scholarly journals Predator complementarity dampens variability of phytoplankton biomass in a diversity-stability trophic cascade

2019 ◽  
Author(s):  
Chase J. Rakowski ◽  
Caroline E. Farrior ◽  
Schonna R. Manning ◽  
Mathew A. Leibold
Keyword(s):  
Trophic Cascade ◽  
Phytoplankton Biomass ◽  
Trophic Cascades ◽  
Trophic Levels ◽  
Cascading Effects ◽  
Predator Diversity ◽  
Laboratory Microcosm ◽  
Average Biomass ◽  
Basal Resources ◽  
The Stability

AbstractTrophic cascades – indirect effects of predators that propagate down through food webs – have been extensively documented, especially in aquatic ecosystems. It has also been shown that predator diversity can mediate these trophic cascades, and, separately, that herbivore biomass can impact the stability of primary producers. However, whether predator diversity can cause cascading effects on the stability of lower trophic levels has not yet been studied. We conducted a laboratory microcosm experiment and a field mesocosm experiment manipulating the presence and coexistence of two heteropteran predators and measuring their effects on zooplankton herbivores and phytoplankton basal resources. We predicted that, if the predators partitioned their herbivore prey, for example by size, then co-presence of the predators would lead to 1) increased average values and 2) decreased temporal variability of phytoplankton basal resources. We present evidence that the predators partitioned their herbivore prey and found that their simultaneous suppression of herbivore groups reduced the variability of edible (smaller) phytoplankton biomass, without affecting mean phytoplankton biomass. We also found that phytoplankton that were more resistant to herbivory were not affected by our manipulations, indicating that the zooplankton herbivores played an important role in mediating this cascading diversity-stability effect. Our results demonstrate that predator diversity may indirectly stabilize basal resource biomass via a “diversity-stability trophic cascade,” seemingly dependent on predator complementarity and the vulnerability of taxa to consumption, but independent of a classic trophic cascade in which average biomass is altered. Predator diversity, especially if correlated with diversity of prey use, may be important for regulating ecosystem stability, and this relationship suggests biological control methods for improving the reliability of microalgal yields.

Large mammals generate both top-down effects and extended trophic cascades on floral-visitor assemblages

2019 ◽  
Vol 35 (4) ◽  
pp. 185-198 ◽  
Author(s):  
Allison Louthan ◽  
Emily Valencia ◽  
Dino J. Martins ◽  
Travis Guy ◽  
Jacob Goheen ◽  
...  
Keyword(s):  
Trophic Cascade ◽  
Structural Equation ◽  
Trophic Cascades ◽  
Trophic Levels ◽  
Large Mammals ◽  
Top Down ◽  
Cascading Effects ◽  
Floral Visitor ◽  
Show Evidence ◽  
Floral Visitors

AbstractCascading effects of high trophic levels onto lower trophic levels have been documented in many ecosystems. Some studies also show evidence of extended trophic cascades, in which guilds dependent on lower trophic levels, but uninvolved in the trophic cascade themselves, are affected by the trophic cascade due to their dependence on lower trophic levels. Top-down effects of large mammals on plants could lead to a variety of extended trophic cascades on the many guilds dependent on plants, such as pollinators. In this study, floral-visitor and floral abundances and assemblages were quantified within a series of 1-ha manipulations of large-mammalian herbivore density in an African savanna. Top-down effects of large mammals on the composition of flowers available for floral visitors are first shown, using regressions of herbivore activity on metrics of floral and floral-visitor assemblages. An extended trophic cascade is also shown: the floral assemblage further altered the assemblage of floral visitors, according to a variety of approaches, including a structural equation modelling approach (model with an extended trophic cascade was supported over a model without, AICc weight = 0.984). Our study provides support for extended trophic cascades affecting floral visitors, suggesting that trophic cascades can have impacts throughout entire communities.

Effect of an invasive filter-feeder on the zooplankton assemblage in a coastal lagoon

2015 ◽  
Vol 96 (6) ◽  
pp. 1201-1210 ◽  
Author(s):  
Martin Bruschetti ◽  
Tomas Luppi ◽  
Oscar Iribarne
Keyword(s):  
Phytoplankton Biomass ◽  
Food Resource ◽  
Zooplankton Community ◽  
Grazing Intensity ◽  
Trophic Levels ◽  
Grazing Impact ◽  
Filter Feeder ◽  
Cascading Effects ◽  
Mesocosm Experiments ◽  
The Impact

Depletion of phytoplankton biomass by the introduced reef-forming polychaete Ficopomatus enigmaticus has previously been observed in the Mar Chiquita lagoon (37°40′S 57°23′W; Argentina), but the effect of polychaetes on the higher trophic levels is still unknown. To evaluate the effect of this polychaete on the zooplankton assemblage, replicated mesocosm experiments (N = 10) were performed during spring, summer and winter. Mesocosms with reefs and without reefs were installed and grazing intensity and the effect on the zooplankton assemblage by the polychaetes were assessed. Our results show that the reefs of F. enigmaticus generate minor changes in overall composition of zooplankton assemblage. Although the structure of the zooplankton assemblage was different between seasons, the impact of the reefs was not significant in any of them. There was no relationship between the decline of food resource by grazing and changes in the structure of the zooplankton assemblage. Thus, contrary to our hypothesis, the grazing impact of the invasive polychaete on the biomass of primary producers did not generate cascading effects to higher trophic levels. However, changes in some components of the zooplankton assemblage (e.g. cladocerans) clearly show that the reefs of F. enigmaticus have the potential to affect the structure of the zooplankton community. The lack of data of community composition and abundance of zooplankton before the invasion limits the understanding of how this polychaete might have affected the structure and abundance of the zooplankton of this lagoon. Nevertheless this work suggests that these changes may not be so significant.

scholarly journals Beyond the fish-Daphnia paradigm: testing the potential for Neoplea striola (Hemiptera: Pleidae) to cause a trophic cascade in subtropical ponds

2021 ◽  
Author(s):  
Chase J. Rakowski ◽  
Mathew A. Leibold
Keyword(s):  
Food Web ◽  
Trophic Cascade ◽  
Trophic Cascades ◽  
Zooplankton Community ◽  
Trophic Levels ◽  
Food Web Interactions ◽  
Top Predators ◽  
Invertebrate Predators ◽  
Consumption Rates ◽  
Central Texas

AbstractTrophic cascades, or indirect effects of predators on non-adjacent lower trophic levels, are thought to pervade diverse ecosystems, though they tend to be stronger in aquatic ecosystems. Most research on freshwater trophic cascades focused on temperate lakes where Daphnia tend to dominate the zooplankton community, and these studies identified that Daphnia plays a key role in facilitating trophic cascades by linking fish to algae with strong food web interactions. However, Daphnia are rare or absent in most tropical and subtropical lowland freshwaters, and many invertebrate predators have received little attention in food web research despite being common and widespread. Therefore, we aimed to test whether trophic cascades are possible in small warmwater ponds where small invertebrates are the top predators and Daphnia are absent. We collected naturally occurring plankton communities from small fishless water bodies in central Texas and propagated them in replicate pond mesocosms. We removed zooplankton from some mesocosms, left the plankton community intact in others, and added one of two densities of the predaceous insect Neoplea striola to others. Following an incubation period we then compared biomasses of plankton groups to assess food web effects between the trophic levels including whether Neoplea caused a trophic cascade by reducing zooplankton. The zooplankton community became dominated by copepods which prefer large phytoplankton and exhibit a fast escape response. Perhaps due to these qualities of the copepods and perhaps due to slow consumption rates by Neoplea on key grazers, no food web effects were found other than zooplankton marginally reducing large phytoplankton. More research is needed to understand the behavior and ecology of Neoplea, but trophic cascades may generally be weak or absent in subtropical and tropical lowland freshwaters where Daphnia is rare.

scholarly journals Destabilizing effects on a classic tri-trophic oyster-reef cascade

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0242965
Author(s):  
Virginia R. Schweiss ◽  
Chet F. Rakocinski
Keyword(s):  
Trophic Cascade ◽  
Oyster Reef ◽  
Trophic Cascades ◽  
Oyster Shell ◽  
Mud Crab ◽  
Predator Species ◽  
Multiple Predators ◽  
Stone Crab ◽  
The Stability ◽  
Mud Crabs

How interactions among multiple predators affect the stability of trophic cascades is a topic of special ecological interest. To examine factors affecting the stability of the classic tri-trophic oyster reef cascade within a different context, configurations of three predators, including the Gulf toadfish, Gulf stone crab, and oystershell mud crab, were manipulated together with either oyster shell or limestone gravel substrate within a multiple predator effects (MPE) experiment. Additionally, a complimentary set of trait-mediated-indirect interaction (TMII) experiments examined the inhibition of oyster consumption relative to mud-crab size and top predator identity in the absence of other cues and factors. The classic tri-trophic cascade formed by the toadfish-mud crab-oyster configuration was potentially weakened by several interactions within the MPE experiment. Consumption of oysters and mud crabs by the intraguild stone crab was undeterred by the presence of toadfish. Although mud crab feeding was inhibited in the presence of both toadfish and stone crabs, estimated non-consumptive effects (NCEs) were weaker for stone crabs in the MPE experiment. Consequently, the total effect was destabilizing when all three predator species were together. Inhibition of mud crab feeding was inversely related to direct predation on mud crabs within the MPE experiment. Complimentary TMII experiments revealed greater inhibition of mud crab feeding in response to stone crabs under sparse conditions. TMII experiments also implied that inhibition of mud crab feeding could have largely accounted for NCEs relative to oysters within the MPE experiment, as opposed to interference by other mud crabs or top predators. An inverse relationship between mud crab size and NCE strength in the TMII experiment disclosed another potentially destabilizing influence on the tri-trophic-cascade. Finally, although habitat complexity generally dampened the consumption of oysters across MPE treatments, complex habitat promoted mud crab feeding in the presence of toadfish alone. This study underscores how ecological interactions can mediate trophic cascades and provides some additional insights into the trophic dynamics of oyster reefs for further testing under natural conditions.

scholarly journals Intraspecific difference among herbivore lineages and their host-plant specialization drive the strength of trophic cascades

2019 ◽  
Author(s):  
Arnaud Sentis ◽  
Raphaël Bertram ◽  
Nathalie Dardenne ◽  
Jean-Christophe Simon ◽  
Alexandra Magro ◽  
...  
Keyword(s):  
Host Plant ◽  
Trophic Cascade ◽  
Trophic Cascades ◽  
Ecological Factors ◽  
Trophic Levels ◽  
Ecological Communities ◽  
Intraspecific Trait Variation ◽  
Host Plant Specialization ◽  
Joint Influence ◽  
Intraspecific Difference

AbstractTrophic cascades—the indirect effect of predators on non-adjacent lower trophic levels—are important drivers of the structure and dynamics of ecological communities. However, the influence of intraspecific trait variation on the strength of trophic cascade remains largely unexplored, which limits our understanding of the mechanisms underlying ecological networks. Here we experimentally investigated how intraspecific difference among herbivore lineages specialized on different host plants influences the strength of trophic cascade in a terrestrial tritrophic system. We found that the occurrence and strength of the trophic cascade are strongly influenced by herbivores’ lineage and host-plant specialization but are not associated with density-dependent effects mediated by the growth rate of herbivore populations. Our findings stress the importance of intraspecific heterogeneities and evolutionary specialization as drivers of the strength of trophic cascades and underline that intraspecific variation should not be overlooked to decipher the joint influence of evolutionary and ecological factors on the functioning of multi-trophic interactions.

scholarly journals Stability trophic cascades in food chains

2018 ◽  
Vol 5 (11) ◽  
pp. 180995 ◽  
Author(s):  
David W. Shanafelt ◽  
Michel Loreau
Keyword(s):  
Simple Model ◽  
General Theory ◽  
Food Chain ◽  
Empirical Studies ◽  
Trophic Cascades ◽  
Trophic Levels ◽  
Individual Species ◽  
Food Chains ◽  
Top Down ◽  
The Stability

While previous studies have evaluated the change in stability for the addition or removal of individual species from trophic food chains and food webs, we know of no study that presents a general theory for how stability changes with the addition or removal of trophic levels. In this study, we present a simple model of a linear food chain and systematically evaluate how stability—measured as invariability—changes with the addition or removal of trophic levels. We identify the presence of trophic cascades in the stability of species. Owing to top-down control by predation and bottom-up regulation by prey, we find that stability of a species is highest when it is at the top of the food chain and lowest when it is just under the top of the food chain. Thus, stability shows patterns identical to those of mean biomass with the addition or removal of trophic levels in food chains. Our results provide a baseline towards a general theory of the effect of adding or removing trophic levels on stability, which can be used to inform empirical studies.

Switching effect on the stability of the prey-predator system with three trophic levels

1986 ◽  
Vol 122 (3) ◽  
pp. 251-262 ◽  
Author(s):  
Hiroyuki Matsuda ◽  
Kohkichi Kawasaki ◽  
Nanako Shigesada ◽  
Ei Teramoto ◽  
Luigi M. Ricciardi
Keyword(s):  
Trophic Levels ◽  
Switching Effect ◽  
The Stability ◽  
Predator System

Physical forcing and the dynamics of the pelagic ecosystem in the eastern tropical Pacific: simulations with ENSO-scale and global-warming climate drivers

2003 ◽  
Vol 60 (9) ◽  
pp. 1161-1175 ◽  
Author(s):  
George M Watters ◽  
Robert J Olson ◽  
Robert C Francis ◽  
Paul C Fiedler ◽  
Jeffrey J Polovina ◽  
...  
Keyword(s):  
Global Warming ◽  
Phytoplankton Biomass ◽  
Southern Oscillation ◽  
Tropical Pacific ◽  
Trophic Levels ◽  
Eastern Tropical Pacific ◽  
Ecosystem Models ◽  
Pelagic Ecosystem ◽  
Physical Forcing ◽  
Physical Effects

We used a model of the pelagic ecosystem in the eastern tropical Pacific Ocean to explore how climate variation at El Niño – Southern Oscillation (ENSO) scales might affect animals at middle and upper trophic levels. We developed two physical-forcing scenarios: (1) physical effects on phytoplankton biomass and (2) simultaneous physical effects on phytoplankton biomass and predator recruitment. We simulated the effects of climate-anomaly pulses, climate cycles, and global warming. Pulses caused oscillations to propagate through the ecosystem; cycles affected the shapes of these oscillations; and warming caused trends. We concluded that biomass trajectories of single populations at middle and upper trophic levels cannot be used to detect bottom-up effects, that direct physical effects on predator recruitment can be the dominant source of interannual variability in pelagic ecosystems, that such direct effects may dampen top-down control by fisheries, and that predictions about the effects of climate change may be misleading if fishing mortality is not considered. Predictions from ecosystem models are sensitive to the relative strengths of indirect and direct physical effects on middle and upper trophic levels.

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