自然死亡率变化对黄海蓝点马鲛渔业管理的影响     

陈宁  张崇良  孙铭  徐宾铎  薛莹  任一平  陈勇 《海洋学报(英文版)》2018,37(8):21-30

传统的渔业资源评估方法对数据有一定的要求，而现有的许多渔业缺乏相关数据，造成了渔业评估和管理上的障碍。特别是自然死亡率，由于观测和计算的困难，研究中一般通过经验公式等方法进行假话，而不同来源的数据和估算方法的结果存在较大差异，可能导致在渔业资源评估和管理中很大的不确定性。本研究以蓝点马鲛（Scomberomorus niphonius）为例，利用MSE比较了22种基于有限数据的渔业管理规程（MP），筛选出DCAC、SPMSY、curE75、minlenLopt1 4种对于M不确定性较为稳健的的管理方法，并针对不同年代的自然死亡率以及通过不同计算方法得出的自然死亡率对这4种MP进行了管理策略评价。结果表明：M自1980s至今的不同年代间有显著降低趋势，该变化对MP管理效果产生了较强影响。随着M降低，种群B>0.5BMSY的概率显著上升，而过度捕捞可能性在不同MP间有方向性的差异。M变化对对curE75、minlenLopt1的长期产量的影响较小，而对DCAC、SPMSY的AAVY<15%的可能性变化较大，即降低产量的波动。不同M估算方法的估计值相差不大，对MP管理影响不明显。综合结果来看，Cur75受自然死亡率不确定性影响较小，对于渔业资源的开发和保护两个方面有着最好的权衡，最适用于我国蓝点马鲛渔业的管理。  相似文献   

Changes in fisheries management in Mexico: Effects of increasing scientific input and public participation     

《Ocean & Coastal Management》2003,46(6-7):507-526

In this article, we analyze a change in the role of federal institutions in charge of managing Mexican fisheries during the mid-1990s. During 30 years, the fishery policy in Mexico began by promoting an accelerated fishing effort. This worked through 1981, when the country recorded its highest landings (1.6 million metric tons), but landings have not increased subsequently whereas the number of fishermen has continued to increase. In 1995, the federal administration acknowledged the problems: biological over-exploitation; over-capitalization; monopoly in commercialization; failures in loan payments; failures in controlling effort; obsolete vessels and equipment; and social conflicts for the resources. In an attempt to resolve some of these problems, the administration implemented structural changes in management, science and enforcement institutions. This arrangement established goals and introduced instruments in fisheries management: it determined the biological status of most of the fisheries; applied the precautionary approach for those fully exploited or over-exploited fisheries; gave scientific advice an important role in decision making; and involved the users in decision making. This article evaluates these changes in management policy by document review, participation and interviewing management and scientists who participated in this process. We analyze, in particular, the use of science-based categorization of fisheries status, and the introduction of public participation. The interview data demonstrate that sustainable Mexican fisheries require an evolution to a more public participatory policy, in order to strengthen local institutions and fishermen over federal institutions, which should lead to a re-definition of regulation of fisheries resources.  相似文献   

From Vegetable Box to Seafood Cooler: Applying the Community-Supported Agriculture Model to Fisheries     

Lisa M. Campbell  Noëlle Boucquey  Joshua Stoll  Henry Coppola  Martin D. Smith 《社会与自然资源》2014,27(1):88-106

Community-supported fisheries (CSF) projects show signs of rapid growth. Modeled on community-supported agriculture (CSA) projects, CSFs share objectives of reducing social and physical distance between consumers and producers and re-embedding food systems in social and environmental contexts. This article offers a comparison of CSF and CSA, situated in the differences between seafood and agricultural products, and fishing and farming. We draw on economic and resource theory, past research on CSA, and a member survey from a case study CSF. Survey results show CSF members are interested in accessing high-quality, fresh, local seafood, and in supporting fishing communities, and they believe that participating in a CSF achieves both. They are less certain that a CSF can address environmental concerns, and few identify environmental motives as their primary reason for participating. The latter contrasts with CSA research results, and we contextualize these findings in our broader comparison.  相似文献   

Knowledge to Action: Investigating Implicit Knowledge Production Models Held Among Forest Science Researchers     

Patrick W. Lyons  Laura Lindenfeld  Linda Silka 《社会与自然资源》2014,27(5):459-474

Criticisms of conventional knowledge production systems target their inability to address complex issues involving natural resources. In response, several researchers have adopted participatory research methodologies, incorporating more holistic problem-solving approaches that greatly value the knowledge and abilities of stakeholders. This case study explores forest science researchers' engagement strategies with stakeholders and how researchers can incorporate alternative approaches to knowledge production. We conducted semistructured interviews with forest science researchers, asking direct questions about how they define and work with stakeholders. Analysis revealed a great awareness among researchers for the need to cooperate with stakeholders and to incorporate their knowledge and abilities into the research process, as well as lamentations over structural, institutional, and resource limitations inhibiting the adoption of these practices. Our results reveal both how forest science researchers and institutes work with stakeholders and how they can better incorporate these stakeholder engagement methodologies into their research practices.  相似文献   

A 3000-year varved record of glacier activity and climate change from the proglacial lake Hvítárvatn,Iceland     

Darren J. Larsen  Gifford H. Miller  Áslaug Geirsdóttir  Thorvaldur Thordarson 《Quaternary Science Reviews》2011,30(19-20):2715-2731

A suite of environmental proxies in annually laminated sediments from Hvítárvatn, a proglacial lake in the central highlands of Iceland, are used to reconstruct regional climate variability and glacial activity for the past 3000 years. Sedimentological analysis is supported by tephrostratigraphy to confirm the continuous, annual nature of the laminae, and a master varve chronology places proxies from multiple lake cores in a secure geochronology. Varve thickness is controlled by the rate of glacial erosion and efficiency of subglacial discharge from the adjacent Langjökull ice cap. The continuous presence of glacially derived clastic varves in the sediment fill confirms that the ice cap has occupied the lake catchment for the duration of the record. Varve thickness, varve thickness variance, ice-rafted debris, total organic carbon (mass flux and bulk concentration), and C:N of sedimentary organic matter, reveal a dynamic late Holocene climate with abrupt and large-scale changes in ice-cap size and landscape stability. A first-order trend toward cooler summers and ice-cap expansion is punctuated by notable periods of rapid ice cap growth and/or landscape instability at ca 1000 BC, 600 BC, 550 AD and 1250 AD. The largest perturbation began ca 1250 AD, signaling the onset of the Little Ice Age and the termination of three centuries of relative warmth during Medieval times. Consistent deposition of ice-rafted debris in Hvítárvatn is restricted to the last 250 years, demonstrating that Langjökull only advanced into Hvítárvatn during the coldest centuries of the Little Ice Age, beginning in the mid eighteenth century. This advance represents the glacial maximum for at least the last 3 ka, and likely since regional deglaciation 10 ka. The multi-centennial response of biological proxies to the Hekla 3 tephra deposition illustrates the significant impact of large explosive eruptions on local environments, and catchment sensitivity to perturbations.  相似文献   

Transverse structure of subtidal flow in a weakly stratified subtropical tidal inlet     

Amy F. Waterhouse  Arnoldo Valle-Levinson 《Continental Shelf Research》2010,30(3-4):281-292

The transverse structure of exchange flows and lateral flows as well as their relationship to the subtidal variability are investigated in a subtropical inlet, Ponce de Leon Inlet, Florida. Two surveys were executed during different phases of the tidal month to determine the spatial structure of subtidal exchange flows. Data from fixed moorings were used to depict the temporal variability of the spatial structure established in the surveys. The data suggested a tidally rectified pattern of net outflow in the channel and inflow over shoals with a negligible influence of streamwise baroclinic pressure gradients on the dynamics and slight modifications due to the wind. Onshore winds strengthened net inflows but weakened net outflows, rarely reversing them, while offshore winds increased net outflows and weakened net inflows. Curvature effects were found to be important in modifying secondary circulations. Slight modifications to the secondary flows were also caused by stream-normal baroclinicity during one survey. Most important, the intensity of the exchange flows was modulated by tides, with the largest exchange flows developing in response to the strongest tidal rectification of spring tides.  相似文献   

New evidence of the total glaciation of the Isla Grande de Tierra Del Fuego     

《Journal of South American Earth Sciences》1999,12(3):343-348

The stratigraphy and preliminary interpretation of a new locality with glacial deposits in a previously interpreted ice-free area in Tierra del Fuego are presented. These deposits consist of basal proglacial gravels (at least 4–5 m thick) covered by the Drift Cabo Campo del Medio. The drift consists of a lower, 2 m thick, lodgment till and a upper, 7 m thick, glaciotectonized composite till, reflecting basal glacier shearing and upthrusting of glaciofluvial deposits and lodgment till, with superimposed deformation by gelifluction. These two main drift packages are interpreted as ground moraines, reflecting two corresponding glacial advances with an intervening recess of the glacier front. The altitude of the Drift Campo del Medio, well above younger fluvioglacial deposits related to the Last Glaciation, the degree of erosional modifications, and its external position, to the NE of the Last Glaciation moraine system, are evidence suggesting that the Drift Cabo Campo del Medio was related to a glaciation older than the Penultimate Glaciation. The finding of this locality sheds new light on the old controversy of total vs partial ice coverage of the island.  相似文献   

我国海洋绿潮生态动力学研究进展   总被引：2，自引：0，他引：2  

刘桂梅  李海  王辉  柴扉 《地球科学进展》2010,25(2):147-153

在近几年我国绿潮生态学研究的基础上,回顾了绿潮藻生活史,温度、盐度、光强和营养盐等对其生态行为的影响,以及绿潮成因、溯源和海洋生态模型方面取得的新进展。在现阶段取得的主要研究进展基础上,提出今后我国绿潮研究及其发展趋势应侧重于建立并完善海洋生态环境立体监测和观测系统,开展针对海洋绿潮问题的综合性研究,开发业务化的绿潮生态动力学数值预报预警系统。  相似文献   

Mercury methylation dynamics in estuarine and coastal marine environments — A critical review     

Karen A. Merritt  Aria Amirbahman   《Earth》2009,96(1-2):54-66

Considerable recent research has focused on methylmercury (MeHg) cycling within estuarine and coastal marine environments. Because MeHg represents a potent neurotoxin that may magnify in marine foodwebs, it is important to understand the mechanisms and environmental variables that drive or constrain methylation dynamics in these environments. This critical review article explores the mechanisms hypothesized to influence aqueous phase and sediment solid phase MeHg concentrations and depth-specific inorganic Hg (II) (Hg_i) methylation rates (MMR) within estuarine and coastal marine environments, and discusses issues of terminology or methodology that complicate mechanism-oriented interpretation of field and laboratory data. Mechanisms discussed in this review article include: 1) the metabolic activity of sulfate reducing bacteria (SRB), the microbial group thought to dominate mercury methylation in these environments; 2) the role that Hg_i concentration and/or speciation play in defining depth-specific Hg_i methylation rates; and 3) the depth-dependent balance between MeHg production and consumption within the sedimentary environment. As discussed in this critical review article, the hypothesis of SRB community control on the Hg_i methylation rate in estuarine and coastal marine environments is broadly supported by the literature. Although Hg_i speciation, as a function of porewater inorganic sulfide and/or dissolved organic matter concentration and/or pH, may also play a role in observed variations in MMR, the nature and function of the controlling ligand(s) has not yet been adequately defined. Furthermore, although it is generally recognized that the processes responsible for MeHg production and consumption overlap spatially and/or kinetically in the sedimentary environment, and likely dictate the extent to which MeHg accumulates in the aqueous and/or sediment solid phase, this conceptual interpretation requires refinement, and would benefit greatly from the application of kinetic modeling.  相似文献   

Identification of an E3 ubiquitin-protein ligase in the softshell clam (Mya arenaria).     

M L Kelley  R J Van Beneden 《Marine environmental research》2000,50(1-5):289-293

Softshell clams (Mya arenaria) were exposed to dioxin in controlled laboratory experiments in order to study their molecular response to dioxin exposure. A complementary DNA (cDNA) fragment with sequence similarity to E3 ubiquitin-protein ligase appeared to be upregulated in dioxin-exposed clams compared to controls. E3 covalently ligates ubiquitin onto a protein, targeting it for degradation. Our findings suggest that the ubiquitin-mediated proteolytic pathway in the softshell clam may be activated by dioxin exposure. Because the clam E3-predicted amino acid sequence is most similar to a specific vertebrate E3 protein (E6-AP), we hypothesize that dioxin may stimulate ubiquitin-mediated degradation of cell-cycle regulatory proteins, such as the tumor suppressor p53, which promotes cell proliferation. This pathway has been observed in human cervical cancer. Partial cDNA sequence of the clam E3 has been identified using the differential display polymerase chain reaction (ddPCR) and RACE (Rapid Amplification of cDNA Ends) PCR; the full-length sequence is currently being determined. Discovering the molecular mechanism(s) stimulated by dioxin exposure in this invertebrate model may contribute to a better understanding of the effects of dioxin on marine organisms.  相似文献