Feeding variability among individual aquatic predators in experimental channels

1993 ◽  
Vol 71 (10) ◽  
pp. 2033-2037 ◽  
Author(s):  
Roger S. Wotton ◽  
Mark S. Wipfli ◽  
Luke Watson ◽  
Richard W. Merritt

Experiments were conducted in experimental channels to study feeding variability through time and between conspecific individuals of four species of lotic predators. Large and small Rhyacophila dorsalis (Trichoptera: Rhyacophilidae) were given black fly larvae, mainly Simulium ornatum (Diptera: Simuliidae) of two size classes during laboratory feeding trials lasting up to 5 days. Acroneuria lycorias (Plecoptera: Perlidae) were also given black fly larvae (Prosimulium fuscum, S. venustum) during 11-day laboratory feeding trials. Paragnetina media (Perlidae) and Isoperla signata (Plecoptera: Perlodidae), were supplied with a mixed prey assemblage of black fly larvae and mayfly nymphs, Baetis flavistriga (Ephemeroptera: Baetidae), and Epeorus vitrea (Heptageniidae), for 9 days in field experiments. There was significant variability in the consumption of prey among individuals of R. dorsalis, this being true for both large and small predators. Significant among-predator and day-to-day feeding variability also occured with A. lycorias, P. media, and I. signata. Our experiments showed that there are significant differences in prey consumption among individual predators within a given species, and these differences need to be considered when planning, and interpreting, future studies on predator – prey interactions, particularly those conducted in experimental streams.

2003 ◽  
Vol 22 (7) ◽  
pp. 1582-1588 ◽  
Author(s):  
Jay P. Overmyer ◽  
Kevin L. Armbrust ◽  
Ray Noblet
Keyword(s):  

ZOOTEC ◽  
2019 ◽  
Vol 39 (2) ◽  
pp. 477
Author(s):  
Yasmira Wenda ◽  
H.J. Manangkot ◽  
J.L.P. Saerang ◽  
Cherlie L. K. Sarajar

QUAIL (Coturnix-Coturnix Japonica) GROWER PERFORMANCE SUPPLIED WITH MANURE FLOUR DEGRADED BY BLACK FLY LARVAE (H.ILLUCENS L.) TO REPLACE FISH MEAL. This study aims to determine the manure yield of black fly larvae replacing fish meal in the quail feed of the grower phase. The materials used in this study were 100 unsexed quails, 3 weeks old; the dimension of cage was 40 x 40 x 20 cm. The quails were arranged randomly in each unit. The study was realized by using a completely randomized design (CRD) with 4 treatments and 5 replications. The treatments were R0 = 0% degraded manure flour (MHD); R1 = 4% MHD flour; R2 = 8% MHD flour; R3 = 12% MHD flour. The research variables consisted of ration consumption, body weight gain and feed efficiency. The results obtained showed that treatments provide a very significant influence (P <0.01) on ration consumption. Body weight gain and feed efficiency were not significant different (P> 0.05). The conclusion of this study is that MHD flour up to the 12% level can be used in quail rations replacing fish meal. Keywords: Quail, MHD, Fish meal.


1958 ◽  
Vol 36 (6) ◽  
pp. 863-867 ◽  
Author(s):  
L. S. Wolfe ◽  
D. G. Peterson
Keyword(s):  

A new method of estimating the levels of infestation of black-fly larvae in streams is described. Hollow, metal cones, 20 cm high, 10 cm in diameter at the base, and painted white, were placed in infested streams. The cones were held in position with a wire attached to the apexes and fastened to an object in the stream or on the bank. The larvae attached to the cones in preference to stones or vegetation. Counts of those attached gave estimates of the levels of infestation in the streams, the periods when greatest numbers of larvae were moving downstream, and the fluctuations in number of larvae during the summer.


2009 ◽  
Vol 66 (3) ◽  
pp. 566-572 ◽  
Author(s):  
Matt K. Broadhurst ◽  
Russell B. Millar

Abstract Broadhurst, M. K., and Millar, R. B. 2009. Square-mesh codend circumference and selectivity. – ICES Journal of Marine Science, 66: 566–572. Despite the wide-scale assessment and the use of square-mesh codends in demersal trawls, relatively few studies have tested the effects of configurations other than mesh size on their selectivity. We investigated the consequences of increasing the circumference of square-mesh codends used in an Australian penaeid fishery from the expected optimal configuration of ∼33% of maximum diamond-mesh extension to ∼56 and 75%. Three square-mesh designs comprised 27-mm polyamide mesh throughout and had the same length (100 bars, B), but different circumferences (90, 150, and 200 B, respectively). Paired simultaneous comparisons (using twin trawls) of each treatment codend against a small-meshed control revealed significant effects of circumference on the efficiency of the trawl for a small teleost (pink-breasted siphonfish, Siphamia roseigaster) and commercial size classes of school prawns (Metapenaeus macleayi). Compared with the 90 codend, pink-breasted siphonfish catches and prawn count (numbers per 500 g) were both significantly greater in the codends of larger circumference, and these effects are attributed to concomitant (i) convoluted or reduced lateral openings of meshes and (ii) lesser probabilities of organisms encountering meshes in the posterior section. These differences would not preclude the use of codends of larger circumference in the fishery, but they do highlight the need to select appropriate configurations in future studies to reduce the potential for including the confounding effects of different geometries.


2015 ◽  
Vol 36 (4) ◽  
pp. 401-409
Author(s):  
William E. Cooper ◽  
Wade C. Sherbrooke

As an immobile prey monitors an approaching predator, the predator may move at a constant speed directly toward the prey or on a path that bypasses the prey. These scenarios have been studied extensively. Economic escape theory successfully predicts flight initiation distance (FID = predator-prey distance when escape begins). However, predators often alter their speed and may exhibit stops and starts during approaches. Empirical studies have shown that prey rapidly adjust assessed risk to a predator’s changes in approach speed and direction, but effects of interrupted (stop-start) approach are unknown. Because a prey is likely to assess that a nearby predator that resumes approaching has detected it and is attacking, escape theory predicts that assessed risk is greater at a given predator-prey distance when approach resumes than is continuous. Therefore, we predicted that FID is longer when a predator approaches, stops nearby, and renews its approach than when it approaches continuously. Second, although assessed risk increases as duration of the predator’s stop nearby increases, as indicated by latency to flee, we predicted that pause duration does not affect FID because prey interpret resumed approach as attack. Field experiments with two lizards, Sceloporus virgatus and Callisaurus draconoides, verified the predictions: FID was longer for discontinuous than continuous approaches and pause duration did not affect FID. We also observed distance fled and probability of entering refuge, escape behaviors for which theory is undeveloped. Distance fled was unrelated to continuity of approach in both species, as was refuge entry in S. virgatus.


1981 ◽  
Vol 113 (4) ◽  
pp. 281-293 ◽  
Author(s):  
R. J. Sebastien ◽  
W. L. Lockhart

AbstractTwo formulations of methoxychlor were compared with regard to toxicity and availability to aquatic organisms. A particulate formulation was less toxic than an emulsifiable formulation to chironomid larvae, stonefly nymphs, and fish. Similarly the particulate methoxychlor was less rapidly accumulated from water by those same animals than was the emulsified methoxychlor. With black fly larvae, the only filter-feeding animal used, the two formulations were about equal in toxicity, but the particulate formulation was accumulated more readily than emulsified material. Both formulations induced larvae to detach from substrate but emulsifiable methoxychlor acted more quickly. At the time of detachment, larvae exposed to the particulate formulation contained an average of 68 times more methoxychlor than larvae exposed to the emulsion.


1956 ◽  
Vol 7 (3-4) ◽  
pp. 163-168
Author(s):  
Yukio Yoshida ◽  
Yasuo Nakanishi

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