Effects of prey concentration, prey size, predator life stage, predator starvation, and season on predation rates of the carnivorous copepod Euchaeta elongata

1983 ◽  
Vol 75 (1) ◽  
pp. 69-77 ◽  
Author(s):  
J. Yen
Keyword(s):  
Prey Size ◽  
Life Stage ◽  
Prey Concentration ◽  
Euchaeta Elongata ◽  
Predation Rates

scholarly journals Predator–prey interactions between native brine shrimp Artemia parthenogenetica and the alien boatman Trichocorixa verticalis: influence of salinity, predator sex, and size, abundance and parasitic status of prey

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3554 ◽  
Author(s):  
Vanessa Céspedes ◽  
Marta I. Sánchez ◽  
Andy J. Green
Keyword(s):  
Brine Shrimp ◽  
Life Stage ◽  
Predation Rate ◽  
Salt Ponds ◽  
Predator Prey ◽  
Caribbean Islands ◽  
Artemia Parthenogenetica ◽  
Introduced Range ◽  
Cladoceran Zooplankton ◽  
Predation Rates

Trichocorixa verticalis (T. verticalis), native to North America and the Caribbean islands, is an invasive waterboatman species (Corixidae) in the southwest of the Iberian Peninsula. Previous studies in the native range have suggested that predation by T. verticalis can regulate the abundance of Anostracan and Cladoceran zooplankton in saline ecosystems, causing increases in phytoplankton through a trophic cascade. In this experimental study, we tested the predator–prey relationship between the native brine shrimp Artemia parthenogenetica, and T. verticalis from the Odiel salt ponds in SW Spain. In three experiments, we investigated (1) the effects of Artemia life stage (metanauplii, juveniles, and adults), (2) abundance (three, six, and 12 adult Artemia) and (3) parasitic status (Artemia infected with avian cestodes or uninfected) on predation rates by T. verticalis. We also considered how predation rates in all three experiments were influenced by the sex of T. verticalis and by different salinities (25 and 55 g l−1). Experiment 1 showed that predation rates were highest for metanauplii, possibly because their photophilic behavior makes them more prone to predation. In Experiment 2, we found that predation rate was higher for female T. verticalis and the higher salinity, although the strength of the sex effect varied between treatments. Experiment 3 showed that T. verticalis selectively predated adult Artemia infected with cestodes (red in color), as previously reported for predation by avian final hosts. Collectively, these results indicate that T. verticalis are important predators in their introduced range, and are likely to reduce the abundance of Artemia in more salt ponds as they expand their range, thus increasing phytoplankton abundance through trophic cascades.

Predator–prey relationships and predation rates for crustacean zooplankters from some lakes in western Canada

1970 ◽  
Vol 48 (6) ◽  
pp. 1229-1240 ◽  
Author(s):  
R. Stewart Anderson
Keyword(s):  
Prey Species ◽  
Prey Size ◽  
Relative Size ◽  
Experimental Studies ◽  
The Other ◽  
Western Canada ◽  
Potential Predator ◽  
Predator Prey ◽  
Predation Rates

Experimental studies on Diaptoimus shoshone, D. arcticus, D. nevadensis, Cyclops bicuspidatus thomasi, C. vernalis, and Branckinecta gigas show that these predatory species can capture and eat many prey species of various sizes. B. gigas probably combines raptorial with filter feeding and can eat 150 or more smaller crustaceans per day. Adult D. shoshone, D. arcticus, and D. nevadensis eat up to 12 or more cyclopoids or diaptomids per day. Rotifers are also preferred prey. Predation rates are inversely proportional to prey size. Cannibalism probably causes the uniformity in body size and instar of predaceous diaptomids in some populations, C. vernalis and C. b. thomasi can eat six or more prey animals daily, depending on the size of the prey. Predaceous diaptomids and cyclopoids will eat the same prey species at rates which are influenced more by hunger than by abundance of prey. Furthermore, each species is a potential predator on the other, where the role of predator or prey is determined by the relative size or instar of the two groups. Hence, codominance of the zooplankton by predaceous diaptomid and cyclopoid species is unlikely.

Threespine stickleback aggregations create a potential predation refuge for sockeye salmon fry

1992 ◽  
Vol 70 (5) ◽  
pp. 1052-1056 ◽  
Author(s):  
Gregory T. Ruggerone
Keyword(s):  
Sockeye Salmon ◽  
Gasterosteus Aculeatus ◽  
Coho Salmon ◽  
Prey Size ◽  
Threespine Stickleback ◽  
Salmon Fry ◽  
Threespine Sticklebacks ◽  
Series Of Experiments ◽  
Predation Rates ◽  
Predation Refuge

Coho salmon (Oncorhynchus kisutch) frequently consume sockeye salmon (Oncorhynchus nerka) fry in Chignik Lake, Alaska, but have never been observed to consume threespine sticklebacks (Gasterosteus aculeatus), which are often closely associated with sockeye fry. Because coho salmon are visual predators and appear to avoid sticklebacks, a series of experiments was conducted in net pens to determine whether juvenile sockeye associated with threespine sticklebacks experienced less prédation than sockeye without sticklebacks and whether prey size affected prédation rates. Significantly fewer sockeye fry by coho were consumed in the pen containing 60 sticklebacks [Formula: see text] than in the 30-stickleback (4.7 fry/day) and 0-stickleback (4.4 fry/day) pens. An identical experiment with large, yearling sockeye (rather than sticklebacks) did not reveal a significant effect (p = 0.28), although there was a tendency for fewer large fry to be consumed when yearlings were abundant. A third experiment demonstrated predation rates on fry that were 45% lower in the presence of sticklebacks (1.2 fry/day) than in the presence of yearling sockeye (2.2 fry/day). Large sockeye fry (37–44 mm) consumed by coho declined steadily from about 36 to 29 to 22% of the total number of fry eaten as the number of sticklebacks or yearling sockeye increased from 0 to 30 to 60, respectively. These data suggest that the presence of threespine sticklebacks may reduce predation by coho on juvenile sockeye, especially those sockeye similar in size to sticklebacks.

scholarly journals The effectiveness of eyespots and masquerade in protecting artificial prey across ontogenetic and seasonal shifts

2021 ◽  
Author(s):  
Elizabeth G Postema
Keyword(s):  
Color Change ◽  
Prey Size ◽  
Life Stage ◽  
Background Color ◽  
Ontogenetic Changes ◽  
Avian Predators ◽  
Signal Environment ◽  
Different Color ◽  
Bird Feces ◽  
Seasonal Shifts

Abstract When constraints on antipredator coloration shift over the course of development, it can be advantageous for animals to adopt different color strategies for each life stage. Many caterpillars in the genus Papilio exhibit unique ontogenetic color sequences: e.g., early instars that masquerade as bird feces, with later instars possessing eyespots. I hypothesize that larvae abandon feces masquerade in lieu of eyespots due to ontogenetic changes in signaler size. This ontogenetic pattern also occurs within broader seasonal shifts in background color and predator activity. I conducted predation experiments with artificial prey to determine how potential signaling constraints (specifically size and season) shape predation risk, and consequently the expression of ontogenetic color change in Papilio larvae. Seasonally, both predation and background greenness declined significantly from July to September, though there was little evidence that these patterns impacted the effectiveness of either color strategy. Caterpillar size and color strongly affected the attack rate of avian predators: attacks increased with prey size regardless of color, and eyespotted prey were attacked more than masquerading prey overall. These results may reflect a key size-mediated tradeoff between conspicuousness and intimidation in eyespotted prey, and raise questions about how interwoven aspects of behavior and signal environment might maintain the prevalence of large, eyespotted larvae in nature.

Habitat fragmentation causes collapse of kelp recruitment

2020 ◽  
Vol 648 ◽  
pp. 111-123
Author(s):  
C Layton ◽  
MJ Cameron ◽  
M Tatsumi ◽  
V Shelamoff ◽  
JT Wright ◽  
...  
Keyword(s):  
Habitat Fragmentation ◽  
Patch Size ◽  
Life Stage ◽  
Extended Period ◽  
Anthropogenic Disturbances ◽  
Anthropogenic Sources ◽  
Kelp Forests ◽  
Natural Disturbances ◽  
Short Term ◽  
Turf Algae

Kelp forests in many regions are experiencing disturbance from anthropogenic sources such as ocean warming, pollution, and overgrazing. Unlike natural disturbances such as storms, anthropogenic disturbances often manifest as press perturbations that cause persistent alterations to the environment. One consequence is that some kelp forests are becoming increasingly sparse and fragmented. We manipulated patch size of the kelp Ecklonia radiata over 24 mo to simulate persistent habitat fragmentation and assessed how this influenced the demography of macro- and microscopic juvenile kelp within the patches. At the beginning of the experiment, patch formation resulted in short-term increases in E. radiata recruitment in patches <1 m2. However, recruitment collapsed in those same patches over the extended period, with no recruits observed after 15 mo. Experimental transplants of microscopic and macroscopic juvenile sporophytes into the patches failed to identify the life stage impacted by the reductions in patch size, indicating that the effects may be subtle and require extended periods to manifest, and/or that another life stage is responsible. Abiotic measurements within the patches indicated that kelp were less able to engineer the sub-canopy environment in smaller patches. In particular, reduced shading of the sub-canopy in smaller patches was associated with proliferation of sediments and turf algae, which potentially contributed to the collapse of recruitment. We demonstrate the consequences of short- and longer-term degradation of E. radiata habitats and conclude that habitat fragmentation can lead to severe disruptions to kelp demography.

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