scholarly journals CO<sub>2</sub> and nutrient-driven changes across multiple levels of organization in <i>Zostera noltii</i> ecosystems

2014 ◽  
Vol 11 (24) ◽  
pp. 7237-7249 ◽  
Author(s):  
B. Martínez-Crego ◽  
I. Olivé ◽  
R. Santos
Keyword(s):  
Carbon Storage ◽  
Population Level ◽  
Interactive Effects ◽  
Zostera Noltii ◽  
Seagrass Meadows ◽  
Plant Biochemistry ◽  
Individual Effects ◽  
High Nutrient ◽  
The Individual ◽  
Shoot Mortality

Abstract. Increasing evidence emphasizes that the effects of human impacts on ecosystems must be investigated using designs that incorporate the responses across levels of biological organization as well as the effects of multiple stressors. Here we implemented a mesocosm experiment to investigate how the individual and interactive effects of CO2 enrichment and eutrophication scale-up from changes in primary producers at the individual (biochemistry) or population level (production, reproduction, and/or abundance) to higher levels of community (macroalgae abundance, herbivory, and global metabolism), and ecosystem organization (detritus release and carbon sink capacity). The responses of Zostera noltii seagrass meadows growing in low- and high-nutrient field conditions were compared. In both meadows, the expected CO2 benefits on Z. noltii leaf production were suppressed by epiphyte overgrowth, with no direct CO2 effect on plant biochemistry or population-level traits. Multi-level meadow response to nutrients was faster and stronger than to CO2. Nutrient enrichment promoted the nutritional quality of Z. noltii (high N, low C : N and phenolics), the growth of epiphytic pennate diatoms and purple bacteria, and shoot mortality. In the low-nutrient meadow, individual effects of CO2 and nutrients separately resulted in reduced carbon storage in the sediment, probably due to enhanced microbial degradation of more labile organic matter. These changes, however, had no effect on herbivory or on community metabolism. Interestingly, individual effects of CO2 or nutrient addition on epiphytes, shoot mortality, and carbon storage were attenuated when nutrients and CO2 acted simultaneously. This suggests CO2-induced benefits on eutrophic meadows. In the high-nutrient meadow, a striking shoot decline caused by amphipod overgrazing masked the response to CO2 and nutrient additions. Our results reveal that under future scenarios of CO2, the responses of seagrass ecosystems will be complex and context-dependent, being mediated by epiphyte overgrowth rather than by direct effects on plant biochemistry. Overall, we found that the responses of seagrass meadows to individual and interactive effects of CO2 and nutrient enrichment varied depending on interactions among species and connections between organization levels.

scholarly journals CO<sub>2</sub> and nutrient-driven changes across multiple levels of organization in <i>Zostera noltii</i> ecosystems

2014 ◽  
Vol 11 (4) ◽  
pp. 5239-5274 ◽  
Author(s):  
B. Martínez-Crego ◽  
I. Olivé ◽  
R. Santos
Keyword(s):  
Organic Matter ◽  
Carbon Sink ◽  
Co2 Enrichment ◽  
Population Level ◽  
Zostera Noltii ◽  
Biological Organization ◽  
Seagrass Meadows ◽  
Plant Biochemistry ◽  
Sink Capacity ◽  
High Nutrient

Abstract. Increasing evidence emphasizes that the effects of human impacts on ecosystems must be investigated using designs that incorporate the responses across levels of biological organization as well as the effects of multiple stressors. Here we implemented a mesocosm experiment to investigate how the effects of CO2 enrichment and its interaction with eutrophication, scale-up from changes in primary producers at the individual- (biochemistry) or population-level (production, reproduction, and/or abundance) to higher levels of community (macroalgae abundance, herbivory, and global metabolism) and ecosystem organization (detritus release and carbon sink capacity). The responses of Zostera noltii seagrass meadows growing in low- and high- nutrient field conditions were compared. In both meadows, the effect of elevated CO2 levels was mediated by epiphyte proliferation (mostly the cyanobacterium Microcoleus spp.), but not through changes in plant biochemistry or population-level traits. In the low-nutrient meadow, epiphyte proliferation suppressed the CO2 benefits on Z. noltii leaf production and led to increased detritus and decreased organic matter in sediment. Faster and stronger responses to nutrients than to CO2 were observed. Nutrient addition enhanced the nutritional quality of Z. noltii (high N, low C : N and phenolics) and the loss of leaves and shoots, while promoted the proliferation of pennate diatoms and purple bacteria. These changes led to a reduced sediment organic matter, but had no significant effects on herbivory nor on community metabolism. Interestingly, the interaction with CO2 attenuated eutrophication effects. In the high-nutrient meadow, a striking shoot decline caused by amphipod overgrazing was observed, with no response to CO2 and nutrient additions. Our results reveal that under future scenarios of CO2, the responses of seagrass ecosystems will be complex, being mediated by epiphyte proliferation rather than by effects on plant biochemistry. The multi-level responses of the system to nutrients overwhelmed those to CO2 enrichment, but the interaction between stressors reduced the effects of eutrophication. Both, CO2 and nutrient enrichments can reduce the carbon sink capacity of seagrass meadows.

The Interactive Effect of Chlorine, Copper and Nitrite on Methaemoglobin Formation in Red Blood Cells of Dorset Sheep

1992 ◽  
Vol 11 (3) ◽  
pp. 223-228 ◽  
Author(s):  
Cynthia J. Langlois ◽  
Edward J. Calabrese
Keyword(s):  
Blood Cell ◽  
Blood Cells ◽  
Interactive Effect ◽  
Interactive Effects ◽  
In Vitro Experiments ◽  
Simultaneous Exposure ◽  
Individual Effects ◽  
The Individual ◽  
Effect Of Chlorine

Simultaneous exposure to chemicals which can oxidize the haemoglobin of the red blood cell to methaemoglobin is common. Although the effects of some of these agents have been documented individually, little research considers the interactive effects. In-vitro experiments on the treated blood of female Dorset sheep assessed the interactive capacity of chlorite, copper and nitrite to affect methaemoglobin formation. All combinations of doses which produced 2.5, 5, 10% methaemoglobin were tested in all possible combinations (a total of 80), as were the controls. This included data on each chemical alone, each two-way combination and the three-way combination. The response is largely additive (the sum of the individual effects) except for one of the two-way interactions, chlorite/nitrite (P < . 01), which showed antagonism. Chlorite may oxidize nitrite which could explain the less-than-additive response. Overall, the result of combining these agents on methaemoglobin was additive.

scholarly journals Using changes in host demographic rates to reveal the effects of infection with hidden variable models

2020 ◽  
Author(s):  
Jake M. Ferguson ◽  
Andrea González-González ◽  
Johnathan A. Kaiser ◽  
Sara M. Winzer ◽  
Justin M. Anast ◽  
...  
Keyword(s):  
Longitudinal Studies ◽  
Population Level ◽  
Vital Rates ◽  
Hidden Variable ◽  
Demographic Rates ◽  
Public Health Data ◽  
Individual Effects ◽  
Wildlife Populations ◽  
The Individual ◽  
Hidden Variable Models

AbstractThe impacts of disease on host vital rates can be clearly demonstrated using longitudinal studies, but these studies can be expensive and logistically challenging. We examined the utility of hidden variable models to infer the individual effects of disease, caused by infection, from population-level measurements of survival and fecundity when longitudinal studies are not possible. Our approach seeks to explain temporal changes in population-level vital rates by coupling observed changes in the infection status of individuals to an epidemiological model. We tested the approach using both single and coinfection viral challenge experiments on populations of fruit flies (Drosophila melanogaster). Specifically, we determined whether our approach yielded reliable estimates of disease prevalence and of the effects of disease on survival and fecundity rates for treatments of single infections and coinfection. We found two conditions are necessary for reliable estimation. First, diseases must drive detectable changes in vital rates, and second, there must be substantial variation in the degree of prevalence over time. This approach could prove useful for detecting epidemics from public health data in regions where standard surveillance techniques are not available, and in the study of epidemics in wildlife populations, where longitudinal studies can be especially difficult to implement.

scholarly journals Distinguishing within from between individual effects: How to use the within-individual centering method for quadratic pattern

2020 ◽  
Author(s):  
Rémi Fay ◽  
Julien Martin ◽  
Floriane Plard
Keyword(s):  
Linear Relationship ◽  
General Equation ◽  
Evolutionary Dynamics ◽  
Population Level ◽  
List Type ◽  
Ecological Processes ◽  
Individual Pattern ◽  
Individual Effects ◽  
Non Linear ◽  
The Individual

AbstractAny average pattern observed at the population level may confound two different processes: the within-individual process and the between-individual process. Separating within- from between-individual patterns is critical for our understanding of ecological processes and evolutionary dynamics.The within-individual centering method allows distinguishing within from between individual effects and this method has been largely used in ecology to investigate both linear and quadratic patterns. Here we show that two alternative equations could be used for the investigation of quadratic relationships and explain in which circumstances they are valid.We show that these two alternative equations make different assumptions about the shape of the individual pattern. Reviewing the literature, we find that the inappropriate equation has likely been applied by most of the studies investigated quadratic patterns.To investigate properly quadratic patterns using the within individual centering method, it is critical that the pattern assumed by the equation used is consistent with the biological pattern investigated. We illustrate this statement with the example of age-specific trajectories because age corresponds to the most frequent individual-centered variable used for quadratic pattern. Finally, we give the general equation of the within-individual centering method for any non-linear relationship.

scholarly journals Century-long cod otolith biochronology reveals individual growth plasticity in response to temperature

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Szymon Smoliński ◽  
Julie Deplanque-Lasserre ◽  
Einar Hjörleifsson ◽  
Audrey J. Geffen ◽  
Jane A. Godiksen ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Environmental Variability ◽  
Atlantic Cod ◽  
Population Level ◽  
Climatic Conditions ◽  
Individual Growth ◽  
Individual Level ◽  
Thermal Plasticity ◽  
Individual Effects ◽  
The Individual

Abstract Otolith biochronologies combine growth records from individual fish to produce long-term growth sequences, which can help to disentangle individual from population-level responses to environmental variability. This study assessed individual thermal plasticity of Atlantic cod (Gadus morhua) growth in Icelandic waters based on measurements of otolith increments. We applied linear mixed-effects models and developed a century-long growth biochronology (1908–2014). We demonstrated interannual and cohort-specific changes in the growth of Icelandic cod over the last century which were mainly driven by temperature variation. Temperature had contrasting relationships with growth—positive for the fish during the youngest ages and negative during the oldest ages. We decomposed the effects of temperature on growth observed at the population level into within-individual effects and among‐individual effects and detected significant individual variation in the thermal plasticity of growth. Variance in the individual plasticity differed across cohorts and may be related to the mean environmental conditions experienced by the group. Our results underscore the complexity of the relationships between climatic conditions and the growth of fish at both the population and individual level, and highlight the need to distinguish between average population responses and growth plasticity of the individuals for accurate growth predictions.

Predicting the combined effect of herbivory and competition on a plant's shoot mass

1998 ◽  
Vol 76 (2) ◽  
pp. 316-320 ◽  
Author(s):  
R J Reader ◽  
S P Bonser
Keyword(s):  
Combined Effect ◽  
Interactive Effects ◽  
Tissue Loss ◽  
Herbaceous Species ◽  
Herbivore Exclusion ◽  
Neighbour Effects ◽  
Individual Effects ◽  
Two Factors ◽  
The Individual ◽  
Shoot Mass

This study tested whether the shoot mass of a plant growing with both herbivores and neighbours present could be predicted using results of a herbivore-exclusion and neighbour-removal experiment. Since herbivory and competition from neighbours reduce shoot mass in different ways (i.e., tissue loss versus reduction in resource availability), we predicted that the shoot mass of a plant growing with both herbivores and neighbours present should equal the product of three terms; namely, the shoot mass of a plant growing without herbivores or neighbours present, the fraction to which herbivores alone reduced this shoot mass in the herbivore-exclusion treatment, and the fraction to which neighbours alone reduced this shoot mass in the neighbour-removal treatment. We tested this prediction for six herbaceous species, each growing in a different habitat. Values of shoot mass predicted for plants growing with herbivores and neighbours present did not differ significantly (P = 0.05) from actual values of shoot mass measured for the six species. Based on this result, we conclude that combined effect of herbivores and neighbours on shoot mass can be predicted accurately by simply multiplying the individual effects of these two factors, since herbivores and neighbours often have independent, complementary effects on shoot mass.Key words: plant growth, interactive effects, predators, neighbour effects.

scholarly journals Interactive effects between travel behaviour and COVID-19: a questionnaire study

2021 ◽  
Author(s):  
Jinbao Zhang ◽  
Jaeyoung Lee
Keyword(s):  
Early Stage ◽  
Travel Behaviour ◽  
Interactive Effects ◽  
Factors Affecting ◽  
Individual Level ◽  
Passenger Volume ◽  
Spatial Autoregressive ◽  
Railway Passenger ◽  
The Individual ◽  
And Control

Abstract This study has two main objectives: (i) to analyse the effect of travel characteristics on the spreading of disease, and (ii) to determine the effect of COVID-19 on travel behaviour at the individual level. First, the study analyses the effect of passenger volume and the proportions of different modes of travel on the spread of COVID-19 in the early stage. The developed spatial autoregressive model shows that total passenger volume and proportions of air and railway passenger volumes are positively associated with the cumulative confirmed cases. Second, a questionnaire is analysed to determine changes in travel behaviour after COVID-19. The results indicate that the number of total trips considerably decreased. Public transport usage decreased by 20.5%, while private car usage increased by 6.4%. Then the factors affecting the changes in travel behaviour are analysed by logit models. The findings reveal significant factors, including gender, occupation and travel restriction. It is expected that the findings from this study would be helpful for management and control of traffic during a pandemic.

scholarly journals A methodological framework to predict the individual and population‐level distributions from tracking data

Ecography ◽  
2021 ◽  
Author(s):  
Philippine Chambault ◽  
Tarek Hattab ◽  
Pascal Mouquet ◽  
Touria Bajjouk ◽  
Claire Jean ◽  
...  
Keyword(s):  
Population Level ◽  
Tracking Data ◽  
Methodological Framework ◽  
The Individual
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