Exploring Lake Victoria ecosystem functioning using the Atlantis modeling framework

Lake Victoria has experienced human induced pressures such as overfishing, introduction of alien species, increased eutrophication and climate change impacts. However, there is limited understanding of the system dynamics, major processes, drivers and responses to the changes. To address this challenge, we developed the first end-to-end whole ecosystem model (Atlantis) for the lake. The model is spatially resolved into 12 unique dynamic areas based on depth, species composition, physical-chemical characteristics and fisheries management zones. A total of 38 functional groups constitute the biological model. Four fishing fleets with different targeting options are simulated. Reliability of the model is confirmed by the good fit of simulations output to observational data sets. Herein, we describe the evolution of the biophysical system, illustrating how it responded to the aforementioned induced perturbations since 1958. The constructed virtual Lake Victoria ecosystem model provides a platform for exploring the impact of management interventions before actual implementation.     

A system dynamics model to support the management of artisanal dredge fisheries in the south coast of Portugal

This paper presents a management model developed to promote the sustainability of artisanal fisheries, considering socioeconomic and environmental dimensions. The management of artisanal fisheries faces many challenges, including the lack of appropriate tools to support policy makers and stakeholders in the decision‐making process. The model presented in this study is based on system dynamics and allows the simulation of the behavior of the artisanal dredge fishery on the south coast of Portugal, including four main species and two fleets. Two scenarios were simulated to assess the impact of regulatory measures on the system sustainability: scenario 1 simulated a permanent reduction of fishing effort, returning an improvement of biologic and economic sustainability; scenario 2 simulated the closure of one species for a period of one year to allow its recovery. It was found that although the revenue of fisheries decreases in that year, the system is able to return to the average levels of revenue three years after the closure. The study aimed to guide decision makers in the selection of the most appropriate measures toward the preservation of marine ecosystems and socioeconomic stability of fishing communities. The developed system dynamics model, combining available data with knowledge of fisheries experts, proved to be a useful scientific tool to identify management policies and organizational structures leading to greater success. This technique can be applied to the study of other fishery systems worldwide.     

Potential effects of climate change and eutrophication on a large subtropical shallow lake

In many aquatic ecosystems, increased nutrient loading has caused eutrophication, which is reflected in the trophic structure of the ecosystem. In Lake Mangueira, a large shallow subtropical lake in Brazil, nutrient loading has also increased, but it is still unclear what the effects of this increase will be and how this relates to climate change. To evaluate the effects of increased nutrient loadings in such large lake one would need to integrate hydrological and ecological processes into one model, an approach that has rarely been used before. Here, we apply different versions of a complex 3D ecological model, called IPH-TRIM3D-PCLake, which describes the integrated hydrodynamic, water-quality, and biological processes in the lake. First, the nutrient loadings from the watershed were estimated using a separate hydrological water quality model of the watershed based on field data. Second, we calibrated the 3D ecological model for a 6-year monitoring period in the lake using a simplified non-spatial version of the model. Finally, the calibrated ecological model was applied to evaluate the spatial explicit effects of different scenarios of land use, water pumping for irrigation, and climate change. On short term (1.5 year), the system seemed to be rather resilient, probably because of the lake size related to its high inertia. Our simulations indicated warming can increase water transparency in Lake Mangueira which may be related to two factors: (a) the current meso-oligotrophic state of the lake which may easily lead to nutrient limitation; and (b) submerged macrophytes grow during the whole season. The combined effect of climate change and increased nutrient loading, less strong than increased nutrient loading alone. The model can only be used for qualitative predictions of the effect of management scenarios, such as maintenance of water levels in the dry season, and water-pumping rules for irrigation in order to maintain the ecosystem structure and functions in the future under additional stress caused by increased use or climate change.     

中西太平洋金枪鱼围网渔场专题图服务

中西太平洋渔场是世界金枪鱼捕捞产量最高的渔场之一,由于金枪鱼属于中上层高度洄游鱼类,渔场变动较大,借助遥感产品辅助渔场中心判断是一种有效的手段。上海开创远洋渔业有限公司金枪鱼围网主要集中在中西太平洋,生产过程中利用海表温度、叶绿素、海面流场等海况产品辅助捕捞决策。文章基于地理信息和遥感技术,开发了后台数据自动处理软件,完成数据获取、解码、投影转换、专题图制图等流程,完成渔场专题图自动制图,并通过微信、FTP和网站提供服务,可以很好的为渔业分析与管理。     

生态环境监测与管理决策支持系统的研究

依据空间信息的数据库,模型库,知识库,设计和建立生态环境监测与管理决策支持系统,其目的是综合应用遥感和地理信息系统,对生态系统和各种资源环境问题及时地进行监测分析,为促进生态系统的良性循环提供辅助决策支持。     

利用遥感技术建立干旱半干旱地区草地生态健康模型

由于全球气候变化以及人类活动对区域环境的破坏,生态系统环境正在发生变化,进而影响可持续发展。因此对生态系统健康与否的诊断变得非常必要。在中国西北地区,随着沙漠化、水土流失、沙尘暴频发,生态系统和生态环境非常脆弱。研究以甘肃省山丹县作为干旱半干旱典型研究区,选择压力、活力、反弹力作为生态系统健康模型的3个诊断指标,建立干旱半干旱区地区生态系统健康模型。其中压力利用实际载畜量的计算得到活力由1.1 km分辨率年内最大化NDVI获得 反弹力利用每个栅格的多年NDVI变化能力获得。结果表明：山丹县草地近年来生态健康的状况总体显著下降,1990年所有栅格的平均健康值为0.0572,而到了1999年下降为0.032 2,下降幅度达到43.7％ 在山丹县内,生态健康的值相对较高的是山丹军马场草场,这里的植被是覆盖度高,且大面积连成一片 少量的最高值出现在最南部的高中覆盖度草地,它的周围是灌木丛 山丹县其它地方草地是生态健康值很小的,分布在整个县的北部绝大部分。     

Use of a choice-based survey approach to characterise fishing behaviour in a scallop fishery

The predictability of fisher behaviour is an area of considerable uncertainty in fisheries management models. Fisher-derived data could underpin a better understanding, and more realistic predictions of fishing behaviour. Face to face interviews and a choice-based survey were conducted with scallop fishers to collect foraging parameters that could inform a model of fishing behaviour, and to better understand patch choice behaviour. Importantly, we validated survey data against vessel monitoring system and logbook data where possible, demonstrating a good level of accuracy. Environmental parameters central to patch choice were determined (e.g. wave height, distance to port), and three strategies of patch choice behaviour were identified, termed quantity maximiser, quality maximiser, and efficient fisher. Individuals' VMS and logbook data further confirmed and explained these behavioural patterns. This approach provided reliable, highly relevant data for the parameterisation of a fisheries behavioural model, which could lead to more robust and realistic predictive fisheries models.     

基于数据仓库的生态环境监测与管理决策支持系统

在数据仓库的基础上 ,讨论了生态系统监测与管理的内涵和决策模型 ,提出了基于数据仓库的生态系统监测与管理决策支持系统的体系结构以及决策支持系统与数据仓库的融合技术 ,并对系统开发流程、设计与实现中的关键技术进行了探讨。     

Spatiotemporal pattern analysis of potential light seine fishing areas in the East China sea using VIIRS day/night band imagery

Light seine fishing, one of the most efficient methods used in modern fisheries, is performed based on fish phototaxis. In this study, the East China Sea was selected as the study area, and fishing vessel pixels (pixels representing light seine fishing vessels) were detected in five years of Visible Infrared Imaging Radiometer Suite (VIIRS) day/night band (DNB) imagery according to three indicators: the Spike Median Index (SMI), Sharpness Index (SI), and Spike Height Index (SHI). Subsequently, cluster, barycenter, range and direction, and density analyses were conducted to comprehensively evaluate the spatiotemporal patterns of potential light seine fishing areas in the East China Sea. The following conclusions were drawn from the study: (1) the number of fishing vessel pixels exhibited obvious monthly characteristics that are consistent with the fishing moratorium that has been enforced in this region; (2) at the study area scale, light seine fishing occurred in one cluster, and the pattern in the interior of the cluster exhibited spatiotemporal periodicity; (3) the barycenter of the fishing areas displayed opposing movement trends in the first half and the second half of the year, and the movements were closely linked to water temperature changes. In addition, seasonally concentrated fishing areas were observed in winter, spring and summer; (4) the peak fishing month advanced from September to August beginning in 2014, and the fishing areas displayed a strong tendency in orientation that was highly consistent with the distribution of the Kuroshio Front in the East China Sea; and (5) light seine fishing activities were mainly concentrated in the second half of the year, especially in summer, but the intensity has declined in recent years. Our results are in good agreement with the results of other scholars and provide reliable information concerning where and when light seine fishing occurs. These results also suggest that VIIRS DNB imagery can be effectively used to detect light seine fishing areas.     

A Bayesian network approach to model farmers' crop choice using socio-psychological measurements of expected benefits of ecosystem services

Models of ecosystem management typically measure the benefits of ecosystem services in terms of ecological or biophysical variables, which are influenced by management decisions and biophysical/ecological conditions. This study uses farmers' expected benefits of ecosystem services as input variables to model their decision between planting rice, annual crops or perennial crops. Based on the theory of planned behavior, a Bayesian network is constructed to model crop choice depending on attitudes toward the ecosystem services of biomass production, reduction of soil erosion, and water quality improvement. The relative importance of these decision-making criteria is quantified using the Analytical Hierarchy Process. Results indicate that Bayesian networks can use socio-psychological measurements to model decision-making. Especially as an extension to biophysical or economic models, they can serve as a powerful tool for grasping the more abstract socio-psychological dimensions of benefits of ecosystem services, and how they translate into the decisions of ecosystem managers.     

Habitat suitability analysis and identification of potential fishing grounds for swordfish,Xiphias gladius,in the South Atlantic Ocean

Swordfish, Xiphias gladius, is a highly migratory species of important commercial value and widely distributed in three oceans. Recently, the South Atlantic swordfish captured as by-catch in longline fisheries targeting tunas has contributed greatly to the overall Atlantic swordfish's landing. In this study, we have developed a habitat suitability index (HSI) model to examine the relationships between their spatio-temporal distribution and environmental factors and to identify potential fishing grounds for the swordfish in the South Atlantic Ocean using the Taiwanese distant-water longline fishery data and remote-sensing oceanographic data for 1998–2007. All the environmental factors considered – sea surface temperature (SST), mixed layer depth (MLD), sea surface height anomaly (SSHA), chlorophyll-a concentration (CHA) and ocean bathymetry (BAH) – were highly significant with most of the catch-per-unit-effort (CPUE) variation explained by SST. The most optimum habitat (i.e. hotspot) was found in the areas with SSTs of 27–28°C, SSHAs of??0.05 to 0.05 m, CHAs of 0.1–0.2 mg m^?3 and BAHs of??4000 to??4500 m. The arithmetic mean model with five environmental variables was found to be the most appropriate according to the information theory based on the evaluation of different empirical HSI models in combination with different environmental factors. The bimonthly geographic information system maps of the predicted HSI values were cross-validated by the observed CPUE, suggesting that the model can be used as a tool for reliable prediction of potential fishing grounds. Because the distribution and relative abundance of swordfish are sufficiently heterogeneous in space and time, the output of this study could provide a scientific basis for time–area closures based management of this species.     

基于渔船监测系统的近海捕捞水产品溯源

通过对渔船监测系统的船位、航向、航速等信息挖掘,可以进行水产品溯源,保障海洋水产品的食品安全。基于渔船监测系统数据,结合渔场、沿海区划等信息,构建近海捕捞水产品溯源模型,研究渔船溯源、渔区和渔场溯源、渔获溯源,为水产品安全保障提供参考依据。     

A decision support system for fisheries management using operations research and systems science approach

In this paper, we present a general framework, using a systems science approach, for developing a decision support system (DSS) for fisheries management. Decision support systems are quantitative tools for managers to evaluate outcomes of their policies prior to implementation. Our fishery model considers multiple stocks and fisheries simultaneously in balancing catch among targeted and protected fish abundances. Since in the Northeastern US multispecies fishery the distribution of abundance, catch-per-unit-effort and bycatch vary geographically, we focus on a spatial management approach to address their spatial variability. The core component of this DSS applies operations research techniques of simulation and optimization to determine the optimal inter-annual and intra-annual fishing plans in terms of fishing efforts in each sub-area and the time period. The result is the recommended amount to catch from each fish species at each sub-area at any time period so that while management objectives for sustainability of fish stocks are satisfied, the value of landings is maximized. The graphical user interface of the proposed DSS helps users to define inputs, to set constraints and sub-area boundaries, and to visualize the outcomes.     

基于海洋遥感与渔船轨迹数据的多任务鱼情预测

渔情预测,即预测未来鱼群的位置和该区域内鱼量的丰富度.通过了解未来的渔情信息,管理者可以制定行之有效的策略,对渔民来说也可以节省捕鱼过程中的资源消耗.本文从海洋环境遥感数据与AIS渔船轨迹数据着手,分析挖掘鱼群的分布状况,进而对未来的渔情进行预测.根据作业方式的不同,渔船可以分为多种类型,如围网、刺网、拖网、张网等,针...     

Models for fisheries management

Realization of the massive potential harvests from the oceans, coupled with disastrous collapses of substantial fisheries has seen the development over the last 25 years of a quantitative fisheries management science. As an aid to management, models are used to represent fish populations and the effects of exploitation on them. Basic models currently used for fisheries management are reviewed. The models discussed range from the simple surplus production model through to the analytical model of Beverton and Holt incorporating age structure and finally to Kicker's stock-recruitment model. The models are used to examine the dynamics and stability of fish stock when subjected to different exploitation policies. Some of the problems for management in interfacing real fisheries data with the mathematical models are discussed. The goals of management, including catch, fishing effort and economics (e.g. price, cost and inflation) are quantified to produce an objective function which may be used to determine optimal strategies. The optimal harvesting strategies are examined for each model, with a view to developing a general workable robust harvesting policy, independent of the model used.     

渔情海况WebGIS信息服务系统构建

渔情海况是渔业生产和管理过程中的重要辅助信息。以ArcGIS Server为开发平台,后台选用ENVI/IDL提供遥感数据处理服务,ArcObject组件提供地理信息服务,两者一体化集成实现完整的空间信息后台服务,系统能够提供叶绿素、海温、海流、温盐跃层等的信息发布、查询、分析等功能,可以满足渔业生产与科研的需要。     

An open framework for agent based modelling of agricultural land use change

There is growing interest in creating empirically grounded agent based models (ABMs) to simulate land use change at a variety of spatio-temporal scales. The development of land use change models is challenging, as there is a need to connect representations of human behavioural processes to simulations of the biophysical environment. This paper presents a new agent-based modelling framework (Aporia) that has the goal of reducing the complexity and difficulty of constructing high-fidelity land use models. Building on earlier conceptual developments for modelling land use change and the provision of ecosystem services, Aporia was designed to be modular, flexible and open, using a declarative, compositional approach to create complex models from subcomponents. The framework can be tightly or loosely coupled with multiple vegetation models, it can be set up to evaluate a range of ecosystem service indicators, and it can be calibrated for a range of different landscape-scale case studies and modelling styles. The framework is released under an Open Source licence, and can be freely re-used and modified to form the basis of new models. We illustrate this with two case studies implemented using Aporia, exploring different socio-economic scenarios and behavioural characteristics on the land use decisions of Swiss and Scottish farmers. We also discuss the benefits of frameworks in terms of their flexibility, expandability, verification and transparency.     

冻融过程与陆地生态系统碳循环的相互关系研究进展

全球变化与可持续发展研究是当今地学研究的两大主题,陆地生态系统碳循环对全球变化影响重大。冻土中的碳储量占据全球陆地碳储量的重要份额,它对气候变化十分敏感,是气候变化的指示器,研究冻土地区土壤的冻融过程及其与陆地生态系统碳循环之间的相互关系对于全球变化研究具有重要意义。在总结冻融对碳循环过程影响机理的基础上,回顾了国内外关于冻融影响下碳循环模拟研究的主要进展,指出了其存在的主要问题,并对未来冻融与碳循环研究发展趋势做了初步的展望。     

Biodiversity in rubber agroforests,carbon emissions,and rural livelihoods: An agent-based model of land-use dynamics in lowland Sumatra

Rubber agroforests in the mostly deforested lowlands of Sumatra, Indonesia are threatened by conversion into monoculture rubber or oil palm plantations. We applied an agent-based model to explore the potential effectiveness of a payment for ecosystem services (PES) design through a biodiversity rich rubber eco-certification scheme. We integrated conditionality, where compliance with biodiversity performance indicators is prerequisite for awarding incentives. We compared a PES policy scenario to ‘business-as-usual’ and ‘subsidized land use change’ scenarios to explore potential trade-offs between ecosystem services delivery and rural income. Results indicated that a rubber agroforest eco-certification scheme could reduce carbon emissions and species loss better than alternative scenarios. However, the suggested premiums were too low to compete with income from other land uses. Nevertheless, integrating our understanding of household agent behavior through a spatially explicit and agent-specific assessment of the trade-offs can help refine the design of conservation initiatives such as PES.     

A management system for dirty data

A computer system for managing error prone and complex time-series data is described. The system processes statistics on the catches and fishing operations of fishermen operating in New Zealand waters. These statistics are used primarily for fisheries management and, for this purpose, many years of data may be required. Errors in the data can seriously compromise management and must be weeded out as far as possible. The system is organized around four groups of files: an input file in which data are held temporarily for error checking and correction; a master file which provides medium-term storage for the basic data; derived from this, several summary files tailored to the needs of different user groups; and, lastly, archival files in which the basic data are stored in the long term. The most significant feature of the system is providing effective and comprehensive error detection and correction, and in this is has proved most successful.