Invasive grasses,climate change,and exposure to storm‐wave overtopping in coastal dune ecosystems

The world's coastal habitats are critical to human well‐being, but are also highly sensitive to human habitat alterations and climate change. In particular, global climate is increasing sea levels and potentially altering storm intensities, which may result in increased risk of flooding in coastal areas. In the Pacific Northwest (USA), coastal dunes that protect the coast from flooding are largely the product of a grass introduced from Europe over a century ago (Ammophila arenaria). An introduced congener (A. breviligulata) is displacing A. arenaria and reducing dune height. Here we quantify the relative exposure to storm‐wave induced dune overtopping posed by the A. breviligulata invasion in the face of projected multi‐decadal changes in sea level and storm intensity. In our models, altered storm intensity was the largest driver of overtopping extent, however the invasion by A. breviligulata tripled the number of areas vulnerable to overtopping and posed a fourfold larger exposure than sea‐level rise over multi‐decadal time scales. Our work demonstrates the importance of a transdisciplinary approach that draws on insights from ecology, geomorphology, and civil engineering to assess the vulnerability of ecosystem services in light of global change.     

Joint Probability Analysis of Extreme Precipitation and Storm Tide in a Coastal City under Changing Environment

Catastrophic flooding resulting from extreme meteorological events has occurred more frequently and drawn great attention in recent years in China. In coastal areas, extreme precipitation and storm tide are both inducing factors of flooding and therefore their joint probability would be critical to determine the flooding risk. The impact of storm tide or changing environment on flooding is ignored or underestimated in the design of drainage systems of today in coastal areas in China. This paper investigates the joint probability of extreme precipitation and storm tide and its change using copula-based models in Fuzhou City. The change point at the year of 1984 detected by Mann-Kendall and Pettitt’s tests divides the extreme precipitation series into two subsequences. For each subsequence the probability of the joint behavior of extreme precipitation and storm tide is estimated by the optimal copula. Results show that the joint probability has increased by more than 300% on average after 1984 (α = 0.05). The design joint return period (RP) of extreme precipitation and storm tide is estimated to propose a design standard for future flooding preparedness. For a combination of extreme precipitation and storm tide, the design joint RP has become smaller than before. It implies that flooding would happen more often after 1984, which corresponds with the observation. The study would facilitate understanding the change of flood risk and proposing the adaption measures for coastal areas under a changing environment.     

An integrated model of real estate market responses to coastal flooding

Understanding and improving how humans adapt to climate change are priorities in our research community, and coastal settlements are good places to study adaptation. Severe storm events and sea‐level rise are threatening coastal communities with increasing levels of flood damage. Because ownership of coastal assets is distributed among many private and public actors, both individual property owners and public officials must take adaptive actions. This paper introduces an integrated agent‐based and hedonic pricing modeling system to simulate coastal real estate market performance under non‐equilibrium conditions that reflect the effects of storm events. The modeling system, which is used for policy analysis, is calibrated to conditions in two towns in Monmouth County, New Jersey, USA, which were badly damaged by Hurricane Sandy in 2012. The key findings are that (a) coastal real estate markets capitalize flood risk into property values but this discount diminishes rapidly as time passes between storm events, and (b) there is a distinct equity versus efficiency tradeoff in designing public policies to reduce the cost to society of coastal flooding. Stringent regulation of building practices reduces flood damage but drives away poorer home buyers and owners, whereas informational and incentive‐based policies are fairer but less effective. Hands‐off, market‐based retreat from risky areas is socially costly but allows less wealthy people to remain at the shore, albeit in vulnerable situations. Managed retreat should emphasize improved recreational access to coastal amenities while discouraging people from living there.     

Flooding regimes increase avian predation on wildlife prey in tidal marsh ecosystems

Within isolated and fragmented populations, species interactions such as predation can cause shifts in community structure and demographics in tidal marsh ecosystems. It is critical to incorporate species interactions into our understanding when evaluating the effects of sea‐level rise and storm surges on tidal marshes. In this study, we hypothesize that avian predators will increase their presence and hunting activities during high tides when increased inundation makes their prey more vulnerable. We present evidence that there is a relationship between tidal inundation depth and time of day on the presence, abundance, and behavior of avian predators. We introduce predation pressure as a combined probability of predator presence related to water level. Focal surveys were conducted at four tidal marshes in the San Francisco Bay, California where tidal inundation patterns were monitored across 6 months of the winter. Sixteen avian predator species were observed. During high tide at Tolay Slough marsh, ardeids had a 29‐fold increase in capture attempts and 4 times greater apparent success rate compared with low tide. Significantly fewer raptors and ardeids were found on low tides than on high tides across all sites. There were more raptors in December and January and more ardeids in January than in other months. Ardeids were more prevalent in the morning, while raptors did not exhibit a significant response to time of day. Modeling results showed that raptors had a unimodal response to water level with a peak at 0.5 m over the marsh platform, while ardeids had an increasing response with water level. We found that predation pressure is related to flooding of the marsh surface, and short‐term increases in sea levels from high astronomical tides, sea‐level rise, and storm surges increase vulnerability of tidal marsh wildlife.     

Incorporating DEM Uncertainty in Coastal Inundation Mapping

Coastal managers require reliable spatial data on the extent and timing of potential coastal inundation, particularly in a changing climate. Most sea level rise (SLR) vulnerability assessments are undertaken using the easily implemented bathtub approach, where areas adjacent to the sea and below a given elevation are mapped using a deterministic line dividing potentially inundated from dry areas. This method only requires elevation data usually in the form of a digital elevation model (DEM). However, inherent errors in the DEM and spatial analysis of the bathtub model propagate into the inundation mapping. The aim of this study was to assess the impacts of spatially variable and spatially correlated elevation errors in high-spatial resolution DEMs for mapping coastal inundation. Elevation errors were best modelled using regression-kriging. This geostatistical model takes the spatial correlation in elevation errors into account, which has a significant impact on analyses that include spatial interactions, such as inundation modelling. The spatial variability of elevation errors was partially explained by land cover and terrain variables. Elevation errors were simulated using sequential Gaussian simulation, a Monte Carlo probabilistic approach. 1,000 error simulations were added to the original DEM and reclassified using a hydrologically correct bathtub method. The probability of inundation to a scenario combining a 1 in 100 year storm event over a 1 m SLR was calculated by counting the proportion of times from the 1,000 simulations that a location was inundated. This probabilistic approach can be used in a risk-aversive decision making process by planning for scenarios with different probabilities of occurrence. For example, results showed that when considering a 1% probability exceedance, the inundated area was approximately 11% larger than mapped using the deterministic bathtub approach. The probabilistic approach provides visually intuitive maps that convey uncertainties inherent to spatial data and analysis.     

滨海湿地消浪服务空间分布特征——以上海市崇明岛为例

全球气候变化增加了滨海地区遭受侵蚀、风暴潮等灾害的风险,利用自然湿地的消浪功能增强海岸防护是当前研究的热点,但目前对消浪服务的空间分布评估研究相对匮乏。以上海市崇明岛环岛滨海湿地为例,结合GIS与Kobayashi指数形式波高衰减模型评估常规状态下湿地消浪服务的空间分布特征。结果显示,大、小潮升条件下,崇明环岛湿地消波的平均高度分别为0.94、0.54 m与效度分别为83.6%、60.4%,消波高度的空间分布表现为南岸小于北岸,消波效度的空间分布在小潮升时与消波高度相似,而大潮升时南岸的消波效度有明显提升。物理环境与生物因素空间分布及其相互作用的异质性,导致消浪服务的空间分布也具有空间异质性。实际参与消波的断面宽度与不同景观消波服务的评估结果表明,一个断面的所有景观并非都参与到消浪过程中,即使在大潮升时期,不同岸段景观的平均参与度不足71%。潮高与波高的增加并不会使参与消波的景观规模成对应比例的增加,说明消波服务在空间上具有明显的非线性特征。研究可为滨海湿地生态修复空间规划、基于生态系统的海岸带管理、自然资本核算提供科技支撑。     

High‐resolution tide projections reveal extinction threshold in response to sea‐level rise

Sea‐level rise will affect coastal species worldwide, but models that aim to predict these effects are typically based on simple measures of sea level that do not capture its inherent complexity, especially variation over timescales shorter than 1 year. Coastal species might be most affected, however, by floods that exceed a critical threshold. The frequency and duration of such floods may be more important to population dynamics than mean measures of sea level. In particular, the potential for changes in the frequency and duration of flooding events to result in nonlinear population responses or biological thresholds merits further research, but may require that models incorporate greater resolution in sea level than is typically used. We created population simulations for a threatened songbird, the saltmarsh sparrow (Ammodramus caudacutus), in a region where sea level is predictable with high accuracy and precision. We show that incorporating the timing of semidiurnal high tide events throughout the breeding season, including how this timing is affected by mean sea‐level rise, predicts a reproductive threshold that is likely to cause a rapid demographic shift. This shift is likely to threaten the persistence of saltmarsh sparrows beyond 2060 and could cause extinction as soon as 2035. Neither extinction date nor the population trajectory was sensitive to the emissions scenarios underlying sea‐level projections, as most of the population decline occurred before scenarios diverge. Our results suggest that the variation and complexity of climate‐driven variables could be important for understanding the potential responses of coastal species to sea‐level rise, especially for species that rely on coastal areas for reproduction.     

Sensitivity of mangrove soil organic matter decay to warming and sea level change

Mangroves are among the world's most carbon‐dense ecosystems, but they are threatened by rapid climate change and rising sea levels. The accumulation and decomposition of soil organic matter (SOM) are closely tied to mangroves' carbon sink functions and resistance to rising sea levels. However, few studies have investigated the response of mangrove SOM dynamics to likely future environmental conditions. We quantified how mangrove SOM decay is affected by predicted global warming (+4°C), sea level changes (simulated by altering of the inundation duration to 0, 2, and 6 hr/day), and their interaction. Whilst changes in inundation duration between 2 and 6 hr/day did not affect SOM decay, the treatment without inundation led to a 60% increase. A warming of 4°C caused SOM decay to increase by 21%, but longer inundation moderated this temperature‐driven increase. Our results indicate that (a) sea level rise is unlikely to decrease the SOM decay rate, suggesting that previous mangrove elevation gain, which has allowed mangroves to persist in areas of sea level rise, might result from changes in root production and/or mineral sedimentation; (b) sea level fall events, predicted to double in frequency and area, will cause periods of intensified SOM decay; (c) changing tidal regimes in mangroves due to sea level rise might attenuate increases in SOM decay caused by global warming. Our results have important implications for forecasting mangrove carbon dynamics and the persistence of mangroves and other coastal wetlands under future scenarios of climate change.     

Effect of salinity-altering pulsing events on soil organic carbon loss along an intertidal wetland gradient: a laboratory experiment

Salinity changes resulting from storm surge, tides, precipitation, and stormwater run-off are common in coastal wetlands. Soil microbial communities respond quickly to salinity changes, altering the rate of soil organic carbon (SOC) loss and associated biogeochemical processes. This study quantified the impact of salinity-altering pulses on SOC loss, defined as microbial respiration (CO₂ flux) at high and low tide, CH₄ flux, and dissolved OC (DOC) release, in 3 intertidal wetlands (Jacksonville, FL, USA). Intact soil cores from a freshwater tidal, brackish, and salt marsh were exposed to simulated tides and 3 salinity pulsing events during a 53-day laboratory experiment. Soil and water physio-chemical properties, nutrient release, and microbial indicators were measured. Microbial respiration was the dominate pathway of SOC loss (>97 %). Soil hydraulic conductivity was greater in brackish and salt marshes and was critical to overall soil respiration. High tide CO₂ flux was greatest in the freshwater marsh (58 % of SOC loss) and positively correlated with DOC concentration; low tide CO₂ flux was greatest in brackish and salt marshes (62 and 70 % of SOC loss, respectively) and correlated with NH₄ ⁺ and microbial biomass. The freshwater marsh was sensitive to brackish pulses, causing a 112 % increase in respiration, presumably from accelerated sulfate reduction and N-cycling. SOC loss increased in the salt marsh pulsed with freshwater, suggesting freshwater run-off may reduce a salt marsh’s ability to keep-pace with sea level rise. Increased inundation from storm surges could accelerate SOC loss in freshwater marshes, while decreasing SOC loss in brackish and salt marshes.     

基于土地利用变化情景的城市暴雨洪涝灾害风险评估——以深圳市茅洲河流域为例

近年来频发的暴雨洪涝成为威胁城市可持续发展的主要灾害类型,而土地利用变化改变了区域原有的景观结构和水文过程,是城市暴雨洪涝灾害风险加剧的重要诱因,定量探讨土地利用变化对暴雨洪涝灾害及其风险影响具有重要意义。以深圳市茅洲河流域为例,基于CLUE-S模型、SCS模型及等体积淹没算法等,对12种暴雨洪涝致灾-土地利用承灾情景下的城市暴雨洪涝灾害风险进行定量模拟。研究结果显示,相同土地利用空间格局下城市暴雨洪涝灾害随暴雨致灾危险性增加风险加剧显著;在同等致灾危险性水平下随建设用地面积增加,中等风险和高风险区面积均呈现较为明显的增加趋势,中、高风险区面积与建设用地面积的增加率表现出较高的协同变化特征;以50年遇危险性水平为例,随着建设用地面积由基期的15368.85hm~2增加至近期16076.07hm~2和远期16750.89hm~2,高风险区面积由254.07hm~2增加至276.48hm~2和286.2hm~2。由此可见,尽管暴雨强度的增加是城市暴雨洪涝灾害风险加剧的根本诱因,但是以建设用地面积增加为表征的土地利用变化对暴雨洪涝灾害风险的影响不容忽视。     

Can Humic Water Discharge Counteract Eutrophication in Coastal Waters?

A common and established view is that increased inputs of nutrients to the sea, for example via river flooding, will cause eutrophication and phytoplankton blooms in coastal areas. We here show that this concept may be questioned in certain scenarios. Climate change has been predicted to cause increased inflow of freshwater to coastal areas in northern Europe. River waters in these areas are often brown from the presence of high concentrations of allochthonous dissolved organic carbon (humic carbon), in addition to nitrogen and phosphorus. In this study we investigated whether increased inputs of humic carbon can change the structure and production of the pelagic food web in the recipient seawater. In a mesocosm experiment unfiltered seawater from the northern Baltic Sea was fertilized with inorganic nutrients and humic carbon (CNP), and only with inorganic nutrients (NP). The system responded differently to the humic carbon addition. In NP treatments bacterial, phytoplankton and zooplankton production increased and the systems turned net autotrophic, whereas the CNP-treatment only bacterial and zooplankton production increased driving the system to net heterotrophy. The size-structure of the food web showed large variations in the different treatments. In the enriched NP treatments the phytoplankton community was dominated by filamentous >20 µm algae, while in the CNP treatments the phytoplankton was dominated by picocyanobacteria <5 µm. Our results suggest that climate change scenarios, resulting in increased humic-rich river inflow, may counteract eutrophication in coastal waters, leading to a promotion of the microbial food web and other heterotrophic organisms, driving the recipient coastal waters to net-heterotrophy.     

PCR detection of pathogenic viruses in southern California urban rivers

AIMS: To investigate human viral contamination in urban rivers and its impact on coastal waters of southern California, USA. METHODS AND RESULTS: Three types of human viruses (adeno, entero and hepatitis A) were detected using nested- and RT-PCR from 11 rivers and creeks. Faecal indicator bacteria as well as somatic and F-specific coliphage were also tested. Approximately 50% of the sites were positive for human adenoviruses. However, there was no clear relationship between detection of human viruses and the concentration of indicator bacteria and coliphage. Both faecal indicator bacteria and human viral input at beaches near river mouths were associated with storm events. The first storm of the wet season seemed to have the greatest impact on the quality of coastal water than following storm events. CONCLUSIONS: This study provides the first direct evidence that human viruses are prevalent in southern California urban rivers. Urban run-off impacts coastal water quality most significantly during the storm season. SIGNIFICANCE AND IMPACT OF THE STUDY: To protect human health during water recreational activities, it is necessary to develop effective strategies to manage urban run-off during storm events.     

On the Relationship Between Sea Level and Spartina alterniflora Production

A positive relationship between interannual sea level and plant growth is thought to stabilize many coastal landforms responding to accelerating rates of sea level rise. Numerical models of delta growth, tidal channel network evolution, and ecosystem resilience incorporate a hump-shaped relationship between inundation and plant primary production, where vegetation growth increases with sea level up to an optimum water depth or inundation frequency. In contrast, we use decade-long measurements of Spartina alterniflora biomass in seven coastal Virginia (USA) marshes to demonstrate that interannual sea level is rarely a primary determinant of vegetation growth. Although we find tepid support for a hump-shaped relationship between aboveground production and inundation when marshes of different elevation are considered, our results suggest that marshes high in the intertidal zone and low in relief are unresponsive to sea level fluctuations. We suggest existing models are unable to capture the behavior of wetlands in these portions of the landscape, and may underestimate their vulnerability to sea level rise because sea level rise will not be accompanied by enhanced plant growth and resultant sediment accumulation.     

Circatidal rhythmic behaviour in the coastal tiger beetle Callytron inspecularis in Japan

Larvae of the coastal tiger beetle Callytron inspecularis (W. Horn) (Coleoptera: Cicindelidae) plug their burrow opening before submergence at high tide. Field observations showed that burrow plugging was a rhythmic behaviour that coincided with the tidal cycle (ca. 12.4 h). On average, larvae plugged their burrows 41.8 min before the tide covered the habitat. The mean interval between consecutive burrow-plugging events in the field was 12.40 h. In the laboratory, in the absence of tidal inundation, the mean interval between consecutive burrow-plugging events was 12.45 h. This suggests that the burrow-plugging rhythm of the coastal tiger beetle is governed by an endogenous circatidal rhythm.     

Ichthyoplankton transport in relation to floodplain width and inundation and tributary creek discharge in the lower Savannah River of Georgia and South Carolina

We report the results of a 3-year study of ichthyoplankton in the lower Savannah River and its coastal plain tributaries. Sampling was weekly from February through July in 1983, 1984 and 1985. Ichthyoplankton transport was used as an estimate of ichthyoplankton production. Ichthyoplankton transport in the river, for both total and most common taxa, was highest in 1983 and lowest in 1985. Ichthyoplankton transport into the river from tributary streams was also highest in 1983 and lowest in 1985. Ichthyoplankton transported from these tributaries sometimes comprised a significant percent of the larval transport at the next river station downstream from the tributary mouth. The highest larval transport occurred when the spring flood pulse was most elevated for the longest time, and larval transport at particular river stations or creeks was correlated with floodplain width in 1983 and 1984, years when flood pulses were high enough so that the adjacent floodplain was inundated during or following spawning. In 1985 the flood pulse was brief, inundation levels were low, and inundation occurred in February before most fish had spawned. Except for American shad and sunfishes, larval transport for all common taxa was greatly reduced in 1985 compared to 1983.     

Two mechanisms of aquatic and terrestrial habitat change along an Alaskan Arctic coastline

Arctic habitats at the interface between land and sea are particularly vulnerable to climate change. The northern Teshekpuk Lake Special Area (N-TLSA), a coastal plain ecosystem along the Beaufort Sea in northern Alaska, provides habitat for migratory waterbirds, caribou, and potentially, denning polar bears. The 60-km coastline of N-TLSA is experiencing increasing rates of coastline erosion and storm surge flooding far inland resulting in lake drainage and conversion of freshwater lakes to estuaries. These physical mechanisms are affecting upland tundra as well. To better understand how these processes are affecting habitat, we analyzed long-term observational records coupled with recent short-term monitoring. Nearly the entire coastline has accelerating rates of erosion ranging from 6 m/year from 1955 to 1979 and most recently peaking at 17 m/year from 2007 to 2009, yet an intensive monitoring site along a higher bluff (3–6 masl) suggested high interannual variability. The frequency and magnitude of storm events appears to be increasing along this coastline and these patterns correspond to a greater number of lake tapping and flooding events since 2000. For the entire N-TLSA, we estimate that 6% of the landscape consists of salt-burned tundra, while 41% is prone to storm surge flooding. This offset may indicate the relative frequency of low-magnitude flood events along the coastal fringe. Monitoring of coastline lakes confirms that moderate westerly storms create extensive flooding, while easterly storms have negligible effects on lakes and low-lying tundra. This study of two interacting physical mechanisms, coastal erosion and storm surge flooding, provides an important example of the complexities and data needs for predicting habitat change and biological responses along Arctic land–ocean interfaces.     

Extreme storms cause rapid but short-lived shifts in nearshore subtropical bacterial communities

Climate change scenarios predict tropical cyclones will increase in both frequency and intensity, which will escalate the amount of terrestrial run-off and mechanical disruption affecting coastal ecosystems. Bacteria are key contributors to ecosystem functioning, but relatively little is known about how they respond to extreme storm events, particularly in nearshore subtropical regions. In this study, we combine field observations and mesocosm experiments to assess bacterial community dynamics and changes in physicochemical properties during early- and late-season tropical cyclones affecting Okinawa, Japan. Storms caused large and fast influxes of freshwater and terrestrial sediment – locally known as red soil pollution – and caused moderate increases of macronutrients, especially SiO₂ and PO₄³⁻, with up to 25 and 0.5 μM respectively. We detected shifts in relative abundances of marine and terrestrially derived bacteria, including putative coral and human pathogens, during storm events. Soil input alone did not substantially affect marine bacterial communities in mesocosms, indicating that other components of run-off or other storm effects likely exert a larger influence on bacterial communities. The storm effects were short-lived and bacterial communities quickly recovered following both storm events. The early- and late-season storms caused different physicochemical and bacterial community changes, demonstrating the context-dependency of extreme storm responses in a subtropical coastal ecosystem.     

Uncommon southwest swells trigger sea urchin disease outbreaks in Eastern Atlantic archipelagos

Recurrent sea urchin mass mortality has recently affected eastern Atlantic populations of the barren‐forming sea urchin Diadema africanum. This new episode of die‐off affords the opportunity to determine common meteorological and oceanographic conditions that may promote disease outbreaks. The population dynamics of this sea urchin species are well known—urchin barrens have persisted for many decades along most of the coastlines off the archipelagos of Madeira, Selvages, and the Canary Islands, where they limit macroalgae biomass growth. However, this new and explosive mortality event decimated the sea urchin population by 93% on Tenerife and La Palma Islands. Two severe episodes of southwestern rough sea that led to winter storms, in February 2010 (Xynthia) and February 2018 (Emma), preceded both mass mortality events. The autumn and winter months of those years were anomalous and characterized by swells with an average wave height above 2 m that hit the south and southwest sides of the islands. The amoeba Paramoeba brachiphila was the only pathogen isolated this time from the moribund and dead sea urchins, suggesting that the amoeba was the primary cause of the mortality. This new sea urchin die‐off event supports the “killer‐storm” hypothesis that has been already described for western Atlantic coasts. These anomalous southwest storms during winters generate pronounced underwater sediment movement and large‐scale vertical mixing, detected in local tide gauge, which may promote paramoebiasis. This study presents valuable insights about climate‐mediated changes in disease frequency and its impacts on the future of coastal marine ecosystems in the Atlantic.     

Mangrove response to environmental change in Australia's Gulf of Carpentaria

Across their range, mangroves are responding to coastal environmental change. However, separating the influence of human activities from natural events and processes (including that associated with climatic fluctuation) is often difficult. In the Gulf of Carpentaria, northern Australia (Leichhardt, Nicholson, Mornington Inlet, and Flinders River catchments), changes in mangroves are assumed to be the result of natural drivers as human impacts are minimal. By comparing classifications from time series of Landsat sensor data for the period 1987–2014, mangroves were observed to have extended seawards by up to 1.9 km (perpendicular to the coastline), with inland intrusion occurring along many of the rivers and rivulets in the tidal reaches. Seaward expansion was particularly evident near the mouth of the Leichhardt River, and was associated with peaks in river discharge with LiDAR data indicating distinct structural zones developing following each large rainfall and discharge event. However, along the Gulf coast, and particularly within the Mornington Inlet catchment, the expansion was more gradual and linked to inundation and regular sediment supply through freshwater input. Landward expansion along the Mornington Inlet catchment was attributed to the combined effects of sea level rise and prolonged periods of tidal and freshwater inundation on coastal lowlands. The study concluded that increased amounts of rainfall and associated flooding and sea level rise were responsible for recent seaward and landward extension of mangroves in this region.     

Implications of global climatic change and energy cost and availability for the restoration of the Mississippi delta

Over the past several thousand years, inputs from the Mississippi River formed the Mississippi delta, an area of about 25,000 km². Over the past century, however, there has been a high loss of coastal wetlands of about 4800 km². The main causes of this loss are the near complete isolation of the river from the delta, mostly due to the construction of flood control levees, and pervasive hydrological disruption of the deltaic plain. There is presently a large-scale State-Federal program to restore the delta that includes construction of water control structures in the flood control levees to divert river water into deteriorating wetlands and pumping of dredged sediment, often for long distances, for marsh creation. Global climate change and decreasing availability and increasing cost of energy are likely to have important implications for delta restoration. Coastal restoration efforts will have to be more intensive to offset the impacts of climate change including accelerated sea level rise and changes in precipitation patterns. Future coastal restoration efforts should also focus on less energy-intensive, ecologically engineered management techniques that use the energies of nature as much as possible. Diversions may be as important for controlling salinity as for providing sediments and nutrients for restoring coastal wetlands. Energy-intensive pumping-dredged sediments for coastal restoration will likely become much more expensive in the future.