献
2.
Indices of abundance and reproduction rate are considered in some groups of aquatic and terrestrial vertebrates from the zones of technogenic disasters. Upon a critical population decline caused by external destructive factors, such as emissions of acute ecotoxicants, the ecophysiological and behavioral compensatory mechanisms are activated, which provide for restoration of the total population size to the optimum within a short period of time. Environmental pollution with substances disturbing the reproductive function has the gravest consequences for animals. In this case, population size may remain fairly high, and, therefore, the effect of enhanced reproduction as a response to population decline does not take place, which eventually leads to a gradual but irreversible destruction of the population. Pathologies of reproduction should be used as a criterion for assessing the state of animals in the zones of technogenic disasters.Translated from Ekologiya, No. 1, 2005, pp. 32–38.Original Russian Text Copyright © 2005 by Shilova, Shatunovskii. 相似文献
3.
长江生物多样性在人为影响下面临严重威胁,物种监测是生物多样性保护的基础,为完善长江水生态监测体系,实现高效无损伤的物种监测,在长江中下游干流3个江段(新滩、安庆和芜湖)采集水样,建立长江水样环境DNA宏条形码物种检测体系并评估其有效性.结果表明:①长江中下游环境DNA宏条形码检测到32个物种,包括20种鱼类、1种水生哺乳动物(长江江豚)和11种陆生动物,其中鱼类物种包括鲤形目、鲇形目、鲈形目和鲱形目,其种数占鱼类总种数的比例分别为60%、25%、10%和5%.②长江中下游渔获物中资源量居首位的鲤形目在环境DNA调查中序列数最多,占鱼类总序列的96.2%,其次为鲱形目(占比为3.5%),鲇形目和鲈形目占比较低,分别为0.2%和0.1%,4个类目序列相对丰度与渔获物种资源量组成差异较大.③环境DNA调查次数约占传统渔获物调查次数的几十至几百分之一,采样时间不足努力量最少的渔获物调查的1%,检测到的鱼类种数为传统调查总数的31%~49%.④安庆采样点位于长江中下游长江江豚密度最高的江段,其环境DNA检出率和序列相对丰度在3个采样点中均最高.研究显示:长江水样环境DNA包含水陆复合生态系统的生物多样性信息,利用水样环境DNA宏条形码可检测不同类群的水生和陆生物种;对于鱼类物种检测,环境DNA宏条形码比传统调查方法效率更高,可对传统调查结果进行补充;环境DNA宏条形码生物多样性检测主要受分子标记体系和核酸序列数据库限制,获取全面的物种多样性和资源量信息需要对检测分析方法进行进一步完善. 相似文献
4.
Conservation and management applications of the REEF volunteer fish monitoring program 总被引:2,自引:0,他引:2
Pattengill-Semmens CV Semmens BX;Reef Environmental Education Foundation 《Environmental monitoring and assessment》2003,81(1-3):43-50
The REEF Fish Survey Project is a volunteer fish monitoring program developed by the Reef Environmental Education Foundation (REEF). REEF volunteers collect fish distribution and abundance data using a standardized visual method during regular diving and snorkeling activities. Survey data are recorded on preprinted data sheets that are returned to REEF and optically digitized. Data are housed in a publicly accessible database on REEF's Web site (http: //www.reef.org). Since the project's inception in 1993, over 40,000 surveys have been conducted in the coastal waters of North America, tropical western Atlantic, Gulf of California and Hawaii. The Fish Survey Project has been incorporated into existing monitoring programs through partnerships with government agencies, scientists, conservation organizations, and private institutions. REEF's partners benefit from the educational value and increased stewardship resulting from volunteer data collection. Applications of the data include an evaluation of fish/habitat interactions in the Florida Keys National Marine Sanctuary, the development of a multi-species trend analysis method to identify sites of management concern, assessment of the current distribution of species, status reports on fish assemblages of marine parks, and the evaluation of no-take zones in the Florida Keys. REEF's collaboration with a variety of partners, combined with the Fish Survey Project's standardized census method and database management system, has resulted in a successful citizen science monitoring program. 相似文献
5.
Thomas W. May Michael J. Walther Jimmie D. Petty James F. Fairchild Jeff Lucero Mike Delvaux Jill Manring Mike Armbruster David Hartman 《Environmental monitoring and assessment》2001,72(2):179-206
The Republican River Basin of Colorado,Nebraska, and Kansas lies in a valley which contains PierreShale as part of its geological substrata. Selenium is anindigenous constituent in the shale and is readily leached intosurrounding groundwater. The Basin is heavily irrigated throughthe pumping of groundwater, some of which is selenium-contaminated, onto fields in agricultural production. Water,sediment, benthic invertebrates, and/or fish were collected from46 sites in the Basin and were analyzed for selenium to determinethe potential for food-chain bioaccumulation, dietary toxicity,and reproductive effects of selenium in biota. Resultingselenium concentrations were compared to published guidelines orbiological effects thresholds. Water from 38% of the sites (n = 18) contained selenium concentrations exceeding 5 g L-1, which is reported to be a high hazard for selenium accumulation into the planktonic food chain. An additional 12 sites (26% of the sites) contained selenium in water between 3–5 g L-1, constituting a moderate hazard. Selenium concentrations in sedimentindicated little to no hazard for selenium accumulation fromsediments into the benthic food chain. Ninety-five percent ofbenthic invertebrates collected exhibited selenium concentrationsexceeding 3 g g-1, a level reported as potentially lethal to fish and birds that consume them. Seventy-five percent of fish collected in 1997, 90% in 1998, and 64% in 1999 exceeded 4 g g-1selenium, indicating a high potential for toxicity andreproductive effects. However, examination of weight profilesof various species of collected individual fish suggestedsuccessful recruitment in spite of selenium concentrations thatexceeded published biological effects thresholds for health andreproductive success. This finding suggested that universalapplication of published guidelines for selenium may beinappropriate or at least may need refinement for systems similarto the Republican River Basin. Additional research is needed todetermine the true impact of selenium on fish and wildliferesources in the Basin. 相似文献
6.
Rashed MN 《Environmental monitoring and assessment》2001,68(1):75-89
Cadmium and lead were determined in different tissues (muscle,gill, stomach, intestine, liver, vertebral column and scales) of Tilapia nilotica from the High Dam Lake, Aswan (Egypt) to assess the lake water pollution with those toxic metals. Fish samples were chosen from different ages and weights to be analyzed along with samples of the aquatic plant(Najas armeta), sediment and lake water.The results showed that cadmium and lead concentrations were higher in fish scales and vertebral column than in the other parts of the fish. Cadmium and lead levels in High Dam lake water and fish (Tilapia nilotica) were a result of the pollution which uptakes from aquatic plants, sediments andgasoline containing lead that leaks from fishery boats. Tilapia nilotica fish was used as a good bio-assay indicator for the lake pollution with cadmium and lead. The fish musclesin this study were in the safety baseline levels for man consumption. 相似文献
7.
本试验在10±1℃、不喂食条件下测定鲤鱼在30天受汞毒期间鳃、脑和肝胰脏蓄积汞和尾鳍微血管血流速度及30天解毒期间排出汞和血流速度的变化。试验结果:受毒期间鳃中汞的蓄积量最多,解毒期间鳃中汞的排出速度最快;受毒期间血流速度随受毒时间的延长而减慢,又随试验浓度的增高而减慢,解毒期间血流速度随解毒时间的延长而加快;受毒期间高浓度试验组鱼鳃、脑和肝胰脏中汞的蓄积量与血流速度呈负相关,解毒期间鱼鳃中汞的排出量与血流速度呈正相关,汞的浓度与血流速度呈负相关。 相似文献
8.
厦门西港海水质量对鱼卵胚胎发育畸形率的影响 总被引:3,自引:1,他引:3
以养殖场培育的花尾胡椒鲷受精卵为实验材料测试了厦门西域5个站位的表层水水样对花尾胡椒鲷受精卵的胚胎发育毒性,并运用GC-MS手段分析了水样中的美国EPA优控的16PAHs组分的含量。结果表明:3号站位(厦门市工业和生活污水主要排放口的外侧)和4号站位(厦门西港的港区)的水样对鱼卵的胚胎发育的毒性最强。8号站位(位于主航道并濒临嵩屿电厂)的水样对鱼卵胚胎发良的毒性次之,1号站位(湾口)和5号站位(内港)的水样对鱼卵的胚胎发育的毒性较小。水样中的PAHs含量分析结果表明,仅用水样中的PAHs含量不能全面地反映水样对鱼卵胚胎发育的毒性。最后,对本实验方法应用于海洋环境生物监测的有效性进行了探讨。 相似文献
9.
在长沙县百倍冲水库进行多年的试验研究结果表明,开发利用库内长期荒芜的大片消落区种植黑麦草;荒山堤坝上种植扁穗牛鞭草、岸杂一号狗牙根、皇草、幼林间种植鸡脚草、拉丁鲁白三叶等饲草配套养鱼和防止水土流失、防淤减积试验获得成功。库内鲜鱼产量由种草前常年1000kg提高到7000~8000kg,泥砂淤积量每年减少0.516×104m3,经济生态效益显著。 相似文献
10.