Investigating dune-building feedback at the plant level: Insights from a multispecies field experiment

Coastal foredunes provide the first line of defense against rising sea levels and storm surge and for this reason there is increasing interest in understanding and modeling foredune formation and post-storm recovery. However, there is limited observational data available to provide empirical guidance for the development of model parameterizations. To provide guidance for improved representation of dune grass growth in models, we conducted a two-year multi-species transplant experiment on Hog Island, VA, U.S.A. and measured the dependence of plant growth on elevation and distance from the shoreline, as well as the relationship between plant growth and sand accumulation. We tracked total leaf growth (length) and aboveground leaf length and found that Ammophila breviligulata (American beachgrass) and Uniola paniculata (sea oats) grew more than Spartina patens (saltmeadow cordgrass) by a factor of 15% (though not statistically significant) and 45%, respectively. Our results also suggest a range of basal/frontal area ratios (an important model parameter) from 0.5-1 and a strong correlation between transplant growth and total sand deposition for all species at the scale of two years, but not over shorter temporal scales. Distance from the shoreline and elevation had no effect on transplant growth rate but did have an effect on survival. Based on transplant survival, the seaward limit of vegetation at the end of the experiment was approximately 30 m from the MHWL and at an elevation of 1.43 m, corresponding to inundation less than 7.5% of the time according to total water level calculations. Results from this experiment provide evidence for the dune-building capacity of all three species, suggesting S. patens is not a maintainer species, as previously thought, but rather a moderate dune builder even though its growth is less stimulated by sand deposition than A. breviligulata and U. paniculata. © 2019 John Wiley & Sons, Ltd.     

Are seagrass beds indicators of anthropogenic nutrient stress in the rocky intertidal?

It is well established that anthropogenic nutrient inputs harm estuarine seagrasses, but the influence of nutrients in rocky intertidal ecosystems is less clear. In this study, we investigated the effect of anthropogenic nutrient loading on Phyllospadix spp., a rocky intertidal seagrass, at local and regional scales. At sites along California, Washington, and Oregon, we demonstrated a significant, negative correlation of urban development and Phyllospadix bed thickness. These results were echoed locally along an urban gradient on the central California coast, where Phyllospadix shoot δ¹⁵N was negatively associated with Phyllospadix bed thickness, and experimentally, where nutrient additions in mesocosms reduced Phyllospadix shoot formation and increased epiphytic cover on Phyllospadix shoots. These findings provide evidence that coastal development can threaten rocky intertidal seagrasses through increased epiphytism. Considering that seagrasses provide vital ecosystem services, mitigating eutrophication and other factors associated with development in the rocky intertidal coastal zone should be a management priority.     

汕头海岸湿地示范区的环境综合管理

汕头海岸湿地由于丰富的生物多样性以及突出的人地矛盾,被联合国环境署和全球环境基金资助的"扭转南海和泰国湾的环境退化趋势"项目确定为湿地示范区。本文在对汕头海岸湿地示范区的海岸环境现状、威胁、现有管理框架进行深入分析的基础上,采用因果链分析的方法,构建了跨部门的社区参与的综合管理模式,拟通过实施综合管理,实现汕头海岸湿地的可持续发展。     

Development and application of a remote sensing-based salinity prediction model for a large estuarine lake in the US Gulf of Mexico coast

Salinity in estuaries is highly variable due to river discharge, tidal motion, and winds. Information on the spatial and temporal changes in salinity can provide important ecological indications, but accurate monitoring of the space–time variability for a large estuary is often costly and time-consuming. This study applied remote sensing techniques to develop a salinity prediction model for Lake Pontchartrain, a large estuarine lake located in the Northern Gulf of Mexico, USA. “Ground truth” salinity was measured along two transects across the lake and near the shoreline. Water-leaving reflectance from the measurement locations was extracted from Landsat Thematic Mapper (TM) images pre-processed through “banding” noise reduction and radiometrical correction approaches. Ordinary least square and ridge regression methods were performed to identify model parameters and to determine relationships between salinity and reflectance. Salinity in the lake on eight dates was predicted with the developed model. Difference in salinity level and patterns, and impacts of Hurricanes Katrina and Rita on salinity were assessed with ANOVA and Fuzzy Similarity methods. The results showed that the model achieved a high power in prediction of the lake salinity (R² = 0.89 and RMSE of validation = 0.27). Reflectance from TM bands 1, 2, and 4 was positively correlated to salinity levels and explained 1.9%, 20.3%, and 10.2% variance in salinity levels. Reflectance from bands 3 and 5 was negatively correlated to salinity and explained 34.1% and 31.2% variance. Under normal circumstances without the impacts of hurricanes, the lake salinity presented two patterns with average salinity level of 5.5 ppt. After Katrina’s landfall, the average was significantly increased by 1.1 ppt and the spatial patterns were altered. The pattern on 30 August 2005 was the most dissimilar one as compared to the two normal patterns, and then followed by the patterns on 9 and 25 October, and 7 September 2005. This study demonstrated that satellite remote sensing techniques can be applied to monitor salinity in coastal environments, and that freshwater discharge not only affects salinity levels and patterns under normal conditions but also is crucial for the return of salinity patterns to normal conditions after hurricane disturbance.     

Hydrogen peroxide production in marine bathing waters: Implications for fecal indicator bacteria mortality

Hydrogen peroxide concentrations [H(2)O(2)] have been measured over the last two decades in multiple studies in surface waters in coastal, estuarine and oceanic systems. Diurnal cycles consistent with a photochemical production process have frequently being observed, with [H(2)O(2)] increasing by two orders of magnitude over the course of the day, from low nM levels in the early morning to 10(2)nM in late afternoon. Production rates range from <10 for off-shore ocean waters to 20-60nMh(-1) for near-shore coastal and estuarine environments. Slow night-time loss rates (<10nMh(-1)) have been attributed to biological and particle mediated processes. Diurnal cycles have also frequently been observed in fecal indicator bacteria (FIB) levels in surf zone waters monitored for microbial water quality. Measured peak peroxide concentrations in surface coastal seawaters are too low to directly cause FIB mortality based on laboratory studies, but likely contribute to oxidative stress and diurnal cycling. Peroxide levels in the surf zone may be increased by additional peroxide production mechanisms such as deposition, sediments and stressed marine biota, further enhancing impacts on FIB in marine bathing waters.     

Long waves dissipation and harmonic generation by coastal vegetation

In this paper, we study the harmonic generation and energy dissipation as water waves propagating through coastal vegetation. Applying the homogenization theory, linear wave models have been developed for a heterogeneous coastal forest in previous works (e.g. [17], [10], [11]). In this study, the weakly nonlinear effects are investigated. The coastal forest is modeled by an array of rigid and vertically surface-piercing cylinders. Assuming monochromatic waves with weak nonlinearity incident upon the forest, higher harmonic waves are expected to be generated and radiated into open water. Using the multi-scale perturbation theory, micro-scale flows in the vicinity of cylinders and macro-scale wave dynamics are separated. Expressing the unknown variables (e.g. velocity, free surface elevation) as a superposition of different harmonic components, the governing equations for each mode are derived while different harmonics are interacting with each other because of nonlinearity in the cell problem. Different from the linear models, the leading-order cell problem for micro-scale flow motion, driven by the macro-scale pressure gradient, is now a nonlinear boundary-value-problem, while the wavelength-scale problem for wave dynamics remains linear. A modified pressure correction method is employed to solve the nonlinear cell problem. An iterative scheme is introduced to connect the micro-scale and macro-scale problems. To demonstrate the theoretical results, we consider incident waves scattered by a homogeneous forest belt in a constant shallow depth. Higher harmonic waves are generated within the cylinder array and radiated out to the open water region. The comparisons of numerical results obtained by linear and nonlinear models are presented and the behavior of different harmonic components is discussed. The effects of different physical parameters on wave solutions are discussed as well.     

我国海岸线退出机制的建立和完善

为加强我国海岸线资源的使用和管理,优化海岸线的开发利用和保护,促进海洋经济和资源环境的可持续发展,文章在概述海岸线退出机制的内涵及其研究和实践进展的基础上,分析该机制的建立和完善。研究结果表明:我国目前尚未形成系统和综合的海岸线退出机制,主要在法律、制度、经济和社会4个方面面临困境;应坚持绿色发展等4项原则,针对擅自改变海岸线用途等6种情形,分别采用强制退出、倒逼退出和协议退出3种模式,建立和实施海岸线退出机制;通过完善法律法规和制度体系、长效运作机制、海岸线资源再配置以及补偿措施,完善海岸线退出机制。     

我国沿海地区重特大海洋动力灾害应对策略研究

我国沿海地区是极端天气和气候事件易发频发区,也是重要的人口和经济聚集地。在全球气候变化背景下,风暴潮、海浪、海冰和海啸等海洋动力灾害的形成机理、发生规律、时空特征、损失程度呈现出新的特点,重特大海洋动力灾害对我国沿海地区造成的威胁不容忽视。文章阐述海洋动力灾害时空分布特征,在分析我国沿海地区应对海洋动力灾害现状基础上,提出我国沿海地区应对重特大海洋动力灾害的对策与建议:建议开展重特大海洋动力灾害防御相关立法研究,制订国家层面应对重特大海洋动力灾害专项应急预案,建立健全重特大海洋动力灾害保险风险补偿机制以及提升重特大海洋动力灾害科技支撑能力。     

基于三维激光扫描技术的人防工事模型重构与应用分析

人防工事狭长且内部环境复杂,对其保护利用需要提供丰富多样的基础资料和成果。三维激光扫描技术突破了传统单点精确测量的局限,可以大面积地获取被测对象表面的三维坐标数据,具有连续、快速、非接触、自动、全天候工作等优势。本文以某段人防工事为例,研究了三维激光扫描的工作流程,并以点云数据为基础进行三维模型的重构和测绘图的制作,完成对点云质量的分析评价。     

The U.K. Marine and Coastal Access Bill—A missed opportunity to enhance protection from marine environmental pollution?

The Marine and Coastal Access Bill, when it becomes law, may well be considered a welcome addition to the legislation protecting the marine coastal environment. It is argued, however, in this paper that the Bill could have addressed a number of issues including the matter of shipowners’ privileges, locus standi, the designation and setting up of an environmental fund, and the difficulties associated with places of refuge for vessels in distress.