中国主要陆地生态系统服务功能与生态安全

生态系统服务是国际生态学研究的前沿和热点,表现出向生态系统服务机理和区域集成方法两大方向发展的趋势.开展陆地生态系统服务研究,是生态系统恢复、生态功能区划和建立生态补偿机制、保障国家生态安全的重大战略需求.面向国家重大需求和生态系统服务研究的国际前沿,以主要陆地生态系统为对象,"中国主要陆地生态系统服务功能与生态安全"项目拟解决3个科学问题:①生态系统结构-过程-服务功能的相互作用机理;②生态系统服务功能的尺度特征与多尺度关联;③生态系统服务功能评估的指标与模型.通过上述研究,发展生态系统服务研究的理论与方法,为国家的生态建设和环境保护提供科学支撑.     

Habitat Restoration from an Ecosystem Goods and Services Perspective: Application of a Spatially Explicit Individual-Based Model

Estuarine ecosystems provide many services to humans, but these ecosystems are also under pressure from human development, which has led to large investments in habitat protection and restoration. Restoration in estuaries is typically focused on emergent and submerged vegetation with the goal of achieving target areal coverage based on historic conditions. Such restoration targets assume no spatial heterogeneity in habitat value and bypass the functional target of restoring or maintaining delivery of ecosystem goods and services (EGS). We have developed a spatially explicit individual-based behavioral model intended to explore the functional role of habitat restoration on EGS delivery in an index system (Tampa Bay, FL) and for an index EGS (recreational fishing). Model scenarios are based on interaction of inter-annual differences in salinity/temperature patterns (wet, dry, average) with hindcasted “increases” in coverage and distribution of seagrass. Model predictions indicated that the effect of seagrass restoration to historic (1950s) levels on both fish and fishery production is dependent on salinity and temperature. This dependence is based on predicted fish response both to habitat changes and the effective spatial scale of different habitat components. Overall, average salinity/temperature conditions facilitated the highest positive functional response to seagrass restoration with extreme wet/dry years yielding lower or even negative functional responses, but these responses were localized and not homogenous about the estuary. The results of this study provide a methodology for using functional targets in restoration planning and highlight the importance of considering the entire habitat mosaic in valuing restored habitat from an EGS perspective.     

Restoring groundwater levels after tunneling: a numerical simulation approach to tunnel sealing decision-making

Tunneling is often unpopular with local residents and environmentalists, and can cause aquifer damage. Tunnel sealing is sometimes used to avoid groundwater leakage into the tunnel, thereby mitigating the damage. Due to the high cost of sealing operations, a detailed hydrogeological investigation should be conducted as part of the tunneling project to determine the impact of sealing, and groundwater modeling is an accurate method that can aid decision-making. Groundwater-level drawdown induced by the construction of the Headrace water-conveyance tunnel in Sri Lanka dried up 456 wells. Due to resulting socio-environmental problems, tunnel sealing was decided as a remedy solution. However, due to the expectation of significant delays and high costs of sealing, and because the water pressure in the tunnel may prevent groundwater seepage into the tunnel during operation, there was another (counter) decision that the tunnel could remain unsealed. This paper describes groundwater modeling carried out using MODFLOW to determine which option—sealed or unsealed tunnel—is more effective in groundwater level recovery. The Horizontal Flow Barrier and River packages of MODFLOW were used to simulate sealed and unsealed tunnels, respectively. The simulation results showed that only through tunnel sealing can the groundwater level be raised to preexisting levels after 18 years throughout the study area. If the tunnel remains unsealed, about 1 million m³/year of water conveyed by the tunnel will seep into the aquifer, reducing the operational capacity of the tunnel as a transport scheme. In conclusion, partial tunnel sealing in high-impact sections is recommended.

     

珠江口及琼东北海区元素地球化学特征及物质来源

为了更好的了解南海北部近陆表层沉积物特征及分布,通过对珠江口至海南岛东北海区进行表层沉积物取样测试,共获取了约3 500个样品粒度数据,700余个样品元素地球化学数据。该区域沉积物粒度以粉砂及细砂为主,分选性为较差及差,沉积物常量元素组合以SiO2、Al2O3、Fe2O3、CaO、K2O、MgO及Na2O为主,这7种氧化物占沉积物总量的90％以上（平均值）。对沉积物常量元素百分含量值进行了相关性分析,最终将调查海域沉积物划分为3个不同的区域,分别为珠江口及粤西区域（Ⅰ）、琼州海峡东分布区（Ⅱ）及琼东分布区（Ⅲ）,同时综合分析得出了各区域沉积物运移的路径趋势。     

Estimating Benefits in a Recovering Estuary: Tampa Bay,Florida

Restoration and preservation of riparian forests and coastal marshes provides nutrient removal and other biochemical and physical functions which may preclude, reduce, or delay the need for additional water treatment, while also protecting human health. We examined the ecosystem goods and related potential cost savings for the Tampa Bay community from seagrass expansion (more than 3,100 ha since 1990), coastal marsh, and mangrove restoration/recovery (more than 600 ha since 1990), and habitat that has been maintained or preserved. Habitats in and around Tampa Bay provide nutrient reductions equivalent to just over US$22 million per year in avoided wastewater treatment plant costs. Future accrual of value associated with maintaining the ecosystem good of usable clean water could rapidly increase to as high as ～US$3 billion per year, when one takes into account the additional costs of water treatment and storm water diversion infrastructure that is likely as the region’s population continues to grow. There is additional value accrual close to a quarter million dollars per year based on avoided social costs to the global community due to greenhouse gases sequestered by bay habitats. Most human beneficiaries associated with the maintenance of usable clean water in Tampa Bay are part of the surrounding regional community. The large current and future cost savings for the community surrounding Tampa Bay and additional benefits for the global community speak to the value of maintaining a healthy bay through past and continued restoration and preservation efforts.     

Mercury sources and transformations in a man-perturbed tidal estuary: The Sinnamary Estuary, French Guiana

The distribution, partition and speciation of mercury (Hg) were studied along the redox gradient of an anthropogenically perturbed tropical estuary, the Sinnamary Estuary in French Guiana. This system is a partially mixed estuary characterized by an anoxic freshwater end-member, while the marine end-member consists of the Amazon Plume.The set up of an artificial oxygenation system in the anoxic freshwater end-member generates sharp gradients of major chemical species (iron, sulfides, etc.) coupled with intense organic matter (OM) turnover. The coexistence of oxygenated waters and dissolved sulfides in an organic rich environment depicts the Upper Sinnamary Estuary (USE: part of Sinnamary Estuary under the tidal influence but upstream of the salt intrusion) as a potential site for Hg methylation. The concentrations of all mercury compounds (HgT) in the unfiltered samples (HgT_UNF), in the dissolved (HgT_D) and particulate (HgT_P) phases of the USE average 11 ± 3, 6 ± 2 and 5 ± 3 (i.e. 600 ± 200 pmol g⁻¹) pmol L⁻¹, respectively. Average concentrations of monomethylmercury (MMHg) in the unfiltered (MMHg_UNF), dissolved (MMHg_D) and particulate (MMHg_P) phases were 3.7 ± 1.0, 2.0 ± 0.9 and 1.8 ± 1.2 (i.e. 220 ± 130 pmol g⁻¹) pmol L⁻¹, respectively. Water oxygenation and sulfides concentrations emerged to play a critical role in controlling MMHg levels. Additionally, iron cycling, acid-base mechanisms, and redox-dependent processes were involved in the MMHg partitioning between phases.Overall, the USE constitutes a biogeochemical reactor that gathers partitioning and methylation processes. The permanent MMHg inputs from the anoxic freshwater end-member combined with the intense endogenous Hg methylation ensures high-MMHg levels in both dissolved and particulate phases. To illustrate, the USE exports 60 ± 20% more MMHg_UNF than it imports: 5.5 ± 0.7 vs. 3.5 ± 1.2 kg year⁻¹.     

Wetland Accretion Rate Model of Ecosystem Resilience (WARMER) and Its Application to Habitat Sustainability for Endangered Species in the San Francisco Estuary

Salt marsh faunas are constrained by specific habitat requirements for marsh elevation relative to sea level and tidal range. As sea level rises, changes in relative elevation of the marsh plain will have differing impacts on the availability of habitat for marsh obligate species. The Wetland Accretion Rate Model for Ecosystem Resilience (WARMER) is a 1-D model of elevation that incorporates both biological and physical processes of vertical marsh accretion. Here, we use WARMER to evaluate changes in marsh surface elevation and the impact of these elevation changes on marsh habitat for specific species of concern. Model results were compared to elevation-based habitat criteria developed for marsh vegetation, the endangered California clapper rail (Rallus longirostris obsoletus), and the endangered salt marsh harvest mouse (Reithrodontomys raviventris) to determine the response of marsh habitat for each species to predicted >1-m sea-level rise by 2100. Feedback between vertical accretion mechanisms and elevation reduced the effect of initial elevation in the modeled scenarios. Elevation decreased nonlinearly with larger changes in elevation during the latter half of the century when the rate of sea-level rise increased. Model scenarios indicated that changes in elevation will degrade habitat quality within salt marshes in the San Francisco Estuary, and degradation will accelerate in the latter half of the century as the rate of sea-level rise accelerates. A sensitivity analysis of the model results showed that inorganic sediment accumulation and the rate of sea-level rise had the greatest influence over salt marsh sustainability.     

Microbial Nitrogen Cycling in Estuaries: From Genes to Ecosystem Processes

Nitrogen (N) is one of the primary nutrients required to build biomass and is therefore in high demand in aquatic ecosystems. Estuaries, however, are frequently inundated with high concentrations of anthropogenic nitrogen, which can lead to substantially degraded water quality. Understanding drivers of biogeochemical N cycling rates and the microbial communities responsible for these processes is critical for understanding how estuaries are responding to human development. Estuaries are notoriously complex ecosystems: not only do individual estuaries by definition encompass gradients of salinity and other changing environmental conditions, but differences in physical parameters (e.g., bathymetry, hydrodynamics, tidal flushing) lead to a tremendous amount of variability in estuarine processes between ecosystems, as well. Here, we review the current knowledge of N cycling processes in estuaries carried out by bacteria and archaea, including both biogeochemical rate measurements and molecular characterizations of N cycling microbial communities. Particular attention is focused on identifying key environmental factors associated with distinct biogeochemical or microbial regimes across numerous estuaries. Additionally, we describe novel metabolisms or organisms that have recently been discovered but have not yet been fully explored in estuaries to date. While the majority of research has been conducted in the benthos, we also describe data from estuarine water columns. Understanding both the common patterns and the differences between estuaries has important implications for how these critical ecosystems respond to changing environmental conditions.     

The Role of Marsh-Derived Macrodetritus to the Food Webs of Juvenile Chinook Salmon in a Large Altered Estuary

The goal of this study was to determine the food web pathways supporting juvenile Chinook (Oncorhynchus tshawytscha) salmon in the Columbia River estuary through multiple stable isotope analysis (δ¹³C, δ¹⁵N, δ³⁴S). Using this method, we distinguished the role of various organic matter sources in Chinook food webs and interpreted the dynamics of their use both spatially and temporally within the estuary. Our results indicate that subyearling Chinook are associated with fluvial, anthropogenic, estuarine, and marine organic matter sources, with hatchery food and vascular plant detritus being the most dominant sources in juvenile Chinook food webs. Although freshwater phytoplankton is involved in many food web pathways to subyearling Chinook, increased phytoplankton production from the impounded river has not replaced the loss of autochthonous marsh production to fish. Our results indicate that large-scale ecosystem alteration may have decreased the availability and quality of food webs in the estuary and potentially diminished the ability of the Columbia to support Chinook salmon.     

Alteration of Residual Circulation Due to Large-Scale Infrastructure in a Coastal Plain Estuary

Large-scale human-built infrastructure is shown to alter the salinity and subtidal residual flow in a realistic numerical simulation of hydrodynamic circulation in a coastal plain estuary (Tampa Bay). Two model scenarios are considered. The first uses a modern bathymetry and boundary conditions from the years 2001–2003. The second is identical to the first except that the bathymetry is based on depth soundings from the pre-construction year 1879. Differences between the models' output can only result from changes in bay morphology, in particular built infrastructure such as bridges, causeways, and dredging of the shipping channel. Thirty-day means of model output are calculated to remove the dominant tidal signals and allow examination of the subtidal dynamics. Infrastructure is found to steepen the mean axial salinity gradient $ \partial \overline{s}/ dx $ by ~40% when there is low freshwater input but flatten $ \partial \overline{s}/ dx $ by ~25% under more typical conditions during moderate freshwater inflow to the estuary. Deepening of the shipping channel also increases the magnitude of the residual Eulerian circulation, allowing for larger up-estuary salt transport. Local bathymetry and morphology are important. Some regions within the estuary show little change in residual circulation due to infrastructure. In others, the residual circulation can vary by a factor of 4 or more. Major features of the circulation and changes due to infrastructure can be partially accounted for with linear theory.     

Anomalous Biogeochemical Response to a Flooding Event in the Delaware Estuary: A Possible Typology Shift Due to Climate Change

General circulation models have suggested that the number of extreme floods and droughts will increase with climate change; recent analyses of satellite data have demonstrated that these increases have been higher than predicted. Coastal systems, like the Delaware Estuary, can be vulnerable to such extreme weather events. In analyzing the 100- and 80-year records of the two major rivers of the Delaware Estuary, we find that about 20% of the very large and 50% of the extreme daily discharges occurred in the current decade (2001?C2011), and this represents a significant increase in flood occurrence compared with the rest of the discharge record. This is consistent with predictions of increased extreme weather conditions (inundation and drought) from climate change. Previously, we had characterized the Delaware Estuary as usually well mixed in the summer without significant bottom water oxygen depletion, based on our 30-year research efforts, and a 44-year agency monitoring record. In the summer of 2006, an extreme river discharge pushed the Delaware Estuary salinity gradient further downstream than seen in our research record and induced a nutrient influx to the nutrient-poor lower bay regions. As a result, stratification apparently allowed for a rapid phytoplankton biomass increase similar to the spring bloom phenomenon. A simple modeling exercise supports the idea that although unusual for this estuary in the summer, oxygen depletion occurred in response to the bloom biomass falling and decomposing in the isolated bottom waters. Using the summer 2006 anomalous discharge event and the resultant stratification as an illustration, and considering the significant increase in large and extreme floods in the last decade, we suggest that the typology of the Delaware Estuary is shifting as a result of climate change.     

Evolution of Mid-Atlantic Coastal and Back-Barrier Estuary Environments in Response to a Hurricane: Implications for Barrier-Estuary Connectivity

Assessments of coupled barrier island-estuary storm response are rare. Hurricane Sandy made landfall during an investigation in Barnegat Bay-Little Egg Harbor estuary that included water quality monitoring, geomorphologic characterization, and numerical modeling; this provided an opportunity to characterize the storm response of the barrier island-estuary system. Barrier island morphologic response was characterized by significant changes in shoreline position, dune elevation, and beach volume; morphologic changes within the estuary were less dramatic with a net gain of only 200,000 m³ of sediment. When observed, estuarine deposition was adjacent to the back-barrier shoreline or collocated with maximum estuary depths. Estuarine sedimentologic changes correlated well with bed shear stresses derived from numerically simulated storm conditions, suggesting that change is linked to winnowing from elevated storm-related wave-current interactions rather than deposition. Rapid storm-related changes in estuarine water level, turbidity, and salinity were coincident with minima in island and estuarine widths, which may have influenced the location of two barrier island breaches. Barrier-estuary connectivity, or the transport of sediment from barrier island to estuary, was influenced by barrier island land use and width. Coupled assessments like this one provide critical information about storm-related coastal and estuarine sediment transport that may not be evident from investigations that consider only one component of the coastal system.     

Analytical solution for salt intrusion in multiple-freshwater-source estuaries: application to Humen Estuary

Salt intrusion has some negative impact on the estuarine eco-environment as well as the water resource potential. The paper proposes an analytical model to describe salt intrusion in the estuaries with multiple freshwater sources. The impact of river discharge on the salinity distribution changes along the multiple-fresh-source estuaries, which is different from estuaries with single source of freshwater. Our analytical model is derived from the advection–dispersion equation for salinity while taking into account the hydrodynamic variation along the estuary. In this paper, we take the Humen Estuary, a strongly tide-dominated estuary with two major source of freshwater, as an example to illustrate the model. By testing against eight surveys over a complete spring-neap tidal cycle, the analytical model’s capacity to describe salt intrusion in the Humen Estuary is calibrated and validated. The results show that the analytical method can be used to compute the salinity distribution in the multiple-freshwater-source estuaries. In comparison with the field data in the Humen Estuary, the calculated results indicate that the salt intrusion process exhibits remarkable segmentation in the multiple-freshwater-source estuary, although the estuary’s inherent characteristic remains the same throughout the estuary. Moreover, by analyzing the multi-segmental features of the Humen Estuary, an efficient and effective model to predict the salt intrusion length of the Humen Estuary is presented and satisfactory results are obtained to illustrate its practical application.     

The Contribution of Benthic Nutrient Regeneration to Primary Production in a Shallow Eutrophic Estuary,Weeks Bay,Alabama

Benthic oxygen, dinitrogen, and nutrient fluxes (NH₄⁺, NO₃⁻, and PO₄³⁻) were measured monthly during a 1-year period at two locations in Weeks Bay, a shallow (1.4 m) and eutrophic estuary in Alabama. Gross primary productivity (GPP), ecosystem respiration (R), and net ecosystem metabolism were determined from high-frequency dissolved oxygen measurements. Peak water column NO₃⁻ (55 μM) and chlorophyll a (138 μg/l) concentrations were measured during spring and fall, respectively. Sediments were a net source of NH₄⁺ (102 μmol m⁻² h⁻¹) and PO₄³⁻ (0.9 μmol m⁻² h⁻¹) but a sink for NO₃⁻ (−30 μmol m⁻² h⁻¹). Benthic N₂ fluxes indicated net N fixation (12 μmol N m⁻² h⁻¹). Sediment oxygen demand (0.55 g O₂ m⁻² day⁻¹) accounted for <10% of R (7.3 g O₂ m⁻² day⁻¹). Despite high GPP rates (4.7 g O₂ m⁻² day⁻¹), the estuary was net heterotrophic. Benthic regeneration supplied, on average, 7.5% and 4% of primary productivity N and P demands, respectively. These results contrast with the conventional view that benthic regeneration accounts for a large fraction of phytoplankton nutrient demand in shallow estuaries.     

Dissolved and particulate trace metals and their partitioning in a hypoxic estuary: The Tanshui Estuary in Northern Taiwan

The distribution and partitioning of trace metals (Co, Cu, Fe, Mn, Ni, and Zn) between dissolved and particulate phases were studied in the Tanshui Estuary. The upper reach of the estuary is hypoxic and heavily polluted due to domestic and industrial discharges. The concentration ranges of dissolved and leachable particulate trace metals in the Tanshui Estuary were: Co: 0.3–6.1 nM, 1.8–18.6 mg kg⁻¹; Cu: 5–53 nM, 22–500 mg kg⁻¹; Fe: 388–3,364 nM, 1.08–6.67%; Mn: 57–2,914 nM, 209–1,169 mg kg⁻¹; Ni: 7–310 nM, 6–108 mg kg⁻¹; and Zn: 12–176 nM, 62–1,316 mg kg⁻¹; respectively. The dissolved concentrations of the metals were 2–35 times higher than the average values of the world river water. The distributions of dissolved and particulate studied metals, except Mn, in the estuary showed scattering, which could be attributed to the discharges from many industrial wastewater disposal works located in the upper tributaries. The daily input of dissolved metals from the disposal works to the Tanshui Estuary ranged from 0.1–0.4 tons. Dissolved Mn was nearly conservative in the region with salinity higher than 10 psu, while particulate Mn decreased in the region with salinity of 10–15 psu. The concentration increased significantly seawards, corresponding with the distribution of dissolved oxygen. The distribution coefficient (K_D) for Mn in the lower estuary was nearly three orders of magnitude higher than in the upper estuary. This phenomenon may be attributed to the diffusion of Mn from the anoxic sediment in the upper estuary and gradual oxidation into particulate Mn in the middle and lower estuary as the estuarine water became more oxygenated. The distribution coefficient for Cu decreased with increasing salinity. The percentages of trace metals bound by suspended particulate matter decreased in the following order: Fe>Zn, Cu>Co>Mn>Ni.     

Phytoplankton Functional Groups in a Tropical Estuary: Hydrological Control and Nutrient Limitation

Hydrology and nutrients have been indicated as the main driving factors acting on phytoplankton biomass and composition in estuarine systems, although grazing may occasionally have some influence. In order to identify these factors over temporal and spatial scales, we analyzed physical, chemical, and biological properties of a tropical river-dominated estuary during the dry and rainy seasons. As far as we know, this is the first time that the functional groups approach has been used to analyze the changes in phytoplankton composition in an estuary. This recent framework is based on the tolerances and sensitivities in relation to environmental conditions of groups of species, which are labeled by alpha-numeric codes (Reynolds et al., J. Pl. Res. 24:417–428, 2002). In the estuary of Paraíba do Sul River, all phytoplankton groups were represented by freshwater organisms, indicating the strong influence of the river. However, remarkable shifts in composition and biomass occurred from the low to high flushing seasons, due much more to the river discharge than to nutrient availability. The overall results showed no nitrogen, phosphorus, or silica limitation to phytoplankton growth (mean values: dissolved inorganic nitrogen?=?30.5 µM, soluble reactive phosphorus?=?1.45 µM, and silica?=?208.05 µM). The higher river flow supports a lower phytoplankton biomass composed mainly of nanoplankton (<20 µm) fast-growing functional groups, which are able to maintain biomass even in high flushing conditions (X₁), or large heavy organisms, such as some heavy diatoms of group P, which are able to be in suspension in shallow and turbulent systems. The lower river flow led to the coexistence of large organisms (>20 µm) of the groups P and F, which include slow-growing populations typically found in mesotrophic lakes. Although the functional group approach was originally developed for temperate lakes, our data support this approach for a tropical estuarine environment.     

珠江澳门河口沉积物柱样品正构烷烃研究

报道了珠江澳门河口沉积物柱芯榈中正构烷烃的浓度和分布类型,并通过因子分析方法对正构烷烃的来源加以初步探讨。沉积物柱芯样品于１９９７年３月采自珠江澳门河口区,沉积年龄以＾２１０Ｐｂ法稳恒初始放射性模式（ＣＡ模式）测定。样品中的有机污染物以二氯甲烷／丙酮混合溶剂索氏提取后,正构烷烃组分以ＧＣ／ＭＳＤ定量分析测定。研究结果表明,该现代沉积物桩芯样品沉积时间约历时４０ａ,桩芯样品中正构烷烃的含量范围为０．     

Cultural responses to the altithermal: The role of aquifer-related water resources

The focus of this research is Early Archaic adaptation to the hot and dry Altithermal in the North American Great Plains. The view presented here suggests a direct link between Altithermal climatic conditions and cultural responses to those conditions. Water was a key factor in cultural adaptation to arid Altithermal conditions. Statistical analysis reveals a significant relationship between Early Archaic site location and certain sources of groundwater that is not apparent during the periods preceding and succeeding the Altithermal. The distribution of Early Archaic sites may reflect increased emphasis on predictable water supplies offered by aquifers. © 1994 John Wiley & Sons, Inc.     

The application of a segmented tidal mixing model to the Great Bay Estuary,N.H.

Measurements show that in general salt is vertically well-mixed everywhere in the Great Bay Estuary, New Hampshire except near the river entrances at the head of the estuary. Dyer and Taylor’s (1973) modified version of Ketchum’s segmented tidal prism model has been applied to the Great Bay Estuarine System in order to predict high and low water salinity distribution for a specified river flow. The theory has been modified here to account for the mixing which occurs at the junction of two branches of an estuary. The mixing parameter, which in this model is related to the tidal excursion of water in the estuary, has been determined for different segments in the estuary on the basis of a comparison between predictions and a comprehensive data set obtained for a low river flow period. Using a mixing parameter distribution based on the low river flow calibration procedure the salinity distribution has been predicted for high river flow. The resulting salinity distribution compares favorably with observations for most of the estuary. The corresponding flushing times for water parcels entering at the head of the estuary during periods of low and high river flow is 54.5 and 45.9 tidal cycles respectively.     

Contributions of coastal and watershed energy sources to secondary production in a Northeastern Pacific Estuary

We examined the relationship between variation in origin of organic matter and benthic secondary production in a shallow, macrotidal estuary on the United States Pacific Northwest coast, Willapa Bay, Washington. Spatial variation in energy sources and benthic productivity were investigated at both local (vertical height and cross-bank components) and regional (sites within the bay) scales. We determined the stable carbon isotope ratios of oysters (Crassostrea gigas) to evaluate marine versus terrestrial energy sources, compared growth rates of oysters, and made time series measurements of physical variablest at estuarine channel and intertidal stations. The stable carbon isotope ratios of oysters ranged from ?22‰ in inner portions of the estuary to ?18‰ near the mouth and oysters grown on the substrate surface were enriched in δ¹³C relative to those grown in the water column. These patterns are consistent with terrigenous inputs away from the estuary mouth and benthic microalgae in the diets of on-bottom oysters. The highest oyster growth was found at an inner estuary site where riverine inputs are relatively high and coincided, with high ammonium in the water column. However, for most sites in Willapa Bay, oyster growth actually declined away from the estuary mouth. Reducing the time available for feeding by transplanting oysters higher in the intertidal zone had significant negative effects on growth(e.g., a reduction of 27–35% over 0.5 m). Despite the fact that oysters grown on-bottom had access to different resources than those in the water column, their growth was slower at amy given tidal elevation, which may be due to on-bottom competition with other suspension feeders, boundary layer effects, or interference from turbidity. In a practical sense, oyster growers have been adjusting to allochthonous energetic support of food webs in Willapa Bay for more than a century, because they have traditionally moved oysters from southern parts of the bay where recruitment is relatively high to beds where market-size oysters can be grown closer to the mouth. This study provides mechanistic support for these practices and suggests that climatic events on a variety of temporal scales (Pacific Decadal Oscillation, upwelling events) could have economic consequences for aquaculture.