scholarly journals Chaos theory discloses triggers and drivers of plankton dynamics in stable environment

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Irena V. Telesh ◽  
Hendrik Schubert ◽  
Klaus D. Joehnk ◽  
Reinhard Heerkloss ◽  
Rhena Schumann ◽  
...  
Keyword(s):  
Chaos Theory ◽  
Biotic Interactions ◽  
Plankton Community ◽  
Trophic Levels ◽  
Complex Behaviour ◽  
Plankton Dynamics ◽  
Abiotic Environment ◽  
Stable Conditions ◽  
Global Systems ◽  
Modelling And Forecasting

AbstractDespite the enticing discoveries of chaos in nature, triggers and drivers of this phenomenon remain a classical enigma which needs irrefutable empirical evidence. Here we analyze results of the yearlong replicated mesocosm experiment with multi-species plankton community that allowed revealing signs of chaos at different trophic levels in strictly controlled abiotic environment. In mesocosms without external stressors, we observed the “paradox of chaos” when biotic interactions (internal drivers) were acting as generators of internal abiotic triggers of complex plankton dynamics. Chaos was registered as episodes that vanished unpredictably or were substituted by complex behaviour of other candidates when longer time series were considered. Remarkably, episodes of chaos were detected even in the most abiotically stable conditions. We developed the Integral Chaos Indicator to validate the results of the Lyapunov exponent analysis. These findings are essential for modelling and forecasting behaviour of a variety of natural and other global systems.

scholarly journals Identifying appropriate sampling and modelling approaches for analysing distributional patterns of Antarctic terrestrial arthropods along the Victoria Land latitudinal gradient

2010 ◽  
Vol 22 (6) ◽  
pp. 742-748 ◽  
Author(s):  
Tancredi Caruso ◽  
Ian D. Hogg ◽  
Roberto Bargagli
Keyword(s):  
Abiotic Factors ◽  
Relevant Literature ◽  
Biotic Interactions ◽  
Terrestrial Ecosystems ◽  
Climatic Conditions ◽  
Trophic Levels ◽  
Terrestrial Arthropods ◽  
Victoria Land ◽  
Dispersal Capability ◽  
Modelling Techniques

AbstractBiotic communities in Antarctic terrestrial ecosystems are relatively simple and often lack higher trophic levels (e.g. predators); thus, it is often assumed that species’ distributions are mainly affected by abiotic factors such as climatic conditions, which change with increasing latitude, altitude and/or distance from the coast. However, it is becoming increasingly apparent that factors other than geographical gradients affect the distribution of organisms with low dispersal capability such as the terrestrial arthropods. In Victoria Land (East Antarctica) the distribution of springtail (Collembola) and mite (Acari) species vary at scales that range from a few square centimetres to regional and continental. Different species show different scales of variation that relate to factors such as local geological and glaciological history, and biotic interactions, but only weakly with latitudinal/altitudinal gradients. Here, we review the relevant literature and outline more appropriate sampling designs as well as suitable modelling techniques (e.g. linear mixed models and eigenvector mapping), that will more adequately address and identify the range of factors responsible for the distribution of terrestrial arthropods in Antarctica.

scholarly journals Extreme Levels of Ocean Acidification Restructure the Plankton Community and Biogeochemistry of a Temperate Coastal Ecosystem: A Mesocosm Study

2021 ◽  
Vol 7 ◽  
Author(s):  
Carsten Spisla ◽  
Jan Taucher ◽  
Lennart T. Bach ◽  
Mathias Haunost ◽  
Tim Boxhammer ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Fish Larvae ◽  
Plankton Community ◽  
Trophic Levels ◽  
Coastal Regions ◽  
Mesozooplankton Community ◽  
Planktonic Food ◽  
Elemental Stoichiometry ◽  
Secondary Consumers ◽  
Induced Changes

The oceans’ uptake of anthropogenic carbon dioxide (CO2) decreases seawater pH and alters the inorganic carbon speciation – summarized in the term ocean acidification (OA). Already today, coastal regions experience episodic pH events during which surface layer pH drops below values projected for the surface ocean at the end of the century. Future OA is expected to further enhance the intensity of these coastal extreme pH events. To evaluate the influence of such episodic OA events in coastal regions, we deployed eight pelagic mesocosms for 53 days in Raunefjord, Norway, and enclosed 56–61 m3 of local seawater containing a natural plankton community under nutrient limited post-bloom conditions. Four mesocosms were enriched with CO2 to simulate extreme pCO2 levels of 1978 – 2069 μatm while the other four served as untreated controls. Here, we present results from multivariate analyses on OA-induced changes in the phyto-, micro-, and mesozooplankton community structure. Pronounced differences in the plankton community emerged early in the experiment, and were amplified by enhanced top-down control throughout the study period. The plankton groups responding most profoundly to high CO2 conditions were cyanobacteria (negative), chlorophyceae (negative), auto- and heterotrophic microzooplankton (negative), and a variety of mesozooplanktonic taxa, including copepoda (mixed), appendicularia (positive), hydrozoa (positive), fish larvae (positive), and gastropoda (negative). The restructuring of the community coincided with significant changes in the concentration and elemental stoichiometry of particulate organic matter. Results imply that extreme CO2 events can lead to a substantial reorganization of the planktonic food web, affecting multiple trophic levels from phytoplankton to primary and secondary consumers.

Multiple feedbacks due to biotic interactions across trophic levels can lead to persistent novel conditions that hinder restoration.

2020 ◽  
pp. 402-420
Author(s):  
Stephanie G. Yelenik ◽  
Carla M. D'Antonio ◽  
Evan M. Rehm ◽  
Iain R. Caldwell
Keyword(s):  
Species Interactions ◽  
Native Species ◽  
Biotic Interactions ◽  
Terrestrial Ecosystems ◽  
Trophic Levels ◽  
Native Grasses ◽  
Positive Feedbacks ◽  
Mesic Forest ◽  
Management Context ◽  
Multiple Challenges

Abstract Unlike traditional successional theory, Alternate Stable Equilibrium (ASE) theory posits that more than one community state is possible in a single environment, depending on the order that species arrive. ASE theory is often invoked in management situations where initial stressors have been removed, but native-dominated communities are not returning to degraded areas. Fundamental to this theory is the assumption that equilibria are maintained by positive feedbacks between colonizers and their environment. While ASE has been relatively well studied in aquatic ecosystems, more complex terrestrial systems offer multiple challenges, including species interactions across trophic levels that can lead to multiple feedbacks. Here, we discuss ASE theory as it applies to terrestrial, invaded ecosystems, and detail a case study from Hawai'i that exemplifies how species interactions can favour the persistence of invaders, and how an understanding of interactions and feedbacks can be used to guide management. Our system includes intact native-dominated mesic forest and areas cleared for pasture, planted with non-native grasses, and later planted with a monoculture of a native nitrogen-fixing tree in an effort to restore forests. We discuss interactions between birds, understorey fruiting native species, understorey non-native grasses, soils and bryophytes in separate feedback mechanisms, and explain our efforts to identify which of these feedbacks is most important to address in a management context. Finally, we suggest that using models can help overcome some of the challenges that terrestrial ecosystems pose when studying ASE.

scholarly journals Species-specific effects of passive warming in an Antarctic moss system

2019 ◽  
Vol 6 (11) ◽  
pp. 190744 ◽  
Author(s):  
Hannah M. Prather ◽  
Angélica Casanova-Katny ◽  
Andrew F. Clements ◽  
Matthew W. Chmielewski ◽  
Mehmet A. Balkan ◽  
...  
Keyword(s):  
Plant Species ◽  
Fungal Biomass ◽  
Trophic Levels ◽  
Moss Species ◽  
Abiotic Environment ◽  
Invertebrate Communities ◽  
Passive Warming ◽  
Specific Effects ◽  
Species Specific ◽  
Antarctic Moss

Polar systems are experiencing rapid climate change and the high sensitivity of these Arctic and Antarctic ecosystems make them especially vulnerable to accelerated ecological transformation. In Antarctica, warming results in a mosaic of ice-free terrestrial habitats dominated by a diverse assemblage of cryptogamic plants (i.e. mosses and lichens). Although these plants provide key habitat for a wide array of microorganisms and invertebrates, we have little understanding of the interaction between trophic levels in this terrestrial ecosystem and whether there are functional effects of plant species on higher trophic levels that may alter with warming. Here, we used open top chambers on Fildes Peninsula, King George Island, Antarctica, to examine the effects of passive warming and moss species on the abiotic environment and ultimately on higher trophic levels. For the dominant mosses, Polytrichastrum alpinum and Sanionia georgicouncinata , we found species-specific effects on the abiotic environment, including moss canopy temperature and soil moisture. In addition, we found distinct shifts in sexual expression in P . alpinum plants under warming compared to mosses without warming, and invertebrate communities in this moss species were strongly correlated with plant reproduction. Mosses under warming had substantially larger total invertebrate communities, and some invertebrate taxa were influenced differentially by moss species. However, warmed moss plants showed lower fungal biomass than control moss plants, and fungal biomass differed between moss species. Our results indicate that continued warming may impact the reproductive output of Antarctic moss species, potentially altering terrestrial ecosystems dynamics from the bottom up. Understanding these effects requires clarifying the foundational, mechanistic role that individual plant species play in mediating complex interactions in Antarctica's terrestrial food webs.

The interplay of nested biotic interactions and the abiotic environment regulates populations of a hypersymbiont

2019 ◽  
Vol 88 (12) ◽  
pp. 1998-2010
Author(s):  
Alexandre Mestre ◽  
Robert Poulin ◽  
Robert D. Holt ◽  
Michael Barfield ◽  
John C. Clamp ◽  
...  
Keyword(s):  
Biotic Interactions ◽  
Abiotic Environment

scholarly journals Loss of top-down biotic interactions changes the relative benefits for obligate mutualists

2019 ◽  
Vol 286 (1897) ◽  
pp. 20182501 ◽  
Author(s):  
Rong Wang ◽  
Xiao-Yong Chen ◽  
Yan Chen ◽  
Gang Wang ◽  
Derek W. Dunn ◽  
...  
Keyword(s):  
Biotic Interactions ◽  
Trophic Levels ◽  
Fig Wasp ◽  
Negative Effects ◽  
Top Down ◽  
Top Predators ◽  
Natural Range ◽  
Obligate Mutualism ◽  
The Stability ◽  
Food Web Complexity

The collapse of mutualisms owing to anthropogenic changes is contributing to losses of biodiversity. Top predators can regulate biotic interactions between species at lower trophic levels and may contribute to the stability of such mutualisms, but they are particularly likely to be lost after disturbance of communities. We focused on the mutualism between the fig tree Ficus microcarpa and its host-specific pollinator fig wasp and compared the benefits accrued by the mutualists in natural and translocated areas of distribution. Parasitoids of the pollinator were rare or absent outside the natural range of the mutualists, where the relative benefits the mutualists gained from their interaction were changed significantly away from the plant's natural range owing to reduced seed production rather than increased numbers of pollinator offspring. Furthermore, in the absence of the negative effects of its parasitoids, we detected an oviposition range expansion by the pollinator, with the use of a wider range of ovules that could otherwise have generated seeds. Loss of top-down control has therefore resulted in a change in the balance of reciprocal benefits that underpins this obligate mutualism, emphasizing the value of maintaining food web complexity in the Anthropocene.

scholarly journals Effects of Consecutive Extreme Weather Events on a Temperate Dystrophic Lake: A Detailed Insight into Physical, Chemical and Biological Responses

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1411 ◽  
Author(s):  
Maria Calderó-Pascual ◽  
Elvira de Eyto ◽  
Eleanor Jennings ◽  
Mary Dillane ◽  
Mikkel René Andersen ◽  
...  
Keyword(s):  
Global Climate ◽  
Zooplankton Community ◽  
Fold Increase ◽  
Extreme Weather ◽  
Zooplankton Biomass ◽  
Trophic Levels ◽  
Extreme Weather Events ◽  
Weather Events ◽  
Fold Reduction ◽  
Stable Conditions

Between May and July 2018, Ireland experienced an exceptional heat wave, which broke long-term temperature and drought records. These calm, stable conditions were abruptly interrupted by a second extreme weather event, Atlantic Storm Hector, in late June. Using high-frequency monitoring data, coupled with fortnightly biological sampling, we show that the storm directly affected the stratification pattern of Lough Feeagh, resulting in an intense mixing event. The lake restabilised quickly after the storm as the heatwave continued. During the storm there was a three-fold reduction in Schmidt stability, with a mixed layer deepening of 9.5 m coinciding with a two-fold reduction in chlorophyll a but a three-fold increase in total zooplankton biomass. Epilimnetic respiration increased and net ecosystem productivity decreased. The ratio of total nitrogen:total phosphorus from in-lake versus inflow rivers was decoupled, leading to a cascade effect on higher trophic levels. A step change in nitrogen:phosphorus imbalances suggested that the zooplankton community shifted from phosphorus to nitrogen nutrient constraints. Such characterisations of both lake thermal and ecological responses to extreme weather events are relatively rare but are crucial to our understanding of how lakes are changing as the impacts of global climate change accelerate.

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