Applying Dynamic Energy Budget (DEB) theory to simulate growth and bio-energetics of blue mussels under low seston conditions

A Dynamic Energy Budget (DEB) model for simulation of growth and bioenergetics of blue mussels (Mytilus edulis) has been tested in three low seston sites in southern Norway. The observations comprise four datasets from laboratory experiments (physiological and biometrical mussel data) and three datasets from in situ growth experiments (biometrical mussel data). Additional in situ data from commercial farms in southern Norway were used for estimation of biometrical relationships in the mussels. Three DEB parameters (shape coefficient, half saturation coefficient, and somatic maintenance rate coefficient) were estimated from experimental data, and the estimated parameters were complemented with parameter values from literature to establish a basic parameter set. Model simulations based on the basic parameter set and site specific environmental forcing matched fairly well with observations, but the model was not successful in simulating growth at the extreme low seston regimes in the laboratory experiments in which the long period of negative growth caused negative reproductive mass. Sensitivity analysis indicated that the model was moderately sensitive to changes in the parameter and initial conditions. The results show the robust properties of the DEB model as it manages to simulate mussel growth in several independent datasets from a common basic parameter set. However, the results also demonstrate limitations of Chl a as a food proxy for blue mussels and limitations of the DEB model to simulate long term starvation. Future work should aim at establishing better food proxies and improving the model formulations of the processes involved in food ingestion and assimilation. The current DEB model should also be elaborated to allow shrinking in the structural tissue in order to produce more realistic growth simulations during long periods of starvation.     

Modeling iron limitation of primary production in the coastal Gulf of Alaska

A lower trophic level NPZD ecosystem model with explicit iron limitation on nutrient uptake is coupled to a three-dimensional coastal ocean circulation model to investigate the regional ecosystem dynamics of the northwestern coastal Gulf of Alaska (CGOA). Iron limitation is included in the NPZD model by adding governing equations for two micro-nutrient compartments: dissolved iron and phytoplankton-associated iron. The model has separate budgets for nitrate (the limiting macro-nutrient in the standard NPZD model) and for iron, with iron limitation on nitrate uptake being imposed as a function of the local phytoplankton realized Fe:C ratio. While the ecosystem model represents a simple approximation of the complex lower trophic level ecosystem of the northwestern CGOA, simulated chlorophyll concentrations reproduce the main characteristics of the spring bloom, high shelf primary production, and “high-nutrient, low-chlorophyll” (HNLC) environment offshore. Over the 1998–2004 period, model-data correlations based on spatially averaged, monthly mean chlorophyll concentrations are on average 0.7, with values as high as 0.9 and as low as 0.5 for individual years. The model also provides insight on the importance of micro- and macro-nutrient limitation on the shelf and offshore, with the shelfbreak region acting as a transition zone where both nitrate and iron availability significantly impact phytoplankton growth. Overall, the relative simplicity of the ecosystem model provides a useful platform to perform long-term simulations to investigate the seasonal and interannual CGOA ecosystem variability, as well as to conduct sensitivity studies to evaluate the robustness of simulated fields to ecosystem model parameterization and forcing. The ability of the model to differentiate between nitrate-limited, and iron-limited growth conditions, and to identify their spatial and temporal occurrences, is also a first step towards understanding the role of environmental gradients in shaping the complex CGOA phytoplankton community structure.     

Birds, seals and the suspension culture of mussels in Bantry Bay, a non-seaduck area in Southwest Ireland

Concerns about the environmental impacts of mariculture have grown in recent years in response to the rapid expansion of the industry. The blue mussel (Mytilus edulis) is the main product of shellfish mariculture in the Northeast Atlantic and Baltic Sea, with approximately one third of the harvest cultured using suspended longlines within sheltered marine areas. The main aim of this study was to examine the interactions, and assess the impacts (if any) of mussel suspension culture on the seabird and seal community, employing a simultaneous study of culture and control sites. The study spanned a 20-month period (from November 2001 to August 2003) and encompassed six sites in Bantry Bay (Southwest Ireland).There was no significant difference in species richness between mussel and control sites. Similarly, species diversity did not significantly differ between the mussel and control sites although control sites were generally more diverse than mussel sites, the latter particularly dominated by large numbers of Laridae.Significantly higher numbers of Phalacrocoracidae, Laridae and Alcidae were recorded in mussel sites than in control sites. However, no significant difference was found between Gaviidae or common seal (Phoca vitulina) numbers in mussel and control sites. Seasonal patterns of abundance were similar in mussel and control sites, with peak numbers of most species groups occurring in spring.Mussel suspension culture does not appear to have an adverse effect on the abundance of seabirds or common seals in this area. The safe perching platforms provided by suspension culture floats, combined with a number of other factors, contribute to an increased abundance of a number of seabird species, particularly Laridae. The possible interactions between vertebrate predators and mussel suspension aquaculture are discussed and possible explanations for the increased seabird abundance observed in these areas are offered.     

应用物质平衡模型模拟一个半封闭海湾的营养结构和能流特征

The marine ecosystem of the Jiaozhou Bay has degraded significantly in fisheries productivity and its ecological roles as spawning and nursery ground for many species of commercial importance has been declining in recent years. A mass-balanced trophic model was developed using Ecopath with Ecosim to evaluate the trophic structure of the Jiaozhou Bay for improving ecosystem management. The model were parameterized based on the fisheries survey data in the Jiaozhou Bay in 2011, including 23 species groups and one detritus group according to their ecological roles. The trophic levels of these ecological groups ranged from 1(primary producers and detritus) to4.3(large demersal fishes). The estimated total system throughput was 12 917.10 t/(km~2·a), with 74.59% and25.41% contribution of the total energy flows from phytoplankton and detritus, respectively. Network analyses showed that the overall transfer efficiency of the ecosystem was 14.4%, and the mean transfer efficiency was 14.5%for grazing food chain and 13.9% for detritus food chain. The system omnivory index(SOI), Finn's cycled index(FCI) and connectance index(CI) were relatively low in this area while the total primary production/total respiration(TPP/TR) was high, indicating an immature and unstable status of the Jiaozhou Bay ecosystem. Mixed trophic impact analysis revealed that the cultured shellfish had substantial negative impacts on most functional groups. This study contributed to ecosystem-level evaluation and management planning of the Jiaozhou Bay ecosystem.     

紫贻贝养殖产业的现状、问题与对策

为全面系统地了解中国紫贻贝(Mytilus galloprovincialis)养殖产业情况,作者从养殖产量、养殖面积、进出口贸易、养殖生产等方面概述了紫贻贝产业现状,对中国紫贻贝养殖业的种质资源、苗种生产方式、养殖生产流程、养殖方式等进行了综述,并针对紫贻贝养殖中存在的问题,从种质资源、养殖模式、设施设备、食品安全控...     

A general ecosystem model for applications to primary productivity and carbon cycle studies in the global oceans

We have developed a general 1-D multi-component ecosystem model that incorporates a skillful upper ocean mixed layer model based on second moment closure of turbulence. The model is intended for eventual incorporation into coupled 3-D physical–biogeochemical ocean models with potential applications to modeling and studying primary productivity and carbon cycling in the global oceans as well as to promote the use of chlorophyll concentrations, in concert with satellite-sensed ocean color, as a diagnostic tool to delineate circulation features in numerical circulation models. The model is nitrogen-based and the design is deliberately general enough and modular to enable many of the existing ecosystem model formulations to be simulated and hence model-to-model comparisons rendered feasible. In its more general form (GEM10), the model solves for nitrate, ammonium, dissolved nitrogen, bacteria and two size categories of phytoplankton, zooplankton and detritus, in addition to solving for dissolved inorganic carbon and total alkalinity to enable estimation of the carbon dioxide flux at the air–sea interface. Dissolved oxygen is another prognostic variable enabling air–sea exchange of oxygen to be calculated. For potential applications to HNLC regions where productivity is constrained by the availability of a trace constituent such as iron, the model carries the trace constituent as an additional prognostic variable. Here we present 1-D model simulations for the Black Sea, Station PAPA and the BATS site. The Black Sea simulations assimilate seasonal monthly SST, SSS and surface chlorophyll, and the seasonal modulations compare favorably with earlier work. Station PAPA simulations for 1975–1977 with GEM5 assimilating observed SST and a plausible seasonal modulation of surface chlorophyll concentration also compare favorably with earlier work and with the limited observations on nitrate and pCO₂ available. Finally, GEM5 simulations at BATS for 1985–1997 are consistent with the available time series. The simulations suggest that while it is generally desirable to employ a comprehensive ecosystem model with a large number of components when accurate depiction of the entire ecosystem is desirable, as is the prevailing practice, a simpler formulation such as GEM5 (N²PZD model) combined with assimilation of remotely sensed SST and chlorophyll concentrations may suffice for incorporation into 3-D prediction models of primary productivity, upper ocean optical clarity and carbon cycling.     

Numerical model of a mussel longline system: Coupled dynamics

The longline is modelled using lumped masses and tension-only springs including structural damping. The mussel culture is modelled as cylinders attached to the main line and the equations are formulated for the coupled dynamics of the main line, buoys and mussel socks using Kane's formalism. Surface waves are described by Stokes’ second-order wave theory. The hydrodynamic loads are applied via a Morison's equation approach using the instantaneous relative velocities and accelerations between the fluid field, the longline and the attached buoys and mussel masses. The algorithm is presented and the equations are solved using the Runge–Kutta routine “ode45” in MATLAB. Outputs include position, orientation and velocity of all components and tension in all line segments. The numerical model may be used to predict the dynamics of longline systems using drag coefficients determined from field measurements. We expect that the results will be useful for checking and optimizing shellfish aquaculture designs prior to installation and for modifying existing designs to safeguard against failure.     

海洋生态系统动力学模型的稳定性和Hopf分岔研究

海洋生态系统动力学模型的可预测性是模型应用的重要限制因子之一,而模型稳定性则是模型可预测性的前提。本文提出了一个基于降维理论的方法,用于研究质量守恒的营养盐-浮游植物-浮游动物-碎屑(NPZD)这类海洋生态系统动力学模型的稳定性和Hopf分岔。研究结果显示,NPZD模型的非奇异平衡点是稳定的,而当模型参数在临界值附近变动时可能会发生Hopf分岔。同时,本文采用数值模拟的方法对该理论分析结果进行了实例验证。本文提出的基于降维理论的方法能够从理论上有效分析质量守恒系统的稳定性问题和Hopf分岔。     

A trophic model of the Pearl River Delta coastal ecosystem

A 26-compartment steady-state trophic model (1997–1999) was constructed using the Ecopath with Ecosim software to study the general status and development trends of the Pearl River Delta coastal ecosystem. The results show that the values of effective trophic level ranged from 1.00 to 4.21. It was found that a high trophic niche overlap existed in the typical estuarine ecosystem. Mixed trophic impacts show that detritus and the groups at the low trophic levels had positive influences on most groups. The ecosystem was found to be in an immature state during 1997–1999 based on the system statistics.     

Sensitivity analysis of a coastal marine ecosystem

An ecosystem with four compartments, i.e. PO₄-P, phytoplankton, zooplankton and detritus, in a coastal region was considered. Sensitivity analysis of a phosphorus flow model in well-mixed water without currents concludes that (1) the maximal photosynthetic rate,V _m , in Michaelis-Menten relation plays an important role in the distribution of biomass among compartments but the half saturation constant,K _s , is not so important, (2) the natural death rate of phytoplankton is important for the ecosystem, (3) the natural death rate of zooplankton is also effective on the ecosystem.A numerical experiment was also performed on the ecosystem with four compartments are also studied using a dynamical barotropic model of tidal currents of Mikawa Bay (Japan). Diffusion coefficient in diffusion equation plays the role of a linear smoothing parameter in the horizontal distribution of compartment. On the other hand, perturbations of biological parameters cause nonlinear variations in the horizontal distribution of compartment.     

Rosenbrock methods in biogeochemical modelling – A comparison to Runge–Kutta methods and modified Patankar schemes

Modelling biogeochemical processes in the surface ocean is still a difficult task due to the challenge to identify the most convenient integration scheme for the reaction terms. The scheme is expected to deal with the model characteristics of positivity and conservativity as well as with the different time scales involved, which occur e.g., whenever photochemical reactions take place in the water column.This paper presents a numerical comparison of the Rosenbrock methods, ROS3 and ROS4, often used for solving chemical reactions, to the explicit fourth-order Runge–Kutta method and the unconditionally positive modified Patankar schemes. Following their successful application in air chemistry, we here test the hypothesis that the Rosenbrock methods are an optimal choice for marine biogeochemical modelling in terms of efficiency and accuracy. In this study the schemes are compared in terms of runtime and accuracy and are applied to two test cases of different complexity: a zero-dimensional nutrient–phytoplankton–detritus (NPD)-type model and a one-dimensional nutrient–phytoplankton–zooplankton–detritus (NPZD)-type model. Applying the Rosenbrock methods to the simple NPD model shows their advantage over the other applied methods. They give the most accurate results of all solvers, especially for large step sizes, in less computing time due to their semi-implicitness and adaptive step sizing. On the contrary, for the one-dimensional NPZD model problem this is only the case in comparison to the Runge–Kutta solver, while their performance is worse than that of the second-order modified Patankar scheme. They need longer runtimes than the latter ones in order to achieve similarly accurate results. However, the modified Patankar schemes are not conservative if the system reactions contain more than one source compound. Thus, for more complex marine biogeochemical problems, it is recommended to apply the Rosenbrock methods while for simpler models the use of the second-order modified Patankar method is still the best alternative.     

舟山海域外来物种地中海贻贝的自然分布现状及生态影响

以筛选的2个可鉴别的地中海贻贝（Mytilus galloprovincialis）、厚壳贻贝（M.coruscus）及其杂交后代的PCR标记（扩增核基因Glu-5’特异片段PCR标记Me14/Me17和延伸因子1α第一个内含子区段PCR标记引物EFbisF/EFbisR）,对舟山海域3个贻贝主产区（马鞍列岛海域、浪岗山列岛海域、中街山列岛海域）采集的贻贝样本的种类进行鉴别.研究结果显示：100个马鞍列岛海域贻贝个体和30个中街山列岛海域贻贝个体均为厚壳贻贝;而54个浪岗山列岛海域贻贝样本中,16个个体（29.6%）为厚壳贻贝,38个个体（70.4%）为地中海贻贝;3个群体中均未检测到2种贻贝的杂交个体.因此,推测舟山海域地中海贻贝自然分布仅局限于局部海区,但在适宜的海区地中海贻贝可取代厚壳贻贝成为贻贝床的优势物种,舟山海域贻贝床的动态变化值得进一步关注;贻贝样本中没有检测到地中海贻贝与厚壳贻贝的杂交个体,表明调查海域可能没有杂交贻贝分布或数量极少,地中海贻贝通过杂交、基因渐渗污染厚壳贻贝基因组的风险较小.     

胶州湾围隔浮游生态系统氮、磷营养盐迁移-转化模型研究

通过对目前生态动力学模型的总结和综合,以生态系统中氮、磷营养盐循环为主线,建立了适用于海洋围隔浮游生态系统的多变量的营养盐迁移-转化动力学模型.该模型包括浮游植物、浮游动物、溶解无机态营养盐、溶解有机态营养盐和生物碎屑5个模块,涉及溶解无机氮、磷酸盐、溶解有机氮、溶解有机磷、浮游植物、浮游动物和生物碎屑7个状态变量.分别利用1999年秋季和2000年夏季胶州湾围隔生态实验数据进行了模型和验证工作,成功地模拟了富加营养盐条件下围隔浮游生态系统中氮、磷营养盐生物化学迁移-转化过程,并确定了20余个参数的量值.     

Assessment of coastal management options by means of multilayered ecosystem models

This paper presents a multilayered ecosystem modelling approach that combines the simulation of the biogeochemistry of a coastal ecosystem with the simulation of the main forcing functions, such as catchment loading and aquaculture activities. This approach was developed as a tool for sustainable management of coastal ecosystems. A key feature is to simulate management scenarios that account for changes in multiple uses and enable assessment of cumulative impacts of coastal activities. The model was applied to a coastal zone in China with large aquaculture production and multiple catchment uses, and where management efforts to improve water quality are under way. Development scenarios designed in conjunction with local managers and aquaculture producers include the reduction of fish cages and treatment of wastewater. Despite the reduction in nutrient loading simulated in three different scenarios, inorganic nutrient concentrations in the bay were predicted to exceed the thresholds for poor quality defined by Chinese seawater quality legislation. For all scenarios there is still a Moderate High to High nutrient loading from the catchment, so further reductions might be enacted, together with additional decreases in fish cage culture. The model predicts that overall, shellfish production decreases by 10%–28% using any of these development scenarios, principally because shellfish growth is being sustained by the substances to be reduced for improvement of water quality. The model outcomes indicate that this may be counteracted by zoning of shellfish aquaculture at the ecosystem level in order to optimize trade-offs between productivity and environmental effects. The present case study exemplifies the value of multilayered ecosystem modelling as a tool for Integrated Coastal Zone Management and for the adoption of ecosystem approaches for marine resource management. This modelling approach can be applied worldwide, and may be particularly useful for the application of coastal management regulation, for instance in the implementation of the European Marine Strategy Framework Directive.     

渤海生态动力过程的模型研究Ⅰ.模型描述

建立了一个NPZD类型的生物化学模型,并将其与原始方程海流模型(POM)、太阳辐射模型和河流输入模型耦合再现渤海的生态动力过程.模拟的初级生产力与实测值吻合较好;此外,该文还首次全方位地检验了渤海f-ratio的特征,通过与莱州湾的实测值比较,模拟结果也显示了相当的准确度.另外,该文在分析f-ratio变化特征的基础上还揭示硝酸盐和铵盐对渤海浮游植物生长的相对贡献率.     

Modelling the impacts of semi-intensive aquaculture on the foodweb functioning of a Nile Delta coastal lake

Nutrient loadings are an important component of aquaculture impacts as they can lead to cascade effects at the ecosystem level. An evaluation of these effects on foodweb functioning is presented and discussed for the case study of Lake Burullus in the Nile Delta, Egypt, where semi-intensive aquaculture in earthen ponds has grown remarkably in recent decades. Estimations of nutrient loads into the lake's brackish water, from agriculture and fish ponds, were assessed. A biogeochemical model was set up and calibrated to simulate the loads from nitrogen, phosphorus and phytoplankton, with and without fish ponds. The biogeochemical model was coupled offline to a foodweb model to test the effects of additional nutrient loads from aquaculture on the lake's foodweb functioning. The results obtained by comparing the present conditions of aquaculture development with a no-aquaculture scenario allowed us to identify a set of indicators of foodweb functioning which are sensitive to changes in nutrient loads from aquaculture. The limited changes in phytoplankton concentration with respect to changes in nutrient loads suggested that primary production in Lake Burullus is presently controlled largely by factors other than nutrient influxes from aquaculture. This study emphasises the potential benefits of using a combination of biogeochemical and foodweb models to assess the cumulative effects of nutrient loading from aquaculture on a receiving water body.     

Perspectives on Biological Research for CO<Subscript>2</Subscript> Ocean Sequestration

Feasibility studies recently suggest that sequestration of anthropogenic CO₂ in the deep ocean could help reduce the atmospheric CO₂ concentration. However, implementation of this strategy could have a significant environmental impact on marine organisms. This has highlighted the urgent need of further studies concerning the biological impact of CO₂ ocean sequestration. In this paper we summarize the recent literature reporting on the biological impact of CO₂ and discuss the research work required for the future. Although fundamental research of the effect of CO₂ on marine organisms before the practical consideration of CO₂ ocean sequestration was limited, laboratory and field studies concerning biological impacts have been increasing after the first international workshop in 1991 discussing CO₂ ocean sequestration. Acute impacts of CO₂ ocean sequestration could be determined by laboratory and field experiments and assessed by simulation models as described by the following papers in this section. On the other hand, chronic effects of CO₂ ocean sequestration, those directly related to the marine ecosystem, would be difficult to verify by means of experiments and to assess using ecosystem models. One of the practical solutions for this issue implies field experiments starting with controlled small scale and eventually to a large scale of CO₂ injection intended to determine ecosystem alteration. This revised version was published online in July 2006 with corrections to the Cover Date.     

基于Ecopath模型的舟山海域褐菖鲉(Sebastiscus marmoratus)生态容量评估

根据2021年渔业资源调查数据构建了含有23个功能组的舟山海域生态系统Ecopath模型,分析了当前舟山海域生态系统总体特征并估算了褐菖鲉在舟山海域的生态容量。结果表明:舟山海域生态系统营养级范围为1.000 (浮游植物和有机碎屑)～4.277 ( 鳐类),石首鱼科、虾类和 鳐类为舟山海域生态系统中的关键种。碎屑食物链和牧食食物链是舟山海域生态系统主要的食物链。碎屑和浮游植物对食物网的贡献率分别为61.32%和38.69%。始于浮游植物和碎屑的营养传递效率分别是9.34%和10.50%,系统总营养传递效率是9.82%。总初级生产量/总呼吸量为2.26,系统连接指数为0.372,系统杂食性指数为0.222。生态系统总体特征反映了舟山海域生态系统的成熟状态较低,生态系统处于不稳定阶段,容易受到外界环境变化的影响。根据模型估算,当褐菖鲉生物量增加至8.6倍时,褐菖鲉达到生态容量0.007 95 t/km²,此时生态系统仍保持平衡,且生态系统总体特征基本稳定。因此,褐菖鲉在舟山海域尚有较大增殖潜力。     

Model study on Bohai ecosystem 1. Model description and primary productivity

1Introduction TheBohaiSea(BS)(37°10′～40°55′N,117°35′～122°15′E)isthelargestinnerseainChi na,andplaysanimportantroleinsupportingthee conomicdevelopmentoffouradjacentprovincesby meansofitsadvantageouspositionforshippingand fisheryresources.However,     

东中国海碳循环时空变化特征:三维物理-生物地球化学数值模型研究

In the east of China's seas, there is a wide range of the continental shelf. The nutrient cycle and the carbon cycle in the east of China's seas exhibit a strong variability on seasonal to decadal time scales. On the basis of a regional ocean modeling system(ROMS), a three dimensional physical-biogeochemical model including the carbon cycle with the resolution(1/12)°×(1/12)° is established to investigate the physical variations, ecosystem responses and carbon cycle consequences in the east of China's seas. The ROMS-Nutrient Phytoplankton Zooplankton Detritus(NPZD) model is driven by daily air-sea fluxes(wind stress, long wave radiation, short wave radiation, sensible heat and latent heat, freshwater fluxes) that derived from the National Centers for Environmental Prediction(NCEP) reanalysis2 from 1982 to 2005. The coupled model is capable of reproducing the observed seasonal variation characteristics over the same period in the East China Sea. The integrated air-sea CO_2 flux over the entire east of China's seas reveals a strong seasonal cycle, functioning as a source of CO_2 to the atmosphere from June to October, while serving as a sink of CO_2 to the atmosphere in the other months. The 24 a mean value of airsea CO_2 flux over the entire east of China's seas is about 1.06 mol/(m~2·a), which is equivalent to a regional total of3.22 Mt/a, indicating that in the east of China's seas there is a sink of CO_2 to the atmosphere. The partial pressure of carbon dioxide in sea water in the east of China's seas has an increasing rate of 1.15 μatm/a(1μtm/a=0.101 325Pa), but p H in sea water has an opposite tendency, which decreases with a rate of 0.001 3 a~(–1) from 1982 to 2005.Biological activity is a dominant factor that controls the pCO_2 air in the east of China's seas, and followed by a temperature. The inverse relationship between the interannual variability of air-sea CO_2 flux averaged from the domain area and Ni?o3 SST Index indicates that the carbon cycle in the east of China's seas has a high correlation with El Ni?o-Southern Oscillation(ENSO).