Presence Of Refuge Research Articles

Effect of seasonality on a nutrient–plankton system with toxicity in the presence of refuge and additional food

Effect of seasonality on a nutrient–plankton system with toxicity in the presence of refuge and additional food

Time-delayed predator–prey interaction with the benefit of antipredation response in presence of refuge

Abstract A field experiment on terrestrial vertebrates observes that direct predation on predator–prey interaction can not only affect the population dynamics but the indirect effect of predator’s fear (felt by prey) through chemical and/or vocal cues may also reduce the reproduction of prey and change their life history. In this work, we have described a predator–prey model with Holling type II functional response incorporating prey refuge. Irrespective of being considering either a constant number of prey being refuged or a proportion of the prey population being refuged, a different growth rate and different carrying capacity for the prey population in the refuge area are considered. The total prey population is divided into two subclasses: (i) prey x in the refuge area and (ii) prey y in the predatory area. We have taken the migration of the prey population from refuge area to predatory area. Also, we have considered a benefit from the antipredation response of the prey population y in presence of cost of fear. Feasible equilibrium points of the proposed system are derived, and the dynamical behavior of the system around equilibria is investigated. Birth rate of prey in predatory region has been regarded as bifurcation parameter to examine the occurrence of Hopf bifurcation in the neighborhood of the interior equilibrium point. Moreover, the conditions for occurrence of transcritical bifurcations have been determined. Further, we have incorporated discrete-type gestational delay on the system to make it more realistic. The dynamical behavior of the delayed system is analyzed. Finally, some numerical simulations are given to verify the analytical results.

Stability of a certain class of a host–parasitoid models with a spatial refuge effect

A certain class of a host–parasitoid models, where some host are completely free from parasitism within a spatial refuge is studied. In this paper, we assume that a constant portion of host population may find a refuge and be safe from attack by parasitoids. We investigate the effect of the presence of refuge on the local stability and bifurcation of models. We give the reduction to the normal form and computation of the coefficients of the Neimark–Sacker bifurcation and the asymptotic approximation of the invariant curve. Then we apply theory to the three well-known host–parasitoid models, but now with refuge effect. In one of these models Chenciner bifurcation occurs. By using package Mathematica, we plot bifurcation diagrams, trajectories and the regions of stability and instability for each of these models.

Stability of a predator–prey model with refuge effect

We consider a predator–prey model, where some prey are completely free from predation within a temporal or spacial refuge. The most common type of spacial refuge, that we investigate here, takes the form where a constant proportion of the prey population is protected. The model is a modification of the classical Nicholson–Bailey host-parasitoid model. In this paper, we study the effect of the presence of refuge on the stability and bifurcation of the system. Moreover, we provide a detailed analysis of the Neimark–Sacker bifurcation of the model.

Effect of habitat complexity on the predation ofBuenoa fuscipennis(Heteroptera: Notonectidae) on mosquito immature stages and alternative prey

Notonectids are well-known predators in aquatic habitats, where mosquito larvae, chironomids, and cladocerans constitute their main diet. Our purpose was to assess the effect of structural complexity on the predatory ability of Buenoa fuscipennis, a common predator in aquatic habitats of Buenos Aires city (Argentina). Buenoa fuscipennis showed type 2 functional responses in both the presence and absence of prey refuge and no differences in attack rate or handling time between refuge treatments. Regarding mosquito size classes, B. fuscipennis exhibited a significantly higher preference for 2(nd) instar larvae and no predation on pupae. In the presence of mosquito larvae and alternative prey, B. fuscipennis preferred mosquitoes over chironomid larvae and adult cladocerans over mosquito larvae. No switching behavior was detected in our experiments. Habitat structure only slightly affected the predator´s consumption rates on mosquito larvae. Overall, preference for prey did not vary with the presence of refuge, except for the preference for mosquitoes over chironomid larvae, which was significantly decreased in the presence of refuge as a consequence of reduced predation on mosquito larvae. The results suggest that B. fuscipennis could efficiently control mosquitoes in structurally simple habitats where chironomids are the most abundant alternative prey but not in temporary pools where cladocerans are abundant.

The Effect of Refuge on Dermestes ater (Coleoptera: Dermestidae) Predation on Musca domestica (Diptera: Muscidae): Refuge for Prey or the Predator?

It is believed that habitat heterogeneity can change the extent of predator-prey interactions. Therefore, in this study we examined the effect of habitat heterogeneity (characterized here as an addition of refuge) on D. ater predation on M. domestica. Predation of D. ater on M. domestica larvae was carried out in experimental habitats with and without refuge, and examined at different prey densities. The number of prey eaten by beetles over 24 h of predator-prey interaction was recorded, and we investigated the strength of interaction between prey and predator in both experimental habitats by determining predator functional response. The mean number of prey eaten by beetles in the presence of refuge was significantly higher than in the absence of refuge. Females had greater weight gains than males. Logistic regression analyses revealed the type II functional response for both experimental habitats, even though data did not fit well into the random predator model. Results suggest that the addition of refuge in fact enhanced predation, as prey consumption increased in the presence of refuge. Predators kept in the presence of refuge also consumed more prey at high prey densities. Thus, we concluded that the addition of refuge was an important component mediating D. ater-M. domestica population interactions. Refuge actually acted as a refuge for predators from prey, since prey behaviors detrimental to predators were reduced in this case.

Size‐related and diel variations in microhabitat use of three endangered small fishes in a Mediterranean coastal stream

This study analysed the microhabitat use of three endangered fish species, Andalusian toothcarp Aphanius baeticus, Iberian loach Cobitis paludica and sand smelt Atherina boyeri, in a coastal stream stretch. Plastic minnow traps were set both during daytime and at night on the bottom and at the surface. Depth and presence of effective refuge were recorded for each trap. To assess size‐related changes in microhabitat use individuals of each species were classified in three size classes. The three species preferentially used bottom positions in the water column, though this behaviour was more evident in the case of Iberian loach. While large Iberian loach remained active at night Andalusian toothcarp and sand smelt were strongly diurnal, especially larger individuals. The three species showed a clear ontogenetic change in microhabitat preferences towards deeper waters. Small Andalusian toothcarp and medium‐sized Iberian loach used deeper microhabitat in the presence of refuge. Large Andalusian toothcarp consistently preferred exposed microhabitat at any time. Andalusian toothcarp using refuge were smaller at any time, while Iberian loach followed this pattern only at night. The differential vulnerability of these species to different predators (aerial and aquatic; diurnal and nocturnal) could explain the observed patterns in microhabitat use. Fish tended to co‐occur in microhabitats either due to habitat characteristics independently of species or due to species independently of habitat. Andalusian toothcarp segregated spatio‐temporally from sand smelt and Iberian loach, but these species occurred independently of each other. According to these co‐occurrence patterns, Andalusian toothcarp would be more sensitive than Iberian loach or sand smelt to interspecific interactions.

Consequences of refuge for the functional response ofDermestes ater(Coleoptera: Dermestidae) toMusca domestica(Diptera: Muscidae)

AbstractIt is well known that a predator has the potential to regulate a prey population only if the predator responds to increases in prey density and inflicts greater mortality rates. Predators may cause such density‐dependent mortality depending on the nature of the functional and numerical responses. Yet, few studies have examined the relationship between the addition of refuges and the characteristic of functional response fits. We investigated whether addition of a refuge changed the type of functional response exhibited byDermestes ateronMusca domestica, comparing the inherent ability ofD. aterto kill houseflies in the absence and in the presence of refuge. An additional laboratory experiment was also carried out to assess handling and searching times exhibited byD. ater. Logistic regression analyses revealed a type III functional response for predator–prey interaction without refuge, and results were described by the random predator equation. The mean number of prey killed did not differ between experimental habitats, indicating that the addition of refuge did not inhibit predation. However, predators that interacted with prey without refuge spent less time searching for prey at higher densities, increasing predatory interaction. We concluded that this interaction may be weak, because data from experiments with refuge fitted poorly to models. However, the high variability and the nonsignificance of the data from the experiment with refuge show the importance of refuge for promoting spatial heterogeneity, which may prevent prey extinction.

Some Factors Regulating Piscivory of Brook Trout,Salvelinus fontinalis, in Lakes of the Laurentian Shield

A survey of 13 lakes containing brook trout, Salvelinus fontinalis, and northern redbelly dace, Phoxinus eos, five lakes containing trout and creek chub, Semotilus atromaculatus, and six lakes containing trout, dace, and chub indicated that prey-fish could represent up to 30% of trout diet by weight. We observed that trout preyed almost exclusively on dace, predation increased with trout size, predation on dace was significantly higher in the Salvelinus-Phoxinus-Semotilus association than in the Salvelinus-Phoxinus association even though trout were significantly smaller in the former than in the latter association, and predation in the Salvelinus-Phoxinus-Semotilus association was higher in two lakes and nearly always absent in the other four. Laboratory experiments indicated that small trout (150–250 mm total length (TL)) preferred small prey-fish (40–60 mm TL), large trout (250–380 mm TL) showed no significant preference with regard to the size of prey-fish (up to 170 mm TL), trout of both size classes preferred dace when dace and chub were present, presence of refuge (Cassandra calyculata) for prey-fish significantly reduced the number of attacks and captures upon dace, and large trout switched from an active to a sit-and-wait foraging pattern when a prey refuge was present.

Density and Dispersion in Laboratory Populations of Caddisfly Larvae (Cheumatopsyche, Hydropsychidae)

In nature and the laboratory, caddisfly larvae of the genus Cheumatopsyche display aggressive behavior and spacing. It was proposed that their dispersal and subsequent patterns of dispersion would be directly related to density. In experiments at varying densities, in bowls with and without a central refuge of pebbles suitable for case construction, larvae dispersed uniformly in the absence of refuge. When numbers were high, aggressive encounters enforced spacing. In the presence of refuge, they aggregated in the clump of pebbles at all densities. When the refuge was filled to capacity, the excess larvae were forced into the periphery.