scholarly journals Inconsistent Relationships of Primary Consumer N Stable Isotope Values to Gradients of Sheep/Beef Farming Intensity and Flow Reduction in Streams

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2239 ◽  
Author(s):  
Katharina Lange ◽  
Colin R. Townsend ◽  
Christoph D. Matthaei
Keyword(s):  
Stable Isotope ◽  
Multiple Stressors ◽  
Human Impacts ◽  
Interactive Effects ◽  
Saturation Curve ◽  
Flow Reduction ◽  
Multiple Stressor ◽  
Primary Consumer ◽  
Primary Consumers ◽  
Intensively Managed

Stable isotope values of primary consumers have been proposed as indicators of human impacts on nitrogen dynamics. Until now, these values have been related only to single-stressor gradients of land-use intensity in stream ecology, whereas potential interactive effects of multiple stressors are unknown. It also remains unknown whether stable isotope values of different primary consumers show similar relationships along gradients of stressor intensities. We sampled three common invertebrate grazers along gradients of sheep/beef farming intensity (0–95% intensively managed exotic pasture) and flow reduction (0–92% streamflow abstracted for irrigation). The δ15N values of the three primary consumers differed substantially along stressor gradients. Deleatidium δ15N values were positively related to farming intensity, showing a saturation curve, whereas Physella snail δ15N values were negatively related to farming intensity and Potamopyrgus snail δ15N values showed no relationship. In addition, Deleatidium stable isotope values responded positively to flow reduction intensity, a previously unstudied variable. An antagonistic multiple-stressor interaction was detected only for the mayfly Deleatidium, which occurred in streams experiencing up to 53% farming intensity. The lack of consistency in the relationships of the most important primary consumer grazers along the studied gradients may reduce their suitability as an indicator of anthropogenic N inputs.

scholarly journals Interactive effects of multiple stressors vary with consumer interactions, stressor dynamics and magnitude

2021 ◽  
Author(s):  
Mischa Turschwell ◽  
Roman Ashauer ◽  
Max Campbell ◽  
Rod Connolly ◽  
Sean Connolly ◽  
...  
Keyword(s):  
Multiple Stressors ◽  
Initial Conditions ◽  
Interactive Effects ◽  
Interaction Type ◽  
Multiple Stressor ◽  
Meta Analyses ◽  
Consumer Interactions ◽  
Underlying Processes ◽  
Process Based Models ◽  
Experiment Duration

Predicting the impacts of multiple stressors is important for informing ecosystem management, but is impeded by a lack of a general framework for predicting whether stressors interact synergistically, additively, or antagonistically. Here we use process-based models to study how interactions generalise across three levels of bio-logical organisation (physiological, population, and community) for a simulated two-stressor experiment on a seagrass model system. We found that the same underlying processes could result in synergistic, additive or antagonistic interactions, with interaction type depending on initial conditions, experiment duration, stressor dynamics, and consumer presence. Our results help explain why meta-analyses of multiple stressor experimental results have struggled to identify predictors of consistently non-additive interactions in the natural environment. Experiments run over longer temporal scales, with treatments across gradients of stressor magnitude, are needed to identify the processes that underpin how stressors interact and provide useful predictions to management.

Can Indirect Herbicide Exposure Modify the Response of the Colorado Potato Beetle to an Organophosphate Insecticide?

2019 ◽  
Vol 112 (5) ◽  
pp. 2316-2323 ◽  
Author(s):  
Aigi Margus ◽  
Miia Rainio ◽  
Leena Lindström
Keyword(s):  
Colorado Potato Beetle ◽  
Target Genes ◽  
Multiple Stressors ◽  
Synergistic Effects ◽  
Oxidative Status ◽  
Interactive Effects ◽  
Invasive Pest ◽  
Lipid Hydroperoxides ◽  
Organophosphate Insecticide ◽  
Potato Beetle

AbstractOrganisms live in complex multivariate environments. In agroecosystems, this complexity is often human-induced as pest individuals can be exposed to many xenobiotics simultaneously. Predicting the effects of multiple stressors can be problematic, as two or more stressors can have interactive effects. Our objective was to investigate whether indirect glyphosate-based herbicide (GBH) exposure of the host plant has interactive effects in combination with an insecticide (azinphos-methyl) on an invasive pest Colorado potato beetle (Leptinotarsa decemlineata Say). We tested the effects of GBH and insecticide on the survival, insecticide target genes expression (acetylcholinesterase genes) and oxidative status biomarkers (glutathione S-transferase [GST], glucose-6-phosphate dehydrogenase [G6PDH], glutathione reductase homolog [GR], glutathione peroxidase homolog [GPx], total glutathione [totGSH], glutathione reduced-oxidized [GSH: GSSG], catalase [CAT], superoxide dismutase [SOD], lipid hydroperoxides). We found that exposure to indirect GBH has no single or interactive effects in combination with the insecticide on larval survival. However, prior exposure to GBH inhibits Ldace1 gene expression by 0.55-fold, which is the target site for the organophosphate and carbamate insecticides. This difference disappears when individuals are exposed to both GBH and insecticide, suggesting an antagonistic effect. On the other hand, oxidative status biomarker scores (PCAs of GPx, GR, and CAT) were decreased when exposed to both stressors, indicating a synergistic effect. Overall, we found that indirect GBH exposure can have both antagonistic and synergistic effects in combination with an insecticide, which should be considered when aiming for an ecologically relevant risk assessment of multiple human-induced stressors.

scholarly journals Towards a unified study of multiple stressors: divisions and common goals across research disciplines

2020 ◽  
Vol 287 (1926) ◽  
pp. 20200421 ◽  
Author(s):  
James A. Orr ◽  
Rolf D. Vinebrooke ◽  
Michelle C. Jackson ◽  
Kristy J. Kroeker ◽  
Rebecca L. Kordas ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Multiple Stressors ◽  
Knowledge Exchange ◽  
Ecological Impacts ◽  
Temporal Complexity ◽  
Multiple Stressor ◽  
Interdisciplinary Knowledge ◽  
Shared Goal ◽  
Common Goals ◽  
Meta Analyses

Anthropogenic environmental changes, or ‘stressors’, increasingly threaten biodiversity and ecosystem functioning worldwide. Multiple-stressor research is a rapidly expanding field of science that seeks to understand and ultimately predict the interactions between stressors. Reviews and meta-analyses of the primary scientific literature have largely been specific to either freshwater, marine or terrestrial ecology, or ecotoxicology. In this cross-disciplinary study, we review the state of knowledge within and among these disciplines to highlight commonality and division in multiple-stressor research. Our review goes beyond a description of previous research by using quantitative bibliometric analysis to identify the division between disciplines and link previously disconnected research communities. Towards a unified research framework, we discuss the shared goal of increased realism through both ecological and temporal complexity, with the overarching aim of improving predictive power. In a rapidly changing world, advancing our understanding of the cumulative ecological impacts of multiple stressors is critical for biodiversity conservation and ecosystem management. Identifying and overcoming the barriers to interdisciplinary knowledge exchange is necessary in rising to this challenge. Division between ecosystem types and disciplines is largely a human creation. Species and stressors cross these borders and so should the scientists who study them.

scholarly journals Invasion-mediated effects on marine trophic interactions in a changing climate: positive feedbacks favour kelp persistence

2019 ◽  
Vol 286 (1899) ◽  
pp. 20182866 ◽  
Author(s):  
Ricardo J. Miranda ◽  
Melinda A. Coleman ◽  
Alejandro Tagliafico ◽  
Maria S. Rangel ◽  
Lea T. Mamo ◽  
...  
Keyword(s):  
Climate Change ◽  
Trophic Interactions ◽  
Multiple Stressors ◽  
Grazing Intensity ◽  
Ocean Warming ◽  
Interactive Effects ◽  
Ecological Change ◽  
Climate Change Scenarios ◽  
Ecological Consequences ◽  
Management Actions

The interactive effects of ocean warming and invasive species are complex and remain a source of uncertainty for projecting future ecological change. Climate-mediated change to trophic interactions can have pervasive ecological consequences, but the role of invasion in mediating trophic effects is largely unstudied. Using manipulative experiments in replicated outdoor mesocosms, we reveal how near-future ocean warming and macrophyte invasion scenarios interactively impact gastropod grazing intensity and preference for consumption of foundation macroalgae ( Ecklonia radiata and Sargassum vestitum ). Elevated water temperature increased the consumption of both macroalgae through greater grazing intensity. Given the documented decline of kelp ( E. radiata ) growth at higher water temperatures, enhanced grazing could contribute to the shift from kelp-dominated to Sargassum -dominated reefs that is occurring at the low-latitude margins of kelp distribution. However, the presence of a native invader ( Caulerpa filiformis ) was related to low consumption by the herbivores on dominant kelp at warmer temperatures. Thus, antagonistic effects between climate change and a range expanding species can favour kelp persistence in a warmer future. Introduction of species should, therefore, not automatically be considered unfavourable under climate change scenarios. Climatic changes are increasing the need for effective management actions to address the interactive effects of multiple stressors and their ecological consequences, rather than single threats in isolation.

scholarly journals Stable Isotope Food Web Analysis of a Large Subtropical Lake: Alternative Explanations for15N Enrichment of Pelagic vs. Littoral Fisheries

2003 ◽  
Vol 3 ◽  
pp. 613-622 ◽  
Author(s):  
Karl E. Havens ◽  
Binhe Gu ◽  
Brian Fry ◽  
Carol Kendall
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Food Webs ◽  
Trophic Level ◽  
Stable Isotope Ratio ◽  
Pelagic Zone ◽  
Primary Producers ◽  
Subtropical Lake ◽  
Primary Consumers ◽  
Habitat Enrichment

The food webs of littoral, pelagic, and littoral-pelagic ecotone (interface) regions of a large subtropical lake were investigated using stable isotope ratio methods, expanding the focus of a previous fish-only study to include other food web components such as primary producers and invertebrates. In these food webs, δ13C increased ~4o/oo and δ15N increased ~10o/oo from primary producers to fish. The δ15N of fish was ~9o/oo in the littoral zone, ~10 o/oo in the ecotone, and ~12o/oo in the pelagic zone. The cross-habitat enrichment in fish15N corresponded with both an increase in the size of fish and an increase in the δ15N of primary consumers (mollusks). Despite larger body size in the pelagic zone, fish in all three habitats appear to occur at the same average trophic level (TL = 4), assuming an enrichment factor of 3.4o/oo per trophic level, and normalizing to the δ15N of primary consumers.

Primary Consumer Body Size and Food-Chain Length in Terrestrial Communities

2009 ◽  
Vol 55 (4) ◽  
pp. 329-343 ◽  
Author(s):  
Yoram Ayal ◽  
Elli Groner
Keyword(s):  
Body Size ◽  
Chain Length ◽  
Food Chain ◽  
Energetic Efficiency ◽  
Food Chains ◽  
Food Chain Length ◽  
Primary Consumer ◽  
Size Limitation ◽  
Energy Limitation ◽  
Primary Consumers

Using 21 community food webs, we tested Elton's two hypotheses regarding the main factors limiting food-chain length in terrestrial communities, namely, energy (energy limitation hypothesis—ELH) and body size (size limitation hypothesis—SLH). As predators tend to be larger than their prey, food-chains are size-structured: animal size increases with trophic position. We found a negative correlation between the size of the primary consumer and the length of the chain. Food-chains based on small primary consumers are longer than those based on large primary consumers, and size rather than energetic efficiency is the main contributing factor. We found no correlation between habitat productivity and mean food-chain length. All these findings support the SLH over the ELH. Our results suggest that, as in aquatic communities, a single factor—a predator/prey size-ratio greater than 1—governs the structure of terrestrial communities.

Sequential rather than interactive effects of multiple stressors as drivers of phytoplankton community change in a large lake

2017 ◽  
Vol 62 (7) ◽  
pp. 1288-1302 ◽  
Author(s):  
Noreen E. Kelly ◽  
Joelle D. Young ◽  
Jennifer G. Winter ◽  
Michelle E. Palmer ◽  
Eleanor A. Stainsby ◽  
...  
Keyword(s):  
Phytoplankton Community ◽  
Multiple Stressors ◽  
Community Change ◽  
Interactive Effects ◽  
Large Lake

scholarly journals Interactive effects of environmental variability and human impacts on the long-term dynamics of an Amazonian floodplain lake and a South Atlantic coastal lagoon

Limnologica ◽  
2009 ◽  
Vol 39 (4) ◽  
pp. 306-313 ◽  
Author(s):  
Reinaldo L. Bozelli ◽  
Adriano Caliman ◽  
Rafael D. Guariento ◽  
Luciana S. Carneiro ◽  
Jayme M. Santangelo ◽  
...  
Keyword(s):  
Coastal Lagoon ◽  
Environmental Variability ◽  
Human Impacts ◽  
South Atlantic ◽  
Interactive Effects ◽  
Floodplain Lake ◽  
Atlantic Coastal

scholarly journals Variable responses of temperate calcified and fleshy macroalgae to elevated pCO2 and warming

2015 ◽  
Vol 73 (3) ◽  
pp. 693-703 ◽  
Author(s):  
S. L. Kram ◽  
N. N. Price ◽  
E. M. Donham ◽  
M. D. Johnson ◽  
E. L. A. Kelly ◽  
...  
Keyword(s):  
Growth Rates ◽  
Photosynthetic Efficiency ◽  
Multiple Stressors ◽  
Negative Impact ◽  
Co2 Enrichment ◽  
Elevated Pco2 ◽  
Interactive Effects ◽  
Calcareous Algae ◽  
High Pco2 ◽  
Physiological Tolerance

Abstract Anthropogenic carbon dioxide (CO2) emissions simultaneously increase ocean temperatures and reduce ocean surface pH, a process termed ocean acidification (OA). OA is expected to negatively affect the growth and physiology of many calcified organisms, but the response of non-calcified (fleshy) organisms is less well understood. Rising temperatures and pCO2 can enhance photosynthetic rates (within tolerance limits). Therefore, warming may interact with OA to alter biological responses of macroalgae in complicated ways. Beyond thresholds of physiological tolerance, however, rising temperatures could further exacerbate negative responses to OA. Many studies have investigated the effects of OA or warming independently of each other, but few studies have quantified the interactive effects of OA and warming on marine organisms. We conducted four short-term independent factorial CO2 enrichment and warming experiments on six common species of calcified and fleshy macroalgae from southern California to investigate the independent and interactive effects of CO2 and warming on growth, carbonic anhydrase (CA) enzyme activity, pigment concentrations, and photosynthetic efficiency. There was no effect of elevated pCO2 on CA activity, pigment concentration, and photosynthetic efficiency in the macroalgal species studies. However, we found that calcareous algae suffered reduced growth rates under high pCO2 conditions alone, although the magnitude of the effect varied by species. Fleshy algae had mixed responses of growth rates to high pCO2, indicating that the effects of pCO2 enrichment are inconsistent across species. The combined effects of elevated pCO2 and warming had a significantly negative impact on growth for both fleshy and calcareous algae; calcareous algae experienced five times more weight loss than specimens in ambient control conditions and fleshy growth was reduced by 76%. Our results demonstrate the need to study the interactive effects of multiple stressors associated with global change on marine communities.

scholarly journals A review of the effects of Bythotrephes longimanus and calcium decline on zooplankton communities — can interactive effects be predicted?

2015 ◽  
Vol 23 (4) ◽  
pp. 395-413 ◽  
Author(s):  
Shakira S.E. Azan ◽  
Shelley E. Arnott ◽  
Norman D. Yan
Keyword(s):  
Multiple Stressors ◽  
Current Knowledge ◽  
Canadian Shield ◽  
Interactive Effects ◽  
Bythotrephes Longimanus ◽  
Negative Impacts ◽  
The Individual ◽  
Zooplankton Communities ◽  
Shield Lakes ◽  
Review Current

Anthropogenic stressors including acid deposition, invasive species, and calcium (Ca) decline have produced widespread damage to Canadian Shield lakes, especially to their zooplankton communities. Here, we review current knowledge on the individual effects on zooplankton by the non-indigenous predator Bythotrephes longimanus and Ca decline; we identify knowledge gaps in this literature and examine the likely interactive impacts of Bythotrephes invasions and Ca decline on zooplankton. The negative impacts of Bythotrephes longimanus on zooplankton communities are well known, whereas current understanding of the effects of declining Ca on zooplankton is restricted to Daphnia spp.; hence, there is a large knowledge gap on how declining Ca may affect zooplankton communities in general. The co-occurring impacts of Bythotrephes and declining Ca have rarely been studied at the species level, and we expect daphniids, particularly Daphnia retrocurva and Daphnia pulicaria, to be the most sensitive to both stressors. We also expect a synergistic negative interaction on cladocerans in lakes with both stressors, leaving a community dominated by Holopedium glacialis and (or) copepods. Our predictions form testable hypotheses but since species and ecosystem response to multiple stressors are difficult to predict, we may actually see ecological surprises in Canadian Shield lakes as Bythotrephes continues to spread and Ca levels continue to fall.

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