Characterization of the waterbird communities wintering in Tunisian coastal lagoons

This article aims at studying wintering waterbirds in Tunisian coastal lagoons in order to support effective conservation measures. Species number and abundance of wintering waterbirds were assessed in January, each year from 2002 to 2007, in 10 lagoon sites belonging to four different lagoon systems. We counted 76 species and on average more than 120,000 birds per year, which represented more than 25% of the national population sizes. The most abundant taxonomic groups were waterfowls and waders, which also represented the highest species number. In general, the six most abundant bird species comprised collectively more than 77% of all birds counted. Considering all the studied lagoon systems collectively, for 13 species the lagoon systems should be considered as of international importance according the Ramsar Convention as they support regularly more than 1% of the populations. Only the lagoon system of the North held regularly more than 20,000 birds. The species abundances and species richness varied significantly among year and among lagoon systems. Based on our results we proposed priority conservation measures, these ecosystems being of major importance for wintering birds, at both national and international level.     

Causality between abundance and diversity is weak for wintering migratory waterbirds

相似文献   

Wintering bird communities in newly-formed wetland in the Yangtze River estuary

We compared wintering bird communities and their habitats among three shoals at Jiuduansha, a newly-formed wetland in the Yangtze River estuary. The highest species richness and diversity were recorded in Shangsha, which is the highest shoal, and the highest abundance and lowest species diversity were recorded in Xiasha, which is the lowest shoal. Shangsha had the largest abundance of perching birds whereas Xiasha was the most abundant in waterbirds. Bird assemblages showed different associations with the different habitat types—perching birds were favored by reed (Phragmites australis) communities, shallow water foragers and dabbling ducks preferred sea-bulrush (Scirpus mariqueter) communities, and moist-soil foragers and gulls showed a preference for bare intertidal zones. All bird assemblages, however, avoided the smooth cordgrass (Spartina alterniflora) communities, which are dominated by an alien invasive plant. The composition of avian communities was related to habitat types at the three shoals. Our results suggest that the newly-formed tidelands can provide suitable habitats for waterbirds and that the lower tidelands can attract more waterfowl than the higher tidelands. Because the shoal with low species diversity could have exclusive bird species, conservation efforts should not concentrate only on the area with high species diversity. The estuarine wetlands should be considered as a whole when conservation strategies are designed. The alien invasive plant should, moreover, be effectively controlled, to provide suitable habitats for birds.     

Diversity of terrestrial isopods in the northern Tunisian wetlands

To evaluate the influence of wetland types on the distribution of terrestrial isopods, species richness, relative abundance and diversity indices were studied in the supralittoral zone of 95 wetlands in the north‐western of Tunisian dorsal, belonging to six types: lagoon, hill reservoir, river, dam, lake and sebkha. We tested the following hypothesis: (i) is isopod diversity influenced by wetland types? (ii) is isopod diversity influenced by bioclimatic zones? and (iii) what are the environmental factors influencing isopod distribution? A total of 3255 individuals belonging to twenty species of terrestrial isopods were captured. Species richness differs significantly between wetland types. A highly significant positive relationship between species richness and both humidity and altitudinal gradient was described. The dendrogram of similarities showed a divergence of the lagoons compared to the remaining wetland types.     

安徽沿江浅水湖泊越冬水鸟群落的集团结构

长江中下游湖泊是越冬水鸟的重要栖息地,随着湖泊渔业养殖强度的不断加大,湖泊湿地严重退化,水鸟的越冬生态受到影响。为揭示长江中下游浅水湖泊越冬水鸟对湿地资源的利用特征,2008年12月至2009年3月,通过扫描取样法采集安徽省长江沿江升金湖、菜子湖和武昌湖3个浅水湖泊30种越冬水鸟的取食行为百分比数据,利用聚类分析法对越冬水鸟进行集团划分,并采用无倾向对应法(DCA)分析越冬水鸟的取食特征。聚类分析结果表明,安庆沿江湖泊越冬水鸟群落可分为4个集团,即深水取食集团G1、挖掘和啄取集团G2、浅水取食集团G3和泥滩拾取集团G4。G2集团的鸟种最多,共有13种,优势种为鸿雁(Anser cygnoides)、豆雁(Anser fabalis);G3集团次之,共6种,优势种为小天鹅(Cygnus columbianus)、白琵鹭(Platalea leucorodia);G4集团共5种,优势种为黑腹滨鹬(Calidris alpina)、鹤鹬(Tringa erythropus)和红脚鹬(Tringa totanus);G1集团水鸟种类有6种。这些水鸟的觅食生境主要在湖泊滩涂和浅水区域,其食物资源的可利用性和觅食对策共同决定群落组成结构。DCA分析表明,取食方式及取食时运动方式组成的觅食对策决定了集团食物资源的分割,草滩中取食鸟类主要采用静止取食和啄取方式,泥滩取食集团主要采取拾取及奔-停取食,深水区取食集团则主要采用潜水方式取食,因此,维持湖泊不同区域的丰富食物资源对于保护湖泊丰富的水鸟资源具有重要意义。     

若尔盖湿地水鸟多样性季节性动态分析

若尔盖湿地位于青藏高原东缘,是我国最大的高寒泥炭湿地之一。2010年从3月至12月,对若尔盖湿地水鸟种类、数量和分布进行了较为系统的调查。共记录到48种26050只水鸟,隶属于6目12科,其中雁鸭类水鸟最多,共统计到21408只,占水鸟总数的82.2%。3月和10月是若尔盖湿地水鸟的高峰期,11月是低谷期,主要是由于水鸟的迁离和越冬水鸟尚未到达的缘故。尕海是若尔盖湿地的重要组成部分,全年物种数和水鸟数量占了整个若尔盖湿地较大的比例。卫星跟踪的结果表明,青海湖斑头雁在若尔盖湿地与云南和贵州的越冬水鸟汇合,因此加强若尔盖湿地禽流感的防控是非常重要的。     

Diversity of waterbirds wintering in Douz wetlands (south Tunisia): factors affecting wetland occupancy and species richness

Understanding the environmental factors shaping wetland attractiveness for waterbirds is an important question in wetland ecology and for conservation purposes. However, detailed data from numerous North African wetlands, notably those situated in inland areas, are still lacking. Thus, the aim of this study was to identify the factors influencing wetland use by waterbirds wintering in one of such poorly known habitat systems, namely the Saharan wetland complex of Douz, in south-western Tunisia. Thirty-four waterbird species (20 wading birds and 14 waterfowl species) were found to winter in this area. Using discriminant function analyses, we found that wetland size was the unique variable discriminating between occupied and unoccupied sites for total waterbirds and wading birds, while waterfowl distribution was related to both wetland size and water depth. Wetland size also provided the strongest predictor of species richness of wading birds, waterfowl and total waterbirds. Overall, our findings highlight the importance of wetland size as a key factor determining the attractiveness of wetlands for waterbirds wintering in the Saharan wetland complex of Douz. The possible explanations of this wetland size effect are discussed.     

Effects of flyway‐wide weather conditions and breeding habitat on the breeding abundance of migratory boreal waterbirds

Anthropogenic habitat loss and climate change are among the major threats to biodiversity. Bioclimatic zones such as the boreal and arctic regions are undergoing rapid environmental change, which will likely trigger changes in wildlife communities. Disentangling the effects of different drivers of environmental change on species is fundamental to better understand population dynamics under changing conditions. Therefore, in this study we investigate the synergistic effect of winter and summer weather conditions and habitat type on the abundance of 17 migratory boreal waterbird species breeding in Finland using three decades (1986–2015) of count data. We found that above‐average temperatures and precipitations across the western and northern range of the wintering grounds have a positive impact on breeding numbers in the following season, particularly for waterbirds breeding in eutrophic wetlands. Conversely, summer temperatures did not seem to affect waterbird abundance. Moreover, waterbird abundance was higher in eutrophic than in oligotrophic wetlands, but long term trends indicated that populations are decreasing faster in eutrophic than in oligotrophic wetlands. Our results suggest that global warming may apparently benefit waterbirds, e.g. by increased winter survival due to more favourable winter weather conditions. However, the observed population declines, particularly in eutrophic wetlands, may also indicate that the quality of breeding habitat is rapidly deteriorating through increased eutrophication in Finland which override the climatic effects. The findings of this study highlight the importance of embracing a holistic approach, from the level of a single catchment up to the whole flyway, in order to effectively address the threats that waterbirds face on their breeding as well as wintering grounds.     

Agricultural ponds as alternative habitat for waterbirds: spatial and temporal patterns of abundance and management strategies

The progressive lost of natural wetlands as a consequence of human activities has lead to the use of new habitats by the species linked to water presence. In Southeast Spain, thousands of irrigation ponds have been lately constructed to store water for agriculture and are used by waterbirds as an alternative habitat. For this study, breeding and wintering waterbirds were counted in a subset of irrigation ponds between 2002 and 2007. Breeding communities were more abundant than wintering communities, but they presented a similar richness and diversity. The ponds were selected by waterbirds according to their characteristics, and breeding communities were more selective than wintering communities. Our results enhance the importance of pond size (area), connectivity (distance to the nearest wetland) and habitat quality (resource offer and construction material) in the pond selection process. The presence and design of these impoundments could be playing a crucial role for some waterbirds species. Therefore, the long-term information provided here can be useful for establishing management strategies for these artificial wetlands.     

极端洪水作用下升金湖消落带生境变化对越冬水鸟群落结构的影响

水鸟是湿地生境质量的重要指示性动物类群,可敏感地反映湿地环境变化。浅水通江湖泊消落带具有复杂多样的生境和丰富的食物资源,是水鸟特别是越冬水鸟的重要聚集区,其食物资源的丰富度和可获得性受水文节律影响。在极端洪水作用下,消落带生境变化对越冬水鸟群落结构及其多样性的影响是一个值得关注的水鸟及湿地生态学问题。选择了具有典型消落带生境的升金湖作为研究区域,对2019年(正常水位)和2020年(异常水位)两个越冬季水鸟的数量、种类进行调查统计,分析了消落带的生境变化情况对越冬水鸟群落结构的影响。2019年越冬期,记录到水鸟(50984.20±9595.71)只(n=5),隶属7目13科51种;2020年越冬期,记录到水鸟(27923.00±13808.47)只(n=5),隶属7目12科53种。整个越冬季消落带的水鸟种类略增但数量减少,2019年游禽中的优势种为豆雁,2020年游禽中的优势种增加为豆雁和斑嘴鸭,但涉禽中的优势种由白琵鹭、反嘴鹬、凤头麦鸡转变为苍鹭、大白鹭和反嘴鹬。洪水导致的草滩-水域混合区生境面积减小使湿生植物退化,可能是导致以豆雁为主的食苔草水鸟数量大幅度减少的重要原因;因湖水延迟...     

Rapid climate driven shifts in wintering distributions of three common waterbird species

Climate change is predicted to cause changes in species distributions and several studies report margin range shifts in some species. However, the reported changes rarely concern a species' entire distribution and are not always linked to climate change. Here, we demonstrate strong north‐eastwards shifts in the centres of gravity of the entire wintering range of three common waterbird species along the North‐West Europe flyway during the past three decades. These shifts correlate with an increase of 3.8 °C in early winter temperature in the north‐eastern part of the wintering areas, where bird abundance increased exponentially, corresponding with decreases in abundance at the south‐western margin of the wintering ranges. This confirms the need to re‐evaluate conservation site safeguard networks and associated biodiversity monitoring along the flyway, as new important wintering areas are established further north and east, and highlights the general urgency of conservation planning in a changing world. Range shifts in wintering waterbirds may also affect hunting pressure, which may alter bag sizes and lead to population‐level consequences.     

安徽沿江两个浅水型湖泊越冬水鸟的季节动态(英文)

安徽沿江浅水型通江湖泊湿地是东亚-澳大利亚迁徙水鸟的重要越冬地和停歇地。近年来,高强度的渔业养殖使湿地严重退化,对越冬水鸟构成威胁。为了解湿地变化对越冬迁徙水鸟的影响,2007年11-2008年4月和2008年11月-2009年4月,对安徽菜子湖和升金湖11个样带内越冬水鸟的种类、数量及空间分布进行了调查,并分析了湖泊渔业模式对水鸟分布的影响。两个湖泊共统计到越冬水鸟7目12科43种。其中,菜子湖群38种,密度为8.2ind./hm2;升金湖42种,密度为3.5ind./hm2,优势种为鸿雁(Anser cygnoides)、豆雁(Anser fabalis)、小天鹅(Cygnus columbianus)和黑腹滨鹬(Calidris alpina)。越冬水鸟种类和数量在12月底-次年1月上旬达到最大值,但不同类型越冬群最大数量出现的具体时期有所不同。根据水鸟组成的聚类分析,可将水鸟栖息地分为三组。水鸟的分布与渔业模式有关,在自然捕捞区,鹤类、雁鸭类和鸻鹬类密度较大,在围网养殖区密度较小,而鹭类的密度在各湖区变化都较小。本研究结果提示,发展可持续渔业对于长江中下游浅水湖泊湿地越冬水鸟资源的保护具有重要意义。     

­­Cross-taxon congruence in wetlands: Assessing the value of waterbirds as surrogates of macroinvertebrate biodiversity in Mediterranean Ramsar sites

Wetlands are among the most threatened habitats and the species they support among the most endangered taxa. Measuring and monitoring wetland biodiversity is vital for conservation, restoration and management, and often relies on the use of surrogate taxa. Waterbirds are commonly used as flagships of biodiversity and are the subject of major conservation initiatives. Therefore, it is important to assess the extent to which waterbirds indicate the general biodiversity of wetlands and serve as surrogates.We explore the relationships between community composition and species richness of waterbirds and aquatic macroinvertebrates in 36 Ramsar wetlands in southern Spain to assess if waterbirds are good surrogates for other taxonomic groups. Specifically, we aimed to (i) test the congruence of patterns of species composition and richness among waterbirds and aquatic macroinvertebrates; and (ii) investigate which environmental variables are associated with the biodiversity patterns of waterbirds and macroinvertebrates, with the purpose of identifying key factors explaining potential discordance in these patterns.We found a limited concordance between assemblage patterns of both taxonomic groups that may be related to their contrasting responses to environmental gradients. Assemblages of waterbirds appear to be more affected by climate variables and water surface area, whereas conductivity was the most important factor influencing macroinvertebrate communities. Furthermore, we found a negligible or inverse relationship in their patterns of richness, with wetlands with higher waterbird species richness showing significantly lower richness of Hemiptera and macroinvertebrate families, and no significant relationship with Coleoptera. In addition, GLM models showed that, in general, different environmental variables are related with the richness patterns of the different taxonomic groups.Given the importance of the Ramsar convention for the conservation of an international network of wetlands, our findings underline the limited potential of waterbirds as aquatic biodiversity indicators in Mediterranean wetlands, and the need for caution when using waterbirds as flagships. An integrative analysis of different biological communities, using datasets from different taxonomic groups, is a necessary precursor for successful conservation policies and monitoring. Our results illustrate the need to create a diversified and complete network of protected sites able to conserve multiple components of wetland biodiversity.     

Amphipoda and Isopoda diversity around Tunisian wetlands (North Africa) in relation to environmental conditions

Amphipoda and Isopoda were sampled in 40 Tunisian wetlands, and their fauna were compared at four different types: lagoon, sebkhas, dams and hill reservoir. At each station, eight quadrates of 50 × 50 cm were randomly placed. Amphipoda and Isopoda were collected by hand. They were identified to species level. At each station, analyses of organic matter, sodium, calcium and heavy metals content from the soil collected in each station were performed. We recorded 19 and eight species for respectively Isopoda and Amphipoda and caught 3,035 specimens in total. The highest isopod's species richness (11 species) was noted around hill reservoirs and dams, a quite similar richness in the banks of lagoons (10 species) but only six species in the sebkhas. Eight amphipod species were recorded in the supralittoral zone of lagoons, three species around sebkhas but no amphipods were found in samples from dams and hill reservoirs. Isopod species richness was positively correlated with soil humidity. However, the distribution of the species Orchestia mediterranea, Orchestia gammarellus, Orchestia montagui, Orchestia stephenseni and Platorchestia platensis was related to soil metal concentrations.     

Are artificial wetlands good alternatives to natural wetlands for waterbirds? – A case study on Chongming Island, China

Loss of natural wetlands is a global phenomenon that has been a serious threat to the wildlife. A common practice is to construct artificial wetlands to compensate for the loss of natural wetlands. To test whether artificial wetlands as habitats for waterbirds are good alternatives to natural wetlands, we compared species richness, abundance, and seasonal dynamics of waterbird communities of natural (here tidelands) and artificial wetlands (here aquacultural ponds) on Chongming Island, China. Our results indicate that habitat preference of waterbirds showed seasonal difference: most of the shorebirds were found on tidelands in spring, whereas most of the natatorial birds were recorded in aquacultural ponds in winter. Waterbirds preferred the tidelands rather than aquacultural ponds in both spring and autumn, whereas they showed no preference for either the tidelands or the ponds in summer and winter. It is concluded that natural wetlands are better habitats for waterbirds than artificial wetlands on Chongming Island, while the artificial ones are also suitable habitats for waterbirds in winter. The waterbirds might use artificial wetlands only when natural wetlands are unavailable or of poor quality. An over-emphasis that artificial wetlands are suitable habitats for waterbirds might encourage land managers to convert natural wetlands into the artificial ones, resulting in considerable loss of bird diversity. Therefore, for the purpose of bird conservation, it would be a better practice to conserve natural wetlands rather than to construct artificial ones after destruction of natural wetlands.     

Importance of gravel pits for the conservation of waterbirds in the Garonne river floodplain (southwest France)

The loss of natural wetlands throughout the World has made created habitats such as gravel pits, reservoirs or rice fields potentially important for waterbird conservation. In southwest France, the increasing abundance of gravel pits has allowed several bird species to colonize the region. The avian community was studied from 1996 to 1998 in six gravel pits in the Garonne floodplain. A total of 39 species of waterbirds were recorded, with higher abundance during the winter and post-breeding periods. We analyzed habitat use to identify key environmental factors determining the temporal and spatial distribution of the avian community. The presence of submerged macrophytes was found to be the most important factor influencing the distribution of waterbirds. The presence of paths in the vicinity of the areas reduced both the total number of birds and species richness owing to human disturbance. Gravel pits have an increasingly important role in the conservation of bird biodiversity. By controlling disturbance and management of vegetation, managers can enhance this role.     

崇明东滩抛荒鱼塘的自然演替过程对水鸟群落的影响

人工湿地抛荒的现象普遍存在,但针对抛荒后的自然演替过程对水鸟群落影响的研究较少.于2007、2008、2011年对崇明东滩自然抛荒的人工鱼塘水鸟群落展开调查,探究抛荒后的自然演替过程对水鸟群落结构及不同水鸟类群的影响.3a累计观察到水鸟59种12819只,隶属6目12科.其中抛荒前最多,共53种11001只;抛荒第1年22种1673只;抛荒第4年最少,9种145只.鱼塘抛荒后水鸟种类和数量下降剧烈,物种多样性先上升再下降,均匀度逐年上升,优势度先下降再上升.方差分析结果表明,5个群落特征都存在极显著年度差异(P1＜0.01;P2＜0.01;P3＜0.01;P4=0.003;P5＜0.01).非参数检验结果表明,不同类群水鸟的种类和数量逐年下降趋势明显,且年际差异极显著.即抛荒后的自然演替过程对水鸟群落产生了不利影响.建议采取人工管理措施防止旱化,增加环境异质性,恢复水鸟群落多样性.     

A functional perspective for breeding and wintering waterbird communities: temporal trends in species and trait diversity

Waterbird communities are prone to strong temporal changes both seasonally and annually, but little is known about how this affects their functional diversity and community assembly. Detecting temporal trends in taxonomic and functional diversity within (alpha diversity) and between (beta diversity) communities in breeding and wintering seasons could give insight into the ecological processes driving those trends. In this study, we investigated trends in wintering and breeding waterbirds within and between eleven wetlands in Mediterranean Spain, using a 28‐year time‐series up to 2017. We assessed the temporal trends in taxonomic and functional diversity measures, and compared observed functional diversity values with null expectations, in order to explore the mechanisms driving community assembly. We found increases over time in species richness and in the occupied functional space for both wintering and breeding communities, indicating that species with distinct functional roles were added in both seasons. However, the distribution of the abundances in the functional space was different for breeding and wintering communities. Dissimilarity of species and functional traits decreased among wetlands, suggesting that some of the same functional traits were added to the different wetlands, increasing regional homogenization through time. This is reflected in increases over time in mean body mass, diet plasticity and in the importance of fish in waterbird diets, plus declines in the dietary importance of invertebrates and in plasticity of feeding strata. Furthermore, species composition between wintering and breeding communities, but not trait composition, has become more similar through time. Our results highlight that annual changes, and especially seasonal changes, in the composition of waterbird communities have different effects on their functional diversity, and are influenced by opposing community assembly mechanisms.     

Comparing the diversity and composition of waterbird functional traits between natural,restored, and artificial wetlands

1. The restoration of degraded areas and the creation of artificial ecosystems have partially compensated for the continuing loss of natural wetlands. However, the success of these wetlands in terms of the capacity of supporting biodiversity and ecosystem functions is unclear. Research is needed to improve our understanding of the value of restored and constructed wetlands for functional diversity of freshwater fauna.
2. We compared natural, restored, and artificially created wetlands present within the Doñana Natural Space, Spain and valued as important for waterbirds. We evaluated if these wetlands are equivalent in terms of waterbird functional trait diversity and composition, during both the wintering and breeding seasons. We modelled functional diversity measures and functional group species richness describing species diet, body mass, and foraging techniques with generalised linear mixed models in 20 wetlands monitored between 2006 and 2011. We used three different statistical approaches to evaluate the robustness of our results.
3. Artificial wetlands constructed for conservation failed to reach the functional diversity of natural and restored wetlands. Unexpectedly, artificial ponds constructed for fish production performed better, and even exceeded natural wetlands for functional richness during winter. Fish ponds stood out as having a unique functional composition, connected with increase in richness of opportunistic gulls and decrease of species sensitive to high salinity. Overall, the functional structure of breeding communities was more affected by wetland type than wintering communities.
4. Our findings suggest that compensating the loss of natural wetlands with restored and artificial wetlands results in systems with altered waterbird-supported functions, such as seed dispersal or nutrient cycling. Protection of natural Mediterranean wetlands is vital to maintain the original diversity and composition of waterbird functional traits. Furthermore, restoration must be prioritised over the creation of artificial wetlands, which, even when intended for conservation, may not provide an adequate replacement.

     

黄河流域水鸟保护优先区及空缺

黄河流域为迁徙水鸟提供重要的繁殖地、越冬地和停歇地。然而,黄河流域正面临着农业开垦、城市化、水资源分布不均等一系列的生态安全问题,威胁迁徙水鸟种群及其栖息地稳定性。因此,识别黄河流域重要的水鸟栖息地分布区域,分析当前的保护现状对于开展水鸟及栖息地保护至关重要。以黄河流域为研究区,搜集整合来自国内外观鸟网站(eBird、全球生物多样性信息库(GBIF)和中国观鸟记录中心(BirdReport))、文献和水鸟调查报告中的水鸟调查数据,沿用三个国际上通用的水鸟重要栖息地识别标准,确定了黄河流域水鸟保护优先区。在此基础上,使用水鸟栖息地重要性指数确定水鸟保护优先区保护优先等级,结合国家自然保护地名录,分析水鸟保护优先区保护空缺状况。结果显示:黄河流域共有47个水鸟保护优先区,主要分布在黄河流域中游和下游,其中河南省和山东省水鸟保护优先区较多。满足水鸟保护优先区识别标准的水鸟共14种,其中,极危物种有2个,濒危物种有1个,易危物种有5个。水鸟保护优先区保护优先等级处于I、II和III类的分别有2个、8个和37个。有20个水鸟保护优先区处于保护空缺状态,占总数的42.55%,主要集中在黄河中游和下游,其中,水鸟保护优先等级处于I类或II类的地块有3个,建议将这些保护空缺地以自然保护区、保护小区或国家公园形式纳入湿地保护地体系,并加强长期监测。