Habitat quality of estuarine nursery grounds: Integrating non-biological indicators and multilevel biological responses in Solea senegalensis

Estuaries are highly valuable ecosystems that provide various goods and services to society, such as food provision and supporting nursery habitats for various aquatic species. Estuarine habitat quality assessment is thus critical in managing both ecological and economic value. In this work, various biological and non-biological indicators of habitat quality in estuarine nursery areas were determined, encompassing local environmental conditions, chemical contamination, anthropogenic pressures, juvenile Solea senegalensis condition, biomarkers response to contamination and juvenile density. The various indicators provided an integrated view on habitat quality and their responses were broadly concordant. Nursery quality assessment based on anthropogenic pressure indicators and fish biomarker responses were very similar, signaling nursery areas with higher anthropogenic pressure in Tejo and Ria de Aveiro estuaries. Yet, favorable environmental conditions across all sites could have contributed to lessen the potential hazardous biological effects of exposure to anthropogenic stressors, resulting in soles’ fairly good condition and generally high juvenile density. Nevertheless, a mismatch between high juvenile density and high estuarine contribution to adult coastal populations was observed in areas with higher anthropogenic pressures. Although a causal relationship cannot be established, the results emphasize the need to fully understand how the estuarine period spent in estuaries and local processes determine the quantity and quality of juveniles exported to marine adult populations, which is critical to achieve the full potential of the fish production service of estuaries and coastal stock replenishment.     

Site-Specific Structural Variations Accompanying Tubular Assembly of the HIV-1 Capsid Protein

The 231-residue capsid (CA) protein of human immunodeficiency virus type 1 (HIV-1) spontaneously self-assembles into tubes with a hexagonal lattice that is believed to mimic the surface lattice of conical capsid cores within intact virions. We report the results of solid-state nuclear magnetic resonance (NMR) measurements on HIV-1 CA tubes that provide new information regarding changes in molecular structure that accompany CA self-assembly, local dynamics within CA tubes, and possible mechanisms for the generation of lattice curvature. This information is contained in site-specific assignments of signals in two- and three-dimensional solid-state NMR spectra, conformation-dependent ¹⁵N and ¹³C NMR chemical shifts, detection of highly dynamic residues under solution NMR conditions, measurements of local variations in transverse spin relaxation rates of amide ¹H nuclei, and quantitative measurements of site-specific ¹⁵N–¹⁵N dipole–dipole couplings. Our data show that most of the CA sequence is conformationally ordered and relatively rigid in tubular assemblies and that structures of the N-terminal domain (NTD) and the C-terminal domain (CTD) observed in solution are largely retained. However, specific segments, including the N-terminal β-hairpin, the cyclophilin A binding loop, the inter-domain linker, segments involved in intermolecular NTD–CTD interactions, and the C-terminal tail, have substantial static or dynamical disorder in tubular assemblies. Other segments, including the 3₁₀-helical segment in CTD, undergo clear conformational changes. Structural variations associated with curvature of the CA lattice appear to be localized in the inter-domain linker and intermolecular NTD–CTD interface, while structural variations within NTD hexamers, around local 3-fold symmetry axes, and in CTD–CTD dimerization interfaces are less significant.     

Spatial metrics for detecting ecosystem degradation in the ridge-slough patterned landscape

Indicators of landscape condition should be selected based on their sensitivity to environmental changes and their capacity to provide early warning detection of those changes. We assessed the performance of a suite of spatial-pattern metrics selected to quantify the condition of the ridge-slough landscape in the Everglades (South Florida, USA). Spatial pattern metrics (n = 14) that describe landscape composition, geometry and hydrologic connectivity were enumerated from vegetation maps of twenty-five 2 × 2 km primary sampling units (PSUs) that span a gradient of hydrologic and ecological condition across the greater Everglades ecosystem. Metrics were assessed in comparison with field measurements from each PSU of landscape condition obtained from regional surveys of soil elevation, which have previously been shown to capture dramatic differences between conserved and degraded locations. Elevation-based measures of landscape condition included soil elevation bi-modality (BI_SE), a binary measure of landscape condition, and also the standard deviation of soil elevation (SD_SE), a continuous measure of condition. Metric performance was assessed based on the strength (sensitivity) and shape (leading vs. lagging) of the relationship between spatial pattern metrics and these elevation-based measures. We observed significant logistic regression slopes with BI_SE for only 4 metrics (slough width, ridge density, directional connectivity index – DCI, and least flow cost – LFC). More significant relationships (n = 8 metrics) were observed with SD_SE, with the strongest associations for slough density, mean ridge width, and the average length of straight flow, as well as for a suite of hydrologic connectivity metrics (DCI, LFC and landscape discharge competence – LDC). Leading vs. lagging performance, inferred from the curvature of the association obtained from the exponent of fitted power functions, suggest that only DCI was a leading metric of the loss of soil elevation variation; most metrics were indeterminate, though some were clearly lagging. Our findings support the contention that soil elevation changes from altered peat accretion dynamics precede changes in landscape pattern, and offer insights that will enable efficient monitoring of the ridge-slough landscape as part of the ongoing Everglades restoration effort.     

The use of ecological integrity indicators within the natural capital index framework: The ecological and economic value of the remnant natural capital of México

In this paper, the ecological integrity hierarchy framework (EIHF) and the natural capital index framework (NCI) are integrated as decision-making tools for evaluating the natural capital of Mexico. Two hierarchy-levels of ecological integrity indicators are used to estimate the quality and quantity of the natural capital, the amount of ecological degradation and ecological sustainability. After human transformation, the extent still considered as “natural” in the country is ∼67%; while the amount of human transformed areas is ∼33%, which gives a total estimate of NCI = 0.334; i.e., only ∼33.4% of the national capital remains available, while ∼33% is ecologically degraded. Furthermore, the critical natural capital; i.e., the legacy for future generations that remains in the country is only ∼12%. The total estimated value of the current natural capital in Mexico is ∼$457.1 billion/yr, which is ∼435 times greater than the national GDP ($1.051 billion in 2010). The cost of maintaining the degradation of the natural capital is ∼$144.6 billion/yr (∼138 times greater than national GDP in 2010). The potential value of the natural capital after restoration would be ∼$602 billion/yr. Valuing the natural capital can be helpful for strategic environmental evaluations and useful for spatial decision support systems that evaluate natural capital as a decision-making tool.     

Tree-rings,a key ecological indicator of environment and climate change

Due to wide spatial distribution, high annual resolution, calendar-exact dating, and high climate sensitivity, tree-rings play an important role in reconstructing past environment and climate change over the past millennium at regional, hemispheric or even global scales, so tree-rings can help us to better understand climate behaviour and its mechanisms in the past and then predict variation trends for the future. In this paper, we will review latest advances in tree-ring-based climate reconstructions in China and their applications in modelling past local/regional climate change, capturing historical climatic extreme events, as well as analyzing their link to large-scale climate patterns.     

基于多尺度协同的长沙市生态网络构建与层级优化

城市化背景下人类与自然环境的矛盾呈现出多尺度、层级化特征，而传统生态网络的构建方式较少考虑不同尺度下生态要素的关系，无法从区域落实到中心城区，难以形成系统性的解决方案。研究在综合梳理各尺度生态网络构建方法的基础上，以长沙市为例，基于形态学空间格局分析（Morphological Spatial Pattern Analysis，MSPA）、景观连通性原理和生态斑块重要性评价识别生态源地，并通过多层级生态阻力面的确定，综合运用最小费用路径（Least-cost path method，LCP）、电路理论、层级传导理论、尺度嵌套等方法对市域、都市区、中心城区的生态网络进行了协同构建和层级优化，最后基于不同尺度生态网络的特点应用并落实到多层级的国土空间规划体系中。研究结果表明：（1）长沙市域生态网络和都市区生态网络具有较好的层级嵌套特征；共识别两尺度生态叠合源地14个、生态叠合廊道15条，主要通过中心城区内的湘江、浏阳河和捞刀河部分河段与外围生态绿圈相衔接，形成"外环内楔"的空间格局。（2）确定市域重要廊道、市域潜在廊道、生态叠合廊道、都市区重要廊道、都市区潜在廊道的核心保护面积共501.14 km²，并提取位于生态廊道核心保护区范围内的生态夹点和生态障碍点，以进一步落实生态保护修复策略。（3）得到具有重要生态连通功能的中心城区生态绿道长度441.2 km，生态修复单元56个，并结合生态阻力值划分为5级进行针对性修复。（4）基于不同尺度生态网络的衔接、嵌套，最终构建"市域总体生态安全格局-都市区城市生态空间发展格局-以城市绿道为基础的中心城区生态修复单元"，并与不同层级的国土空间规划体系相对应。研究结果将为以大城市为中心的跨尺度生态系统修复和生态安全格局构建提供科学参考。