EARLY WARNINGS FOR CATASTROPHIC SHIFTS IN ECOSYSTEMS: COMPARISON BETWEEN SPATIAL AND TEMPORAL INDICATORS

2010 ◽  
Vol 20 (02) ◽  
pp. 315-321 ◽  
Author(s):  
RAUL DONANGELO ◽  
HUGO FORT ◽  
VASILIS DAKOS ◽  
MARTEN SCHEFFER ◽  
EGBERT H. VAN NES
Keyword(s):  
Algal Blooms ◽  
Design Management ◽  
Leading Indicators ◽  
Lake Eutrophication ◽  
Warning Signals ◽  
Spatial Variance ◽  
Lake Model ◽  
Eutrophic Water ◽  
Catastrophic Shifts ◽  
Early Warnings

The task of providing leading indicators of catastrophic regime shifts in ecosystems is fundamental in order to design management protocols for those systems. Here we address the problem of lake eutrophication (that is, nutrient enrichment leading to algal blooms) using a simple spatial lake model. We discuss and compare different spatial and temporal early warning signals announcing the catastrophic transition of an oligotrophic lake to eutrophic conditions. In particular, we consider the spatial variance and its associated patchiness of eutrophic water regions. We found that spatial variance increases as the lake approaches the point of transition to a eutrophic state. We also analyze the spatial and temporal early warnings in terms of the amount of information required by each and their respective forewarning times. From the consideration of different remedial procedures that can be followed after these early signals we conclude that some of these indicators are not early enough to avert the undesired impending shift.

scholarly journals Control of Algal Blooms in Eutrophic Water Using Porous Dolomite Granules

2017 ◽  
Vol 54 (2) ◽  
pp. 108-113 ◽  
Author(s):  
Jae-Hoon Huh ◽  
Young-Hoon Choi ◽  
Shin Haeng Lee ◽  
Sun Hee Cheong ◽  
Ji Whan Ahn
Keyword(s):  
Algal Blooms ◽  
Eutrophic Water

Odorous Substances and Cyanobacterial Toxins in Prairie Drinking Water Sources

1992 ◽  
Vol 25 (2) ◽  
pp. 147-154 ◽  
Author(s):  
S. L. Kenefick ◽  
S. E. Hrudey ◽  
E. E. Prepas ◽  
N. Motkosky ◽  
H. G. Peterson
Keyword(s):  
Drinking Water ◽  
Water Samples ◽  
Algal Blooms ◽  
Algal Biomass ◽  
Cyanobacterial Blooms ◽  
Eutrophic Lakes ◽  
Cyanobacterial Toxins ◽  
Eutrophic Water ◽  
Odorous Substances ◽  
Water Uses

Algal blooms in eutrophic lakes have been regarded by some as primarily an aesthetic nuisance for recreational and drinking water uses despite well documented incidents of livestock and wildlife poisoning attributed to cyanobacterial toxins. A survey was conducted of three eutrophic, water supply lakes and eight rural dugouts experiencing cyanobacterial blooms. Biomass was characterized for dominant cyanobacterial genera and analyses were conducted for the hepatotoxins, microcystin LR and RR and the neurotoxin, anatoxin-a. Some water samples collected simultaneously were screened for geosmin, 2-methylisoborneol and β-cyclocitral. Results showed that microcystin LR (LD50 of 50 µg/kg in mice) was present in concentrations up to 500 µg/g of algal biomass and microcystin LR levels were generally related to the proportion of Microcystis in the collected algal biomass. There was no relationship between the presence of microcystin LR and the presence of any of the odour compounds. Consequently, cyanobacterial odour-causing compounds in water did not provide reliable warning of the presence of the microcystin LR in these cyanobacterial blooms.

scholarly journals Inferring critical points of ecosystem transitions from spatial data

2017 ◽  
Author(s):  
Sabiha Majumder ◽  
Krishnapriya Tamma ◽  
Sriram Ramaswamy ◽  
Vishwesha Guttal
Keyword(s):  
Dynamical Systems ◽  
Critical Point ◽  
Critical Points ◽  
Spatial Data ◽  
Spatial Model ◽  
Stable State ◽  
Alternative Stable State ◽  
Warning Signals ◽  
Spatial Variance ◽  
Ecosystem State

AbstractEcosystems can undergo abrupt transitions from one state to an alternative stable state when the driver crosses a threshold or a critical point. Dynamical systems theory suggests that systems take long to recover from perturbations near such transitions. This leads to characteristic changes in the dynamics of the system, which can be used as early warning signals of imminent transitions. However, these signals are qualitative and cannot quantify the critical points. Here, we propose a method to estimate critical points quantitatively from spatial data. We employ a spatial model of vegetation that shows a transition from vegetated to bare state. We show that the critical point can be estimated as the ecosystem state and the driver values at which spatial variance and autocorrelation are maximum. We demonstrate the validity of this method by analysing spatial data from regions of Africa and Australia that exhibit alternative vegetation biomes.

Potential bioavailability of phosphorus in citrus orchard soil to Microcystis aeruginosa

2011 ◽  
Vol 63 (6) ◽  
pp. 1298-1302 ◽  
Author(s):  
Y. Okubo ◽  
T. Inoue ◽  
K. Yokota ◽  
K. Tsushima
Keyword(s):  
Microcystis Aeruginosa ◽  
Algal Blooms ◽  
Sole Source ◽  
P Fractions ◽  
Citrus Orchard ◽  
Nutrient Runoff ◽  
Eutrophic Water ◽  
Orchard Soil ◽  
Particulate Form ◽  
Limiting Nutrient

Algal blooms in eutrophic water bodies are controlled by inputs of phosphorus (P) as the growth-limiting nutrient. Runoff particulate P associated with soil from fields often predominates among P fractions. Here, an algal bioassay to investigate the potential bioavailability of particulate P in soil collected from a citrus orchard was conducted. Microcystis aeruginosa was cultured in medium containing soil as the sole source of P. The P in the soil was not notably solubilized after autoclaving. Analyses of chlorophyll-a, suspended solids, particulate organic carbon, and particulate organic nitrogen showed that M. aeruginosa could utilize some of the P present in the soil, perhaps that in particulate form, but this form of P was not sufficient to maintain optimum growth.

scholarly journals CyanoHABs: unavoidable evolutionary ecological consequence for low nutrient-requiring cyanobacteria in eutrophic water

2021 ◽  
Author(s):  
Wenduo Cheng ◽  
Somin Hwang ◽  
Qisen Guo ◽  
Haibei Zhang ◽  
Leyuan Qian ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Nutrient Requirements ◽  
Key Factors ◽  
Narrow Angle ◽  
Eutrophic Water ◽  
Evolutionary Radiation ◽  
Cyanobacterial Harmful Algal Blooms ◽  
Multiple Species ◽  
Water Eutrophication

The mechanism of cyanobacterial harmful algal blooms (CyanoHABs) is complicated and confusing. One major reason is they are studied primarily from an ecological perspective and on bloom-forming species only. This narrow angle loses a broader evolutionary and ecological context in which CyanoHABs occur and fails to provide information on relevant components to achieve a wholistic understanding. To derive a comprehensive mechanism of CyanoHABs, we examine CyanoHABs through the overlooked evolutionary and ecological lenses: evolutionary radiation, ecological comparison with co-living algae, and recently identified genomic functional repertoire between blooming and non-blooming species. We found key factors: (1) elaborate diverse functional repertoire and low nutrient requirement in cyanobacteria molded by early adaptive evolution, (2) cyanobacteria having lower nutrient requirements than green algae indeed, (3) there is no directed evolution in biological functions toward water eutrophication in cyanobacteria, (4) the CyanoHAB-associated functional repertoire are more abundant and complete in blooming than non-blooming species. These factors lead us to postulate a preliminary mechanism of CyanoHABs as a synergistic quad: superior functional repertoire, established with long adaptive radiation under nutrient-deficient conditions and not evolved toward eutrophic conditions, enables cyanobacteria to efficiently utilize elevated nutrients under current eutrophic regime for excess growth and CyanoHABs thereof, due to their lower nutrient requirements than co-living algae. This preliminary synthesis without doubt needs further empirical testing, which can be undertaken with more comparative studies of multiple species using integrated systems biology approaches.

Multiple Stable States and Catastrophic Shifts in Ecosystems

Ecology ◽  
2019 ◽  
Author(s):  
Sonia Kéfi
Keyword(s):  
Alternative Stable States ◽  
Direct Consequence ◽  
Theoretical Models ◽  
Economic Consequences ◽  
Design Management ◽  
Stable States ◽  
Natural Systems ◽  
Restoration Strategies ◽  
Multiple Stable States ◽  
Catastrophic Shifts

The idea that ecosystems may have multiple alternative stable states dates back to the late 1960s–early 1970s, when ecologists realized that this type of behavior could arise in simple mathematical models. A direct consequence is that such ecosystems can suddenly switch (or “tip”) between their alternative stable states rather than gradually responding to changes. In other terms, in these ecosystems, a small environmental perturbation can cause large, discontinuous, and irreversible changes, referred to as catastrophic shifts. This idea has attracted increasing interest in the literature over the years, and has become even more relevant in the current context of global change. Examples of catastrophic shifts in ecosystems include the eutrophication of shallow lakes, the desertification of drylands, and the degradation of coral reefs. Theoretical models have investigated the conditions under which alternative stable states and catastrophic shifts occur. A well-recognized cause of alternative stable states is the presence of strong positive—or self-reinforcing—feedback processes that maintain each of the stable ecosystem states. Understanding the mechanisms underlying the emergence of alternative stable states can help design management as well as restoration strategies for ecosystems. Because catastrophic shifts can have dramatic ecological and economic consequences, approaches have been proposed to detect possible alternative stable states in natural systems, and indicators of approaching ecosystem transitions have been identified (so-called early warning signals of critical slowing down).

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