scholarly journals Insect-mediated apparent competition between mammals in a boreal food web

2021 ◽  
Vol 118 (30) ◽  
pp. e2022892118
Author(s):  
Guillemette Labadie ◽  
Philip D. McLoughlin ◽  
Mark Hebblewhite ◽  
Daniel Fortin
Keyword(s):  
Large Scale ◽  
Rangifer Tarandus ◽  
Choristoneura Fumiferana ◽  
Insect Pest ◽  
Apparent Competition ◽  
Trophic Levels ◽  
Salvage Logging ◽  
Predator Prey ◽  
Consumer Interactions ◽  
The Impact

While the important role of animal-mediated interactions in the top-down restructuring of plant communities is well documented, less is known of their ensuing repercussions at higher trophic levels. We demonstrate how typically decoupled ecological interactions may become intertwined such that the impact of an insect pest on forest structure and composition alters predator–prey interactions among large mammals. Specifically, we show how irruptions in a common, cyclic insect pest of the boreal forest, the spruce budworm (Choristoneura fumiferana), modulated an indirect trophic interaction by initiating a flush in deciduous vegetation that benefited moose (Alces alces), in turn strengthening apparent competition between moose and threatened boreal caribou (Rangifer tarandus caribou) via wolf (Canis lupus) predation. Critically, predation on caribou postoutbreak was exacerbated by human activity (salvage logging). We believe our observations of significant, large-scale reverberating consumer–producer–consumer interactions are likely to be common in nature.

scholarly journals Linking Terrestrial and Aquatic Biodiversity to Ecosystem Function Across Scales, Trophic Levels, and Realms

2021 ◽  
Vol 9 ◽  
Author(s):  
Kyla M. Dahlin ◽  
Phoebe L. Zarnetske ◽  
Quentin D. Read ◽  
Laura A. Twardochleb ◽  
Aaron G. Kamoske ◽  
...  
Keyword(s):  
Ecosystem Function ◽  
Large Scale ◽  
Information Science ◽  
Spatial Scales ◽  
Biodiversity Loss ◽  
Relative Strength ◽  
Trophic Levels ◽  
Aquatic Biodiversity ◽  
Patterns And Processes ◽  
The Impact

Global declines in biodiversity have the potential to affect ecosystem function, and vice versa, in both terrestrial and aquatic ecological realms. While many studies have considered biodiversity-ecosystem function (BEF) relationships at local scales within single realms, there is a critical need for more studies examining BEF linkages among ecological realms, across scales, and across trophic levels. We present a framework linking abiotic attributes, productivity, and biodiversity across terrestrial and inland aquatic realms. We review examples of the major ways that BEF linkages form across realms–cross-system subsidies, ecosystem engineering, and hydrology. We then formulate testable hypotheses about the relative strength of these connections across spatial scales, realms, and trophic levels. While some studies have addressed these hypotheses individually, to holistically understand and predict the impact of biodiversity loss on ecosystem function, researchers need to move beyond local and simplified systems and explicitly investigate cross-realm and trophic interactions and large-scale patterns and processes. Recent advances in computational power, data synthesis, and geographic information science can facilitate studies spanning multiple ecological realms that will lead to a more comprehensive understanding of BEF connections.

Impacts of macrozoobenthic invasions on a temperate coastal food web

2020 ◽  
Vol 653 ◽  
pp. 19-39
Author(s):  
AS Jung ◽  
HW van der Veer ◽  
CJM Philippart ◽  
AM Waser ◽  
BJ Ens ◽  
...  
Keyword(s):  
Food Web ◽  
Native Species ◽  
Wadden Sea ◽  
Marine Species ◽  
Trophic Levels ◽  
Food Web Structure ◽  
Total Consumption ◽  
Predator Prey ◽  
Carbon Transfer ◽  
The Impact

Invasions of marine species are changing coastal food webs worldwide, impacting on trophic interactions between native species (e.g. predator-prey relationships). Here, the impact of 3 macrozoobenthic invasive species on food web structure and functioning at Balgzand (western Wadden Sea) is quantified by using ecological network analysis (ENA). The bivalves Ensis leei and Magallana gigas were observed for the first time in 1984 and 2001, respectively, and the polychaete Marenzelleria viridis appeared in 1989. Although E. leei and M. viridis reached similar peak biomasses in the 2000s (ca. 1700 and 2000 mg C m-2, respectively), the bivalve consumption was higher (>45% of total consumption) than that of the polychaete (<10%). Biomass and impact of M. gigas remained relatively low. E. leei occupied an ecological niche that was relatively unoccupied, which led to competitive advantage with respect to other suspension feeders. Increasing biomass of E. leei coincided with a 70% increase of trophic carbon transfer from primary to secondary producers and an 80% increase from secondary producers to detritus. Carbon flows from secondary producers to higher trophic levels were reduced by more than 60%. These shifts in trophic transfer were stronger than those observed during the invasion of M. gigas in the NE Wadden Sea. At Balgzand, biomass of M. gigas and M. viridis rapidly declined to low values in the 2010s, implying a temporally limited impact. In the 2010s, E. leei was still responsible for 30% of the total consumption in the 2010s, indicating a longer-term impact.

scholarly journals Using predator-prey theory to predict outcomes of a broad-scale test of apparent competition

2020 ◽  
Author(s):  
R Serrouya ◽  
M Wittmann ◽  
B McLellan ◽  
Heiko Wittmer ◽  
S Boutin
Keyword(s):  
Rangifer Tarandus ◽  
Field Experiments ◽  
Puma Concolor ◽  
Field Studies ◽  
Apparent Competition ◽  
Ecological Communities ◽  
Predator Prey ◽  
Theoretical Predictions ◽  
Scale Test ◽  
The University

© 2015 by The University of Chicago. 0003-0147/2015/18505-55371$15.00. All rights reserved. Apparent competition is an important process influencing many ecological communities. We used predator-prey theory to predict outcomes of ecosystem experiments aimed at mitigating apparent competition by reducing primary prey. Simulations predicted declines in secondary prey following reductions in primary prey because predators consumed more secondary prey until predator numbers responded to reduced prey densities. Losses were exacerbated by a higher carrying capacity of primary prey and a longer lag time of the predator’s numerical response, but a gradual reduction in primary prey was less detrimental to the secondary prey. We compared predictions against two field experiments where endangered woodland caribou (Rangifer tarandus caribou) were victims of apparent competition. First, when deer (Odocoileus sp.) declined suddenly following a severe winter, cougar (Puma concolor) declined with a 1– 2-year lag, yet in the interim more caribou were killed by cougars, and caribou populations declined by 40%. Second, when moose (Alces alces) were gradually reduced using a management experiment, wolf (Canis lupus) populations declined but did not shift consumption to caribou, and the largest caribou subpopulation stabilized. The observed contrasting outcomes of sudden versus gradual declines in primary prey supported theoretical predictions. Combining theory with field studies clarified how to manage communities to mitigate endangerment caused by apparent competition that affects many taxa.

scholarly journals Transmission Dynamics of Resistant Bacteria in a Predator-Prey System

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Xubin Gao ◽  
Qiuhui Pan ◽  
Mingfeng He
Keyword(s):  
Human Health ◽  
Large Scale ◽  
Equilibrium Points ◽  
Predation Rate ◽  
Resistant Bacteria ◽  
Mathematical Methods ◽  
Predator Prey ◽  
Prey System ◽  
The Stability ◽  
The Impact

This paper discusses the impact on human health caused by the addition of antibiotics in the feed of food animals. We use the established transmission rule of resistant bacteria and combine it with a predator-prey system to determine a differential equations model. The equations have three steady equilibrium points corresponding to three population dynamics states under the influence of resistant bacteria. In order to quantitatively analyze the stability of the equilibrium points, we focused on the basic reproduction numbers. Then, both the local and global stability of the equilibrium points were quantitatively analyzed by using essential mathematical methods. Numerical results are provided to relate our model properties to some interesting biological cases. Finally, we discuss the effect of the two main parameters of the model, the proportion of antibiotics added to feed and the predation rate, and estimate the human health impacts related to the amount of feed antibiotics used. We further propose an approach for the prevention of the large-scale spread of resistant bacteria and illustrate the necessity of controlling the amount of in-feed antibiotics used.

scholarly journals What ocean biogeochemical models can tell us about bottom-up control of ecosystem variability

2011 ◽  
Vol 68 (6) ◽  
pp. 1030-1044 ◽  
Author(s):  
A. Gnanadesikan ◽  
J. P. Dunne ◽  
J. John
Keyword(s):  
Interannual Variability ◽  
Phytoplankton Biomass ◽  
Large Scale ◽  
Trophic Levels ◽  
Areal Extent ◽  
Bottom Up ◽  
High Productivity ◽  
Biogeochemical Models ◽  
Ocean Reanalyses ◽  
The Impact

Abstract Gnanadesikan, A., Dunne, J. P., and John, J. 2011. What ocean biogeochemical models can tell us about bottom-up control of ecosystem variability. – ICES Journal of Marine Science, 68: 1030–1044. Processes included in earth system models amplify the impact of climate variability on phytoplankton biomass and, therefore, on upper trophic levels. Models predict much larger relative interannual variability in large phytoplankton biomass than in total phytoplankton biomass, supporting the goal of better constraining size-structured primary production and biomass from remote sensing. The largest modelled variability in annually averaged large phytoplankton biomass is associated with changes in the areal extent of relatively productive regions. Near the equator, changes in the areal extent of the high-productivity zone are driven by large-scale shifts in nutrient fields, as well as by changes in currents. Along the poleward edge of the Subtropical Gyres, changes in physical mixing dominate. Finally, models indicate that high-latitude interannual variability in large phytoplankton biomass is greatest during spring. Mechanisms for producing such variability differ across biomes with internal ocean processes, such as convection complicating efforts to link ecosystem variability to climate modes defined using sea surface temperature alone. In salinity-stratified subpolar regions, changes in bloom timing driven by salinity can produce correlations between low surface temperatures and high productivity, supporting the potential importance of using coupled atmosphere–ocean reanalyses, rather than simple forced ocean reanalyses, for attributing past ecosystem shifts.

scholarly journals Avoidance of roads and selection for recent cutovers by threatened caribou: fitness-rewarding or maladaptive behaviour?

2012 ◽  
Vol 279 (1746) ◽  
pp. 4481-4488 ◽  
Author(s):  
Christian Dussault ◽  
Véronique Pinard ◽  
Jean-Pierre Ouellet ◽  
Réhaume Courtois ◽  
Daniel Fortin
Keyword(s):  
Habitat Selection ◽  
Rangifer Tarandus ◽  
Negative Impact ◽  
Relative Effect ◽  
Trophic Levels ◽  
Road Density ◽  
Functional Link ◽  
Calf Survival ◽  
Large Animals ◽  
The Impact

The impact of anthropogenic disturbance on the fitness of prey should depend on the relative effect of human activities on different trophic levels. This verification remains rare, however, especially for large animals. We investigated the functional link between habitat selection of female caribou ( Rangifer tarandus ) and the survival of their calves, a fitness correlate. This top-down controlled population of the threatened forest-dwelling caribou inhabits a managed forest occupied by wolves ( Canis lupus ) and black bears ( Ursus americanus ). Sixty-one per cent of calves died from bear predation within two months following their birth. Variation in habitat selection tactics among mothers resulted in different mortality risks for their calves. When calves occupied areas with few deciduous trees, they were more likely to die from predation if the local road density was high. Although caribou are typically associated with pristine forests, females selected recent cutovers without negative impact on calf survival. This selection became detrimental, however, as regeneration took place in harvested stands owing to increased bear predation. We demonstrate that human disturbance has asymmetrical consequences on the trophic levels of a food web involving multiple large mammals, which resulted in habitat selection tactics with a greater short-term fitness payoff and, therefore, with higher evolutionary opportunity.

scholarly journals Viral infection switches the balance between bacterial and eukaryotic recyclers of organic matter during algal blooms

2021 ◽  
Author(s):  
Flora Vincent ◽  
Matti Gralka ◽  
Guy Schleyer ◽  
Daniella J Schatz ◽  
Miguel Cabrera-Brudau ◽  
...  
Keyword(s):  
Organic Matter ◽  
Viral Infection ◽  
Algal Blooms ◽  
Large Scale ◽  
Deep Ocean ◽  
Trophic Levels ◽  
Microbiome Composition ◽  
Carbon Release ◽  
Open Question ◽  
The Impact

Algal blooms are hotspots of marine primary production and play central roles in microbial ecology and global nutrient cycling. When blooms collapse, organic carbon is transferred to higher trophic levels, microbial respiration or sinking in proportions that depend on the dominant mortality agent. Viral infection can lead to bloom termination, but its impact on the fate of carbon remains an open question. Here, we characterized the consequences of viral infection on the microbiome composition and biogeochemical landscape of marine ecosystems by conducting a large-scale mesocosm experiment. Moniroting of seven induced coccolithophore blooms, which showed different degrees of viral infection, revealed that only high levels of viral infection caused significant shifts in the composition of free-living bacterial and eukaryotic assemblages. Intriguingly, viral infection favored the growth of eukaryotic heterotrophs (thraustochytrids) over bacteria as potential recyclers of organic matter. By combining modeling and quantification of active viral infection at a single-cell resolution, we estimate that viral infection can increase per-cell rates of extracellular carbon release by 2-4.5 fold. This happened via production of acidic polysaccharides and particulate inorganic carbon, two major contributors to carbon sinking into the deep ocean. These results reveal the impact of viral infection on the fate of carbon through microbial recyclers of organic matter in large-scale coccolithophore blooms.

scholarly journals Decomposing the effects of ocean environments on predator–prey body-size relationships in food webs

2018 ◽  
Vol 5 (7) ◽  
pp. 180707 ◽  
Author(s):  
Tomoya Dobashi ◽  
Midori Iida ◽  
Kazuhiro Takemoto
Keyword(s):  
Body Size ◽  
Food Webs ◽  
Oxygen Concentration ◽  
Large Scale ◽  
Small Body ◽  
Large Body ◽  
Predator Prey ◽  
Body Sizes ◽  
And Function ◽  
The Impact

Body-size relationships between predators and their prey are important in ecological studies because they reflect the structure and function of food webs. Inspired by studies on the impact of global warming on food webs, the effects of temperature on body-size relationships have been widely investigated; however, the impact of environmental factors on body-size relationships has not been fully evaluated because climate warming affects various ocean environments. Thus, here, we comprehensively investigated the effects of ocean environments and predator–prey body-size relationships by integrating a large-scale dataset of predator–prey body-size relationships in marine food webs with global oceanographic data. We showed that various oceanographic parameters influence prey size selection. In particular, oxygen concentration, primary production and salinity, in addition to temperature, significantly alter body-size relationships. Furthermore, we demonstrated that variability (seasonality) of ocean environments significantly affects body-size relationships. The effects of ocean environments on body-size relationships were generally remarkable for small body sizes, but were also significant for large body sizes and were relatively weak for intermediate body sizes, in the cases of temperature seasonality, oxygen concentration and salinity variability. These findings break down the complex effects of ocean environments on body-size relationships, advancing our understanding of how ocean environments influence the structure and functioning of food webs.

scholarly journals Anti-Insect Secondary Metabolites from Fungal Endophytes of Conifer Trees

2009 ◽  
Vol 4 (11) ◽  
pp. 1934578X0900401 ◽  
Author(s):  
Mark W. Sumarah ◽  
J. David Miller
Keyword(s):  
Choristoneura Fumiferana ◽  
Insect Pest ◽  
Fungal Endophytes ◽  
Abies Balsamea ◽  
Grass Species ◽  
Herbivorous Insects ◽  
Insect Toxins ◽  
Conifer Trees ◽  
The Impact ◽  
Chemical Pesticides

Choristoneura fumiferana is the most economically-important insect pest in eastern North America. Historically, strategies to control epidemics have relied on chemical pesticides that are no longer approved for use. The presence of fungal endophytes in cool area grass species and their role in reducing the impact of herbivorous insects is well understood. Recent work has demonstrated that foliar endophytes of conifers also produce anti-insect toxins. Field and nursery studies testing trees infected with the rugulosin producing endophyte Phialocephala scopiformis reduced the growth and development of C. fumiferana. The study of foliar endophytes from a variety of conifers including: Picea mariana, P. rubens and P. glauca as well as Abies balsamea and Larix laricina for the discovery of other anti-insect toxins are discussed. These endophytes are horizontally transmitted thus they are not present in nursery seedlings. Inoculating seedlings with toxigenic endophyte strains has been demonstrated to be effective in providing the tree with tolerance to herbivorous insects.

scholarly journals Interdecadal variability in the Gulf of Maine zooplankton community, with potential impacts on fish recruitment

2005 ◽  
Vol 62 (7) ◽  
pp. 1511-1523 ◽  
Author(s):  
Andrew J. Pershing ◽  
Charles H. Greene ◽  
Jack W. Jossi ◽  
Loretta O'Brien ◽  
Jon K.T. Brodziak ◽  
...  
Keyword(s):  
Time Series ◽  
Large Scale ◽  
Gulf Of Maine ◽  
Principal Component ◽  
Trophic Levels ◽  
Interdecadal Variability ◽  
Calanus Finmarchicus ◽  
Rapid Decline ◽  
Zooplankton Abundance ◽  
The Impact

Abstract We used principal component analysis (PCA) to explore interannual changes in a time-series lasting more than 40 years of zooplankton abundance from NOAA's Continuous Plankton Recorder (CPR) survey. This analysis identified a complex of taxa, including Centropages typicus, Oithona spp., Pseudocalanus spp., and Metridia lucens that followed a common pattern of interdecadal variability characterized by a dramatic increase in these taxa around 1990, followed by a rapid decline in 2002. All of these taxa showed a large proportional increase in winter abundance between the 1980s and 1990s. These changes could be driven by increased primary productivity during winter, caused by a large-scale freshening of the Northwest Atlantic Shelf. In addition to the “community shift” mode, the analysis found a strong mode of interannual variability attributed to previously described changes in the abundance of late-stage Calanus finmarchicus. To explore the impact of these modes on higher trophic levels, we correlated the zooplankton modes with recruitment time-series from 12 fish stocks from the Gulf of Maine region. Several significant correlations were found, suggesting that the changes in the zooplankton modes may reflect broad changes in the Gulf of Maine ecosystem.

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