汕尾甲湖湾附近海域鱼类结构季节变动研究

[目的]探讨甲湖湾附近海域2016年4个季度鱼类群落结构和营养级指数季节变化。[方法]以Pielou指数、Shannon-Winener指数和Margalef指数描述鱼类群落多样性特点。采用Pinkas的相对重要性指数(IRI)计算鱼类群落优势种的组成。运用ABC曲线法分析鱼类群落的季节变化。[结果]各季节调查共计捕获鱼类83种,其中肉食性鱼类占84.34%,底层鱼类占59.04%,暖水性鱼类占75.90%。各季节间优势种变化较为明显。在时空分布上,生物量密度和尾数密度最高均出现在夏季,生物量和尾数密度四季总体上呈现北高南低、东高西低的分布趋势。多样性方面,夏、秋季鱼类种类组成相对较为丰富,冬季生物量优势度最高。2016年度平均营养级指数为3.427,秋季高营养级鱼类平均体质量最高。[结论]甲湖湾海域鱼类以中、高级肉食性为主。鱼类年度平均营养级属于中级水平。海域渔业资源处于过度开发状态。     

Climate impact on plankton ecosystems in the Northeast Atlantic

It is now widely accepted that global warming is occurring, yet its effects on the world's largest ecosystem, the marine pelagic realm, are largely unknown. We show that sea surface warming in the Northeast Atlantic is accompanied by increasing phytoplankton abundance in cooler regions and decreasing phytoplankton abundance in warmer regions. This impact propagates up the food web (bottom-up control) through copepod herbivores to zooplankton carnivores because of tight trophic coupling. Future warming is therefore likely to alter the spatial distribution of primary and secondary pelagic production, affecting ecosystem services and placing additional stress on already-depleted fish and mammal populations.     

滇池北岸蓝藻富集区浮游藻类多样性及主要污染因子时空变化研究

[目的]分析滇池北岸蓝藻富集区浮游藻类的多样性及主要污染因子的时空变化特征.[方法] 2007年1月～2011年12月,对滇池北岸蓝藻富集区的浮游藻类群落构成、叶绿素a、总氮、总磷浓度开展了逐月监测,分析浮游藻类多样性及水污染因子的时空变化.[结果]2007～2011年,滇池北岸蓝藻富集区浮游藻类属的多样性呈略微上升趋势,近岸区域属的多样性低于远岸区域;叶绿素a、总氮、总磷浓度近岸区域呈降低趋势,远岸区域呈略微升高趋势;叶绿素a、总氮、总磷浓度近岸区域高于远岸区域.[结论]该研究为滇池蓝藻水华控制及各项治理工作的成效评估提供了参考依据.     

Fishing down marine food webs

The mean trophic level of the species groups reported in Food and Agricultural Organization global fisheries statistics declined from 1950 to 1994. This reflects a gradual transition in landings from long-lived, high trophic level, piscivorous bottom fish toward short-lived, low trophic level invertebrates and planktivorous pelagic fish. This effect, also found to be occurring in inland fisheries, is most pronounced in the Northern Hemisphere. Fishing down food webs (that is, at lower trophic levels) leads at first to increasing catches, then to a phase transition associated with stagnating or declining catches. These results indicate that present exploitation patterns are unsustainable.     

Remote acoustic detection of a turbidity current surge

A turbidity current surge has been detected in a leveed submarine channel in Rupert Inlet, British Columbia, with the use of acoustic sounders operating at 42.5, 107, and 200 kilohertz.     

Fish schools: an asset to corals

Schools of juvenile haemulid fish feed in sea grass beds at night. By day they rest over coral heads, where they excrete substantial quantities of ammonium and particulate nitrogen and phosphorus into the nutrient-poor waters. The percentages of these nutrients contributed by the fish were comparable to those from other sources. Coral heads with resident fish schools grew faster than those without resident schools, indicating that fish may be more beneficial to the corals than has been assumed.     

Farm to school in British Columbia: mobilizing food literacy for food sovereignty

Farm to school programs have been positioned as interventions that can support goals of the global food sovereignty movement, including strengthening local food production systems, improving food access and food justice for urban populations, and reducing distancing between producers and consumers. However, there has been little assessment of how and to what extent farm to school programs can actually function as a mechanism leading to the achievement of food sovereignty. As implemented in North America, farm to school programs encompass activities not only related to school food procurement, but also to the development of student knowledge and skills under the framework of food literacy. Research on farm to school initiatives has largely been conducted in countries with government-supported national school feeding programs; this study examines farm to school organizing in Canada, where there is no national student nutrition program. Using qualitative fieldwork and document analysis, we investigate the farm to school movement in British Columbia, in a context where civil society concerns related to education and health have been the main vectors of farm to school mobilization. Our analysis suggests that, despite limited institutional infrastructure for school meals, the British Columbia farm to school movement has contributed toward realizing goals of food sovereignty through two main mechanisms: advocacy for institutional procurement of local and sustainable foods and mobilizing food literacy for increased public engagement with issues of social justice and equity in food systems.     

运用稳定同位素技术研究千岛湖秋季刺网渔获物的食性和营养级

利用稳定性同位素技术,对2011年9月至11月期间利用浙江千岛湖主要渔具之一的刺网采集的渔获物开展了食物源和营养级的分析研究。结果表明,千岛湖鱼类主要食物源的δ13C值跨度范围较大(-29.7‰~-23.9‰),其中浮游植物的δ13C值最高,颗粒有机物(POM)的δ13C值最低。食物源的δ15N值变化范围较小,以浮游植物最高(8.5‰),颗粒有机物最低(5.1‰)。与食物源的同位素值分布趋势相反,消费者的δ13C值浮动范围相对较小(-29.7‰~-21.6‰),而δ15N值的浮动范围相对较大(5.1‰~14.8‰)。消费者的营养级从1.9到3.6,分属于3个营养等级,鱼类的营养级全部分布在第3到第4营养级之间,且与其食性特征有较好的一致性,但是两种外来种鱼类中的一种草食性鱼类团头鲂的营养级却高达3.4,而肉食性的斑点叉尾的营养级则仅为3.0,说明其在千岛湖的食性均已发生了很大变化。同位素示踪方法研究的结果还表明千岛湖水体中的碳源主要是浮游植物。     

甘肃省农村居民恩格尔系数与消费结构评价

以甘肃省农村居民消费为研究对象,初步测算了甘肃省城乡居民恩格尔系数;比较、分析了城乡居民恩格尔系数变化特征;同时,根据此变化特征,将甘肃省农村居民消费结构发展变化过程划分为3个阶段,并对各阶段农村居民消费结构变化和恩格尔系数波动进行了分析和评价.结果表明,甘肃省农村居民生活状况整体上符合恩格尔系数变化规律.但是利用恩格系数分析居民生活水平状况还应与其他因素相结合才能得到较准确的结论.     

Varved Marine Sediments in a Stagnant Fjord

Varved sediments, containing planktonic marine diatoms, occur in Saanich Inlet, British Columbia. An olive-gray lamina, rich in opal, apparently forms during the bloom of Skeletonema costatum in the spring or summer, after which an olive-black lamina is deposited.     

Homeward sound

Despite spending weeks at sea as larvae, potentially scattered over many kilometers, young coral reef fish find suitable settlement habitat and in some cases return to their natal reefs. We report that some dominant families of larval reef fish use the sounds made by fish and shrimp resident on reefs to help them locate and settle on reefs and that some fish groups use specific components of the reef sound to guide their behavior. These findings could offer potential for active management of reef fisheries.     

Effects of fish in river food webs

Experimental manipulations of fish in a Northern California river during summer base flow reveal that they have large effects on predators, herbivores, and plants in river food webs. California roach and juvenile steelhead consume predatory insects and fish fry, which feed on algivorous chironomid larvae. In the presence of fish, filamentous green algae are reduced to low, prostrate webs, infested with chironomids. When the absence of large fish releases smaller predators that suppress chironomids, algal biomass is higher, and tall upright algal turfs become covered with diatoms and cyanobacteria. These manipulations provide evidence that the Hairston, Smith, Slobodkin-Fretwell theory of trophic control, which predicts that plants will be alternately limited by resources or herbivores in food webs with odd and even numbers of trophic levels, has application to river communitics.     

Challenges of modeling ocean basin ecosystems

With increasing pressure for a more ecological approach to marine fisheries and environmental management, there is a growing need to understand and predict changes in marine ecosystems. Biogeochemical and physical oceanographic models are well developed, but extending these further up the food web to include zooplankton and fish is a major challenge. The difficulty arises because organisms at higher trophic levels are longer lived, with important variability in abundance and distribution at basin and decadal scales. Those organisms at higher trophic levels also have complex life histories compared to microbes, further complicating their coupling to lower trophic levels and the physical system. We discuss a strategy that builds on recent advances in modeling and observations and suggest a way forward that includes approaches to coupling across trophic levels and the inclusion of uncertainty.     

Consumer Versus Resource Control in Freshwater Pelagic Food Webs

Models predict that food-web structure is regulated by both consumers and resources, and the strength of this control is dependent on trophic position and food-web length. To test these hypotheses, a meta-analysis was conducted of 11 fish (consumer)-by-nutrient (resource) factorial plankton community experiments. As predicted, zooplankton biomass was under strong consumer control but was weakly stimulated by nutrient additions; phytoplankton biomass was under strong resource control with moderate control by fish. However, the phytoplankton and zooplankton responses to nutrient additions did not follow theoretical predictions based on the number of trophic levels in the food web.     

扎龙湿地水体重金属沿食物链的生物累积分析

采用原子吸收法,对苍鹭(Ardea cinerea)卵、雏鸟的肝、肾、肌肉、羽毛4种组织器官及泥鳅(Misgurnus bipartitus)、细鳞斜颌鲴(Plagiognathops Microlepis)、葛氏鲈塘鳢(Perccotus glehni)、麦穗鱼(Pseudorasbora parva)、银鲫(Carassius auratus gibelio)及湖(?)(Phoxinus percnurus)6种鱼类组织内的Cu、Zn、Mn、Cd、Pb等重金属的含量进行了测定,分析了这几种重金属在鱼体内及卵和雏鸟体内含量的分布关系,结果表明:重金属Cu、Zn、Mn、Pb和Cd在苍鹭体内各组织中积累量不同,其总含量依次为Zn>Cu>Mn>Cd>Pb;在25日龄苍鹭雏鸟各组织中,肝脏和羽毛的5种金属的含量较其它组织器官高。在扎龙湿地生态系统不同营养级生物体内,重金属Cu、Zn、Mn、Pb、Cd的含量随食物链等级的升高而积累放大,水体中重金属的含量最低,鱼体内重金属含量次之,而苍鹭体内重金属含量最高,体内积累量沿生物营养等级而递增的规律性很强。在此基础上,探讨了重金属元素经食物链产生的生物累积放大作用对位于食物链最高营养级鸟类生存所构成的潜在威胁,从而为珍稀水禽保护及管理措施的制定提供一些依据。     

3种划蝽食性的初步研究

以水绵、丝藻、死鱼、活鱼、活水草、死水草和底泥为供试食物,以存活时间、消化道残留物的颜色和食物的变化为依据,推断3种划蝽在实验室内的取食食物.研究表明,3种划蝽均能利用水藻和腐烂有机物,但它们的营养生态位发生了分化,显斑原划蝽(Cymatia apparens (Distant))嗜好取食丝藻,并能取食水绵、腐烂水草和死鱼,但不能利用底泥;钟丽烁划蝽(Sigara bellula (Horvath))嗜好水绵,能利用腐烂水草、底泥、丝藻和死鱼;沙棘小划蝽(Micronecta sahibergi (Jakovlev))嗜好丝藻和底泥,能取食死鱼、腐烂水草和水绵.     

Sudden productivity collapse associated with the Triassic-Jurassic boundary mass extinction

The end-Triassic mass extinction is one of the five most catastrophic in Phanerozoic Earth history. Here we report carbon isotope evidence of a pronounced productivity collapse at the boundary, coincident with a sudden extinction among marine plankton, from stratigraphic sections on the Queen Charlotte Islands, British Columbia, Canada. This signal is similar to (though smaller than) the carbon isotope excursions associated with the Permian-Triassic and Cretaceous-Tertiary events.     

Turbidity current activity in a british columbia fjord

A year-long monitoring program within an elongated channel-fan system in Bute Inlet of British Columbia, Canada, detected active sand-transporting turbidity currents. Measurements of bottom velocities and sediment collected in traps, as well as damage to moorings and equipment, captured the signatures of frequent energetic events. Maximum calculated velocities achieved were 335 centimeters per second, with flow thicknesses of more than 30 meters. Coarse sand was transported at least 6 to 7.5 meters above the sea floor. Turbidity currents flowed a minimum distance of 25.9 kilometers, but possibly as far as 40 to 50 kilometers, over bottom slopes of generally less than 1 degrees.     

不列颠哥伦比亚黑鳕鱼养殖的潜在经济效益

主要研究不列颠哥伦比亚省黑鳕鱼养殖的潜在经济效益。不列颠哥伦比亚省一个黑鳕鱼苗种场已经开始以黑鳕鱼海水网箱养殖为目的苗种培育,这个唯一的黑鳕鱼苗种场培育出的鱼苗将有效地支持该地区目前的黑鳕鱼养殖。该地区黑鳕鱼养殖区纯收益受2个关键问题影响:一是如果全球参与黑鳕鱼养殖;二是如果不列颠哥伦比亚限制黑鳕鱼的养殖,而其他地区却不限制。研究结果表明:在不列颠哥伦比亚采用落后的水产养殖模式,可能获得较低的养殖利润。然而,当生产增长到期望的养殖水平时,黑鳕鱼的养殖利润将迅速下降。如果不列颠哥伦比亚野生黑鳕鱼的溢价控制在20%～25%以上,养殖禁令可能对该省和加拿大是有利的。