Foraging by a young-of-the-year piscivore: the role of predator size, prey type, and density

2005 ◽  
Vol 62 (10) ◽  
pp. 2330-2342 ◽  
Author(s):  
Tracy L Galarowicz ◽  
David H Wahl
Keyword(s):  
Benthic Invertebrates ◽  
Prey Selection ◽  
Handling Time ◽  
Prey Type ◽  
Benthic Invertebrate ◽  
Ontogenetic Changes ◽  
Functional Responses ◽  
Fish Prey ◽  
Young Of The Year ◽  
Diet Shifts

Young-of-the-year piscivores undergo ontogenetic diet shifts, but mechanisms influencing prey selection and implications for growth are unclear. We examined foraging and growth of 20- to 150-mm walleye (Sander vitreus) fed either zooplankton, benthic invertebrates, or fish over a range of prey densities in the laboratory. The number of each prey type consumed was influenced by walleye size and prey density. Walleye exhibited type II functional responses on each prey type; attack coefficients were constant across zooplankton and fish densities but decreased with benthic invertebrate densities. Handling time estimates were greater for fish than for other prey types but similar for zooplankton and benthos. Foraging efficiencies on zooplankton and benthic invertebrates increased with walleye size but were variable for fish prey. The smallest walleye size class (20 mm) had similar energy return (J·min–1) and growth (g·day–1) on zooplankton, benthic invertebrates, and fish. For larger walleye, both energy return and growth were highest on fish, intermediate on benthic invertebrates, and lowest on zooplankton. Diet shifts of juvenile piscivores and, consequently, growth can be explained by ontogenetic changes in foraging abilities and prey densities.

The influence of prey availability on ontogenetic diet shifts of a juvenile piscivore

2006 ◽  
Vol 63 (8) ◽  
pp. 1722-1733 ◽  
Author(s):  
Tracy L Galarowicz ◽  
Julie A Adams ◽  
David H Wahl
Keyword(s):  
Benthic Invertebrates ◽  
Prey Availability ◽  
Juvenile Fish ◽  
Prey Type ◽  
Ontogenetic Changes ◽  
Foraging Patterns ◽  
Feeding Experiments ◽  
Ontogenetic Diet Shifts ◽  
Predator Foraging ◽  
Diet Shifts

Young-of-year piscivores typically undergo ontogenetic diet shifts from planktivory to benthivory to piscivory. These shifts are often the result of changes in predator foraging abilities, but little is known about the influence of relative prey availability. As a result, we examined diet shifts across a range of sizes (20–150 mm) of a young-of-year piscivore, walleye (Sander vitreus), in feeding experiments in which zooplankton, benthic invertebrates, and fish were made available at different density combinations. Consumption of each prey type changed with walleye size and prey densities. Small juveniles (20 mm) selected zooplankton and fish, whereas larger walleye (40–100 mm) selected benthic invertebrates and fish. Relative prey densities influenced consumption; increased densities of more profitable prey types resulted in reduced consumption of less profitable prey. Walleye larger than 100 mm selected only fish. Foraging efficiencies also varied with size and prey types; small walleye (20 mm) were less likely to pursue benthic invertebrates and retain captured fish. These ontogenetic changes in foraging patterns are linked to prey profitability, have growth consequences for juvenile walleye, and have implications for understanding diet shifts of other juvenile fish.

Use of Functional Response Modeling to Evaluate the Effect of Temperature on Predation of Amblyseius swirskii (Acari: Phytoseiidae) Adults Preying on Tetranychus urticae (Acari: Tetranychidae) Nymphs

2021 ◽  
Author(s):  
Azadeh Farazmand ◽  
Masood Amir-Maafi
Keyword(s):  
Functional Response ◽  
Tetranychus Urticae ◽  
Attack Rate ◽  
Handling Time ◽  
Effect Of Temperature ◽  
Coefficient Of Determination ◽  
Temperature Threshold ◽  
Amblyseius Swirskii ◽  
Functional Responses ◽  
Wide Range

Abstract In this research, functional responses of Amblyseius swirskii Athias-Henriot preying on different Tetranychus urticae Koch nymphal densities (2, 4, 8, 16, 32, 64, and 128) were studied at eight constant temperatures (15, 20, 25, 27.5, 30, 32.5, 35 and 37.5°C) in a circular Petri dish (3-cm diameter × 1-cm height) under lab conditions. At all temperatures, the logistic regression showed a type II functional response. A nonlinear relationship was found between temperature and attack rate and the reciprocal of handling time. The reciprocal of handling time decreased exponentially with increasing temperature. In contrast, the attack rate grew rapidly with increasing temperatures up to an optimum, showing a decreasing trend at higher temperatures. In order to quantify the functional response of A. swirskii over a broad range of temperatures and to gain a better estimation of attack rate and handling time, a temperature-settled functional response equation was suited to our data. Our model showed that the number of prey consumed increased with rising prey density. Also, the predation rates increased with increasing temperatures but decreased at extremely high temperatures. Based on our model, the predation rate begins at the lower temperature threshold (11.73°C) and reaches its peak at upper temperature threshold (29.43°C). The coefficient of determination (R2) of the random predator model was 0.99 for all temperatures. The capability of A. swirskii to search and consume T. urticae over a wide range of temperatures makes it a good agent for natural control of T. urticae in greenhouses.

THE STRUCTURAL AND FUNCTIONAL CHARACTERISTIC OF MACROZOOBENTHOS OF LAKE ZAKITNE

2021 ◽  
pp. 7-14
Author(s):  
Alexenko T. ◽  
Shevchenko I.
Keyword(s):  
Energy Balance ◽  
Benthic Invertebrates ◽  
Trophic Structure ◽  
Functional Characteristic ◽  
Benthic Invertebrate ◽  
Taxonomic Structure ◽  
Total Production ◽  
Food Ration ◽  
Structural And Functional Properties ◽  
Glyptotendipes Glaucus

For the first time, systematic studies of the structural and functional properties of macrozoobenthos of Lake Zakіtne were conducted. A taxonomic list of macroinvertebrates with their zoogeographical characteristics is given. According to the results of research, 3 types of benthic invertebrate groups were identified and described, of which Oligochaeta-Chironomidae type were the most widespread. Only two species were common to all found groups: Einfeldia longipes and Glyptotendipes glaucus of Chiromonidae family. The calculated biotic indices indicate a fairly high degree of use of existing biotopes by macroinvertebrates, as well as the predominance of species characteristic of the α-β-mesosaprobic zone.The variety of ways and mechanisms of feeding of benthic invertebrates is shown. Collectors, scraper collectors, sedimentators, filter feeders, shredders, predators, as well as macroinvertebrates with an indeterminate feeding type were identified in the trophic structure by the predominant type of feeding. The number of species, as well as their representation in trophic groups, varied in different years, yet 54-73% of them were nonpredatory forms.According to the obtained data, the components of the energy balance for macroinvertebrates were calculated. The active participation in the production of organic matter of Chironomidae larvae (from 29 to 62% of the total production of nonpredatory and predatory forms) is indicated. In some years, Ephemeroptera and Mollusca were actively involved in production. The largest flow of energy passed through insects (Ephemeroptera, Trichoptera) and leeches. Attention is drawn to the role of predators, which can significantly reduce the production of groups. High production and food ration of predators do not allow to ignore them when calculating the production of the entire zoocenosis.In average, during the vegetation season, the total production of nonpredatory and predatory benthic invertebrates was 77,89 kJ/m2, and the predator's food ration was 61,80 kJ/m2.Key words:macroinvertebrates, taxonomic structure, trophic structure, community, production, food ration, energy balance. Вперше проведено систематичні дослідження структурно-функціональних властивостей макрозообентосу озера Закітне. Наведено таксономічний список макробезхребетних з їх зоогеографічною характеристикою. За результатами досліджень виявлено та описано 3 типи угруповань донних безхребетних, з яких найбільшепоширення отримали олігохетно-хірономідні комплекси. Лише двавиди виявилися спільними для всіх знайдених угруповань: Einfeldia longipes і Glyptotendipes glaucus (родина Chironomidae).Розраховані біотичні індекси свідчать про достатньо високий ступень використання існуючих біотопів макробезхребетними, а також про переважання видів, що характерні для α-β-мезосапробної зони.Показанарізноманітність способів і механізмів живлення донних безхребетних. У трофічній структурі угруповань за переважаючим способомживлення було виділено збирачів, збирачів-шкребачів, седиментаторів, фільтраторів, подрібнювачів, хижаків, а також макробезхребетних із невизначеним типом живлення. Кількість видів, а також їх представленість утрофічних групах в різні роки була неоднакова, але на 54–73% це були мирні форми.За отриманими даними було розраховано складові енергетичного балансу за макробезхребетними. Вказано на активну участь упродукуванні органічної речовини личинок родини Chironomidae, яким належить від 29 до 62% від сумарної продукції мирних і хижих форм. В окремі роки в продукування активно включалися одноденки та молюски. Найбільший потік енергії проходив через комах (Ephemeroptera, Trichoptera) і п’явок. Звернуто увагу на роль хижаків, які можуть суттєво знижувати продукцію угруповань. Високапродукція і раціон хижаків не дозволяють нехтувати ними при розрахунку продукції всього ценозу.Підраховано, що в середньому за вегетаційний період сумарна продукція мирних і хижих донних безхребетних дорівнювала 77,89 кДж/м2, а раціон хижаків складав 61,80 кДж/м2.Ключові слова: макробезхребетні, таксономічна структура, трофічна структура, угруповання, продукція, раціон, енергетичний баланс.

Larval sand lance (Ammodytes sp.) in the diet of small juvenile wolffish (Anarhichas spp.): predatory interactions in frontal water masses off western Greenland

2002 ◽  
Vol 59 (11) ◽  
pp. 1759-1767 ◽  
Author(s):  
Peter Munk
Keyword(s):  
Fish Larvae ◽  
Stomach Contents ◽  
Prey Type ◽  
Ontogenetic Changes ◽  
Sand Lance ◽  
Larval Size ◽  
Predatory Behaviour ◽  
Dietary Shift ◽  
Abundance Estimates ◽  
Anarhichas Lupus

The predatory behaviour of two species of juvenile wolffish (Anarhichas lupus and Anarhichas minor) was studied during a field campaign across a frontal area off western Greenland. The study focused on ontogenetic changes in prey-type and -size preference of the wolffish and their predatory impact on a cohabiting population of larval sand lance (Ammodytes sp.). Sampling took place along a cross-shelf transect at latitude 66°20' N, and the analysis is based on stomach contents of assembled wolffish (2–5 cm in length) and abundance estimates of plankton and fish. An ontogenetic change in wolffish prey preference was evident as a dietary shift from copepods and smaller amphipods to larger amphipods and fish larvae. The inclusion of fish larvae in the wolffish diet led to a marked increase in prey biomass, and fish larvae constituted up to 77% of diet biomass in the largest juveniles caught. Wolffish selectively targeted the smaller-sized part of the larval sand lance population; hence, larval vulnerability increased with decreasing size. Comparison between estimated predation rates and abundances of predator and prey indicated larval predation mortalities of up to 5% per day, with mortality peaking in the vicinity of a hydrographic front. Hence, findings suggest substantial predation pressure on larvae, primarily related to larval size and distribution.

scholarly journals Feeding Ecology of Short-Toed Snake-Eagle (Circaetus gallicus [Gmelin, 1788]) in the Montados of Iberian Peninsula

2020 ◽  
Vol 28 (2) ◽  
pp. 155-179
Author(s):  
Nuno Onofre ◽  
Luís Sampaio
Keyword(s):  
Relative Abundance ◽  
Diet Composition ◽  
Prey Species ◽  
Prey Selection ◽  
Prey Type ◽  
Generalist Predator ◽  
Important Prey ◽  
Psammodromus Algirus ◽  
Circaetus Gallicus ◽  
Water Snakes

The diet of Short-toed Snake-eagle (Circaetus gallicus) during the breeding season in an area dominated by cork and holm oak parkland forests (Montados) was analyzed in this study. As expected, results showed that snakes are the dominant prey in the diet of this eagle, comprising up to 92.5% of the identified items, if potential secondary prey species were excluded. The Montpellier Snake (Malpolon monspessulanus) was the most consumed one (42.2%), followed by the Ladder Snake (Zamenis scalaris) (28.0%), and the water snakes (Natrix spp.) (14.2%). According to the same criteria, lizards (mainly Psammodromus algirus) and mammals represent between 4.8 and 2.2%, respectively. Other animals such as pond turtle and amphibians are irregular prey (<1%), and no bird remains were found at all. Short-toed Snake-eagle is usually referred as a stenophagic predator where snakes are by far its most important prey type, and where within this taxonomic group it behaves as a generalist predator. In this study this premise was then tested comparing the relative abundance of the snake species with their proportion in the diet composition of the eagle in order to know whether or not prey selection exists with regard to the species of snakes in this region. Results point to a quite plausible "preference" for the Ladder Snake and an "avoidance" for the smooth snakes group (Macroprotodon brevis/Coronella girondica), and possibly for the Horseshoe Whip (Hemorrhois hippocrepis). The avoidance to the Horseshoe Whip must be indirect and habitat related, while in relation to the two smooth snakes it may be due in large extend to its small size, in particular.

Effects of a native crayfish (Orconectes virilis) on the reproductive success and nesting behavior of sunfish (Lepomis spp.)

2004 ◽  
Vol 61 (11) ◽  
pp. 2135-2143 ◽  
Author(s):  
Nathan J Dorn ◽  
Gary G Mittelbach
Keyword(s):  
Reproductive Success ◽  
Lepomis Macrochirus ◽  
Lepomis Gibbosus ◽  
Orconectes Virilis ◽  
Negative Effects ◽  
Fish Prey ◽  
Natural Lakes ◽  
Successful Reproduction ◽  
Young Of The Year ◽  
Native Crayfish

While crayfish are traditionally considered fish prey, they are capable of feeding on substrate-bound fish eggs and their introductions have been blamed for the decline in fish populations in Europe and North America. To investigate their potential effects on fish reproductive success we measured the effects of a native crayfish (Orconectes virilis) on the reproductive success of two substrate-nesting sunfish, pumpkinseed (Lepomis gibbosus) and bluegill (Lepomis macrochirus), in replicated pond experiments. Crayfish were observed feeding on eggs in both experiments. Crayfish presence delayed successful reproduction by pumpkinseeds in densely vegetated ponds, resulting in lower young-of-the-year biomass in ponds with crayfish. In the second experiment, with bluegills in less-vegetated ponds, crayfish prevented successful reproduction entirely. However, when we added crayfish-proof exclosures to the crayfish ponds late in the summer, bluegills located the crayfish-free habitat and successfully reproduced inside the exclosures (1 month after first successful reproduction in control ponds). The results of these experiments demonstrate the potential strong negative effects of crayfish on sunfish reproduction and suggest that the spatial distribution of crayfish and other egg predators may influence fish nesting behaviors and habitat choices. Further studies are needed to determine the magnitude of crayfish effects in natural lakes and ponds where sunfish and crayfish co-occur.

scholarly journals Development of a foraging model framework to reliably estimate daily food consumption by young fishes

2017 ◽  
Vol 74 (10) ◽  
pp. 1668-1681 ◽  
Author(s):  
David Deslauriers ◽  
Alex J. Rosburg ◽  
Steven R. Chipps
Keyword(s):  
Water Temperature ◽  
Food Consumption ◽  
Prey Density ◽  
Handling Time ◽  
Prey Type ◽  
Daily Consumption ◽  
Model Framework ◽  
Fish Feeding ◽  
Daily Food Consumption ◽  
Daily Food

We developed a foraging model for young fishes that incorporates handling and digestion rate to estimate daily food consumption. Feeding trials were used to quantify functional feeding response, satiation, and gut evacuation rate. Once parameterized, the foraging model was then applied to evaluate effects of prey type, prey density, water temperature, and fish size on daily feeding rate by age-0 (19–70 mm) pallid sturgeon (Scaphirhynchus albus). Prey consumption was positively related to prey density (for fish >30 mm) and water temperature, but negatively related to prey size and the presence of sand substrate. Model evaluation results revealed good agreement between observed estimates of daily consumption and those predicted by the model (r2 = 0.95). Model simulations showed that fish feeding on Chironomidae or Ephemeroptera larvae were able to gain mass, whereas fish feeding solely on zooplankton lost mass under most conditions. By accounting for satiation and digestive processes in addition to handling time and prey density, the model provides realistic estimates of daily food consumption that can prove useful for evaluating rearing conditions for age-0 fishes.

Diel feeding and prey selection of three size classes of shortfinned eel (Anguilla australis) in New Zealand

1998 ◽  
Vol 49 (5) ◽  
pp. 421 ◽  
Author(s):  
P. M. Sagar ◽  
G. J. Glova
Keyword(s):  
New Zealand ◽  
Prey Selection ◽  
Microhabitat Use ◽  
Night Time ◽  
Fish Prey ◽  
Size Classes ◽  
Anguilla Australis ◽  
Selection Indices ◽  
Feeding Periodicity ◽  
Selection Of

Benthic macroinvertebrates and three size classes of shortfinned eel (Anguilla australis, Anguillidae) were sampled in a lowland New Zealand stream over a 24-h period in summer to investigate diel feeding periodicity and prey selection. Fish of all three size classes fed mostly from post-dusk to dawn, with larger fish tending to consume a greater proportion of their prey during night-time. The number of prey taxa consumed increased with increasing size of fish. Prey selection indices indicated that: (1) the smallest eels (80–100 mm total length, TL) preferentially consumed ostracods (Crustacea) and larvae of Chironomidae (Diptera) and Psilochorema sp. (free-living Trichoptera); (2) medium-sized eels (101–199 mm TL) preferred larvae of Chironomidae, and Costachorema sp., Hydrobiosis sp. and Psilochorema sp.; and (3) large eels (200–300 mm TL) preferred ostracods, Psilochorema sp. and Hudsonema amabilis (cased Trichoptera). Eels of all size classes showed selection for soft-bodied or easily broken prey over those with hard cases which would have been more difficult to digest. There was considerable overlap in the diets of medium and large eels. Differences in the timing of feeding between the three size classes of eel are explained in terms of microhabitat use; differences in diet are explained in terms of prey size, and are also related to eel size.

Acoustic basis for fish prey selection by echolocating odontocetes

2004 ◽  
Vol 116 (4) ◽  
pp. 2503-2504
Author(s):  
Whitlow W. L. Au ◽  
Kelly J. Benoit‐Bird ◽  
Ronald Kastelein ◽  
Sander van de Heul
Keyword(s):  
Prey Selection ◽  
Fish Prey

Hunting Behavior, Prey Selection, and Energetics of Snail Kites in Guyana: Consumer Choice by a Specialist

The Auk ◽  
1983 ◽  
Vol 100 (1) ◽  
pp. 84-92 ◽  
Author(s):  
Steven R. Beissinger
Keyword(s):  
Consumer Choice ◽  
Prey Selection ◽  
Activity Patterns ◽  
Caloric Intake ◽  
Handling Time ◽  
Time Of Day ◽  
Rice Fields ◽  
Hunting Behavior ◽  
Time Activity ◽  
Prey Handling

Abstract The hunting behavior, snail size selection, and time-activity patterns of non-breeding Snail Kites (Rostrhamus sociabilis sociabilis) were studied in Guyana rice fields. Kites spent 62% of the photoperiod perching, 19% foraging, 13% in maintenance activities, and 6% flying. As the day progressed, the percentage of daylight hours spent perching increased significantly, while foraging decreased significantly. Kites successfully captured and ingested Pomacea snails in 78% of the foraging bouts observed. The mode of hunting was evenly split between coursing (50.7%) and still-hunting (49.3%). Searching and returning times were related to time of day, as significantly more coursing hunts and still-hunts occurred in mornings and late afternoons, respectively. Prey handling time was the most time-consuming component of a foraging bout. Time spent searching for prey, returning, or handling prey was not related to snail size. The size distribution of captured snails differed significantly from that of available snails; kites selected more medium snails and fewer small snails and took large snails in equal frequency to that at which large snails were available. Kites captured the same-sized snails when coursing as when still-hunting. As rice grew, kite utilization of rice fields declined, and the frequency of still-hunting decreased while course-hunting attempts increased. The daily caloric intake of kites was estimated to be 104.2 kcal, the daily energy expenditure 85.7 kcal. Results are discussed in relation to consumer choices of specialists. The most important decision a foraging Snail Kite may make is what patch to search in and how long to search before abandoning patches.

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