Consequences of the Sudden Removal of Nearly All Mussels and Cockles from the Dutch Wadden Sea

Abstract. Three successive years of recruitment failure, intensive fishery, and high rates of natural mortality eliminated all intertidal mussel beds and nearly all cockle beds from the Dutch Wadden Sea in the course of 1990. In late 1990 and early 1991, zoobenthic biomass and particularly bivalve stocks were unprecedentedly low. The following unusual events were noted:

• 1)

  Relatively high diatom and chlorophyll concentrations in the autumn of 1990 and an exceptionally early and dense spring bloom of diatoms in March 1991;
• 2)

  Exceptionally early onset of rapid growth in the bivalve Macoma balthica in March 1991;
• 3)

  Above-average weights of the soft parts of bivalves in the 1990/91 winter;
• 4)

  Elevated mortality rates in bivalves that could serve as alternative prey for birds specialised on big bivalves (oystercatchers and eiders);
• 5)

  Signs of food shortage in such birds: high mortality rates and emigration to other feeding areas;
• 6)

  A rapid recovery of the benthos started in the summer of 1991, accelerated by an exceptionally high recruitment in some of the affected species.

It is concluded that the Wadden Sea ecosystem responded in an elastic way to the removal of two of its key species. The events are not seen as merely coincidental but are regarded as a chain of causes and effects.     

南极长城站附近的脊椎动物 Ⅰ鸟类

本文对在南极长城站区附近活动的6科11种鸟类的数量、分布、繁殖、行为、栖息环境等作了比较详细的报道。作者认为:(1)在长城站区附近分布的鸟类全为肉食性种类;(2)企鹅在整个食物链中占有非常重要的作用;(3)亲鸟的护幼行为较强;(4)所观察到的鸟类全为早成或半早成鸟,但亲鸟育雏期又都较长,这是一种特殊习性。     

青海湖候鸟迁徙系统的构建与应用

介绍青海湖候鸟迁徙系统的体系结构、主要功能等,以青海湖重要繁殖水鸟迁徙路线上重要停歇地的禽流感预警与风险评估为例介绍该系统的核心功能,并以代码展示了该功能的具体实现思路。     

苏干湖夏季鸟类调查及观鸟潜力评价

苏干湖位于甘肃省西部阿克赛哈萨克族自治县境内,地处青藏高原北缘。该湖为多种水鸟的重要栖息地,已建为侯鸟自然保护区,但迄今未见有鸟类的专门调查。１９９７年７月至８月期间在该地区采用定点观察和路线观察法对苏干湖的水域、浅滩、沼泽和周围草地的鸟类进行了调查。调查的重点为鸟类的种类构成和居群数量,共记录到各种栖息生境的４６种鸟类,个体数量达２万多只,表明苏干湖是一处极为重要的湿地,并有观鸟旅游的价值。同时需加强对这一保护区的管理     

黑河流域中游湿地水禽资源与保护

黑河流域中游位于我国候鸟三大迁徙途径西部路线的中段,境内湖泊、沼泽、滩涂星罗棋布,是候鸟在迁徙飞越干旱荒漠、草原的过程中获得丰富食物、水源和得到良好休整的重要驿站,这里水禽资源丰富,共分布有水禽49种,其中国家Ⅰ、Ⅱ级重点保护鸟类8种;列入中澳候鸟保护协定的13种;列入中日候鸟保护协定的32种。必须从保护湿地水禽的生存空间、加强疫源疫病监测、加强基础研究、恢复水禽栖息环境、提高保护能力等方面入手加强水禽资源的保护。     

Visualizing aerial wildlife movements: Internet sources of Doppler radar for the classroom

Doppler radar imagery is a useful classroom tool for studying the movement and spatio-temporal distribution of animals. In this paper we present a basic introduction to Doppler radar and the base products used to garner biological and geographical data. We draw upon imagery depicting bat and avian movements to illustrate how radar imagery may be beneficially used in the classroom to examine habitat use and species distribution at the landscape scale. Additionally we provide references for data acquisition and real-time animated imagery available on the Internet. We hope the information and imagery provided here will help instructors enrich the classroom experience for their students, while at the same time demonstrating real-world applications for the use of radar imagery in biogeographic studies.     

Spatial conservation planning framework for assessing conservation opportunities in the Atlantic Forest of Brazil

Historic rates of habitat change and growing exploitation of natural resources threaten avian biodiversity in the Brazilian Atlantic Forest, a global biodiversity hotspot. We implemented a twostage framework for conservation planning in the Atlantic Forest. First, we used ecological niche modeling to predict the distributions of 23 endemic bird species using 19 climatic metrics and 12 spectral and radar remote sensing metrics. Second, we utilized the principle of complementarity to prioritize new sites to augment the Atlantic Forest's existing reserves. The best predictors of bird distributions were precipitation metrics (the seasonality of rainfall) and radar remote sensing metrics (QSCAT). The existing protected areas do not include 10% of the habitat of each of the 23 endemic species. We propose a more economical set of protected areas by reducing the extent to which new sites duplicate the biodiversity content of existing protected areas. There is a high concordance between the proposed conservation areas that we designed using computerized algorithms and Important Bird Areas prioritized by BirdLife International. Insofar as deforestation in the Atlantic Forest is similar to land conversion in other biodiversity hotspots, our methodology is applicable to conservation efforts elsewhere in the world.     

Rocky relationships: the petroglyphs of the Murujuga (Burrup Peninsula and Dampier Archipelago) in Western Australia

The petroglyphs of the Murujuga (Burrup Peninsula and Dampier Archipelago) in Western Australia are of exceptional cultural value for the nation. It is Australia’s largest and most significant collection of aboriginal rock art essentially as petroglyphs, with the number estimated at more than one million engravings. The Murujuga is a textbook example of ancient and modern times colliding as it also hosts potentially polluting, major industrial complexes such as iron ore and salt ports; liquefied natural gas, liquid ammonia and ammonium nitrate plants; railway lines, pipelines and rock quarries. The work presented in this paper is underpinned by an annual monitoring study of 10 selected sites including two control sites located on Dolphin and Gidley islands and eight test sites located closer to the industrial areas. The main rock types of the Murujuga, gabbro and granophyre, have been affected by weathering consisting of a cm-thick leached zone capped by a skin of orange and red iron and manganese oxides. The petroglyphs were engraved by removing the few top millimetres of the iron oxide-rich layer and the contrast with the paler leached zone clearly showing the carved motifs. Phosphorus is abnormally enriched in the leached zone and the surface coating, with manganese exclusively on the surface coating, demonstrating the impact of bird droppings and ‘desert varnish’ on the rocks. The colour difference and the hematite–goethite ratio, measured with a field portable reflectance spectrometer, between the background and engraving provides a tool to estimate the relative age of the petroglyphs and the selection of the backgrounds. As the fine-grained granophyres were preferentially chosen from the coarser-grained gabbros to host the petroglyphs, the goethitic (or yellower) backgrounds were prepared as canvas before being engraved. Many petroglyphs register the food items of the area, which changed as the last ice age ended and sea levels rose. We hypothesise that based on their locations and colour difference the constraint for the oldest age of the petroglyphs exceeds 17 000?years BP.     

鄱阳湖植食越冬候鸟粪便对洲滩湿地薹草枯落物分解过程及碳、氮、磷释放的影响

于2017年1月-2017年6月采用分解袋技术和鸟粪添加试验研究了鄱阳湖湿地植食性越冬水鸟粪便和典型洲滩湿地植物薹草枯落物分解过程中碳、氮、磷释放动态的差异性以及植食性越冬水鸟粪便的加入对鄱阳湖湿地薹草分解过程的影响.结果表明,不同分解时间内薹草枯落物、薹草+鸟粪中薹草枯落物和鸟粪3种样品的干物质损失率和分解速率的差异性都十分显著,其数值都表现为薹草+鸟粪中薹草样品 > 薹草枯落物样品 > 鸟粪样品.鸟粪的加入显著加速了薹草分解进程,使其平均分解速率提升了约21.23%.Olson负指数模型模拟预测显示,薹草+鸟粪中薹草、薹草枯落物和鸟粪样品分解完成50%所需的时间依次为259、314和355天,分解完成95%所需的时间大约依次约为3.1、3.7和4.2年.3种样品碳、氮、磷都表现为净释放模式,其相对回归指数之间差异性也显著.碳相对归还指数都表现为薹草+鸟粪中薹草 > 薹草枯落物 > 鸟粪,氮相对归还指数和磷相对归还指数值都表现为鸟粪 > 薹草+鸟粪中薹草 > 薹草枯落物.本研究推测鸟粪添加给分解环境带来额外的营养物质,使分解者微生物的数量、种类、活性增加以及鸟粪刺激产生了一系列降解酶,如木质素酶、纤维素酶、蔗糖酶等,胞外酶数量和活性增加,是鸟粪促进薹草分解的关键因素,而样品中初始养分含量以及分解过程碳、氮、磷化学计量比的变化是造成其分解速率和养分释放差异显著的主要原因.