The Salton Sea as critical habitat to migratory and resident waterbirds

Concern about the Salton Sea ecosystem, based on potential impacts of increasing salinity, contaminants, disease outbreaks, and large die-offs of birds, is heightened because of tremendous prior loss and degradation of wetland habitat in western North America. In 1999, we used a variety of survey methods to describe patterns of abundance of birds at the Salton Sea and in adjacent habitats. Our results further documented the great importance of the Salton Sea within the Pacific Flyway to wintering, migratory, and breeding waterbirds. Exclusive of Eared Grebes, we estimated about 187000 individual waterbirds at the Salton Sea in January, 88000 in April, 170000 in August, and 261000 in November. Additional surveys of Eared Grebes in November and December suggested the total population of all waterbirds was about 434000 to 583000 in those months, respectively. We also documented breeding by about 14000 pairs of colonial waterbirds. Waterbirds were particularly concentrated along the northern, southwestern, southern, and southeastern shorelines and river deltas. By contrast, some species of wading birds (Cattle Egret, White-faced Ibis, Sandhill Crane) and shorebirds (Mountain Plover, Whimbrel, Long-billed Curlew) were much more numerous in agricultural fields of the Imperial Valley than in wetland habitats at the Sea. Various studies indicate the Salton Sea is of regional or national importance to pelicans and cormorants, wading birds, waterfowl, shorebirds, and gulls and terns. Important taxa are the Eared Grebe, American White Pelican, Double-crested Cormorant, Cattle Egret, White-faced Ibis, Ruddy Duck, Yuma Clapper Rail, Snowy Plover, Mountain Plover, Gull-billed, Caspian, and Black terns, and Black Skimmer. Proposed restoration projects should be carefully assessed to ensure they do not have unintended impacts and are not placed where large numbers of breeding, roosting, or foraging birds concentrate. Similarly, plans to enhance opportunities for recreation or commerce at the Sea should aim to avoid or minimize disturbance to birds. Future research should focus on filling gaps in knowledge needed to effectively conserve birds at the Salton Sea.     

The Assemblage of Birds Foraging in Native West Indian Pine (Pinus occidentalis) Forests of the Dominican Republic during the Nonbreeding Season1

We studied avian resource use in a native West Indian pine (Pinus occidentalis) forest in the Cordillera Central of the Dominican Republic during the nonbreeding season. The forest is characterized by a fairly open pine canopy and a dense mixed-broadleaf and pine understory. We used a principal components analysis of 23 foraging characters for 23 bird species, including foraging height, the proportional use of 5 different foraging methods, 3 horizontal positions and foliage densities, and 11 foraging substrates. Five principal components accounted for 74 percent of the total variance of the assemblage variables and resulted in the delineation of at least 5 foraging guilds. 78 percent of bird species had mean foraging heights of 5.0–10.0 m, corresponding to the region of overlap of pine and broadleaf vegetation. As a result, the diversity of foraging substrates and maneuvers used by birds, rather than foraging height, appears to be the primary means by which birds that exploit this habitat separate ecologically. Migrant wood warblers (Parulinae) are probably able to integrate into the community because of little diet overlap between residents and migrants, and the fairly specialized nature of their largely insectivorous foraging habits. Avian foraging in this habitat may reflect the effects of frequent disturbance such as hurricanes.     

西双版纳勐海县勐阿水库对亚洲象迁移活动和人—象冲突的潜在影响

2020年1—12月,采用半结构式访查法、痕迹跟踪调查法和无人机跟踪调查法相结合的方法,对拟建西双版纳勐海县勐阿水库涉及区域的亚洲象种群结构、迁移路线等进行了调查,并采用样方法和3S技术对该区域亚洲象取食植物和栖息地适宜性进行了调查和分析,以探讨拟建勐阿水库可能对亚洲象迁移活动和人—象冲突的潜在影响。结果表明：(1)拟建勐阿水库区域活动的亚洲象小种群被称为澜沧江西部种群或西双版纳勐海—普洱澜沧种群,仅由19头亚洲象(10头雄性,9头雌性)组成,有2条亚洲象迁移路线穿越该区域;(2)在研究区域共统计到亚洲象取食植物12目19科32属33种,基本能满足该象群的取食需求;(3)海拔、坡度、植被隐蔽度及食物资源等生态因子的适宜性分析结果显示,大部分区域(包括占总面积14.61%的最适生境和占总面积82.05%的相对适宜生境)都能满足该亚洲象小种群的基本生活需求;(4)2条亚洲象迁移路线中的1条将因水库建设而阻断,迫使该象群改变原来的迁移路线;(5)水库淹没区的植被将被永久破坏,原本连片的适宜栖息地也将受到进一步切割和压缩影响;(6)当食物资源无法满足亚洲象生存需求时,它们可能会选择进入可在较短时间内获得大量食物的农耕区取食农作物和经济作物,随着人流、车流大量增加,亚洲象与人相遇的概率也会大幅度增加。分析认为,拟建勐阿水库将淹没1条迁移通道,对亚洲象迁移活动造成阻碍,迫使象群改变路线,还可能导致更为严重的人—象冲突。建议在水库工程设计和建设过程中采取有效的保护管理措施,减少工程项目对亚洲象种群及其栖息地的负面影响;水库建设和管理部门、林业和草原管理部门等应加强对亚洲象活动的监测和预警,避免亚洲象肇事造成人员伤亡和更大的经济损失。     

蜜蜂上颚腺及其分泌物研究进展

上颚腺是蜜蜂重要的外分泌腺体,其分泌物是维系蜂群社会性结构的重要物质。蜂王和工蜂上颚腺分泌物合成均以硬脂酸为合成前体,但在脂肪酸的β-氧化过程中表现出级型差异性,导致分泌物组分比例不同。蜂王上颚腺分泌物以9-羰基-2癸烯酸(9-ODA)为主,有吸引工蜂和雄蜂、抑制工蜂卵巢发育等作用;工蜂上颚腺分泌物以10-羟基-2癸烯酸(10-HDA)和10-羟基癸酸(10-HDAA)为主,是蜂王浆的重要组成部分。同时,这种具备典型级型差异的分泌物组成又具有级型间可塑性,在不同蜂种间也存在区别。近年来在转录水平和蛋白水平的一些研究进一步揭示了级型间差异的分子基础。针对蜜蜂上颚腺及其分泌物的研究在蜜蜂生物学、行为学和蜂产品质量控制等方面具有重要的意义。本文通过总结国内外相关研究进展,旨在为上颚腺分泌物的作用机制、生物合成机制等领域的进一步深入研究提供借鉴。     

Greater shrub dominance alters breeding habitat and food resources for migratory songbirds in Alaskan arctic tundra

Climate warming is affecting the Arctic in multiple ways, including via increased dominance of deciduous shrubs. Although many studies have focused on how this vegetation shift is altering nutrient cycling and energy balance, few have explicitly considered effects on tundra fauna, such as the millions of migratory songbirds that breed in northern regions every year. To understand how increasing deciduous shrub dominance may alter breeding songbird habitat, we quantified vegetation and arthropod community characteristics in both graminoid and shrub dominated tundra. We combined measurements of preferred nest site characteristics for Lapland longspurs (Calcarius lapponicus) and Gambel's White‐crowned sparrows (Zonotrichia leucophrys gambelii) with modeled predictions for the distribution of plant community types in the Alaskan arctic foothills region for the year 2050. Lapland longspur nests were found in sedge‐dominated tussock tundra where shrub height does not exceed 20 cm, whereas White‐crowned sparrows nested only under shrubs between 20 cm and 1 m in height, with no preference for shrub species. Shrub canopies had higher canopy‐dwelling arthropod availability (i.e. small flies and spiders) but lower ground‐dwelling arthropod availability (i.e. large spiders and beetles). Since flies are the birds' preferred prey, increasing shrubs may result in a net enhancement in preferred prey availability. Acknowledging the coarse resolution of existing tundra vegetation models, we predict that by 2050 there will be a northward shift in current White‐crowned sparrow habitat range and a 20–60% increase in their preferred habitat extent, while Lapland longspur habitat extent will be equivalently reduced. Our findings can be used to make first approximations of future habitat change for species with similar nesting requirements. However, we contend that as exemplified by this study's findings, existing tundra modeling tools cannot yet simulate the fine‐scale habitat characteristics that are critical to accurately predicting future habitat extent for many wildlife species.     

Experimental evidence for the effect of habitat loss on the dynamics of migratory networks

Migratory animals present a unique challenge for understanding the consequences of habitat loss on population dynamics because individuals are typically distributed over a series of interconnected breeding and non‐breeding sites (termed migratory network). Using replicated breeding and non‐breeding populations of Drosophila melanogaster and a mathematical model, we investigated three hypotheses to explain how habitat loss influenced the dynamics of populations in networks with different degrees of connectivity between breeding and non‐breeding seasons. We found that habitat loss increased the degree of connectivity in the network and influenced population size at sites that were not directly connected to the site where habitat loss occurred. However, connected networks only buffered global population declines at high levels of habitat loss. Our results demonstrate why knowledge of the patterns of connectivity across a species range is critical for predicting the effects of environmental change and provide empirical evidence for why connected migratory networks are commonly found in nature.     

Interaction of angio-associated migratory cell protein with the TPα and TPβ isoforms of the human thromboxane A₂ receptor

In humans, thromboxane (TX) A₂ signals through the TPα and TPβ isoforms of its G-protein coupled TXA₂ receptor (TP) to mediate a host of (patho)physiologic responses. Herein, angio-associated migratory cell protein (AAMP) was identified as a novel interacting partner of both TPα and TPβ through an interaction dependent on common (residues 312-328) and unique (residues 366-392 of TPβ) sequences within their carboxyl-terminal (C)-tail domains. While the interaction was constitutive in mammalian cells, agonist-stimulation of TPα/TPβ led to a transient dissociation of AAMP from immune complexes which coincided with a transient redistribution of AAMP from its localization in an intracellular fibrous network. Although the GTPase RhoA is a downstream effector of both AAMP and the TPs, AAMP did not influence TP-mediated RhoA or vice versa. Small interfering RNA (siRNA)-mediated disruption of AAMP expression decreased migration of primary human coronary artery smooth muscle cells (1° hCoASMCs). Moreover, siRNA-disruption of AAMP significantly impaired 1° hCoASMC migration in the presence of the TXA₂ mimetic U46619 but did not affect VEGF-mediated cell migration. Given their roles within the vasculature, the identification of a specific interaction between TPα/TPβ and AAMP is likely to have substantial functional implications for vascular pathologies in which they are both implicated.     

Using demographic data to better interpret pitfall trap catches

The results of pitfall trapping are often interpreted as abundance in a particular habitat. At the same time, there are numerous cases of almost unrealistically high catches of ground beetles in seemingly unsuitable sites. The correlation of catches by pitfall trapping with the true distribution and abundance of Carabidae needs corroboration. During a full year survey in 2006/07 in the Lake Elton region (Volgograd Area, Russia), 175 species of ground beetles were trapped. Considering the differences in demographic structure of the local populations, and not their abundances, three groups of species were recognized: residents, migrants and sporadic. In residents, the demographic structure of local populations is complete, and their habitats can be considered "residential". In migrants and sporadic species, the demographic structure of the local populations is incomplete, and their habitats can be considered "transit". Residents interact both with their prey and with each other in a particular habitat. Sporadic species are hardly important to a carabid community because of their low abundances. The contribution of migrants to the structure of carabid communities is not apparent and requires additional research. Migrants and sporadic species represent a "labile" component in ground beetles communities, as opposed to a "stable" component, represented by residents. The variability of the labile component substantially limits our interpretation of species diversity in carabid communities. Thus, the criteria for determining the most abundant, or dominant species inevitably vary because the abundance of migrants in some cases can be one order of magnitude higher than that of residents. The results of pitfall trapping adequately reflect the state of carabid communities only in zonal habitats, while azonal and disturbed habitats are merely transit ones for many species of ground beetles. A study of the demographic structure of local populations and assessment of the migratory/residential status of particular carabid species are potential ways of increasing the reliability of pitfall trap information.     

Determination of ornithine, putrescine, N-methylputrescine and N-methylpyrroline pools in tobacco tissue by high-performance liquid chromatography

A procedure for the determination of metabolites of the biochemical pathway ornithine to N-methyl-δ¹-pyrrolinium salt (N-methylpyrroline) is described. Plant tissue was extracted with 0.5 M HCl and the extract purified on C₁₈-cartridges. Ornithine was reacted with o -phthaldialdehyde, putrescine and N-methylputrescine with dansyl chloride and the products were separated by reversed-phase high-performance liquid chromatography (HPLC). N-methylpyrroline was determined by cation-exchange HPLC without derivatization. The metabolites in the roots of tobacco ( Nicotiana ) species with different nicotine-producing capacities were determined. Furthermore, the specific activities of the enzymes ornithine decarboxylase (EC 4.1.1.17), putrescine N-methyltransferase (EC 2.1.1.53) and N-methylputrescine oxidase were determined. Both the metabolite pools and the enzyme activities were correlated with the different nicotine-producing capacities of the different tobacco species.