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regime shift in Lake Dianchi(China) during the last 50 years

Journal of Oceanology and Limnology 2018年第4期36卷 1075-1090页

作者： WANG Yingcai WANG Weibo WANG Zhi LI Genbao LIU Yongding Yangtze Valley Water Environment Monitoring Center Wuhan 430010 China Institute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China Laboratory of Aquatic Botany and Watershed Ecology Wuhan Botanical Garden Chinese Academy of Sciences Wuhan 430074 China Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China

Lake Dianchi has undergone accelerated alternations resulting from human activities during the last 50 years, and provides an exceptional example for the study of regime shift in a shallow lake. Focusing on regime shift, we systematically studied and analysed alternations of key components of its ecosystem, including water parameters, phytoplankton and zooplankton biomass, macrophyte composition and fish populations. We found that the shifting course of Lake Dianchi went through three major phases, corresponding to three distinct states: Phase I clean, stable state during the 1950 s; Phase II transitional state during the 1970 s–1980 s; and phase III stable, turbid state since 1993. We analysed all data and samples, identifying the threshold concentrations at which regime shift occurred: total nitrogen(TN) and phosphorus(TP) reaching 1.2 mg/L and 0.13 mg/L, respectively. Results from this study strongly suggest that the increasing input of external nutrients, reclaiming land from the lake and foreign fish invasion were major inducements to the accelerated shift of Lake Dianchi to its turbid, stable state. These findings provide valuable guidelines for potential efforts to reverse this unnatural process in Lake Dianchi. The restoration may need to:(1) thoroughly and accurately identify pollution sources to control and reduce excessive external nutrients flowing into the lake;(2) return reclaimed land to the lake and recover the littoral zone to its natural state to facilitate increased restoration of macrophytes; and(3) strategically adjust fish populations by reducing benthivorous and filter-feeding fish populations that prey on zooplankton, while enlarging zooplankton populations to control phytoplankton biomass.

关键词： regime shift Lake Dianchi eutrophication altemative state driving force ecosystem

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Cloudiness regime shift during 1946—1992 recorded by coral in the South China Sea

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Acta Oceanologica Sinica 2005年第5期24卷 27-34页

作者： GAO Rongzhen SUN Donghuai WANG Dongxlao YANG Xiaoyi Key Laboratory of Tropical Marine Environmental Dynamics South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China Laboratory of Marginal Sea Geology South China Sea Institute of Oceanology ＆ Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510301 China Qingdao Meteorological Administration Qingdao 266003 China

By extracting and comparing long-term trend components of coral gray value, sea surface temperature, cloudiness, and net heat flux for the period of 1946-1992, the relationships among them are addressed. There exists a prominent regime shift in the cloudiness associated with the corresponding variabilities of sea surface temperature and net heat flux occurred in the mid-1960s, which can be successfully recorded by coral gray value, a climatic proxy. Long-term cloudiness variations in the South China Sea are completely opposite to the equatorial western Pacific in the past five decades, whereas they share a similar trend to that over Asian monsoon prevailing waters. The fact that the coral gray value is highly correlated to cloudiness provides a unique perspective on utilizing this coral to study cloudiness variations in the pre-instrumental period.

关键词： coral gray value cloudiness regime shift South China Sea

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Lake regime shift from submerged macrophyte to phytoplankton affected phosphorus speciation in sediment and eutrophic state in Caohai Lake,Guizhou,China

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Journal of Oceanology and Limnology 2023年第6期41卷 2262-2275页

作者： Jixing DONG Yanmin GUO Pinhua XIA Yuanbin TIAN Feifei ZHENG Anyan LI Tao LIN Ruiwen LI Guizhou Province Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment Guizhou Normal UniversityGuiyang 550001China Yangtze River Basin Ecological Environment Monitoring and Scientific Research Center Yangtze River Basin Ecological Environment Supervision and Administration BureauMinistry of Ecological EnvironmentWuhan 430010China

To understand the effect of regime shift in Caohai Lake in Yunnan-Guizhou Plateau,SW China from submerged macrophyte dominance to phytoplankton dominance on the specification and distribution of phosphorus and on ecological and environmental states,changes in phosphorus specification in the sediments and water were *** form,composition,and distribution of phosphorus in sediment were sampled in July 2020(before regime shift)and July 2021(after regime shift)were *** reveal that phosphorus content in sediment was lower than that those of Erhai Lake and Dianchi Lake,Yunnan,SW China,on the same plateau,and was lower than those of Taihu Lake,Chaohu Lake,and Poyang Lake in the middle-lower Changjiang(Yangtze)River *** phosphorus(Or-P)was the main form(up to 60%),followed by inactive phosphorus(Ina-P),and the active phosphorus(Act-P),the least,which is opposite to those of Taihu Lake and Poyang Lake in the middle-lower Changjiang River Plain in the eastern ***-P content was high,indicating a high potential risk of phosphorous *** the regime shift,the total phosphorus in sediment decreased from 0.87±0.13 to 0.70±0.13 g/*** proportion of Or-P and Act-P decreased from 68.23% to 65.32% and from 5.35% to 4.69%,*** contrast,the proportion of Ina-P increased from 26.42% to 29.99%.The Moran’s I index revealed that the heterogeneity of the spatial distributions of the total phosphorus(S-TP)and Act-P in the sediments before regime shift was significant(Pregime shift was not significant(P>0.05).The regime shift aggravated the eutrophication of the lake,the trophic level index(TLI)increased from 48.42 to 54.49(Pregime shift in the lake from submerged macrophyte dominance to phytoplankton dominanc

关键词： Caohai Lake sediment phosphorus specification regime shift

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Covariation of the Indonesian Throughflow and South China Sea Throughflow Associated with the 1976/77 regime shift

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Advances in Atmospheric Sciences 2010年第1期27卷 87-94页

作者：刘钦燕王东晓周文谢强张燕 Key Laboratory of Tropical Marine Environmental Dynamics South China Sea Institute of OceanologyChinese Academy of Sciences Guy Carpenter Asia-Pacific Climate Impact Centre CityU-IAP Laboratory for Atmospheric SciencesCity University of Hong Kong South China Sea Marine Engineering Prospecting State Oceanic Administration

Changes in the Indonesian Throughflow （ITF） and the South China Sea throughflow-measured by the Luzon Strait Transport （LST）-associated with the 1976/77 regime shift are analyzed using the Island Rule theory and the Simple Ocean Data Assimilation dataset. Results show that LST increased but ITF transport decreased after 1975. Such changes were induced by variations in wind stress associated with the regime shift. The strengthening of the easterly wind anomaly east of the Luzon Strait played an important role in the increase of LST after 1975, while the westerly wind anomaly in the equatorial Pacific contributed significantly to the decrease in ITF transport after 1975; accounting for 53% of the change. After 1975, the Kuroshio Current strengthened and the Mindanao Current weakened in response to a decrease in the total transport of the North Equatorial Current. Both the North Equatorial Countercurrent and the South Equatorial Current weakened after 1975, and an anomalous cyclonic circulation in the western equatorial Pacific prevented the tropical Pacific water from entering the Indian Ocean directly.

关键词： Indonesian throughflow Luzon Strait Transport regime shift wind anomaly

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Predicting ecological regime shift under climate change： New modelling techniques and potential of molecular-based approaches

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Current Zoology 2013年第3期59卷 403-417页

作者： Richard STAFFORD V. Anne SMITH Dirk HUSMEIER Thomas GRIMA Barbara-ann GUINN School of Applied Sciences Boumemouth University BH12 5BB UK School of Biology University of St Andrews St Andrews KY 16 9ST UK School of Mathematics and Statistics University of Glasgow G 12 8QW UK Department of Life Sciences University of Bedfordshire LU1 3JU UK

Ecological regime shift is the rapid transition from one stable community structure to another, often ecologically infe- rior, stable community. Such regime shifts are especially common in shallow marine communities, such as the transition of kelp forests to algal turfs that harbour far lower biodiversity. Stable regimes in communities are a result of balanced interactions be- tween species, and predicting new regimes therefore requires an evaluation of new species interactions, as well as the resilience of the ＇stable＇ position. While computational optimisation techniques can predict new potential regimes, predicting the most likely community state of the various options produced is currently educated guess work. In this study we integrate a stable regime op- timisation approach with a Bayesian network used to infer prior knowledge of the likely stress of climate change （or, in practice, any other disturbance） on each component species of a representative rocky shore community model. Combining the results, by calculating the product of the match between resilient computational predictions and the posterior probabilities of the Bayesian network, gives a refined set of model predictors, and demonstrates the use of the process in determining community changes, as might occur through processes such as climate change. To inform Bayesian priors, we conduct a review of molecular approaches applied to the analysis of the transcriptome of rocky shore organisms, and show how such an approach could be linked to meas- ureable stress variables in the field. Hence species-specific microarrays could be designed as biomarkers of in situ stress, and used to inform predictive modelling approaches such as those described here.

关键词： regime shift Phase shift Altemative stable state Intertidal Food web Resilience

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Precipitation regime shift Associated with the Pacific Decadal Oscillation in the Maritime Continent

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American Journal of Climate Change 2020年第2期9卷 123-135页

作者： V. Kokorev J. Ettema P. Siegmund G. van der Schrier Faculty of Geo-Information Science and Earth Observation University of Twente Enschede The Netherlands Royal Netherlands Meteorological Institute (KNMI) De Bilt The Netherlands

Recent changes in precipitation regime in South-East Asia are a subject of ongoing discussion. In this article, for the first time, evidence of a precipitation regime shift during the mid-1970s in the Northern Hemispheric part of South-East Asia is demonstrated. The detection of regime shifts is made possible by using a new comprehensive dataset of daily precipitation records (South-East Asian Climate Assessment and Dataset) and applying a novel Bayesian approach for regime shift detection. After the detected regime shift event in the mid-1970s, significant changes in precipitation distribution occurred in the Northern Hemispheric regions—Indochina Peninsula and the Philippines. More specifically, dry days became up to 10% more frequent in some regions. However, no precipitation regime shift is detected in Southern Hemisphere regions—Java and Northern Australia, were the number of observed dry days increased gradually.

关键词： regime shift Pacific Decadal Oscillation Precipitation South-East Asia Bayesian Methods

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regime shifts in the North Pacific Simulated by a COADS-driven Isopycnal Model

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Advances in Atmospheric Sciences 2003年第5期20卷 743-754页

作者：王东晓王佳吴立新刘征宇 LED South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou510301 Guangzhou Institute of Tropical Ocean and MeterologyCMAGuangzhou510080 International Arctic Research Center University of Alaska FairbanksAlaska 99775-7340USA Department of Atmospheric and Oceanic Sciences University fo Wsiconsin-MadisonWisconsin 53706-1695USA

The Miami Isopycnal Coordinate Ocean Model (MICOM) is adopted to simulate the intevdecadal variability in the Pacific Ocean with most emphasis on regime shifts in the North Pacific. The computational domain covers 60°N to 40°S with an enclosed boundary condition for momentum flux, whereas there are thermohalirie fluxes across the southern end as a restoring term. In addition, sea surface salinity of the model relaxes to the climatological season cycle, which results in climatological fresh water fluxes. Surface forcing functions from January 1945 through December 1998 are derived from the Comprehensive Ocean and Atmospheric Data Set (COADS). Such a numerical experiment reproduces the observed evolution of the interdecadal variability in the heat content over the upper 400-m layer by a two-year lag. Subduction that occurs at the ventilated thermocline in the central North Pacific is also been simulated and the subducted signals propagate from 35°N to 25°N, taking about 8 to 10 years, in agreement with the expendable Bathy Thermograph observation over recent decades. Interdecadal signals take a southwest-ward and downward path rather than westward propagation, meaning they are less associated with the baroclinic planetary waves. During travel, the signals appear to conserve potential vorticity. Therefore, the ventilated thermocline and related subduction are probably the fundamental physics for interdecadal variability in the mid-latitude subtropics of the North Pacific.

关键词： North Pacific ventilated thermocline regime shift isopycnal model

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Rolling Gaussian Process Regression with Application to regime shifts

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Applied Mathematics 2022年第11期13卷 859-868页

作者： William Menke Lamont-Doherty Earth Observatory of Columbia University Palisades NY USA

Gaussian Process Regression (GPR) can be applied to the problem of estimating a spatially-varying field on a regular grid, based on noisy observations made at irregular positions. In cases where the field has a weak time dependence, one may desire to estimate the present-time value of the field using a time window of data that rolls forward as new data become available, leading to a sequence of solution updates. We introduce “rolling GPR” (or moving window GPR) and present a procedure for implementing that is more computationally efficient than solving the full GPR problem at each update. Furthermore, regime shifts (sudden large changes in the field) can be detected by monitoring the change in posterior covariance of the predicted data during the updates, and their detrimental effect is mitigated by shortening the time window as the variance rises, and then decreasing it as it falls (but within prior bounds). A set of numerical experiments is provided that demonstrates the viability of the procedure.

关键词： Rolling Gaussian Process Regression regime shift Moving Window Analysis Woodbury Identity Bordering Method

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Application of subfossil cladocerans(water fleas) in assessing ecological resilience of shallow Yangtze River floodplain lake systems(China)

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Science China Earth Sciences 2018年第9期61卷 1157-1168页

作者： Giri KATTEL Ke ZHANG Xiangdong YANG State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of Sciences Environmental Hydrology and Water Resources Group Department of Infrastructure EngineeringThe University of Melbourne

Majority of shallow floodplain lake ecosystems of the middle and lower reaches of the Yangtze River(China) have gone through serious eutrophication problems over the recent past. The severe environmental deterioration accompanied by cyanobacterial blooms have become major water resource management challenges in the region. An advanced research method is urgently needed to tackle these challenges. The concept of ecological resilience address pressing questions of non-linear dynamics, threshold effects and regime shifts in shallow floodplain lakes, and help manage the ecosystem effectively. Palaeolimnological techniques are important for assessing long term resilience and associated thresholds effects of shallow lake ecosystems. However, the lack of reliable proxy methods available, the assessment of long term ecological resilience of shallow Yangtze River lake systems has become increasingly difficult. Cladocerans(water fleas) play a central role in lacustrine food webs by responding to external drivers and internal ecosystem processes in lakes. Their subfossils are well preserved and becoming one of potential proxy indicators of lake ecosystems change for a longer time scale. This study explores the potential application of subfossil cladocerans and their ephippia in assessing a long term ecological resilience and help better management strategies of lake ecosystems and water resources of the middle and lower reaches of the Yangtze River in China.

关键词： Subfossil cladoceran Yangtze River lake system Food web Ecological resilience regime shift Threshold

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A restoration-promoting integrated floating bed and its experimental performance in eutrophication remediation

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Journal of Environmental Sciences 2014年第5期26卷 1090-1098页

作者： Yiming Guo Yunguo Liu Guangming Zeng Xinjiang Hu Xin Li Dawei Huang Yunqin Liu Yicheng Yin College of Environmental Science and Engineering Hunan University Key Laboratory of Environmental Biology and Pollution Control (Hunan University) Ministry of Education

Numerous studies on eutrophication remediation have mainly focused on purifying water first, then restoring submerged macrophytes. A restoration-promoting integrated floating bed （RPIFB） was designed to combine the processes of water purification and macrophyte restoration simultaneously. Two outdoor experiments were conducted to evaluate the ecological functions of the RP1FB. Trial 1 was conducted to compare the eutrophication purification among floating bed, gradual-submerging bed （GSB） and RPIFB technologies. The results illustrated that RPIFB has the best purification capacity. Removal efficiencies of RPIFB for TN, TP,NH4＋-N, NO3-N, CODcr, Chlorophyll-a and turbidity were 74.45%, 98.31%, 74.71%, 88.81%, 71.42%, 90.17% and 85%, respectively. In trial 2, influences of depth of GSB and photic area in RPIFB on biota were investigated. When the depth of GSB decreased and the photic area of RPIFB grew, the height of Potamogeton crispus Linn. increased, but the biomass of Canna indica Linn. was reduced. The mortalities of Misgurnus anguillicaudatus and Bellamya aeruginosa in each group were all less than 7%. All results indicated that when the RPIFB was embedded into the eutrophic water, the regime shift from phytoplankton-dominated to macrophyte-dominated state could be promoted. Thus, the RPIFB is a promising remediation technology for eutrophication and submerged macrophyte restoration.

关键词： submerged macrophyte restoration eutrophication floating bed regime shift

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