Temporal variability in functional responses and prey selectivity of the pelagic mysid, Mysis mixta , in natural prey assemblages

2001 ◽  
Vol 138 (3) ◽  
pp. 575-583 ◽  
Author(s):  
M. Viherluoto ◽  
M. Viitasalo
Keyword(s):  
Temporal Variability ◽  
Prey Selectivity ◽  
Functional Responses ◽  
Natural Prey ◽  
Mysis Mixta

Prey selectivity of wolves in Banff National Park. I. Prey species

1993 ◽  
Vol 71 (1) ◽  
pp. 130-139 ◽  
Author(s):  
David J. Huggard
Keyword(s):  
National Park ◽  
Prey Type ◽  
Prey Selectivity ◽  
Functional Responses ◽  
Encounter Rates ◽  
Factors Affecting ◽  
Habitat Overlap ◽  
Banff National Park ◽  
Mountain Goats ◽  
Number Of Individuals

I examined the components generating selectivity in wolves preying on five ungulate species in Banff National Park, Alberta. Overall selectivity for elk and deer species, and apparent avoidance of bighorn sheep and mountain goats, were due primarily to lower habitat overlap of wolves with the latter two species, and therefore lower encounter rates. For social ungulates, I argue that the herd should be considered the unit of encounter, with encounter rates proportional to the number of herds rather than the number of individuals. However, large herds predictably associated with certain areas may be visited intentionally by wolves, increasing effective encounter rates. Foraging theory suggests that all ungulate prey should be equally profitable to wolves upon encounter and therefore the factors affecting encounter rates are critical in determining prey selectivity. A simple model incorporating different habitat overlap, herd sizes, and predictable herds predicts qualitatively different functional responses of wolves to changes in density of the different prey types. The model also demonstrates how apparent selectivity for a prey type can result from the different ways in which prey are encountered.

scholarly journals Ratio-dependent functional responses - tests with the zooplanktivore Mysis mixta

2001 ◽  
Vol 216 ◽  
pp. 181-189 ◽  
Author(s):  
S Hansson ◽  
BT De Stasio ◽  
E Gorokhova ◽  
MA Mohammadian
Keyword(s):  
Functional Responses ◽  
Mysis Mixta ◽  
Ratio Dependent

scholarly journals Predicting the ecological impacts of a new freshwater invader: functional responses and prey selectivity of the ‘killer shrimp’,Dikerogammarus villosus, compared to the nativeGammarus pulex

2013 ◽  
Vol 59 (2) ◽  
pp. 337-352 ◽  
Author(s):  
Jennifer A. Dodd ◽  
Jaimie T. A. Dick ◽  
Mhairi E. Alexander ◽  
Calum MacNeil ◽  
Alison M. Dunn ◽  
...  
Keyword(s):  
Ecological Impacts ◽  
Prey Selectivity ◽  
Functional Responses ◽  
Dikerogammarus Villosus

scholarly journals Determination of optimal prey for rearing tropical gar Atractosteus tropicus (Lepisosteiformes: Lepisosteidae)

2018 ◽  
Vol 66 (3) ◽  
pp. 1018
Author(s):  
Luis H. Escalera-Vázquez ◽  
Omar Domínguez-Domínguez ◽  
Eduardo Molina-Domínguez ◽  
S.S.S. Sarma ◽  
S. Nandini
Keyword(s):  
Functional Response ◽  
Fish Species ◽  
Prey Species ◽  
Prey Selection ◽  
Larval Feeding ◽  
Prey Selectivity ◽  
Functional Responses ◽  
Wide Range ◽  
Tropical Gar ◽  
Atractosteus Tropicus

Larval feeding studies of both ornamental and consumable fish species are important for formulating successful management, and culture strategies for conservation purposes. In the present study, we evaluated prey selectivity for the tropical gar Atractosteus tropicus in the larval stage (first 8 weeks) using the zooplankton Artemia fransiscana, Daphnia pulex and Moina macrocopa as prey following the hypothesis that prey selection of the fish species is related not only to prey species preferences but to the difference in prey densities present in the environment. Functional responses were tested at prey densities of 0.2, 0.5, 1.0, 2.0, 4.0 and 8.0 ind. mL-1 and analyzed using Manly’s α. For prey selectivity, we used the three zooplankton species at three different densities. In these two experiments the fish larvae were allowed to feed for 45 min. To quantify feeding behavior (encounters, attacks, captures, ingestions, rejections) we used a density of 1 ind. mL-1 using each prey species based on 10 minutes of direct observation. Our results showed a functional response Type II for A. tropicus preying mostly on A. franciscana and M. macrocopa. The Manly’s α index showed that M. macrocopa and A. franciscana are the most preys selected. The values for encounters for the three prey species were relatively constant during the eight weeks. Encounter values for the cladocerans were low in comparison to A. franciscana; however, high success in capture and ingestion was observed for all prey species used. Our results from the functional response experiments supports the hypothesis that A. tropicus is an active predator presenting a functional response of a carnivorous fish and the shift in prey selection suggests that even at low prey availability, A. tropicus is able to manipulate and feed on zooplankton of wide range in size. Also, according to our results, we suggest the use of a mix of A. franciscana and M. macrocopa to feed A. tropicus in culture systems in concentrations ≈ 2 ind. mL-1 during the first 3 weeks of age and then shift to M. macrocopa from the 4 week. Our results, in conjunction with studies on the survivorship of the juveniles would aid in conservation efforts and improve the production of gars in aquaculture.

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