Effects of fish on plankton dynamics: a theoretical analysis

2000 ◽  
Vol 57 (6) ◽  
pp. 1208-1219 ◽  
Author(s):  
Marten Scheffer ◽  
Sergio Rinaldi ◽  
Yuri A Kuznetsov
Keyword(s):  
Phytoplankton Biomass ◽  
Food Limitation ◽  
Homoclinic Bifurcation ◽  
The Other ◽  
Fish Density ◽  
Nutrient Concentrations ◽  
Field Observations ◽  
Top Predator ◽  
Predator Prey ◽  
Young Of The Year

We present an expansion of a classical minimal Daphnia-algae model to account for effects of fish as a top predator. Our analyses suggest that in most situations, the plankton should show hysteresis in response to predation pressure by fish. Thus, there exist two distinct regimes, one in which Daphnia is controlled (overexploited) by fish and phytoplankton biomass is high and another in which Daphnia is relatively unaffected (underexploited) by planktivores and algae are controlled by Daphnia. Switches from one regime to the other occur abruptly at a critical fish density. This is in line with field observations and experimental results. Our model predicts that the critical fish density for Daphnia collapse is higher in systems with higher ambient nutrient concentrations. The model also shows how intrinsic predator-prey oscillations in the planktonic system can facilitate the switch to the algal-dominated regime where Daphnia is controlled by fish. In terms of dynamical systems theory, this switch happens through a homoclinic bifurcation. In biological terms, Daphnia collapses due to food limitation and is subsequently overexploited by fish. This is indeed the sequence of mechanisms observed at the end of the spring clearwater phase in lakes where Daphnia is absent during the summer when the biomass of young-of-the-year planktivorous fish becomes high.

scholarly journals Predator–prey body size relationships when predators can consume prey larger than themselves

2013 ◽  
Vol 9 (3) ◽  
pp. 20121193 ◽  
Author(s):  
Takefumi Nakazawa ◽  
Shin-ya Ohba ◽  
Masayuki Ushio
Keyword(s):  
Body Size ◽  
Prey Size ◽  
The Other ◽  
Field Observations ◽  
Species Identity ◽  
Predator Prey ◽  
Size Dependent ◽  
Fish Predators ◽  
Body Sizes ◽  
Prey Mass

As predator–prey interactions are inherently size-dependent, predator and prey body sizes are key to understanding their feeding relationships. To describe predator–prey size relationships (PPSRs) when predators can consume prey larger than themselves, we conducted field observations targeting three aquatic hemipteran bugs, and assessed their body masses and those of their prey for each hunting event. The data revealed that their PPSR varied with predator size and species identity, although the use of the averaged sizes masked these effects. Specifically, two predators had slightly decreased predator–prey mass ratios (PPMRs) during growth, whereas the other predator specialized on particular sizes of prey, thereby showing a clear positive size–PPMR relationship. We discussed how these patterns could be different from fish predators swallowing smaller prey whole.

Planktivory by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) on microcrustacean zooplankton and dreissenid (Bivalvia: Dreissenidae) veligers in southern Lake Ontario

1995 ◽  
Vol 52 (5) ◽  
pp. 925-935 ◽  
Author(s):  
Edward L. Mills ◽  
Connie Adams ◽  
Robert O'Gorman ◽  
Randall W. Owens ◽  
Edward F. Roseman
Keyword(s):  
Laboratory Experiments ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Field Observations ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Consumption Rates ◽  
South Shore ◽  
Young Of The Year ◽  
Veliger Larvae

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.

Predator and prey detection in two species of water bear (Tardigrada)

2019 ◽  
Vol 188 (3) ◽  
pp. 860-864 ◽  
Author(s):  
Harry A Meyer ◽  
Hannah E Larsen ◽  
Nézira O Akobi ◽  
Garret Broussard
Keyword(s):  
Environmental Conditions ◽  
The Other ◽  
Physical Contact ◽  
Nutrient Agar ◽  
Control Treatment ◽  
Prey Detection ◽  
Potential Prey ◽  
Predator Prey ◽  
Petri Dishes

Abstract Tardigrade behavioural studies have focused on responses to abiotic environmental conditions. Predator–prey interactions have received some attention, but not how predators and prey might detect one another. Here, we investigate whether a predatory tardigrade species is attracted to, and a potential prey tardigrade avoids, areas previously occupied by the other. In our experiments, Milnesium lagniappe was the predator and Macrobiotus acadianus the prey. Petri dishes with non-nutrient agar were used as experimental arenas. In one treatment, we allowed Macrobiotus to roam over half of the agar for 20 h, while leaving the other half free of Macrobiotus. We then removed the prey and introduced the predator. In the control treatment, no prey were added. Results indicated that Milnesium individuals were significantly concentrated in the area previously occupied by Macrobiotus, whereas no such concentration was evident when Macrobiotus had not been present. A similar protocol was used to test whether Macrobiotus avoided areas previously occupied by the predator. As expected, Macrobiotus were significantly concentrated in the area never occupied by Milnesium, unlike the control treatment. These results suggest that both species can detect the other without physical contact and react accordingly. Given that the experiments were conducted in darkness, detection is probably olfactory.

scholarly journals Universal Evolutionary Model for Periodical Species

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Eric Goles ◽  
Ivan Slapničar ◽  
Marco A. Lardies
Keyword(s):  
Fitness Function ◽  
Evolutionary Model ◽  
Prime Numbers ◽  
Life Cycles ◽  
The Other ◽  
Exclusion Principle ◽  
Greatest Common Divisor ◽  
Predator Prey ◽  
Integer Multiple ◽  
New Period

Real-world examples of periodical species range from cicadas, whose life cycles are large prime numbers, like 13 or 17, to bamboos, whose periods are large multiples of small primes, like 40 or even 120. The periodicity is caused by interaction of species, be it a predator-prey relationship, symbiosis, commensalism, or competition exclusion principle. We propose a simple mathematical model, which explains and models all those principles, including listed extremal cases. This rather universal, qualitative model is based on the concept of a local fitness function, where a randomly chosen new period is selected if the value of the global fitness function of the species increases. Arithmetically speaking, the different interactions are related to only four principles: given a couple of integer periods either (1) their greatest common divisor is one, (2) one of the periods is prime, (3) both periods are equal, or (4) one period is an integer multiple of the other.

scholarly journals Prey-Predator Interactions in Two and Three Species Population Models

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Arild Wikan ◽  
Ørjan Kristensen
Keyword(s):  
Basin Of Attraction ◽  
Chaotic Regime ◽  
Population Models ◽  
The Other ◽  
Predator Population ◽  
Top Predator ◽  
Multiple Attractors ◽  
Species Population ◽  
Predator Interactions ◽  
Qualitative Structure

Discrete nonlinear two and three species prey-predator models are considered. Focus is on stability and nonstationary behaviour. Regarding the two species model, depending on the fecundity of the predator, we show that the transfer from stability to instability goes through either a supercritical flip or a supercritical Neimark-Sacker bifurcation and moreover that there exist multiple attractors in the chaotic regime, one where both species coexist and another where the predator population has become extinct. Sizes of basin of attraction for these possibilities are investigated. Regarding the three species models, we show that the dynamics may differ whether both predators prey upon the prey or if the top predator preys upon the other predator only. Both the sizes of stable parameter regions as well as the qualitative structure of attractors may be different.

Field observations on the social relationships between adult female and juvenile Richardson's ground squirrels

1973 ◽  
Vol 51 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Gail R. Michener
Keyword(s):  
Social Relationships ◽  
Adult Female ◽  
Ground Squirrels ◽  
The Other ◽  
Field Observations ◽  
Agonistic Interactions ◽  
The Social ◽  
And Behavior

Field observations were conducted in southern Saskatchewan in 1969 and 1971. Adult female Richardson's ground squirrels and their own young engaged predominantly in nasal and cohesive contacts while adults and young from other litters engaged predominantly in agonistic contacts. Identification sometimes occurred at a distance based on the location and behavior of the other animal.Newly emerged juveniles remained close to the home burrow and engaged mainly in non-agonistic interactions with both their mothers and other adults. Not until juveniles were 6–7 weeks old and were familiar with the area used by the mother did they correctly identify adults regardless of where the interaction occurred.

Effect of Water Body Morphology on Phytoplankton Biomass and Species Composition

2013 ◽  
Vol 777 ◽  
pp. 375-379
Author(s):  
Yue Hong Zhang ◽  
Fei Peng Li ◽  
Hu Hu Zhao ◽  
Hai Ping Zhang
Keyword(s):  
Species Composition ◽  
Water Body ◽  
Environmental Variables ◽  
Phytoplankton Biomass ◽  
Population Variation ◽  
Nutrient Concentrations ◽  
Body Morphology ◽  
Key Factor ◽  
Lake Type ◽  
River Type

Environmental variables, phytoplankton biomass and species composition in Nanhu Lake in Yingdong Village, Chongming Island were monitored from August 2010 to September 2011. The relationship between environmental variables and population variation of phytoplankton was discussed. The results showed that water body morphology was the key factor leading to the variation of phytoplankton community. In river-type waters the level of phytoplankton biomass was generally higher than that in lake-type waters, especially in summer. During the period of seasonal change, in river-type waters Cyanophyta dominated longer with the succession from Cyanophyta to Chlorophyta and Bacillariophyta occurred later than that in lake-type waters. Redundancy analysis (RDA) indicated that the morphology of enclosed waters had influence on phytoplankton biomass and species composition. One of the mechanisms may be that water body morphology could have impact on the growth and species dynamics of phytoplankton indirectly by affecting nutrient concentrations.

scholarly journals Trophic cascades alter eco-evolutionary dynamics and body size evolution

2020 ◽  
Vol 287 (1938) ◽  
pp. 20200526
Author(s):  
Thomas M. Luhring ◽  
John P. DeLong
Keyword(s):  
Body Mass ◽  
Trophic Level ◽  
Evolutionary Dynamics ◽  
Trophic Cascades ◽  
Trophic Levels ◽  
Chain Model ◽  
Top Predator ◽  
Predator Prey ◽  
Top Predators ◽  
Time Changes

Trait evolution in predator–prey systems can feed back to the dynamics of interacting species as well as cascade to impact the dynamics of indirectly linked species (eco-evolutionary trophic cascades; EETCs). A key mediator of trophic cascades is body mass, as it both strongly influences and evolves in response to predator–prey interactions. Here, we use Gillespie eco-evolutionary models to explore EETCs resulting from top predator loss and mediated by body mass evolution. Our four-trophic-level food chain model uses allometric scaling to link body mass to different functions (ecological pleiotropy) and is realistically parameterized from the FORAGE database to mimic the parameter space of a typical freshwater system. To track real-time changes in selective pressures, we also calculated fitness gradients for each trophic level. As predicted, top predator loss generated alternating shifts in abundance across trophic levels, and, depending on the nature and strength in changes to fitness gradients, also altered trajectories of body mass evolution. Although more distantly linked, changes in the abundance of top predators still affected the eco-evolutionary dynamics of the basal producers, in part because of their relatively short generation times. Overall, our results suggest that impacts on top predators can set off transient EETCs with the potential for widespread indirect impacts on food webs.

scholarly journals Phytoplankton Biomass Dynamics in Tropical Coastal Waters of Jakarta Bay, Indonesia in the Period between 2001 and 2019

2020 ◽  
Vol 8 (9) ◽  
pp. 674 ◽  
Author(s):  
Ario Damar ◽  
Franciscus Colijn ◽  
Karl-Juergen Hesse ◽  
Luky Adrianto ◽  
Yonvitner ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Algal Blooms ◽  
Temporal Dynamics ◽  
Inorganic Nitrogen ◽  
Outer Part ◽  
Middle Part ◽  
Nutrient Concentrations ◽  
Marine Biota ◽  
Chl A ◽  
Hypoxic Conditions

A study of nutrients, underwater light dynamics, and their correlation with phytoplankton biomass was conducted in the tropical estuary of Jakarta Bay, Indonesia, in the dry season during the period from 2001 to 2019. This study analyzed the spatial and temporal dynamics of phytoplankton biomass and its correlation with phytoplankton biomass. There was significant increase in nutrient concentration in Jakarta Bay, with annual means of 27.97 µM dissolved inorganic nitrogen (DIN) and 11.31 µM phosphates in 2001, increasing to 88.99 µM DIN and 25.92 µM phosphates in 2019. Increased mean nutrient concentrations were accompanied by increased mean phytoplankton biomass, from 15.81 µg Chl-a L−1 in 2001 to 21.31 µg Chl-a L−1 in 2019. The eutrophication status of Jakarta Bay waters was calculated using the Tropical Index for Marine Systems eutrophication index, which showed increased areas of hyper-eutrophic and eutrophic zones, while the mesotrophic area decreased. The hyper-eutrophic zone dominated the areas around river mouths and the inner part of the bay, while eutrophic status was observed in the middle part of the bay and mesotrophic status was found in the outer part of the bay. The area of hyper-eutrophic water increased 1.5-fold, from 75.1 km2 in 2001 to 114.0 km2 in 2019. Increasing eutrophication of the bay has had negative ecological consequences including algal blooms, hypoxic conditions, and mass mortality of marine biota, and it urgently requires remediation.

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