scholarly journals Richness of Primary Producers and Consumer Abundance Mediate Epiphyte Loads in a Tropical Seagrass System

Diversity ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 384 ◽  
Author(s):  
Luke Hoffmann ◽  
Will Edwards ◽  
Paul H. York ◽  
Michael A. Rasheed

Consumer communities play an important role in maintaining ecosystem structure and function. In seagrass systems, algal regulation by mesograzers provides a critical maintenance function which promotes seagrass productivity. Consumer communities also represent a key link in trophic energy transfer and buffer negative effects to seagrasses associated with eutrophication. Such interactions are well documented in the literature regarding temperate systems, however, it is not clear if the same relationships exist in tropical systems. This study aimed to identify if the invertebrate communities within a tropical, multispecies seagrass meadow moderated epiphyte abundance under natural conditions by comparing algal abundance across two sites at Green Island, Australia. At each site, paired plots were established where invertebrate assemblages were perturbed via insecticide manipulation and compared to unmanipulated plots. An 89% increase in epiphyte abundance was seen after six weeks of experimental invertebrate reductions within the system. Using generalised linear mixed-effect models and path analysis, we found that the abundance of invertebrates was negatively correlated with epiphyte load on seagrass leaves. Habitat species richness was seen to be positively correlated with invertebrate abundance. These findings mirrored those of temperate systems, suggesting this mechanism operates similarly across latitudinal gradients.

2015 ◽  
Vol 23 (4) ◽  
pp. 443-460 ◽  
Author(s):  
Michael J. Lawrence ◽  
Holly L.J. Stemberger ◽  
Aaron J. Zolderdo ◽  
Daniel P. Struthers ◽  
Steven J. Cooke

War is an ever-present force that has the potential to alter the biosphere. Here we review the potential consequences of modern war and military activities on ecosystem structure and function. We focus on the effects of direct conflict, nuclear weapons, military training, and military produced contaminants. Overall, the aforementioned activities were found to have overwhelmingly negative effects on ecosystem structure and function. Dramatic habitat alteration, environmental pollution, and disturbance contributed to population declines and biodiversity losses arising from both acute and chronic effects in both terrestrial and aquatic systems. In some instances, even in the face of massive alterations to ecosystem structure, recovery was possible. Interestingly, military activity was beneficial under specific conditions, such as when an exclusion zone was generated that generally resulted in population increases and (or) population recovery; an observation noted in both terrestrial and aquatic systems. Additionally, military technological advances (e.g., GPS technology, drone technology, biotelemetry) have provided conservation scientists with novel tools for research. Because of the challenges associated with conducting research in areas with military activities (e.g., restricted access, hazardous conditions), information pertaining to military impacts on the environment are relatively scarce and are often studied years after military activities have ceased and with no knowledge of baseline conditions. Additional research would help to elucidate the environmental consequences (positive and negative) and thus reveal opportunities for mitigating negative effects while informing the development of optimal strategies for rehabilitation and recovery.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Courtney G. Collins ◽  
Sarah C. Elmendorf ◽  
Robert D. Hollister ◽  
Greg H. R. Henry ◽  
Karin Clark ◽  
...  

AbstractRapid climate warming is altering Arctic and alpine tundra ecosystem structure and function, including shifts in plant phenology. While the advancement of green up and flowering are well-documented, it remains unclear whether all phenophases, particularly those later in the season, will shift in unison or respond divergently to warming. Here, we present the largest synthesis to our knowledge of experimental warming effects on tundra plant phenology from the International Tundra Experiment. We examine the effect of warming on a suite of season-wide plant phenophases. Results challenge the expectation that all phenophases will advance in unison to warming. Instead, we find that experimental warming caused: (1) larger phenological shifts in reproductive versus vegetative phenophases and (2) advanced reproductive phenophases and green up but delayed leaf senescence which translated to a lengthening of the growing season by approximately 3%. Patterns were consistent across sites, plant species and over time. The advancement of reproductive seasons and lengthening of growing seasons may have significant consequences for trophic interactions and ecosystem function across the tundra.


2021 ◽  
pp. oemed-2020-107039
Author(s):  
Jingyi Qin ◽  
Wei Xia ◽  
Gaodao Liang ◽  
Shunqing Xu ◽  
Xiuge Zhao ◽  
...  

ObjectivesThis study aimed to evaluate whether PM2.5 exposure in a highly polluted area (>100 µg/m3) affects glucose and lipid metabolism in healthy adults.MethodsWe recruited 110 healthy adults in Baoding city, Hebei, China, and followed them up between 2017 and 2018. Personal air samplers were used to monitor personal PM2.5 levels. Eight glucose and lipid metabolism parameters were quantified. We performed the linear mixed-effect models to investigate the relationships between PM2.5 and glucose and lipid metabolism parameters. Stratified analyses were further performed according to sex and body mass index (BMI).ResultsThe concentration of PM2.5 was the highest in spring, with a median of 232 μg/m3 and the lowest in autumn (139 μg/m3). After adjusting for potential confounders, we found that for each twofold increase in PM2.5, the median of insulin concentration decreased by 5.89% (95% CI −10.91% to −0.58%; p<0.05), and ox-LDL increased by 6.43% (95% CI 2.21% to 10.82%; p<0.05). Stratified analyses indicated that the associations were more pronounced in females, overweight and obese participants.ConclusionsExposure to high PM2.5 may have deleterious effects on glucose and lipid metabolism. Females, overweight and obese participants are more vulnerable.


2005 ◽  
Vol 53 (1-2) ◽  
pp. 93-108 ◽  
Author(s):  
Bénédicte Pasquer ◽  
Goulven Laruelle ◽  
Sylvie Becquevort ◽  
Véronique Schoemann ◽  
Hugues Goosse ◽  
...  

2010 ◽  
pp. 111-145
Author(s):  
Thomas Lacher ◽  
"Jr Bickham ◽  
Claude Gascon ◽  
Rhys Green ◽  
Robin Moore ◽  
...  

Author(s):  
А.В. Лебедев ◽  
В.В. Кузьмичев

Сосна обыкновенная является одной из основных лесообразующих пород Европы, а ее древесина находит широкое применение в лесопромышленном комплексе. При оценке углерододепонирующих функций считается, что конверсионные коэффициенты являются константными по времени. Последние исследования показывают, что происходящие климатические изменения оказывают существенное влияние на прирост древесины и ее свойства. Цель данного исследования – выявление долговременных тенденций в изменении биомассы фракций деревьев сосны обыкновенной в Европе, происходящих с 1940 г. Для проверки гипотезы о влиянии календарного года на биомассу фракций деревьев проводился регрессионный анализ с применением линейных моделей смешанных эффектов. Проведенный статистический анализ позволил выявить достоверное влияние (при p < 0,05) календарного года только на биомассу стволов в коре. Наиболее сильно изменения проявляются для деревьев в молодняках и средневозрастных насаждениях, где происходит формирование наибольшего радиального прироста. Для крупномерных стволов, согласно результатам моделирования, снижение биомассы стволов в коре не прослеживается. В ближайшие десятилетия в результате продолжающихся климатических изменений процесс снижения биомассы и плотности древесины крупномерных стволов должен усилиться. Выявленные изменения биомассы сопровождаются снижением плотности древесины, что происходит в результате увеличения в структуре годичного прироста более рыхлой и менее плотной ранней древесины. Таким образом, в условиях ускоряющихся темпов роста древесных растений объемы стволов и запасы древесины не должны напрямую пересчитываться в депонированный углерод с учетом исторических значений конверсионных коэффициентов. Это также следует учитывать при мониторинге, моделировании и использовании углерода и биомассы в лесах в условиях глобальных изменений. Scots pine is one of the main forest-forming species in Europe, and its wood is widely used in the timber industry. When evaluating carbon-depositing functions, the conversion rations are assumed to be constant over time. Recent studies show that the ongoing climatic changes have a significant impact on the growth of trees and wood properties. Therefore, the purpose of this study is to identify long-term trends in the change in the biomass of Scots pine tree fractions in Europe since 1940. To test the hypothesis about the influence of the calendar year on the biomass of tree fractions, regression analysis was performed using linear mixed-effect models. The performed statistically analysis made it possible to reveal a significant effect (p < 0.05) of the calendar year only on the biomass of the trunks in the bark. The changes are most pronounced for trees in young and middle-aged stands, where the formation of the greatest radial growth occurs. For large-sized trunks, according to the simulation results, the biomass of the stems in the bark is not traced. In the coming decades, as a result of ongoing climate change, the decline in biomass and wood density of largesized stems should intensify. The revealed changes in biomass are accompanied by a decrease in wood density, which occurs as a result of an increase in the structure of the annual growth of looser and less dense early wood. Thus, in the context of accelerating growth rates of woody plants, the volume of trunks and wood stock should not be directly converted into deposited carbon, considering the historical values of conversion rations. This should also be considered when monitoring, modeling and using carbon and biomass in forests in the face of global change.


Author(s):  
Miriti Jane Kinya ◽  
Kenneth Lawrance Wanjau ◽  
Nyagweth Ebenezer Odeyo

The study sought to assess the importance of classifying incubators based on the programs offered for optimum performance. Client selection criteria were assessed through three constructs namely: models that fit program goals, uniqueness of ideas, and standard selection tool. A mixed cross-sectional and causal design was adopted and a census was carried out targeting all the 51 incubators. Primary data was collected with an incubator program as a grouping/ cluster variable yielding a multilevel data structure with incubator centres nested in programs. Linear mixed effect models were fitted using Stata to assess the study objective taking into account the fixed effects for the incubator centre level (level-1) and random effects for the program level (level-2). The uniqueness of ideas was found to have a significant fixed effect on performance at level one while at level two, the study found significant random intercepts of incubator centre performance across the programs. Models that match program goals and standard selection tools were also found to have significant random slopes as level two random covariates in the model. Based on the findings of significant random slopes, the study concluded that incubator classification is key for client selection criteria and enhances incubator performance.


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